Transcript B1 Revision - Rougemont School

Cells – Answer the Following
• Identify the main types of microscope used
today, how they work, and with their
advantages and disadvantages.
Cells – Answer the Following
• Identify the main types of microscope used today, how
they work, and with their advantages and disadvantages.
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Light
Passing light through specimen
Advantage: Can be used in school lab
Disadvantage: Low Power
Electron
Uses beams of electrons
Advantage: high power
Disadvantage: only used on dead tissue
Confocal laser scanning microscopy
Produces image on computer screen
Advantage: Produces clearer images
Disadvantage: Expensive/Advanced technology
Cells – Answer the Following
• Identify the main features of bacteria and
viruses.
Cells – Answer the Following
• Identify the main features of bacteria and viruses.
Bacteria
– Contain cell wall, cell membrane and cytoplasm (any 2)
– No nucleus
– Reproduce asexually/by dividing in two
– Earliest forms of life
Viruses
– Smallest forms of life
– So simple not really though of as living
– Contain genetic material/DNA/RNA
– Inside a protein case
– Reproduce inside a host cell
– Release of viruses from host cell kills the cell
– Released viruses attack new host cells
Cells – Answer the Following
• Identify the main features of fungi (e.g. yeast)
and algae.
Cells – Answer the Following
• Identify the main features of fungi (e.g. yeast) and
algae.
Fungi/Yeast
– Yeast are microscopic fungi
– Yeast larger than bacteria
– Have nucleus and cell wall
– Reproduce by budding/growing new cells from existing
ones.
Algae
– Microscopic plant-like organisms (NOT plants)
– Contain cell wall and chloroplasts
– Photosynthetic
Cells – Answer the Following
• Identify the common features of plant and
animal cells, along with their function, then
highlight any differences
Cells – Answer the Following
• Identify the common features of plant and animal
cells, along with their function, then highlight any
differences
Common
– Nucleus - controls activities of cell/contains DNA
– Cell membrane – controls which substances enter/leave
cell
– Cytoplasm – where chemical reactions occur
Differences
– Cellulose cell wall – supports the cell
– Chloroplast – contains chlorophyll/absorbs light for
photosynthesis
– Vacuole – filled with cell sap/stores nutrients
Cells – Answer the Following
• Describe the structure and function of enzymes
Cells – Answer the Following
• Describe the structure and function of enzymes
– Protein molecules
– Long chain of amino acids
– Folded into a specific shape
– Held together by chemical bonds
– Catalyse/speed up reaction
– Substrate fits into active site
– Forms enzyme-substrate complex
– Lock and key theory
Cells – Answer the Following
• Describe and explain the factors which affect
enzyme action
Cells – Answer the Following
• Describe and explain the factors which affect
enzyme action
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Temperature
Increase temp = faster reaction
Molecules move faster
More collisions
Up to optimum
Above optimum
Bonds break/shape changes
Denatures
pH
Each enzyme has own optimum pH
If pH too far from optimum = denatured
Cells – Answer the Following
• Describe the commercial uses of enzymes.
Cells – Answer the Following
• Describe the commercial uses of enzymes.
– Biological washing powders
– Contain digestive enzymes
– Lipases/proteases/carbohydrases (any two)
– Catalyse breakdown of stains
– E.g. greases by lipases/grass stain proteins by
proteases
– Not using enzyme requires higher temp
– Needing more energy
Cells – Answer the Following
• Outline the main roles played in the discovery
of DNA
Cells – Answer the Following
• Outline the main roles played in the discovery
of DNA
– Nucleic acids discovered in 19th century
– Oswald Avery
– Found link between nucleic acids and genes
– Watson and Crick
– Used ball-and-stick models to work out DNA
structure
– Wilkins and Franklin
– Used x-ray crystallography to provide data for W
and C
Cells – Answer the Following
• Describe the Structure of DNA
Cells – Answer the Following
• Describe the Structure of DNA
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Two long chains
Of alternating sugar and phosphate
Chains twisted into double helix
Interlocking spiral
Chain joined by bases
A to T, C to G
Names of bases: adenine, thymine, cytosine, guanine (all 4
required)
Order of bases forms a code
Code determines order in which amino acids join together
To form proteins
Which takes place in the cytoplasm
3 bases code for each amino acid
Triplet code
Cells – Answer the Following
• Outline the main features of mitosis.
Cells – Answer the Following
• Outline the main features of mitosis.
– A form of cell division
– Needed for growth/ replace old cells/repair
damaged tissue (any two)
– Two cells produced
– Genetically identical/same number of chromosomes
Cells – Answer the Following
• Outline the main features of meiosis.
Cells – Answer the Following
• Outline the main features of meiosis.
