Transcript Document

Standard Grade
Biology
Summary Power Point
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Cells
Animal Survival
Plants
Biosphere
Biotechnology
Inheritance
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Cells
Investigating
Aerobic Respiration
Investigating Cell
Division
Structure
Investigating
Enzymes
Investigating
Diffusion
Cell Structure
Cells are the basic units
of all living things.
All cells have three
structures
•cell membrane
•nucleus
•cytoplasm
Cell Structure
Plant cells also have
•cell wall
• large vacuole
•chloroplasts
Part of cell
Function
nucleus
controls cell activities
cell membrane
controls entry and exit of
chemicals
site of chemical reactions
cytoplasm
vacuole
chloroplasts
cell wall
contains cell sap (solution
of sugars and salts)
contain green chemical
chlorophyll which absorbs
light for photosynthesis
gives cell shape and
support
Types of cells
• Cell appearance related to it’s function.
Cell size
• Cell size may be measured in MICRONS
(ųm) or NANOMETRES (nm)
1 mm = 1000 ųm
1 ųm = 1000 nm
Using a microscope
• A microscope has three objective lenses and
an eyepiece lens.
• Each lens has a number written on it, such as
X8, which means this lens magnifies
something 8 times.
• The total magnification is the eyepiece X
objective lens:
eyepiece X10 X objective X20
Total Mag. = 200
eyepiece
course adjustment
handle
fine adjustment
handle
nosepiece
objective lens
stage
mirror
• 1. Place sample on slide. Must be thin
to allow light to pass through.
• 2. Add stain (iodine) to allow cell parts
to be seen clearly.
• 3. Lower cover slip avoiding air bubbles
• 4. Examine using lowest power first.
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Investigating diffusion
• Diffusion occurs in liquids and gases
• Diffusion is the movement of molecules from
where they are in high concentration to where
they are in low concentration
• Diffusion will continue until the molecules are
evenly distributed. This is called equilibrium
• The concentration difference which causes
diffusion to take place is called a
concentration gradient
LOW CONC.
HIGH CONC.
EQUILIBRIUM
Importance of diffusion
• A cell requires certain substances for
survival and its waste substances must
be removed
oxygen
glucose
Carbon
dioxide
Role of the cell membrane
• The membrane contains tiny pores that
allow substances that are small enough
to pass in and out of the cell.
• These substances must be soluble
(dissolve in water)
• Large, insoluble molecules cannot pass
through the membrane
Experiment:The model gut
• To be any use, food must reach individual
cells of the body. This means that food
molecules must be small enough to pass
from the gut to bloodstream through cell
membranes.
water
visking tubing
containing starch and
glucose
1. Tie knot at one end of visking tube
2. Add 10ml starch/glucose solution
using a dropper then tie other end
3. Rinse bag
4. Half fill boiling tube with water and
place bag in tube. Take sample of
water and place on dimple tile. Test
with iodine for starch and clinistix for
glucose.
5. Leave for 15 mins then repeat tests.
Results
Starch
Glucose
Present at
start
Present after
15 mins
Osmosis
• Osmosis is when water moves from a
high water concentration, across a
semi-permeable membrane, to a low
water concentration.
• By considering the concentration of
water on either side of the membrane,
we can decide in which direction water
will move.
Selectively permeable membrane
Distilled water (100% water)
20% glucose (80% water)
10% salt solution (90% water)
20% salt solution
30% sucrose solution
10% salt solution
20% lactose solution
10% salt solution
Experiment: Osmosis in plant cells
• We are going to decide if water has left
or entered potato cells by looking for
mass changes and estimate the
concentration of potato cell sap.
• You will need:
– Cork borer
– 5 test tubes + rack
– Syringe
– Balance
• Method:
10 ml water
10 ml
0.1M
sucrose
10ml
0.2M
sucrose
10ml
0.3M
sucrose
10ml
0.4M
sucrose
• Set up equipment as shown and label tubes
• Measure solutions and add to tubes using
syringe
• Cut 5 pieces of potato using borer and trim to
same length using scissors
• Blot potato samples dry then weigh using
balance
• Record start weights and add to appropriate
tubes
• Leave for 1 hour
• Remove potato, blot dry then re-weigh
Results:
Solution Initial
mass
(g)
water
0.1
sucros
e
0.2
sucros
e
0.3
sucros
Final
mass
(g)
Difference % change Class Av.
in mass (g) in mass
%
(g)
change
Osmosis in plant cells
• When water moves into a plant cell it passes
through the membrane and into the vacoule.
