Transcript NeSA- INQUIRY, THE NATURE OF SCIENCE, AND TECHNOLOGY

NeSA- INQUIRY, THE NATURE OF
SCIENCE, AND TECHNOLOGY
Abilities to do Scientific Inquiry
SC 12.1.1 Students will design and conduct
investigations that lead to the use of logic and
evidence in the formulation of scientific explanations
and models.
OBJECTIVE
•Formulate a testable hypothesis supported by prior knowledge to guide an investigation
A scientific hypothesis is a prediction which can be tested through
controlled experimentation. Scientists base their hypotheses on
observations, questions, previous knowledge (knowledge of
scientific literature) and interpretations (biases).
PRACTICE
1. Which of the following is/are commonly used to establish a
hypothesis?
a. scientific literature
b. observations
c. previous personal knowledge
d. all of these
2. A hypothesis must be both a prediction and be testable.
a. true
b. false
Standard-SC 12.1.1.a
2
ANSWERS & EXPLANATION
1. (d) all of the above
Scientists design hypotheses based on observations of events, previous knowledge they
have, knowledge that is contained in scientific literature and interpretations they have
regarding possible relationships they can predict. Hypothesis propose a logical outcomes of
events that occur through manipulating variables.
2. (a) true
In order for a hypothesis to be tested in a scientific experiment it must make a prediction
based on changes in independent variables and must be a statement that can be tested
through controlled experimentation.
Key Terms
hypothesis
a testable statement about the natural world that can be used to develop inferences and
explanations
Standard-SC 12.1.1.a
3
OBJECTIVE
•Design and conduct logical and sequential scientific investigations with repeated trials and
apply findings to new investigations
The scientific method is the process by which scientists conduct
controlled experiments. This form of scientific inquiry tests single
variables (independent variable) by measuring its affect on another
variable (dependent variable)
PRACTICE
1. The variable that is altered by the scientist in a controlled
experiment is identified as
a. independent
b. dependent
c. controlled
2. A controlled variable is
a. changed in each trial
c. held constant in each trial
Standard-SC 12.1.1.b
b. allowed to change in trials
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ANSWERS & EXPLANATION
1. (a) independent
A scientists purposefully alters ONE variable in an experiment in order to test changes in
another variable.
2. (c) held constant in each trial
Controlled variables are conditions in an experiment that should not affect the dependent
variable. These should be the same for all individual trials.
Key Terms
control group
a group of subjects, closely resembling the experimental group but not receiving the
factor under study, which serves as a comparison to the experimental group
experimental
group
a group of subjects which receive the factor under study
Standard-SC 12.1.1.b
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OBJECTIVE
•SC 12.1.1.c Identify and manage variables and constraints
Scientific investigations are designed to test one variables
(independent variable) influence on another variable (dependent
variable) while attempting to keep all other variables constant
(controlled variables).
PRACTICE
1. A study comparing the weight gain in mice due to the amount
of fat in their diet was conducted. What is the independent
variable?
a. amount of fat
b. weight gain
c. mass of food
2. In the same study above, what is the dependent variable?
a. amount of fat
b. weight gain
c. mass of food
Standard-SC 12.1.1.c
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ANSWERS & EXPLANATION
1. (a) amount of fat
The research was studying the amount of fat in the diet and how it affects the weight
gain in mice. The amount of fat in the diet was determined by the scientist and the
weight gain by the mice was an effect of fat changes. The amount of fat is the
independent variable because it is the variable that was purposefully changed.
2. (b) weight gain
The weight gain by the mice was analyzed by comparing it to the amount of fat in the
diets of the mice. The weight gain is considered dependent on amount of fat.
Standard-SC 12.1.1.c
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OBJECTIVE
•Select and use lab equipment and technology appropriately and accurately
In order to conduct sound scientific investigations scientists must
use appropriate equipment, data collecting instruments/devices
and analyze data using appropriate means. Much of the collecting
and analysis of data is done with technology.
PRACTICE
1. In order to test the acidity of a solution, a scientist would need a
a. balance
b. scale
c. pH meter
d. meter stick
2. What measure would a beaker or flask be able to provide?
a. mass
b. length
c. density
d. volume
Standard-SC 12.1.1.d
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ANSWERS & EXPLANATION
1. (c) a pH meter
pH meters measure the acidity of a solution based on the concentration of hydrogen ions
(H+) that exist in solution. The greater the concentration of hydrogen ions, the higher the
acidity and the lower on the pH scale it is. Acids have pH values which are less than 7 and
bases have pH values greater than 7
2. (d) volume
Beakers and flasks measure the volume of liquids (or gases) in the container.
Standard-SC 12.1.1.d
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OBJECTIVE
•Use tools and technology to make detailed qualitative and quantitative observations
During a scientific investigation scientists must be able to make
observations and measures which are free of bias. Two types of
observations are quantitative (numeric) and qualitative (a
description).
PRACTICE
1. An observation that describes the color of an objective would
be
a. qualitative b. quantitative
c. neither
2. A quantitative observation can be
a. a count
b. a measure
Standard-SC 12.1.1.e
c. both a & b
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ANSWERS & EXPLANATION
1. (a) qualitative
Qualitative observations describe the physical attributes of an object. Examples are color,
shape, texture, odor and taste.
2. (c) both a & b
Quantitative observations are numeric descriptions of an object. Two ways that numeric
observations can be made are counting objects or measuring objects. Measures can include
mass, volume, length, density, brightness, and area.
Standard-SC 12.1.1.e
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OBJECTIVE
•Represent and review collected data in a systematic, accurate, and objective manner
Scientists normally collect data from experiments and organize it
into tables where changes in the dependent variables are
recorded in relation to changes in the independent variable.
Student
finger length (cm)
finger circumference (cm)
Luke
8.1
8.0
Angelina
5.1
4.2
Marcie
4.2
4.5
Pham
7.2
6.3
Wendy
5.6
4.9
PRACTICE
1. Which student has the second longest finger?
a. Luke
b. Wendy
c. Pham
d. Marcie
2. Which student has the smallest length to circumference ratio?
a. Luke
b. Angelina
c. Wendy
d. Marcie
Standard-SC 12.1.1.f
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ANSWERS & EXPLANATION
1. (c) Pham
Luke has the longest finger (8.1 cm) and Pham has the second longest (7.2 cm)
2. (d) Marcie
Marcie has the lowest ratio of length to circumference. She is the only student who has a
finger which is shorter than the circumference. This puts her ratio lower than 1. All other
students have ratios greater than 1 because their lengths are greater than their
circumferences.
Standard-SC 12.1.1.f
Student
finger length (cm)
finger circumference (cm)
Luke
8.1
8.0
Angelina
5.1
4.2
Marcie
4.2
4.5
Pham
7.2
6.3
Wendy
5.6
4.9
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OBJECTIVE
•Analyze and interpret data, synthesize ideas, formulate and evaluate models, and clarify
concepts and explanations
Upon completing a scientific experiment and collecting non-biased
data, a scientist must analyze the data and represent the results in a
way that shows the relationship between the dependent and
independent variable. Graphs are usually used to represent these
relationships.
PRACTICE
1. Which region of the brain has the most receptor binding sites?
a. 1
b. 2
c. 3
d. 4
2. If region 1 is the outer most region and 4 is the inner most region, where are most receptor
binding sites found?
a. outer
b. inner
c. they are the same
Standard-SC 12.1.1.g
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ANSWERS & EXPLANATION
1. (b) 2
Brain region #2 has over 50 binding sites where the other three
regions have less than 40 binding sites.
2. (a) outer
The outer regions ( regions 1 & 2) have more receptors than the
inner regions (regions 3 & 4)
Key Terms
theory
a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws,
inferences, and tested hypotheses
Standard-SC 12.1.1.g
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OBJECTIVE
•Use results to verify or refute a hypothesis
A conclusion is a statement that uses the results from an
experiment to explain whether a hypothesis can be accepted,
refuted or needs modification.
PRACTICE
1. A conclusion has to be a statement which answers the validity
of a
a. hypothesis
b. result
c. data
d. observation
2. The conclusion should describe the relationship between the
dependent variable and the
a. controlled variable
b. dependent variable
c. independent variable
Standard-SC 12.1.1.h
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ANSWERS & EXPLANATION
1. (a) hypothesis
The conclusion needs to explain whether the data & results supported or did not
support the hypothesis.
2. (c) independent
Remember the hypothesis is a prediction of how a dependent variable will
change in relation to an independent variable. The conclusion should state if the
prediction was valid or not valid, based on what the results showed.
Standard-SC 12.1.1.h
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OBJECTIVE
•Propose and/or evaluate possible revisions and alternate explanations
A scientific discussion is the explanation following a conclusion which
describes the research, identifies possible errors within the research,
proposes possible changes in the procedure and compares the
conclusion to existing knowledge.
PRACTICE
1. A student predicted their dog would lose mass through the winter and spring. Did the
results support their hypothesis? How should they change their hypothesis?
Standard-SC 12.1.1.i
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ANSWERS & EXPLANATION
1. The student’s hypothesis did not match their results. They predicted the dog would lose
mass when it really gained mass. The results shows that the masses for each month
increases from January to February.
The student should reject the hypothesis and restate it saying that their dog increases
mass through the winter and spring.
Standard-SC 12.1.1.i
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OBJECTIVE
•Share information, procedures, results, conclusions, and defend findings to a scientific
community (peers, science fair audience, policy makers)
Scientists share the outcomes of research by publishing their findings
in journals which are designed to evaluate the work through peer
editing. It is this sharing that allows science to continually correct our
understanding of the world around us.