– A form of cell division
– Forms gametes/sex cells
– Four cells produced
– Genetically different/half number of chromosomes
Cells – Answer the Following
• Outline the main features of meiosis and how it
leads to a new life.
Cells – Answer the Following
• Outline the main features of meiosis and how it
leads to a new life.
– A form of cell division
– Forms gametes/sex cells
– Four cells produced
– Genetically different/half number of chromosomes
– Fertilisation is joining of gametes
– Forms zygote
– Cells then multiply (by mitosis)
– And specialise/differentiate
Cells – Answer the Following
• Compare the patterns of growth of plants and
animals
Cells – Answer the Following
• Compare the patterns of growth of plants and
animals
– Animals – all regions grow whereas Plants – growth
only at meristems
– Animals – grow to certain size and stop growing
whereas Plants – grow throughout life
– Animals – compact growth form whereas Plants –
spreading/branching growth form
Cells – Answer the Following
• Explain how the pattern of growth for an animal
is well suited to their life.
Cells – Answer the Following
• Explain how the pattern of growth for an animal
is well suited to their life.
– Greater variety of tissues
– Growing all over = tissues/organs grow in
conjunction with each other.
– Growing then stopping
– Allows animals to use energy for other things
– E.g. movement
Cells – Answer the Following
• Explain how the pattern of growth for a plant is
well suited to their life.
Cells – Answer the Following
• Explain how the pattern of growth for a plant is
well suited to their life.
– Main requirements are light and water
– Growing points at tip of shoot and root allow
growth for these resources
– Spreading body form = greater surface area
– For absorbing light
– Parts of plants get eaten
– Growing throughout life allows replacement
Cells – Answer the Following
• What is a stem cell, where are they found and
how are they useful?
Cells – Answer the Following
• What is a stem cell, where are they found and how
are they useful?
– Stem cell is a cell that has retained the ability to
differentiate
– Can become any type of cell
– Found in embryos
– Found in some adult tissues/bone marrow
– Found in meristems of plants
– Can potentially be used to replace damaged cells
– Using own cells overcomes rejection problem
– Embryonic stem cells more useful
– As can differentiate into more types of cells
Transport in Cells – Answer the Following
• What is diffusion and why is it important in
respiration?
Transport in Cells – Answer the Following
• What is diffusion and why is it important in
respiration?
– Movement of molecules/particles
– From high to low concentration
– No energy required/passive
– Usually through selectively permeable membrane
– SPP only allows some molecules through
– Oxygen needed for respiration
– Carbon dioxide produced in respiration
Transport in Cells – Answer the Following
• What is osmosis and how is it important in plant
and animal cells?
Transport in Cells – Answer the Following
• What is osmosis and how is it important in plant and
animal cells?
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Movement of water
From dilute to concentrated solution (or eq.)
Across a selectively permeable membrane
Animal cell in water = water moves in and bursts
Plant cell in water = water moves in but cell wall stops it
bursting
Plant cell in water = water moves in but cell wall stops it
bursting
Plant cell in conc. Solution = water moves out
Cell membrane comes away from cell wall
And becomes plasmolysed
Transport in Cells – Answer the Following
• What is active transport and why is it needed?
Transport in Cells – Answer the Following
• What is active transport and why is it needed?
– Movement of molecules
– From low to high conc./against a conc. gradient
– Energy required
– Used to move substances into a cell
– Where the outside concentration is already very low
Photosynthesis – Answer the Following
• What is photosynthesis and where does it
happen?
Photosynthesis – Answer the Following
• What is photosynthesis and where does it
happen?
– Process plants use to make food
– In leaves
– Equation
– Requires chlorophyll
– To absorb light
– Found in chloroplasts
– Controlled by enzymes
– Denature at high temps.
– So no photosynthesis at high temps
Photosynthesis – Answer the Following
• What happens to the glucose produced in
photosynthesis?
Photosynthesis – Answer the Following
• What happens to the glucose produced in
photosynthesis?
– Provide energy
– In respiration
– Used to make proteins
– If nitrogen source available
– Or cellulose
– Transported to leaves
– As sucrose
– Stored as starch
Photosynthesis – Answer the Following
• What is meant by a limiting factor and what
factors limit the rate of photosynthesis and why?
Photosynthesis – Answer the Following
• What is meant by a limiting factor and what factors
limit the rate of photosynthesis and why?
– Limiting factor – a factor which is controlling the rate of
photosynthesis at a given time
– Temperature
– Affects enzymes
– Increase temp = more photosynthesis
– Until too hot/enzymes denature
– Light
– Provides energy for photosynthesis
– Carbon dioxide concentration
– A raw material of PS
Respiration – Answer the Following
• What is respiration and what are the differences
between aerobic and anaerobic respiration in
animals?