• Osmosis will continue until the cell is fully
stretched (turgid).The cell will not burst as the
cell wall prevents further water entry once the
cell is turgid.
• Plant cells in strong sugar/salt solutions lose
water causing the vacuole to shrink and the
cell membrane to pull away from the cell wall
(plasmolysed).
Osmosis in animal cells
• Animal cells have no cell wall and will
burst if placed in pure water or any
solution with a higher water conc. Than
that of their cytoplasm.
• In strong sugar/salt solutions animal
cells lose water and shrink.
Red blood cells
Strong sugar/salt
solution (shrink)
Normal
Pure water
(burst)
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Investigating enzymes
• Many chemical reactions are required to keep
a cell alive.
• Most reactions happen very slowly so cells
have substances called enzymes which make
reactions go fast enough to keep the cell
alive.
• Enzymes are biological catalysts
• At the end of a reaction, the enzyme remains
unchanged, which means it can be used to
speed the same reaction over and over
again.
Experiment: Breakdown of Hydrogen
peroxide by Catalase
• Hydrogen peroxide breaks down into
water and oxygen.
• Catalase is an enzyme found in living
tissue which catalyses this reaction.
Fresh
potato/liver
Hydrogen
peroxide
Dead
liver/potato
• Label test tubes
• Half fill each tube with hydrogen
peroxide
• Add food samples (should be roughly
same size)
• Observe reaction and test with a
glowing splint in mouth of test tube
Sample
Bubbles? Oxygen? Rate of
reaction
• The substance that an enzyme works
on is called the substrate and the result
of the reaction is called the end
product.The reaction cataylsed by
catalase can be written:
Hydrogen peroxide
(substrate)
Catalase
Water + Oxygen
(end products)
• Enzymes are specific
• This means that an enzyme will only work on
one substrate and will not effect other
substances
• Use a textbook to complete the following
table
Enzyme
Amylase
Catalase
Pepsin
Lipase
Phosphorylase
Substrate End
product
Experiment: Amylase activity
• Amylase is found in saliva. It catalyses
the breakdown of starch to maltose.
maltose
amylase
• Collect two starch agar plates and make a
well in the centre of each using a cork borer.
• Fill one well with fresh amylase and one with
water.
• Leave overnight
• Flood plates with iodine for 5mins then drain
off.
note; iodine will turn blue-black where starch is
present
• Results:
Experiment: using a building up
enzyme
• Phosphorylase is an enzyme found in plant
tissue which builds up the sugar made by
photosynthesis to starch for storage.
Glucose-1-phosphate
Starch chain
• Collect a slice of potato (about 1 cm
thick) and chop into 4 pieces.
• Place in mortar, add spatula of sand
and cover with water
• Grind with pestle
• Pour equal volumes of liquid into 2
centrifuge tubes
• Spin for 5 mins
• Test supernatant liquid for starch.
• Centrifuge until samples are starch free
• Set up dimple tile as shown then add
iodine to rows at times shown:
A
O min
B
C
Column A: 4 drops glucose-1-phosphate
and 4 drops potato extract
Column B: 4drops glucose-1-phosphate
and 4 drops water
3 min
6 min
9 min
Column C: 4drops potato extract and 4
drops water
Enzyme specificity
• The place on an enzyme’s structure where
catalytic activity occurs is called the active
site.
• An enzyme molecule may have many active
sites over its surface.
• Only substrate molecules which fit the active
site exactly will react with the enzyme
• Enzymes and substrates fit together rather
like a lock and key.
Effect of heat on enzyme activity
• Enzymes are proteins and proteins are
affected by changes in temperature.
• Think about the appearance of egg white
before and after it is cooked. High
temperatures permanently change the
structure of a protein.