PRACTICE
1. Tabloids, twitter and facebook are great sources of scientific
research.
a. true
b. false
2. Why does scientific research need to be reviewed by the scientific
community?
Standard-SC 12.1.1.j
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ANSWERS & EXPLANATION
1. (b) false
Scientists commonly seek to publish their work in highly respected and peer-reviewed
sources, such as scientific journal like Science, Nature, Annual Review of Biochemistry &
Cell. These are highly ranked science journals.
2. The process of reviewing scientific research allows other scientists to evaluate each
others work. This is important so that incorrect work is not published and that science
continues to find better explanations.
Standard-SC 12.1.1.j
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OBJECTIVE
•Evaluate scientific investigations and offer revisions and new ideas as appropriate
The body of knowledge known as Science is a continually growing set
of facts, ideas and predictions which are evaluated by other scientists,
policy makers and other community individuals. This knowledge is
built on everyone’s ability to question results, conduct further
research and compare different ideas.
PRACTICE
1. Explain why it is important that scientists attend conferences,
discuss their work and collaborate with each other on
research projects.
Standard-SC 12.1.1.k
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ANSWERS & EXPLANATION
1. Scientific conferences are places where scientists who share a common interest or
research subject meet to discuss current research and newly found information. They
provide an opportunity for scientists to clarify their own research and develop new
research directions.
The October 1927 Fifth
Solvay International
Conference on
Electrons and Photons,
where the world's most
notable physicists met to
discuss the newly
formulated quantum
theory. The leading figures
were Albert Einstein
and Niels Bohr. Seventeen
of the twenty-nine
attendees were or
became Nobel
Prize winners, including
Marie Curie, who alone
among them, had won
Nobel Prizes in two
separate scientific
disciplines.
Standard-SC 12.1.1.k
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OBJECTIVE
•Use appropriate mathematics in all aspects of scientific inquiry
Mathematics is the process by which data is analyzed. Scientists use
mathematic principles to seek relationships between variables in an
experiment. Most graphs represent a mathematic model, outlining
these relationships.
PRACTICE
1. Which of the lines in the graph above has a greater slope?
a. red line
b. black line
Standard-SC 12.1.1.l
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ANSWERS & EXPLANATION
1. (a) red line
Data represented on a graph can be expressed as a mathematic equation. The slope of a
line shows the linear relationship between two variables. A more vertical line has a
greater slope and a more horizontal line has a less slope.
Standard-SC 12.1.1.l
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NeSA- Physical Science
Matter
SC 12.2.1 Students will investigate and describe matter
in terms of its structure, composition and conservation.
OBJECTIVE
•Recognize bonding occurs when outer electrons are transferred (ionic) or shared (covalent)
-Ionic bonds are formed between metals and nonmetals
when electrons are transferred. This forms an ionic
compound, also called a salt.
-Covalent bonds are formed between two nonmetals when
they share electrons. This forms a covalent compound called
a molecule
PRACTICE
1. Which element below would form an ionic bond with iron?
a. sodium
b. oxygen
c. gold
d. copper
2. Chlorine atoms have 7 valence electrons. How many covalent bonds do they commonly
form?
a. one
b. two
c. three
d. eight
Standard- SC 12.2.1.a
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ANSWERS & EXPLANATION
1. (b) Iron reacts with oxygen
Ionic bonds occur between metals and nonmetals. Metals lose electrons to nonmetals
because nonmetals have high pulls on electrons and metals have low pulls on electrons.
Losing electrons is called oxidation and gaining electrons is called reduction.
Iron reacts with oxygen to form rust, ferric oxide, Fe2O3
2. (a) Chlorine normally forms 1 covalent bond with other nonmetals.
Nonmetals share their electrons with other nonmetals in order to fill their valence shell with
eight electrons. They share because two nonmetals both have high pulls on electrons and
therefore overlap to share electrons.
Key Terms
chemical bonding
an attraction between two or more atoms resulting in the formation of different chemical substances
covalent bond
a form of chemical bond characterized by the sharing of a pair of valence electrons between atoms
ionic bond
molecule
a form of chemical bond characterized by transfer of electrons from one atom to another resulting in
the attraction of oppositely charged ions
a group of atoms bonded together forming the smallest fundamental unit of a pure substance
valence electrons
the electrons in the outer shell or energy level that are available for bonding
Standard-SC 12.2.1.a
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OBJECTIVE
•Describe the energy transfer associated with phase changes between solids, liquids, and gasses
Solid particles have the lowest energy and highest
attraction. Melting occurs when heat overcomes the
attractions and separates solid particles. Boiling occurs
when liquid particles gain more heat to escape from each
other’s attractions.
PRACTICE
1. Which of the following processes are endothermic?
a. melting
b. freezing
c. boiling
d. both a & c
2. When ice melts in your hand, energy moves from
a. your hand to the ice b. the ice to your hand
e. no movement of energy
Standard-SC 12.2.1.b
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ANSWERS & EXPLANATION
1. (d) Both melting and boiling
Both melting and boiling require an input of heat, endothermic. Freezing occurs when liquid
particles lose energy and form a solid.
2. (a) your hand to the ice
Thermal energy moves from areas of high concentration (hotter) to areas of low
concentration (colder) until a thermal equilibrium is obtained (temperatures become the
same). For the ice to melt it has to gain heat which your hand provides. Your hand feels cold
because it has lost heat.
Standard-SC 12.2.1.b
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OBJECTIVE
• Describe the three normal states of matter (solid, liquid, gas) in terms of energy, particle
arrangement, particle motion, and strength of bond between molecules
PRACTICE
1. Which state of matter has particles with the highest energy?
a. solid
b. liquid
c. gas
2. Which state of matter has constant shape and volume?
a. solid
b. liquid
c. gas
Standard-SC 12.2.1.c
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ANSWERS & EXPLANATION
1. (c) gas
Energy is either input into a substance or released from a substance. If energy is put in, the
particles move faster and overcome their attractions. The movement of particles is a measure
of energy. The more energy they gain, the faster they move. Solids become liquids and liquids
become gases as the particles gain energy.
When particles lose energy, they slow down and the attractions become greater. Gases
become liquids and liquids become solids as their energy is released.
2. (a) solid
Solid particles have the lowest energy and the highest attraction. The particles in a solid are
therefore held into place (constant shape) through strong attractions and not free to move
(constant volume).
Standard-SC 12.2.1.c
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OBJECTIVE
• Recognize a large number of chemical reactions involve the transfer of either electrons
(oxidation/reduction) or hydrogen ions (acid/base) between reacting ions, molecules, or atoms
Redox reactions occur when one particle loses an
electron and another gains an electron.
Acid/base reactions occur when an acid donates a hydrogen ion
(accepting electrons) and a base accepts a hydrogen ion (donating
electrons).
PRACTICE
1. Iron oxidizes in the presence of oxygen to form rust (iron oxide). What charge does the
iron become if it is oxidized?
a. negative
b. positive
c. neutral
2. Which of the following is true about bases?
a. they donate hydrogen ions
c. they accept hydrogen ions
Standard-SC 12.2.1.d
b. they accept electrons
d. none of the above
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ANSWERS & EXPLANATION
1. (b) positive
Oxidation occurs when an atom loses electrons. Losing electrons causes an atom to have more
protons than electrons, which makes the atom more positive.
Reduction occurs when an atom gains electrons. Gaining electrons causes an atom to have
more electrons than protons, which makes the atom more negative. Think of reduction as
reducing charge by gaining electrons.
2. (c) accept hydrogen ions
Acids are hydrogen ion donors and bases are hydrogen ion acceptors. You may also hear acids
as proton donors and bases are proton acceptors because a hydrogen ion and a proton are
basically the same thing. In order to lose a hydrogen ion to a base, the base must have a pair of
electrons which the hydrogen can bond to (formation of a new covalent bond).
Key Terms
acid
a substance that dissolves in water to release a hydrogen ion (H+)
base
a substance that dissolves in water to release a hydroxide ion (OH-)
chemical
reactions
changes in chemical substances involving bond breaking and/or bond forming resulting in
different chemical substances
Standard-SC 12.2.1.d
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OBJECTIVE
• Identify factors affecting rates of chemical reactions (temperature, particle size, surface area)
A chemical reaction requires reactant particles to interact.
Any factor that increases the interactions will increase the
reaction rate. Here are four common factors :
1.
2.
3.
4.
Temperature- particles move faster and interact more
Surface area- the smaller the “pieces” are, the more they will interact.
Concentration- more particles in a space means more interactions
Catalysts increase interactions without changing themselves
PRACTICE
1. The rate of a reaction is measured by how fast reactants become products.
a. true
b. false
2. Which of the following will NOT increase the rate of a chemical reaction?
a. increasing temperature
b. having gas particles instead of solid particles
c. decreasing concentration
d. adding a catalyst
Standard-SC 12.2.1.e
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ANSWERS & EXPLANATION
1. (a) true
The rate of a chemical reaction is measured by how fast reactants are converted to products.
2. (c) decreasing concentration
The rate of a reaction is affected by how fast reactants particles interact with each other. If the
concentration of reactants is decreased (more spread out) the less they interact and the
reaction rate decreases.