Respiration – Answer the Following
• What is respiration and what are the differences
between aerobic and anaerobic respiration in
animals?
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Process which releases energy from food
Equation for aerobic
Energy need for life process or example
Some energy lost as heat
Why anaerobic respiration takes place i.e. lack of O2
Idea of anaerobic R being less efficient/less energy
Oxygen debt generated in anaerobic R
Pay back debt by breathing faster/deeper
Extra oxygen breaks down the lactic acid
Respiration – Answer the Following
• Identify the similarities and differences in
anaerobic respiration in animals and yeast.
Respiration – Answer the Following
• Identify the similarities and differences in anaerobic
respiration in animals and yeast.
Similarities
– Use glucose as starting molecule
– Absence of oxygen
– Release energy
Differences (comparison needed)
– Animals produce lactic acid whereas yeast produce ethanol
– Animals don’t produce carbon dioxide whereas yeast do
– Process in yeast is referred to as ‘fermentation’ whereas in
animals it is not.
Digestion – Answer the Following
• Identify the main substances that need to be digested by
the body, what each is digested into and why each is
needed.
Digestion – Answer the Following
• Identify the main substances that need to be digested by
the body, what each is digested into and why each is
needed.
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Carbohydrates
Digested into sugars
Needed for energy
Protein
Digested into amino acids
Needed for growth/repair
Fats
Digested into fatty acids and glycerol
Needed for energy
Digestion – Answer the Following
• What food tests do we use and what indicates a
positive result for each test?
Digestion – Answer the Following
• What food tests do we use and what indicates a
positive result for each test?
– Iodine
– Test for starch
– Change from yellow/brown to blue/black
– Benedict’s + place in boiling water bath
– Test for glucose
– Change from blue to brick red
– Biuret solution
– Test for protein
– Change from blue to lilac
Digestion – Answer the Following
• Identify the main enzymes involved in digestion, what
they do, and where in the digestive system they are
found.
Digestion – Answer the Following
• Identify the main enzymes involved in digestion, what
they do, and where in the digestive system they are
found.
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Carbohydrases
Break down starch into sugars
Found in mouth, pancreas/small intestine
Proteases
Break down protein into amino acids
Found in stomach, pancreas/small intestine
Lipases
Break down fats into fatty acids and glycerol
Found in pancreas/small intestine
Digestion – Answer the Following
• Outline the role of the bile in digestion.
Digestion – Answer the Following
• Outline the role of the bile in digestion.
– Produced in the liver
– Stored in gall bladder
– Emulsifies fats/ (breaks up) larger fat droplets into
smaller droplets
– In small intestine
– Increases surface area of fat droplets
– For lipase enzyme to work
Respiratory System – Answer the Following
• Describe how alveoli are adapted for gas
exchange.
Respiratory System – Answer the Following
• Describe how alveoli are adapted for gas
exchange.
– Large number means large surface area
– Thin walls
– Gases pass through quicker/more easily
– Moist lining
– For gases to dissolve into (before diffusing through
wall)
– Good blood supply (for more gas exchange)
Respiratory System – Answer the Following
• Outline the changes that take place in the
respiratory system during expiration.
Respiratory System – Answer the Following
• Outline the changes that take place in the
respiratory system during expiration.
– Diaphragm relaxes
– And becomes dome shaped
– Intercostal muscles contract
– Rib cage moves down
– Volume of thorax decreases
– Pressure in thorax increases
– Air moves out of lungs to equalise pressure
Respiratory System – Answer the Following
• What are cilia and outline how smoking affects
them and how it can lead to disease.
Respiratory System – Answer the Following
• What are cilia and outline how smoking affects
them and how it can lead to disease.
– Hair-like structures lining the cells
– Of the trachea
– Cilia move mucus to top of trachea
– Smoking paralysis cilia
– Mucus in trachea/bronchi cannot be moved up
– Trapped dust/bacteria (in mucus) sinks down into
lungs
– Causes irritation/damages lungs tissue
Respiratory System – Answer the Following
• What is lung cancer and how does smoking make
you more susceptible to it?
Respiratory System – Answer the Following
• What is lung cancer and how does smoking make
you more susceptible to it?
– Cancer – tumours in lungs
– Tumours spread to other parts of body via blood
– Lungs have v. good blood supply
– Smoke contains carcinogens
– Which cause cancer
Respiratory System – Answer the Following
• What is emphysema and how does smoking make
you more susceptible to it?
Respiratory System – Answer the Following
• What is emphysema and how does smoking make
you more susceptible to it?