• Since the function of an enzyme relies on its
shape, any changes in structure make it
permanently inactive or denatured.
1
2
3
• Enzymes are temporarily inactive or
work very slowly at low temperatures
• The temperature at which an enzyme
works best is called the optimum
temperature.
Effect of pH on enzyme activity
• pH is a measure of how acid or alkaline
a solution is.
• Enzyme activity is affected by pH.
• Enzymes work best at an optimum pH.
• Each enzyme works best at a particular
pH related to the conditions in which it
normally operates.
• Pepsin is found in the stomach and is
most active at pH 2-3
• Catalase works best around pH9
• Most enzymes work best around pH 7.
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Cell Division
• Most large animals grow by increasing the
number of cells in the body
• This process is called mitosis and is
controlled by the nucleus
• Genetic information required for the survival
of a living cell is found on structures called
chromosomes which are found in the nucleus
• During mitosis the nucleus divides to from two
daughter nuclei which both receive the same
number of chromosomes which were present
in the original nucleus. Two new cells can
then be formed.
• Every species of plant and animal has a
characteristic number of chromosomes. This
is called the chromosome complement
• Human cells have 46.
• It is important that every new daughter cell
the correct number of chromosomes. Any
changes could result in a cell not carrying the
information to do its job.
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Respiration
• Living things obtain their energy from food.
They use this energy for a variety of needs:
–
–
–
–
–
Growth
Reproduction
Movement
Warmth
Metabolism (chemical reactions)
• The energy in food is chemical energy. Cells
convert this into other types of energy
(movement etc.)
• Some food types contain more energy
than others.
• Fats contain most energy per gram than
carbohydrates or proteins
• Although carbohydrates contain less
energy, it is easier to release the energy
from them
• The body’s main energy supply comes
from the carbohydrate glucose.
• The process that releases this energy is
called:
respiration
Food calorimeter
• A food calorimeter can measure the
energy content of food.
• The energy in food is measured in
Kilojoules (kJ)
• Food samples are burned inside the
calorimeter and the rise in water
temperature is used to determine the
energy content of the sample
Burning food
Food type
Start
temp. C
Final
temp. C
Temp.
difference C
Aerobic respiration
• Oxygen is required by cells to carry out
respiration, therefore the process is called
aerobic respiration
• Respiration can be written as a word
equation:
glucose + oxygen
carbon dioxide + water
+ ENERGY
• Carbon dioxide and water are waste products which
we breathe out
Experiment: Measuring uptake of
oxygen
• We can measure respiration by using a
respirometer. This shows that oxygen is
being used
• Soda lime absorbs any CO2 in air or
produced during respiration.
• Water levels in capillary tubes are equal
on each side at start of experiment
• Living sample added to one side, nonliving sample of same mass added to
other (control).
syringe
Nonliving
sample
Living sample
Soda lime
Soda lime
(absorbs CO2)
coloured liquid
• Results: As the living sample uses up
oxygen for respiration, the volume of air
in the tube decreases. This causes a
decrease in air pressure and the
coloured liquid moves up the tube
towards the living sample to fill the
resulting space.
Experiment: measuring carbon
dioxide production
Tin foil
Bicarbonate indicator
• Bicarbonate indicator tests for the
presence of carbon dioxide.
• It is red in normal air
• It is yellow when carbon dioxide is
produced
• It turns purple when oxygen is produced
Test tube
Indicator after 24
hours
A
B
C
• 1. Which test tube is the control?
• 2. In which test tube has respiration
occurred?
• 3. What process is occuring in test tube B?
Experiment: measuring heat
produced by respiration
Live peas
Dead peas
Vacuum flask
thermometer
Vacuum flask
Temp. at start
(ºC)
Temp. at end
(ºC)
Live peas
Dead peas
• 1. Why are both sets of seeds soaked in
disenfectant before being used?
• 2. Why are the flasks not completely filled
with seeds?
• 3. Not all the energy produced by the seeds
will be produced as heat. What happens to
the rest of the energy?
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Introducing Plants
Growing Plants
Making Food
Subtopic a: Introducing Plants
Uses of Plants
• The Earth has an enormous variety of
plants.