Key Terms
pH
rate of chemical
reaction
the measure of acidity or alkalinity of a solution
the speed at which chemical reactions occur affected by factors such as temperature,
substance surface area, agitation, and pH
Standard-SC 12.2.1.e
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OBJECTIVE
• Recognize the charges and relative locations of subatomic particles (neutrons, protons,
electrons)
PRACTICE
1. Which of the following subatomic particles is found in the nucleus and has a
positive charge?
a. neutron
b. proton
c. electron
d. quark
2. Which of the subatomic particles has the smallest mass?
a. neutron
b. proton
c. electron
Standard-SC 12.2.1.f
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ANSWERS & EXPLANATION
1. (b) proton
The proton has a positive charge and is located in the nucleus. Neutrons have no charge and
are located in the nucleus. Electrons have a negative charge and are located in the energy
levels outside the nucleus
2. (c) electron
The electron has the smallest mass of the particles, approximately 1/2000th the size of a
proton or neutron. The neutron and proton both have approximately the same mass.
Key Terms
electron
a negatively charged subatomic particle located outside the nucleus
neutron
proton
a neutral subatomic particle located inside the nucleus
a positively charged subatomic particle located inside the nucleus
Standard-SC 12.2.1.f
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OBJECTIVE
• Describe properties of atoms, ions, and isotopes
Atoms are the smallest particles of matter which have the properties of that
matter. They are electrically neutral (equal protons and electrons). Ions are
atoms which have gained electrons (anions) or lost electrons (cations).
Isotopes are atoms of an element that
have the same number of protons but
different numbers of neutrons.
PRACTICE
1. An oxygen atom has an atomic number of 8 (contains 8 protons). How many electrons does
an oxygen atom contain?
a. 4
b. 6
c. 8
d. 10
2. The atomic number for lithium is 3 (3 protons). How many neutrons does the Lithium-7
isotope (7Li) contain?
a. 3
b. 4
c. 5
d. 0
Standard-SC 12.2.1.g
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ANSWERS & EXPLANATION
1. (c) 8
The atomic number of an element is the number of protons found in the nucleus. Every atom,
ions or isotope of a specific element contains the same number of protons. Atoms are
electrically neutral and therefore contain the same number of protons and electrons. Oxygen
atoms all contain 8 protons and 8 electrons.
2. (b) 4
Isotopes are atoms of an element that have different numbers of neutrons. The mass number
of an isotope is equal to the number of protons + neutrons and is used to identify the specific
isotope. This number is written after the name or as the upper left superscript with the symbol.
Lithium-7 (7Li) would be an isotope of lithium which has 3 protons and 4 neutrons (3 + 4 = 7).
Key Terms
ion
isotopes
an atom or group of atoms in which the number of electrons is different from the number of
protons resulting in a net charge other than zero
atoms of the same element with different numbers of neutrons
Standard-SC 12.2.1.g
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OBJECTIVE
• Describe the organization of the periodic table of elements with respect to patterns of physical
and chemical properties
The periodic table to the right shows two sets of
trends, the red arrows show increasing trends to
upper right and the blue arrows shows the
increasing trends to lower left.
PRACTICE
1. Which of the following elements has the largest atomic radius?
a. neon (noble gas)
b. chlorine (halogen)
c. potassium (alkali metal)
2. Which family of elements have the highest pull on their electrons?
a. alkali metals
b. transition metals
c. noble gases
Standard-SC 12.2.1.h
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ANSWERS & EXPLANATION
1. (c) potassium (alkali metal)
The trend for atomic radius is to increase towards the bottom left of the periodic tables. Metals
have larger radii than metals in the same period due to having lower pulls on their electrons.
Nonmetals have a higher pull on their electrons and therefore are smaller than metals in the
same period.
2. (c) noble gases
The trend for pull on electrons is to increase to the upper right. Nonmetals have high pulls on
their electrons, are smaller atoms than metals and tend to gain electrons. Metals have lower
pulls on their electrons, are larger than metals and tend to lose electrons.
Key Terms
periodic law
the law stating many physical and chemical properties of the elements recur periodically as
their atomic numbers increase
Standard-SC 12.2.1.h
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NeSA- Physical Science
Force and Motion
SC 12.2.2 Students will investigate and describe the
nature of field forces and their interactions with
matter.
OBJECTIVE
• Describe motion with respect to displacement and acceleration
Displacement is the distance travelled from the starting point
with direction.
Velocity is the rate at which an object changes its displacement.
Acceleration is the rate at which an object changes its velocity.
PRACTICE
1. What is the displacement of a car moving with a uniform velocity of
20 meters per second west for 40 seconds?
a. 200 meters
b. 200 meters west
c. 800 meters
d. 800 meters west
2. What is the acceleration of the object represented by the following graph if it is
travelling north?
a. 2 m/s2 north
b. 4 m/s2 north
c. 8 m/s2 north
d. 12 m/s2 north
Standard-SC 12.2.2.a
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ANSWERS & EXPLANATION
1. (d) 800 meters west
Displacement is a vector quantity that must include direction.
20 m/s * 40 s = 800 meters west
2. (b) 4 m/s2 north
The slope of a velocity/time graph is the acceleration of the object.
Key Terms
acceleration
change in velocity (a = Δv /Δt)
displacement change in position from one point to another (distance and direction)
v = d/t
velocity = displacement / time
Standard-SC 12.2.2.a
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OBJECTIVE
• Describe how the law of inertia (Newton's 1st law) is evident in a real-world event
Newton’s 1st law is the law of inertia. It states that an object at rest
stays at rest and an object in motion stays in motion with the same
speed and in the same direction unless acted upon by an
unbalanced force.
PRACTICE
1. What force causes a projectile to follow a curved path?
a. gravity
b. friction
c. air resistance
d. none of the above
2. Why does a chair stay at rest on the floor?
a. No forces are acting upon it.
b. The forces acting on the chair are unbalanced.
c. The net force on the chair is zero
d. None of the above
Standard-SC 12.2.2.b
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ANSWERS & EXPLANATION
1. (a) gravity
Projectiles accelerate toward the center of the earth due to the force of
gravity. Therefore they follow a curved path.
2. (c) The net force on the chair is zero.
If an unbalanced force acts on the chair its velocity will change.
Key Terms
inertia
the tendency of an object to resist any change in its motion
Standard-SC 12.2.2.b
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OBJECTIVE
• Make predictions based on relationships among net force, mass, and acceleration (Newton's
2nd law)
Newton’s second law states that the acceleration of an
object as produced by a net force is directly proportional
to the magnitude of the net force, in the same direction
as the net force, and inversely proportional to the mass of
the object. This is often represented by the equation
Force = Mass * Acceleration.
PRACTICE
1. For any object, the greater the force that's applied to it, the greater its ____ will
be.
a. inertia
b. acceleration
c. gravity
d. velocity
2. A 3,000-N force acts on a 200-kg object. The acceleration of the object is ____.
a. 50 m/s2
b. 150 m/s2
c. 15 m/s2
d. 26 m/s2
Standard-SC 12.2.2.c
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ANSWERS & EXPLANATION
1. (b) acceleration
A net force on an object will cause it to accelerate.
2. (b) 150 m/s2
By using the equation F=ma we can find that 3000 N / 200 kg = 150 m/s2.
Key Terms
F = ma
net force
Newton's 2nd Law
force = (mass)(acceleration)
vector sum of all forces acting upon an object
the relationship among net force, mass, and acceleration (F = ma)
Standard-SC 12.2.2.c
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OBJECTIVE
• Recognize that all forces occur in equal and opposite pairs (Newton's 3rd law)
Newton's third law states that for every action, there is an equal
and opposite reaction. Therefore, all forces occur in pairs that are
equal in magnitude and opposite in direction.
PRACTICE
1. When a force is exerted on a box, an equal and opposite force is exerted by the box.
These forces are called ____ forces.
a. frictional b. gravitational c. action-reaction d. centripetal
2. If the earth exerts a gravitational force of 980 N on you, what force do you exert on
the earth?
a. 980 N in the same direction
b. 980 N in the opposite direction
c. 0 N
d. not enough information provided
Standard-SC 12.2.2.d
50
ANSWERS & EXPLANATION
1. (c) action/reaction
When you exert a force on a box, the box provides a reaction force in the opposite
direction on you.
2. (b) 980 N in the opposite direction
All action/reaction forces come in pairs that are equal in magnitude and opposite in
direction.
Key Terms
Newton's 3rd Law
all forces occur in equal and opposite pairs
Standard-SC 12.2.2.d
51
OBJECTIVE
• Describe how Newton's 3rd law of motion is evident in a real-world event
All forces that occur have a reactionary force. These
reactionary forces are equal in magnitude and opposite in
direction to the action force.
PRACTICE
1. In the above picture the magnitude of the force the bat exerts on the ball is
_______ the magnitude of the force that the ball exerts on the bat.
a. greater than
b. less than
c. equal to
2.
a.
b.
c.
What force propels a rocket and allows it to accelerate through space?
the action force of the rocket on the gas
the reaction force of the gas on the rocket
neither
Standard-SC 12.2.2.e
52
ANSWERS & EXPLANATION
1. (c) equal to
All action/reaction forces come in pairs that are equal in magnitude and opposite in
direction. Therefore the force on both is the same.
2. (b) the reaction force of the gas on the rocket
The reaction force of the gas on the rocket causes the rocket to accelerate.
The action force of the rocket on the gas causes the gas to accelerate.
Standard-SC 12.2.2.e
53
OBJECTIVE
•Describe gravity as a force that each mass exerts on another mass, which is proportional to the
masses and the distance between them.