– Emphysema caused by inflammation/scarring of lung
tissue
– And damage to alveoli
– Symptoms: persistent cough/difficult to breathe
– Smoke damages cilia
– Lungs become clogged with mucus
– And irritated by dust/particles in the mucus
– (Smoke contains) tar which clogs up lungs
– Making it difficult to breathe
Respiratory System – Answer the Following
• Outline why attitudes to smoking have changed in
recent years.
Respiratory System – Answer the Following
• Outline why attitudes to smoking have changed in
recent years.
– Fewer people smoking.
– People more aware of the effects of passive smoking.
– Smoking bans in public places.
– Cigarette packets carry health warnings.
– age limit for buying been raised from 16 to 18.
– Products /support groups exist
– Pregnant women aware of possible damage to their
babies.
Biodiversity – Answer the Following
• What is meant by ‘biodiversity’ and what can
humans do to protect it?
Biodiversity – Answer the Following
• What is meant by ‘biodiversity’ and what can humans
do to protect it?
– The variety or number of different species in a given area
– Can be protected by legislation
Examples
• Convention on Internal Trade in Endangered Species
• Sites of Special Scientific Interest
• Fishing quotas
– Prevent loss of species by:
• Captive breeding programmes
• National parks
• Seed banks
Biodiversity – Answer the Following
• What are the threats to biodiversity?
Biodiversity – Answer the Following
• What are the threats to biodiversity?
– Biodiversity reduced with any loss of species
– Must aim to stop species becoming extinct
– Endangered species is one with v. low population
– And at risk of extinction
Reasons for reduction in species:
– Changes in land use = loss of habitat
– Climate change
– Over-exploitation e.g. overfishing, animal poaching
– Introduction of alien species which push out existing
species
Biodiversity – Answer the Following
• What is meant by biological and chemical control
and state the advantages of each over the other.
Biodiversity – Answer the Following
• What is meant by biological and chemical control
and state the advantages of each over the other.
– Biol. = the use of living organisms to control the population of
a pest species
– Chem. = the use of chemicals to control the population of a
pest species
Advantages of Biological Control
Advantages of Chemical Control
No chemicals used that may enter the
human food chain.
Specific to the pest
Less complicated to operate.
Doesn’t wipe pest out completely
Cheaper
Can be confined to a particular area
No risk of ‘alien species’ causing own
problem
Biodiversity – Answer the Following
• Outline a sampling technique you would use to
estimate the number of foxgloves in a meadow.
Biodiversity – Answer the Following
• Outline a sampling technique you would use to
estimate the number of foxgloves in a meadow.
– Divide the meadow area to be studied into a grid
– Number each square
– Select square at random
– Place the quadrat in that location.
– Record the number of foxgloves in quadrat.
– Repeat at other locations on the grid.
– Calculate average number in 1m2
– Multiply by total area of meadow
Biodiversity – Answer the Following
• Outline a sampling technique you would use to estimate the
change in plant species from low tide to high tide mark on a sea
shore.
Biodiversity – Answer the Following
• Outline a sampling technique you would use to estimate the
change in plant species from low tide to high tide mark on a sea
shore.
– Use a tape measure to produce a transect
– From low to high tide mark
– Place quadrat at beginning of transect
– Record the number of each species present.
– Repeat by placing the quadrat at regular intervals along the
length of the transect.
Biodiversity – Answer the Following
• Outline how you would use the capture-recapture
technique to estimate the population of an animal
species.
Biodiversity – Answer the Following
• Outline how you would use the capture-recapture
technique to estimate the population of an animal
species.
– A number of individuals of a particular species are
captured.
– Animals are marked (e.g. with a spot of paint).
– Animals released back into the wild.
– Later, another sample of the species is captured.
– Estimate population size (N) using (MC)/R
– M = number captured 1st visit; C = number captured
on second visit; R = number of marked animals
captured on second visit
Biodiversity – Answer the Following
• What conditions must apply in order for the capturerecapture technique to work?
Biodiversity – Answer the Following
• What conditions must apply in order for the capturerecapture technique to work?
– Sufficient time must have elapsed between samples
– There is no large scale movement of animals
– Marking does not affect survival chances of the animal
– The marking does not affect the chances of recapture
by making them more noticeable.
Biodiversity – Answer the Following
• 234 beetles were captured in a garden and marked with
paint. They were released, and three weeks later another
sample, this time of 210 beetles, was taken. Of the 210
captured, 18 were marked with paint. Use the capturerecapture technique to estimate the size of the beetle
population.
Biodiversity – Answer the Following
• 234 beetles were captured in a garden and marked with
paint. They were released, and three weeks later another
sample, this time of 210 beetles, was taken. Of the 210
captured, 18 were marked with paint. Use the capturerecapture technique to estimate the size of the beetle
population.
– N = MC
R
– N = 234 x 210 = 49140 = 2730 Beetles
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