Gravity is an attractive force between any two objects which have
mass. It is directly related to the masses of the two objects and
inversely proportional to the square of the distance between
them. The equation which describes this relationship is
PRACTICE
1. The size of the gravitational force between two objects depends on their ____.
a. inertia
b. frictional forces
c. speed and direction
d. masses and the distance between them
2. The force of gravity between two objects is 10.0 Newtons. If the distance
between them is doubled, what is the new gravitational force?
a. 2.5 Newtons
b. 5.0 Newtons
c. 10.0 Newtons
d. 20.0 Newtons
Standard-SC 12.2.2.f
54
ANSWERS & EXPLANATION
1. (d) masses and distance between them
From the equation:
We can see that the force of gravity is dependent upon both the masses of the two objects and
the distance between them.
2. (a) 2.5 Newtons
Increasing the distance between two objects decreases the force of gravity between them.
The force of gravity is inversely proportional to the square of the distance between two objects.
If the distance between two objects is doubled the force of gravity will be decreases by a factor
of 4 (22 = 4).
10 Newtons / 4 = 2.5 Newtons
Key Terms
Newton's Law of
Universal Gravitation
Standard-SC 12.2.2.f
every mass attracts every other mass with a force directly proportional to the
masses and inversely proportional to the distance between them
55
OBJECTIVE
•Recognize that an attractive or repulsive electric force exists between two charged particles
and that this force is proportional to the magnitude of the charges and the distance between
them
Coulomb’s law states that the force between two charged particles
is directly related to the charge of the particles and inversely
related to the square of the distance between them. The equation
that describes this relationship is
PRACTICE
1. The force between two positively charged particles is
a. attractive
b. repulsive
c. both attractive and repulsive
2. One positively charged particle and one negatively charged particle are separated by
a distance R. If the charge on the positively charged particle is doubled and the
distance between them stays the same, the force will increase by a factor of ______.
a. 0.5
b. 1
c. 2
d. 4
Standard-SC 12.2.2.g
56
ANSWERS & EXPLANATION
1. (b) repulsive
Particles which have the same charge repel one another. Particles which have opposite charges
attract one another.
2. (c) 2
The electric force between two charged particles is directly proportional to the charge of the
particles. Therefore, if the charge of one of the particles is doubled, the electric force between
the charges will double as well.
Key Terms
attraction
(electric)
electric force
repulsion
(electric)
opposite charges pull towards one another
the force between two charged particles that is directly proportional to the magnitude
of the charges and inversely proportional to the distance between them
like charges push away from one another
Standard-SC 12.2.2.g
57
NeSA- Physical Science
Energy
SC 12.2.3 Students will describe and investigate
energy systems relating to the conservation and
interaction of energy and matter.
OBJECTIVE
•Describe mechanical wave properties (speed, wavelength, frequency, amplitude) and how
waves travel through a medium
The wavelength of a wave is how far it takes
to repeat a cycle. (meters)
The frequency of a wave is how many cycles it
completes in one second. (Hertz = 1/second)
The amplitude of a wave is how far a wave’s
crest or trough is from its equilibrium point.
(meters)
The speed of a wave can be found by taking the wavelength time the frequency. This allows
you to find the distance per unit time the wave is covering. Mechanical waves need a medium
to travel through. A medium is a substance or material which can propagate a wave. The only
type of wave which does not need a medium to travel through is an electromagnetic wave.
PRACTICE
1. If a wave completes 20 cycle in 5 seconds, what is its frequency?
a. 2 Hertz
b. 4 Hertz
c. 6 Hertz
d. 8 Hertz
2. Mechanical waves can travel through a vacuum (no matter).
a. True
b. False
Standard-SC 12.2.3.a
59
ANSWERS & EXPLANATION
1. (b) 4 Hertz
Frequency is the amount of cycles a wave completes in one second.
20 cycles / 5 seconds = 4 Hertz
2. (b) False
Mechanical waves need a medium to travel through.
Key Terms
amplitude (wave)
height of the wave
frequency (wave)
mechanical wave
properties
medium
wavelength
number of complete waves that pass a point per second
frequency, wavelength, and speed of a wave through a medium are related by
the formula v=fλ (a.k.a. c = λν)
the substance that carries a wave
distance between adjacent crests
Standard-SC 12.2.3.a
60
OBJECTIVE
•Recognize that the energy in waves can be changed into other forms of energy
The law of conservation of energy states that energy
can not be created or destroyed. Therefore, when
one type of energy is lost, another type of energy is
gained. Energy from waves can be changed into
other forms of energy. This is the case with
electromagnetic radiation, which can be turned into
electrical power.
PRACTICE
1. Energy can be destroyed.
a. True
b. False
2. Energy from waves can be converted into ___________ energy.
a. kinetic
b. potential
Standard-SC 12.2.3.b
c. thermal
d. All of the above
61
ANSWERS & EXPLANATION
1. (b) False
Energy is transferred from one form to another, not created or destroyed.
2. (d) All of the above
Energy from waves can be converted to many types of energy.
Key Terms
forms of energy
transformation of
energy
Standard-SC 12.2.3.b
kinetic (electrical, heat, light, motion, and sound) and potential (chemical,
gravitational, mechanical, and nuclear)
energy can transfer from one form to another (e.g. nuclear to heat, chemical to
mechanical, electrical to light )
62
OBJECTIVE
•Recognize that light can behave as a wave (diffraction and interference)
Light can demonstrate qualities of both a wave and a
particle. Therefore, it exhibits properties of diffraction and
interference.
Diffraction is the change in the directions and intensities of
a group of waves after passing by an obstacle or through a
slit whose size is approximately the same as the wavelength
of the waves.
Interference is the mutual effect on meeting of two wave
trains that constitutes alternating areas of increased and
decreased amplitude.
PRACTICE
1. When light passes through a slit it is diffracted.
a. True
b. False
2. Light interference demonstrates its _______ nature.
a. particle
b. energy
c. wave
Standard-SC 12.2.3.c
63
ANSWERS & EXPLANATION
1. (a) True
Light’s wave nature causes it to be diffracted when it passes through a slit.
2. (c) wave
Interference happens amongst waves, so light interference demonstrates its wave nature.
Key Terms
diffraction
interference
bending of light as it passes around the edge of an object
the effect of waves coinciding to create a new wave pattern
Standard-SC 12.2.3.c
64
OBJECTIVE
•Distinguish between temperature (a measure of the average kinetic energy of atomic or
molecular motion) and heat (the quantity of thermal energy that transfers due to a change in
temperature)
The right box has more kinetic
energy, which means more
thermal energy.
Thermal energy is measured by the kinetic
energy of the particles. Temperature is the
average kinetic energy and heat is the total
kinetic energy. Temperature is
independent of the amount of material
and heat is dependent of the amount of
material.
PRACTICE
1. Which has the greatest amount heat?
a. cup of water at 100oC
b. bucket of water at 50oC
c. swimming pool at 35oC
2. Which is hotter (higher temperature)?
a. cup of water at 100oC
b. bucket of water at 50oC c. swimming pool at 35oC
Standard-SC 12.2.3.d
65
ANSWERS & EXPLANATION
1. (c) swimming pool at 35oC
Heat is a measure of the total thermal energy in a substance. This includes both the kinetic
energy of the particles and the total amount of particles (mass). Even though the average kinetic
energy is lower, there is a lot more water in a swimming pool than in either a cup or bucket.
2. (a) cup of water at 100oC
Temperature (how “hot” something feels) is the average kinetic energy in a substance. The cup
of water has fewer particles than both the bucket and swimming pool, but there is much more
kinetic energy per particle due to the higher temperature. Even though the particles may have a
higher kinetic energy, they will not be able to release much heat because there are fewer
particles. Pouring cup of water at 100oC into a bucket of cold water may not raise the
temperature of the water by much, but a bucket of warm water can raise the colder water much
more because there is more water in the bucket of warm water.
Key Terms
heat
the kinetic energy that flows between two samples of matter due to their difference in
temperature
Standard-SC 12.2.3.d
66
OBJECTIVE
•Compare and contrast methods of heat transfer and the interaction of heat with matter via
conduction, convection, and radiation
Conduction
Direct contact
Heat is transferred by collisions
The man’s hands will gain energy because it is
touching the hot iron directly.
Convection
Transfer of heat in a
fluid
Air is a fluid , the more energetic
particles move from one location to
another transferring heat (in currents).
The child is warming their hands in the air that
has been heated by the campfire.
Radiation
No matter needed
Radiant energy can travel in the space
PRACTICE
between gas molecules,
heat is
transferred by electromagnetic
radiation.
The earth receives radiant energy that travels
through space from the sun. The heat from the
fire is transferred to the hands by radiation
because it can travel through the empty space
between air molecules.
1. How is heat transfer by conduction
different from convection and radiation?
2. Which type of transfer is used to fry an
egg on an electric stove?
3. Which type of transfer is used to cook an
egg in the microwave?
Standard-SC 12.2.3.e
67
ANSWERS & EXPLANATION
1. How is heat transfer by conduction different from convection and radiation?
Conduction is transfer by direct contact, conduction would be transfer through a gas or
liquid and radiation does not need any molecules.
2. Which type of transfer is used to fry an egg on an electric stove? The metal coil would
directly touch the pan and the pan would be in direct contact with the egg, so
conduction is the method of transfer.
3. Which type of transfer is used to cook an egg in the microwave? The microwave oven
uses microwaves, a type of electromagnetic radiation to heat food, so the transfer is
radiation. Notice that the air in the microwave does not heat up like a traditional
convection oven.
Key Terms
conduction
convection
radiation
transfer of heat energy between heat substances that are in direct contact with one
another
the movement of ensembles of molecules with gases and liquids
heat transfer due to electromagnetic waves
Standard-SC 12.2.3.e
68
OBJECTIVE
•Recognize that the production of electromagnetic waves is a result of changes in the motion of
charges or by a changing magnetic field
An electromagnetic wave is a wave of energy having a
frequency within the electromagnetic spectrum and
propagated as a periodic disturbance of the electromagnetic
field. They are produced by a change in the motion of a charge
or by a changing magnetic field.
PRACTICE
1. Electromagnetic waves can be produced by a changing magnetic field.
a. True
b. False
2. Electromagnetic waves contain both an electric field and magnetic field
component.
a. True
b. False
Standard-SC 12.2.3.f
69
ANSWERS & EXPLANATION
1. (a) True
Electromagnetic waves are produced by a change in the motion of a charge or by a
changing magnetic field.
2. (a) True
Electromagnetic waves have both an electric and magnetic field component.
Key Terms
wave
(electromagnetic)
a disturbance that travels through space as a result of changes in the motions of
charges or changing magnetic field
Standard-SC 12.2.3.f
70
OBJECTIVE
•Compare and contrast segments of the electromagnetic spectrum (radio, micro, infrared,
visible, ultraviolet, x-rays, gamma) based on frequency and wavelength
All electromagnetic radiation -- from radio waves to x-rays -- travel at the speed of light. In empty
space this speed is approximately 300,000 kilometers per second!
Each type varies from the other by the wavelength and the frequency of those waves. Radio waves
have a long wavelength, and are not very frequent, gamma waves have a very short wavelength but
are very frequent which gives them the strength to penetrate most objects.
PRACTICE
1. X-rays have a ___________ wavelength
as compared to microwaves.
a. larger b. smaller c. similar
2. ___________ have a high frequency as
compared to ultraviolet waves.
a. Visible light waves
b. Infrared waves
c. gamma waves
Standard-SC 12.2.3.g
71
ANSWERS & EXPLANATION
1. X-rays have a smaller wavelength as compared to microwaves.
X-rays and gamma rays are at the end of the spectrum that has small wavelengths;
the frequency of those waves is much greater than the longer waves, like radio
waves. X-rays are so energetic that they can travel through matter, breaking bonds
as they go.
2. Gamma waves have a high frequency as compared to ultraviolet waves. Gamma
waves have the smallest wavelength and the largest frequency. Ultraviolet waves
are not as frequent and have less penetrating power through matter. (They can
carry enough energy to enter your skin cells, whereas gamma can travel farther into
tissue and is used to treat patients who have cancer.)
Key Terms
electromagnetic
spectrum
Standard-SC 12.2.3.g
a continuum of all electromagnetic waves arranged according to frequency and
wavelength
72
OBJECTIVE
• Recognize that nuclear reactions (fission, fusion, radioactive decay) convert a fraction of the
mass of interacting particles into energy, and this amount of energy is much greater than the
energy in chemical interactions
A chemical change involves changes in electron
distribution in atoms. A nuclear change involves changes
within the nucleus, commonly changes in the number of
protons or neutrons. In every nuclear change, some of
the mass is converted to energy and the energy is found
using Einstein’s equation: E = mc2, where c is the speed of
light (3 x 108 m/s). A common form of released energy is
gamma radiation, a high frequency wave.
PRACTICE
1. A radioactive isotope undergoes nuclear fission. The atomic number of the resultant
particle(s) is always
a. smaller
b. greater
c. the same
d. equal to 1
2. The amount of energy released from a nuclear reaction is directly proportional to
a. type of decay
b. mass change
c. product isotope
Standard-SC 12.2.3.h
73
ANSWERS & EXPLANATION
1. (a) smaller
Nuclear fission involves the splitting of a nucleus. The resulting isotope(s) will always have a
smaller atomic number because the initial nuclear broke into pieces, leaving fewer protons in
each new isotope’s nucleus.
2. (b) mass change
The amount of energy released through mass defect (change in mass) is directly proportional
to the amount of mass lost. According to Einstein’s equation (E = mc2), the more mass that is
lost, the greater the energy released.
Key Terms
nuclear reactions
reactions that convert a fraction of mass into energy (e.g. fission, fusion, radioactive
decay)
Standard-SC 12.2.3.h
74
OBJECTIVE
•Interpret the law of conservation of energy to make predictions for the outcome of an event
The law of conservation of energy (1st law of
thermodynamics) states that the energy in an isolated
system is constant over time but it can change forms and
locations. Knowing the amount of stored energy, we can
predict the amount of energy given off or the amount of
work done. One gram of explosive will always release the
same amount of energy and the same falling apple from a
given height will always release the same amount of energy.
PRACTICE
1. The heat lost by one object in an isolated system must equal the heat
____ by another.
a. gained
b. lost
c. destroyed
d. created
2. If a pendulum (image to the right) contains 100 J of potential energy when
pulled back (1), the amount of kinetic energy at the bottom (3) of the swing
must be (assume no friction)?
a. less than 100 J
b. more than 100 J
c. equal to 100 J
Standard-SC 12.2.3.i
75
ANSWERS & EXPLANATION
1. (a) gained
The law of conservation of energy states that energy can neither be created nor
destroyed, but can change forms or position. If one object in an isolated system
loses energy (heat) the other object must gain that energy (heat).
2. (c) equal to 100 J
The (potential) energy of the pendulum at the beginning must equal the kinetic
energy of the pendulum at the bottom of the swing. The energy it took to raise the
pendulum to the starting height would have been the same energy lost when it falls
back to the starting position.
Key Terms
kinetic energy
potential energy
Standard-SC 12.2.3.i
energy of motion
stored energy
76
OBJECTIVE
•Identify that all energy can be considered to be either kinetic, potential, or energy contained
by a field (e.g. electromagnetic waves)
Kinetic energy is the energy due to the motion of an object.
Potential energy is stored energy due to an object’s position or
composition.
An object’s mechanical energy is the total of its potential energy
and kinetic energy.
Energy can also be contained in a field, such as electromagnetic
waves.
PRACTICE
1. As an object falls through the air, its mechanical energy _________.
a. decreases
b. increases
c. stays the same
2. Energy due to an object’s position is its _________ energy.
a. kinetic
b. potential
c. nuclear
d. chemical
Standard-SC 12.2.3.j
77
ANSWERS & EXPLANATION
1. (c) stays the same
An object’s mechanical energy is the total of its potential energy and kinetic energy. As
an object falls through the air, its potential energy decreases at the same rate its kinetic
energy increases. Therefore its mechanical energy stays the same.
2. (b) potential energy
Energy due to an object’s position or composition is its potential energy.
Standard-SC 12.2.3.j
78
OBJECTIVE
•Identify endothermic and exothermic reactions
Chemical reactions typically involve a change in energy
as they proceed. Heat is a common measure of energy
change within a reaction. Those reactions which give off
heat are called exothermic and those that gain heat are
endothermic.
PRACTICE
1. The combustion of wood is used as a fuel source for cooking. The combustion of wood is
a type of _____________ reaction.
a. endothermic
b. exothermic
c. reversible
d. nuclear
2. An endothermic reaction will have heat written into the equation as a
a. reactant
b. product
c. catalyst
Standard-SC 12.2.3.k
79
ANSWERS & EXPLANATION
1. (b) exothermic
The combustion of wood releases heat which is absorbed by the food source. The
combustion of any fuel source (hydrocarbon) involves the following reaction seen below. It
is the conversion of the fuel (a reduced form of carbon) to a carbon dioxide and water
(more oxidized forms) that releases the energy.
2. (a) reactant
An endothermic reaction requires the input of energy in order to drive the reaction. Heat
would then be considered a reactant because it has to be put into the system.
Key Terms
endothermic reaction
chemical reaction in which heat is absorbed
exothermic reaction
chemical reaction in which heat is released
Standard-SC 12.2.3.k
80
NeSA- Life Science
Structure and Function of Living
Systems
SC 12.3.1 Students will investigate and describe the
chemical basis of the growth, development, and
maintenance of cells.
OBJECTIVE
•Identify the complex molecules (carbohydrates, lipids, proteins, nucleic acids) that make
up living organisms
Carbohydrates- Include sugars (C6H12O6) and starches and are used for energy
storage, and serve as building blocks. They are made of monosaccharides
linked together.
Lipids- (fats, oils, waxes, steroids) Are hydrocarbons that are used for energy
storage, and to line cell membranes. They are made of fatty acids.
Proteins- Are structural materials (hair/nails, muscle) , are enzymes (to
increase reaction rates), and they act as carriers to facilitate getting large
materials into cells. They are made of amino acids and have peptide bonds.
Nucleic Acids -Are made from nucleotides which have 1 sugar (deoxyribose or
ribose), 1 or more phosphate bases and 1 nitrogen base (A,T,C,G,U). They are
molecules that store information as DNA or RNA.
PRACTICE
1. What are the building blocks of carbohydrates?
2. Which molecule is used by cells for increasing reaction rates and is a
component of the cell membrane?
Standard-SC 12.3.1.a
82
ANSWERS & EXPLANATION
1. Carbohydrates are made of simpler substances such as monosaccharides linking together
to make larger molecules which are sugars and starches.
2. Proteins function in many different ways, they provide structure for the muscles, they
transport materials across the cell membrane, they are enzymes which increase the rate
of chemical reactions and they are active in the immune system as defense molecules.
Key Terms
carbohydrate
lipid
nucleic acid
protein
molecule that is the major source of energy for an organism
molecule that stores energy and is the main structure of cell membranes
building block of living organisms that passes genetic information from one generation
to the next (e.g. DNA)
molecule needed by organisms for growth and repair
Standard-SC 12.3.1.a
83
OBJECTIVE
•Identify the form and function of sub-cellular structures that regulate cellular activities
Organelle
Structure
Function
Organelle
Structure
Function
Cell Membrane
Phospholipid bilayerhydrophilic heads,
hydrophobic tails,
proteins embedded in
surface
Semi-permeable
membrane, it helps
regulate the materials
going into and out of the
cell.
(Osmosis/diffusion/facili
tated diffusion/active
transport
Endoplasmic Reticulum
(RER and SER)
Large folded membrane
outside of the nucleus
which holds ribosomes
(RER)
Site of protein synthesis
and transport of newly
made proteins
Cell wall
(plants/bacteria)
Rigid wall which
surrounds cell
membrane
Provides structural
support and helps
prevent dehydration
Folded membrane
structure
Proteins are packaged
here to be moved out of
the cell
Chloroplasts (plants)
A vesicle which holds
chlorophyll
Chlorophyll is the
pigment which absorbs
sun’s energy for
photosynthesis
Mitochondria
Bean shaped organelle
with folded layers inside
Site of Cellular
Respiration ( ATP made
here)
Nucleus
Large membrane bound
structure which holds
DNA
Site of transcription of
mRNA
Ribosomes
Small organelles found
free-floating and on ER
Site of protein synthesis
Golgi Apparatus
PRACTICE
1. Which part of the red blood cell will allow water, oxygen, carbon dioxide, and glucose to
pass through?
Because other substances are blocked from entering, this organelle can be described as:
A perforated. B semi-permeable.
C non-conductive.
D permeable.
2. A cell from heart muscle would probably have an unusually high proportion of
A lysosomes.
B mitochondria.
C mRNA.
D Golgi bodies.
Standard-SC 12.3.1.b
84
ANSWERS & EXPLANATION
1. Which part of the red blood cell will allow water, oxygen, carbon dioxide, and glucose to pass
through? Cell Membrane (plasma membrane)
Because other substances are blocked from entering, this organelle can be described:
B semi-permeable; Some substances (like water) flow into and out of the cell easily, some are
too large, the concentration gradient does not favor what the cell requires or the molecules are
charged so they must enter and leave through different types of proteins channels.
2. A cell from heart muscle would probably have an unusually high proportion of
B mitochondria, since the heart’s muscle cells are constantly contracting a lot of energy (in the
form of ATP ) is required, so the heart has a large amount of mitochondria.
cell membrane
cell wall
chloroplast
cytoplasm
mitochondria
nucleus
organelle
ribosomes
vacuole
thin barrier that surrounds all cells that controls what enters and leaves the cell
strong supporting layer around the cell membrane in some cells
organelle found in some organisms that carries out photosynthesis
the fluid portion of a cell's interior
organelle that converts digested food into cellular energy
organelle that regulates the production of proteins and contains genetic material
subcellular structure
organelle that is the site of protein synthesis
organelle that is used to store materials
Standard-SC 12.3.1.b
85
OBJECTIVE
•Describe the cellular functions of photosynthesis, respiration, cell division, protein synthesis,
transport of materials, and energy capture/release
Process
Overview
Photosynthesis
converts light energy into the
chemical energy of sugars and other
organic compounds
light + 6CO2 + 6H20  C6H12O6 + 6O2
Photosynthesis takes place in
chloroplast
ATP and Sugar Production
Respiration
Sugar is broken down to produce
ATP
Cell Division
Mitosis
C6H12O6 + 6O2  6CO2 + 12H20 +
energy (ATP)
PRACTICE
Cell Cycle: DNA duplicates and is
divided between 2 cells before they
divide.
Respiration occurs in mitochondria
of all organisms
For growth, repair and asexual
reproduction
Protein Synthesis
Proteins are assembled in
ribosomes
Transcription-DNA is template for
mRNA made in nucleus
Translation-amino acids created
and linked by peptide bonds in
ribosomes
Material Transport
Concentration gradient: amount of
materials inside and outside of cell
Diffusion: High to low (No energy)
Osmosis: diffusion of water
Active Transport: Needs energy to
move materials low to high or large
molecules
Energy Capture/Release
Metabolism: Cells need energy to
do many processes
ATP
Energy comes in many forms
(kinetic, potential)
Chemical potential is released using
enzymes
1. Where does photosynthesis take place:
a. Mitochondria
b. nucleus
c. chloroplasts
d. membrane
2. During diffusion, when the concentration of molecules on both sides of a membrane
is the same, the molecules will:
Standard-SC 12.3.1.c
86
ANSWERS & EXPLANATION
1. Photosynthesis occurs in the chloroplasts of the plant cells.
2. Diffusion is the random movement of molecules. When the concentration gradient is
high there is a net movement of molecules from higher to lower until the concentration
gradient is zero (concentration in and out of the cell is the same) at that point the
molecules will continue to move across the membrane in both directions. The solution is
isotonic at that point.
Key Terms
active transport
cell transport that does require energy (e.g. endocytosis, exocytosis)
cellular respiration process that releases energy by breaking down food molecules, in the presence of
oxygen
cellular transport the movement of materials into, out of, or within of a cell
enzyme
protein that speeds up biological reactions
metabolism
set of chemical reactions in the cells of living organisms to sustain life
passive transport
photosynthesis
protein synthesis
selectively
permeable
cell transport that does not require energy (e.g. Diffusion, osmosis)
process by which energy rich molecules are made from water and carbon dioxide in
the presence of light
formation of proteins using information coded on DNA
property of biological membranes that allows some substances to pass across, while
others cannot
Standard-SC 12.3.1.c
87
OBJECTIVE
•Describe how an organism senses changes in its internal or external environment and responds
to ensure survival
Organisms are subjected to changing environments such
as changing environmental temperatures. There are
two ways to deal with this: metabolic process can slow
down and they become sluggish and they can take
measures to conserve metabolic heat and retain for parts
that need it most.
Homeostasis is regulated by feedback loops.
PRACTICE
1. Use the flow chart to describe what happens when a person touches an object that is very
hot.
2. The two body systems that regulate homeostasis are the:
a) cardiovascular and respiratory systems
b) cardiovascular and urinary systems
c) cardiovascular and endocrine systems
d) nervous and cardiovascular systems
e) nervous and endocrine systems
Standard-SC 12.3.1.d
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ANSWERS & EXPLANATION
1. Stimulus: hot object on hand
Thermoreceptors on hand receive the stimulus and send a message via the sensory nerve to
the Central Nervous System (brain and spinal cord) that the tissue is in danger of receiving
damage.
The spinal cord relays a message to the motor neuron directing it to contract the muscle to
remove the hand from the danger.
The muscle contracts, moves the hand, thus creating the response to protect the individual.
2. The nervous and endocrine systems work together to create feedback loops that regulate
hormones in the body.
Key Terms
stimulus
any physical or chemical input that is sensed
Standard-SC 12.3.1.d
89
NeSA- Life Science
Heredity
SC 12.3.2 Students will describe the molecular basis
of reproduction and heredity.
OBJECTIVE
•Identify that information passed from parents to offspring is coded in DNA molecules
Reproduction involves
passing genetic
information (DNA) from
parents to offspring.
Asexual reproduction
involves one parent and
sexual reproduction
involves two parents and
the fusion of gametes.
A chromosome contains DNA, which is a molecule
composed of nucleotides arranged into sequences
called genes.
PRACTICE
1. A segment of DNA which influences traits in offspring is called a(n)
a. nucleotide
b. chromosome
c. gene
d. gamete
2. What cellular structure contains a large amount of genetic information that is passed to
offspring through gametes or binary fission?
a. chromosome
b. nucleotide
c. gene
d. sperm
Standard-SC 12.3.2.a
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ANSWERS & EXPLANATION
1. (c) gene
DNA contains genetic information is the form of nucleotide sequences, which is called a gene.
The genes that an organism contains for a particular trait is called a genotype. The trait that is
expressed in the organism is called a phenotype.
2. (a) chromosome
Chromosomes are condensed forms of DNA which also contain specific proteins called
histones. During cell division or gamete formation, DNA is condensed from chromatin into
chromosomes so that genetic information can be separated for reproduction.
Key Terms
DNA
inheritance
trait
nucleic acid that contains all of the genetic instructions for an organism
passing of genetic material from parent to offspring
specific characteristic of an individual
Standard-SC 12.3.2.a
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OBJECTIVE
•Describe the basic structure of DNA and its function in genetic inheritance
Genes are expressed into traits
through protein synthesis. DNA
is transcribed into mRNA which
is translated into polypeptides,
chains of amino acids.
DNA is a polymer made from nucleotides in the form of a double helix. The two
strands are formed from phosphates and ribose sugars. The “rungs” of the DNA
are formed from complement pairing of the bases, A-T & G-C.
PRACTICE
1. In the DNA double helix structure, adenine is complementary based paired with
a. adenine
b. guanine
c. cytosine
d. thymine
2. During translation, mRNA is copied into a chain of amino acids. How many nucleotides code
for a single amino acid?
a. one
b. two
c. three
d. four
Standard-SC 12.3.2.b
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ANSWERS & EXPLANATION
1. (d) Thymine
DNA is a double helix consisting of four different nucleotides
which are complementary based paired. Adenine pairs with
thymine and cytosine pairs with guanine.
2. (c) three
Amino acids are coded for in a polypeptide from mRNA. There
are 20 known amino acids and only four RNA nucleotides
(adenine, guanine, cytosine & uracil). In order to code for all
the amino acids, three nucleotides are used to code for the
amino acids. These are called codons.
Key Terms
double helix
mitosis
nucleotide
the shape of DNA that resembles a spiral staircase or a twisted ladder
nuclear division in organisms that have a nucleus
building block of a nucleic acid; consisting of a sugar, phosphate, and a nitrogen base
(e.g. adenine, guanine, cytosine, thymine)
Standard-SC 12.3.2.b
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OBJECTIVE
•Recognize how mutations could help, harm, or have no effect on individual organisms
A mutation is a change in the nucleotide sequence of a DNA molecule. If the
change in nucleotide(s) causes a change in the expressed protein, it can alter the
protein and cause harm or it can cause a different phenotype which can be
beneficial. If the mutation occurs in a sequence of DNA which does not affect the
protein structure or the expression of the protein, the mutation has no effect.
Mutations are caused by radiation, viruses, transposons and mutagenic
chemicals, as well as errors that occur during meiosis or DNA replication.
PRACTICE
1. A change in the sequence of amino acids within a gene is know as
a. mutation
b. transcription
c. translation
d. expression
2. In order for a mutation to be harmful, it has to alter the expression of
a. DNA
b. a protein
c. a chromosome d. a cell
Standard-SC 12.3.2.c
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ANSWERS & EXPLANATION
1. (a) mutation
A change in the sequence of DNA is a mutation. There are different ways the sequence can be
changed, such as; point mutations, deletions, insertions, inversions, translocation and
duplications. All of these will alter the nucleotides which can lead to the expression of a
protein.
2. (b) protein
Mutations that affect expression of a protein, either by altering the sequence of amino acids
or affecting the regulation, can lead to either beneficial or negative effects. Those that produce
a phenotype which helps the organism survive will be a beneficial mutation. Mutations which
alter the protein that cause harm or death to the organism are considered negative effects.
Key Terms
mutation
change in the genetic material of a cell
Standard-SC 12.3.2.c
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OBJECTIVE
•Describe that sexual reproduction results in a largely predictable, variety of possible gene
combinations in the offspring of any two parents.
During gamete formation, alleles
on different chromosomes
segregate independently,
producing genetic variation.
Random fertilization defines
variations in gamete union.
PRACTICE
1. How many alleles do most organisms contain for a specific trait?
a. one
b. two
c. three
d. four
2. A Punnett square (figure to the right) shows the possible production of
a. gametes
b. chromosomes c. mutations
d. offspring
Standard-SC 12.3.2.d
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ANSWERS & EXPLANATION
1. (b) two
For many traits an organism contains a paternal allele and a maternal allele, passed down during
fertilization. Alleles are specific expressed forms of a gene. Alleles can be dominant or recessive,
depending on their ability to influence the expression of a trait.
2. (d) offspring.
Independent assortment of chromosomes (alleles) and random fertilization are two forms of
genetic variation. There is a probability associated with the formation of specific gametes and a
probability associated with which gametes are involved in fertilization. These two factors (along
with mutations) are what cause differences between organisms.
Key Terms
alleles
genotype
heterozygous
homozygous
meiosis
alternate forms of a gene
genetic makeup of an organism
having two different alleles for a particular gene
having two identical alleles for a particular gene
the process of nuclear division that reduces the number of chromosomes in a cell by half
phenotype
physical characteristics of an organism
Punnett square model used to determine probabilities of a genetic cross
Standard-SC 12.3.2.d
98
NeSA- Life Science
Flow of Matter and Energy in
Ecosystems
SC 12.3.3 Students will describe, on a molecular
level, the cycling of matter and the flow of energy
between organisms and their environment.
OBJECTIVE
•Explain how the stability of an ecosystem is increased by biological diversity
Biodiversity is the distribution of genes, organisms or
ecosystems in an area. Ecological stability describes the
ability of an ecosystem to resist changes due to limiting
environmental factors, such as the availability of light,
water, space and required nutrients. Required nutrients
are related to an ecosystem’s food web. A more diverse
food web provides greater stability because it prevents
large scale extinctions.
PRACTICE
1. The greater number of species and differences between organisms increases biodiversity.
a. true
b. false
2. What roles do plants perform in a food web?
a. 1st order consumers b. 2nd order consumers
Standard-SC 12.3.3.a
c. 3rd order consumers
d. producers
100
ANSWERS & EXPLANATION
1. (a) true
Biodiversity is measured by the number of different genes, organisms, species and ecosystems
found in an area. As the variance in these factors increases, the biodiversity increases.
2. (d) producers
Plants function as producers in a food web, commonly the first trophic level. They take energy
sources (typically sunlight) and raw materials in order to produce food for other organisms.
Key Terms
biological diversity
the degree of variation of life forms within a given ecosystem
Standard-SC 12.3.3.a
101
OBJECTIVE
•Recognize that atoms and molecules cycle among living and nonliving components of the
biosphere
Biogeochemical cycles
show how specific
elements or molecules
move between different
elements of the biosphere.
Examples are water,
nitrogen, carbon and
phosphorus.
PRACTICE
1. Which of the following does not comprise a biogeochemical cycle?
a. carbon
b. water
c. light
d. nitrogen
2. Most elements involved in biogeochemical cycles are recycled from dead organisms by
a. consumers b. producers
c. carnivores
d. decomposers
Standard-SC 12.3.3.b
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ANSWERS & EXPLANATION
1. (c) Light
Light is not cycled through living and nonliving components. Light is absorbed by photosynthetic
organisms where the energy is incorporated to produce food.
2. (d)
Decomposers are organisms that use dead or non-living organic compounds as their food
resource. These are commonly bacteria, fungi and various worms. These organisms convert nonusable organic sources into usable resources that can be re-incorporated by other organisms.
Key Terms
atom
biogeochemical
cycle
biosphere
basic unit of matter
cycle by which materials necessary for organisms are circulated through the environment
(e.g. water, carbon, nitrogen)
area on and around Earth where life exists
Standard-SC 12.3.3.b
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OBJECTIVE
•Explain how distribution and abundance of different organisms in ecosystems are limited by
the availability of matter and energy and the ability of the ecosystem to recycle materials
The biodiversity of an ecosystem is dependent
upon limiting factors. These include availability to
water, nutrients, sunlight, nesting space, shelter,
predation pressures and temperatures. Organisms
that can resist changes in limiting resources are
tolerant. When limiting factors fall within the
optimum tolerance range, population sizes
increase.
PRACTICE
1. Which of the following is NOT a limiting factor in determining an organism’s habitat?
a. a source of water
b. available food c. limited predation d. all are factors
2. What is the outcome when limiting factors are outside of tolerance range for an organism?
a. extinction
b. high reproduction rates c. maximum growth
Standard-SC 12.3.3.c
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ANSWERS & EXPLANATION
1. (d) all are factors
All of the factors listed are limiting factors.
2. (a) extinction
When limiting factors lie outside of the optimum zone of tolerance, living conditions become
difficult and an species’ reproductive success falls while death rates increase. This will lead to
extinction.
Key Terms
biome
a group of ecosystems that share similar climates and organisms
Standard-SC 12.3.3.c
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OBJECTIVE
•Analyze factors which may influence environmental quality
Environmental quality measures the conditions of the
environment as it relates to sustaining an ecosystem.
Factors that are used to assess the environmental quality
are air quality, water quality, waste, pollution, noise level,
climate change and habitat conditions.
PRACTICE
1. Which of the following is not considered an environmental quality factor?
a. amount of rainfall
b. high water nitrates c. minimal vegetation d. all are factors
2. All environmental quality factors have tolerable limits which still are able to maintain life.
a. true
b. false
Standard-SC 12.3.3.d
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ANSWERS & EXPLANATION
1. (d) all are factors
Any measureable factor in the environment which can affect the survivability of an organism or
a species is considered an environmental quality factors.
2. (a) true
Environmental quality factors have been tested to see what the tolerant ranges are for many
organisms. As long as the factor is within the tolerable ranges, life should be generally
unaffected.
Key Terms
environmental quality
Standard-SC 12.3.3.d
the state of environmental conditions
107
NeSA- Life Science
Biodiversity
SC 12.3.4 Students will describe the theory of
biological evolution.
OBJECTIVE
•Identify different types of adaptations necessary for survival (morphological, physiological, behavioral)
Populations evolve, individuals cannot evolve. A population has continuity from generation to generation. The genetic
makeup of a population may change over time. Genetic variation is necessary for evolution to occur. Adaptations occur
over many generations. Individuals are being selected, ones with certain traits (and genes) reproduce and pass their genes
to the next generation.
Most biological structures have the ability to serve alternative functions. This does not imply that a structure was formed
in anticipation of future use. Instead the organism solved it’s survival problems with what was available.
Homologous structures are parts of organisms that have the same origin, but may not have the same function.
 Analogous structures are parts of different organisms with similar function, but not similar origins. Example: streamline
body of the whale (mammal) and a shark.
Some physiological adaptations include the evolution of a more complex nervous system, a closed circulatory system or
mechanisms which have created a “warm-blooded” organism.
A behavioral adaptation could be a behavior that enables an animal to better evade it’s predator.
Mimicry of leaves by insects is an adaptation for evading predators. This example is a katydid
from Costa Rica.
PRACTICE
1. The creosote bush is a desert-dwelling plant that produces toxins that prevent
other plants from growing nearby, thus reducing competition for nutrients and
water. Is this an adaptation and if so, name the type. A. No B. Yes, Behavioral
C. Yes, Morphological structure
D. Yes, Physiological
2. Is echolocation in bats is adaptation for catching insects?
Standard-SC 12.3.4.a
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ANSWERS & EXPLANATION
1. D, The bush’s ability to produce these proteins which are toxins is a physiological
adaptation.
(Morphological structures describe body structure, namely shape and form. Over time
the katydid’s leaf-like structure is a trait that has been selected for over many
generations. )
2. Yes, echolocation is a behavioral trait, (but the fact that it requires a specific structure to
have that ability would also be a morphological adaptation as well).
Key Terms
behavioral
morphological
physiological
related to the way something acts
the form or structure of something
related to the way something functions
Standard-SC 12.3.4.a
110
OBJECTIVE
•Recognize that the concept of biological evolution is a theory which explains the consequence of the interactions of: (1)
the potential for a species to increase its numbers, (2) the genetic variability of offspring due to mutation and
recombination of genes, (3) a finite supply of the resources required for life, and (4) the ensuing selection by the
environment of those offspring better able to survive and leave offspring.
Darwin noticed that people could determine how animals look, how they behave as well as
characteristics by “artificial selection”. He noticed that there were different characteristics
that people would chose from to have mild-mannered pets, strong work animals or even
nice looking pigeons. When he went on his voyage he thought that if people can select for
favorable traits and those selected traits would be passed down to offspring, why couldn’t
nature do the same thing? He noticed a few principles: more individuals would be born
than could actually survive, there was a variety of characteristics present in each
population, and the earth is dynamic (changing). Darwin who was a naturalist collected
finches and when they were examined he noticed all of the different types. The islands
where they were collected from had a changing climate over the years and at some periods,
there was drought, and scarcity of resources so the birds who were better suited to get food
(according to their beak’s makeup) would survive and pass that trait on to their offspring.
PRACTICE
1.
Which of the following statements is true about Charles Darwin?
a) He believed that evolution was due to the inheritance of acquired characteristics.
b) He supported Lamarck's explanation of how evolution occurred.
c) He understood that the variation that exists in natural populations of plants or animals is the result of repeated mutations.
d) none of these
2. Through careful observation, Charles Darwin came to understand that:
a) populations of plants and animals in nature most often
consist of individuals that are clones of each other b) those individuals whose variation gives them an advantage in staying alive long
enough to reproduce are more likely to pass their traits on to the next generation c) populations of a species that become isolated
from others by adapting to different environmental niches quickly become extinct d) all of the above
Standard-SC 12.3.4.b
111
ANSWERS & EXPLANATION
1. The answer is NONE of these:
Darwin only knew there was variation among individuals and he hypothesized that nature
selected individuals with favorable traits which then would have accumulated over time.
He did not believe as Lamarck did that individuals could gain a characteristic and pass it on
to their offspring. At this point, there wasn’t any work on mutations or molecular analysis
that he would have known about.
2. B is correct:
If an individual has a trait that allows it to get more food or to avoid being killed by
predators or illness, it will have a greater chance of reproducing. As a result, more of the
next generation will inherit the genes for the advantageous trait.
Key Terms
biological evolution descent with modification of organisms from common ancestors
genetic variability
recombination
tendency of individual genetic characteristics in a population to differ from one
another
formation of new and different sets of chromosomes or genes
Standard-SC 12.3.4.b
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OBJECTIVE
•Explain how natural selection provides a scientific explanation of the fossil record and the molecular similarities among the
diverse species of living organisms
Variation is a key concept in evolution, it comes from different places and it recorded in the fossil record.
Mutations are permanent, random chemical changes in the DNA molecule that pare passed on to offspring
Variation from recombination can occur more quickly than variation due to random mutations. This deals
with sexual reproduction. Crossing over, independent assortment, and the combination of genes from two
individuals all create genetic variation.
Variation from migration when organisms move from one population to another they introduce new genes
into the population or remove genes when individuals leave. Some examples include body shapes and colors,
chromosomal variations and protein variations.
PRACTICE
1. The example of the peppered moths living near English industrial
cities demonstrates that: a) a change in an environment can
result in the evolution of species living there b) evolution occurs
so slowly that it is not possible to determine that it has happened
in less than a million years c) the environment near these cities
has always favored dark colored moths
2. Charles Darwin concluded that the 13 species of finches on the
Galápagos Islands: a) were identical to 13 finch species in
northwestern South America 600 miles to the east b) probably
evolved from one ancestral South American species
Standard-SC 12.3.4.c
This is an example of natural selection, the
population of moths changed as the industrial
revolution affected the trees, changing which
variety of moths was most easily seen by
predators.
113
ANSWERS & EXPLANATION
1. A. a change in an environment can result in the evolution of species living there .
Although this does not show evolution over a long period of time, the moths that were studied
and how the population changed is a good example of how natural selection can occur over a
relatively short time span.
2. B He surmised that the Galápagos finches had evolved from a species from the mainland.
He believed that the birds migrated to different islands, each with different food sources and
climates, and that nature selected for survival varieties best suited to exploit them.
Key Terms
fossil record
natural selection
collection of preserved organisms or their traces stored in Earth
process by which organisms that are most suited to their environment survive and
reproduce most successfully
Standard-SC 12.3.4.c
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OBJECTIVE
•Apply the theory of biological evolution to explain diversity of life over time
Individuals of a species vary, some variations are heritable. More
individuals will be produced than the environment can support, so
individuals are forced to compete for resources. Individuals with
favorable traits (and genotypes) will survive, reproduce and pass
those favorable traits to the offspring.
Over time environments will change and favor different traits, but an
entire population will not likely be “selected out”. Gene pools will
vary, thus there exists great diversity of organisms over time.
PRACTICE
1. Earth has undergone some catastrophic changes from time to time. Which of these most likely explains why life on
Earth continued following these catastrophes?
A.Dominant species had a slow mutation rate.
B. Many species filled the same niche.
C. A strong species had many different characteristics.
D. A wide diversity of species existed.
2. If a paleontologist finds fossils of many different species existing in the same area at approximately the same time,
the paleontologist can conclude that the ecosystem in this area had a high degree of
A climatic variation.
B episodic speciation.
C biological diversity.
D geographic isolation.
Standard-SC 12.3.4.d
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ANSWERS & EXPLANATION
1. Although there have been at least 5 mass extinctions, because there is so much variation
among individuals some organisms have been able to survive great environmental change.
2. Many different types of fossils indicate a great deal of biological diversity.
Standard-SC 12.3.4.d
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NeSA- Earth & Space Science
Earth in Space
SC 12.4.1 Students will investigate and describe the
known universe.
OBJECTIVE
•Describe the formation of the universe using the Big Bang Theory
The Big Bang Theory states that 13.7 billion years ago the universe
was extremely hot and dense. At that point it began to expand
and cool rapidly, which eventually led to the formation of our
universe as we now know it. This sudden, rapid expansion is
known as the “Big Bang”. Two of the primary sources of evidence
that support the Big Bang Theory are the CMB (Cosmic Microwave
Background) and the current expanding nature of our universe.
PRACTICE
1. The approximate age of the universe is __________ old.
a. 4.7 million years
b. 4.7 billion years
c. 13.7 million years
d. 13.7 billion years
2. The universe is currently ______.
a. contracting
b. expanding
Standard-SC 12.4.1.a
c. none of the above
118
ANSWERS & EXPLANATION
1. (d) 13.7 billion years old
The Big Bang Theory shows that the universe is 13.7 billion years old. Our solar system is
4.7 billion years old.
2. (b) expanding
The Doppler effect shows that the universe is currently expanding.
Key Terms
big bang
the prevailing theory that the universe began as one mass that then expanded into the state
of the current universe
Standard-SC 12.4.1.a
119
OBJECTIVE
•Recognize that stars, like the Sun, transform matter into energy by nuclear reactions which
leads to the formation of other elements
Stars have fusion reactions occurring
within them that lead to the formation of
new elements and release a tremendous
amount of energy. Fusion is the process
by which two small atoms combine to
form a bigger atom and release energy.
All elements with an atomic number equal to or less than iron (26) are
formed within fusion reactions in stars. Elements with atomic numbers
greater than iron are formed within supernovae.
PRACTICE
1. The process happening within the sun that provides the energy for our solar system is
known as ___________.
a. fusion
b. fission
c. combustion
d. oxidation
2. Elements are formed within __________.
a. planets
b. black holes
c. comets
Standard-SC 12.4.1.b
d. stars
120
ANSWERS & EXPLANATION
1. (a) fusion
Fusion reactions within our sun produce the energy the sun provides.
2. (d) stars
Elements are formed within the fusion reactions occurring within stars.
Key Terms
convection
heat transfer in a fluid by the circulation of currents due to differences in density
Standard-SC 12.4.1.b
121
OBJECTIVE
•Describe stellar evolution
All stars start out as a collection of dust and gas
known as a nebula. As gravity pulls the matter
closer together eventually hydrogen begins to fuse
at its core. Stars which fuse hydrogen at their core
are called “main sequence stars”. When a star runs
out of hydrogen, it becomes a red giant. Red giants
eventually collapse due to gravity. The star then
becomes either a white dwarf, neutron star, or black
hole depending on its amount of mass.
PRACTICE
1. Stars which burn hydrogen at their core are called __________.
a. black holes
b. red giants
c. white dwarves
d. main sequence stars
2. What force causes stars to form?
a. Friction
b. Heat
Standard-SC 12.4.1.c
c. Gravity
122
ANSWERS & EXPLANATION
1. (d) main sequence stars
Main sequence stars, like our sun, are fusing hydrogen at
their core.
2. (c) gravity
The force of gravity is what causes gas and dust to form a
nebula and eventually a star.
Key Terms
stellar evolution
sequence of changes that occurs in a star as it age; this process is driven by gravity
due to mass and pressure due to nuclear fusion
Standard-SC 12.4.1.c
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