• Plants provide us with some extremely
important uses.
Brainstorm some uses of plants
Tea/Coffee/Cocoa
Paper
Medicines
Cooking Oils
Perfumes
Rubber
Fabrics e.g.
cotton
Food
Timber
• Food
All food on Earth comes directly or
indirectly from plants e.g. carrot,
potato, wheat etc.
• Medicines
A lot of the medicines we use contain
ingredients that were originally from
plants.
Examples
Name of
Plant
Poppy
Drug
Use
extracted
Morphine Pain Killer
Foxglove
Digitoxin
Treats
heart
disease
Rosy
Vincristine Treats
Periwinkle
leukaemia
Learn at least one!
Ecological Loss
• If any species of plant is allowed to die out, the
possible consequences are very serious .
• Many plants represent potential resources (food or
raw materials) which may become essential in the
future.
• Every plant provides food and / or shelter for a variety
of organisms, some of which may only be able to live
on that particular species.
• The genetic characteristics of a particular plant may
turn out to be very useful. Biologists can transfer
such characteristics from one species to another, and
the loss of any species means a reduction in the total
reserves of available genes.
Potential Uses of Plants
• New food sources.
There are a large number of plants that are
edible but are not yet produced on a
commercial scale.
• New Medicines
There are many drugs that still have to be
studies. They may hold the cure to cancer
or AIDS.
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Subtopic b: Growing Plants
Structure of a Seed
A seed is made of the
embryo (root & shoot) and
a supply of food, both
enclosed in a tough seed
coat.
Structure
Function
Embryo
Grows into a plant
(undeveloped plant)
Seed Coat
Protects internal
structures of seed
Food Store (Seed
Leaves - cotyledons)
Contain starchy food
which embryo uses to
grow.
Activity
Examine some broad bean seeds by
peeling off the seed coat and opening
the seed. Test the food store with
iodine solution.
What is the food store mainly
composed of?
Germination
• Germination is when
a seed starts to
grow a root & shoot
which develops into
a new plant.
• This only happens
when the conditions
are suitable.
Experiment – Conditions for Growth
• Set up the apparatus shown in the
diagram and leave for a few days.
20 Cress seeds
20 Cress seeds
20 Cress seeds
20 Cress seeds
Oxygen
NO Oxygen
Oxygen
Oxygen
Water
Water
NO Water
Water
Room Temp
Room Temp
Room Temp
Freezing Temp
Results
Test tube
No. of seeds
germinated
1
2
3
4
0
0
20
0
Conclusion:
In order for seeds to germinate they
need
• ____________
• ____________
• ____________ e.g. 22ºC
The Effect of Temperature on Germination
• Germination is affected by
temperature.
• The temperature that seeds will
germinate best at is known as the
optimum temperature.
• The table below shows the number
of seeds germinating at each
temperature out of 40
Temperatue
(ºC)
10
15
20
25
30
35
40
45
No.
germinating
12
20
28
37
31
22
15
6
%
germination
Questions
1. Calculate the % germination at each
temperature and complete the table.
2. Plot a line graph of these results to
show % germination at each
temperature.
3. Describe the effect of temperature
on the germination of the seeds.
4. What was the optimum temperature
for germination in these seeds?
Your graph should have this shape:
• Flowers are the reproductive organ of flowering plants.
• It is here that the seeds are made.
Petals
Stamen/anther
Stigma
Style
Ovary
Sepal
Nectary
Structure
Function
Sepals
Protect the unopened bud
Petals
Brightly coloured to attract
insects
Stamens
Male part of the flower
Anthers
Produce male sex cells (pollen)
Stigma
Female part which collects pollen
Ovary
Produces female sex cells
(ovules)
Nectaries Produces nectar which attracts
insects
• Pollination is the transfer
of pollen (male sex cell)
from the male anther to
the female stigma.
• If pollen is transferred to
the stigma of a flower on a
different plant this, it is
called cross pollination.
• If pollen is transferred to
the stigma of the same
flower, it is called
self pollination.
Crosspollination
Selfpollination
Feature
Bright coloured petals
Scented petals
Contain nectar
Function
Attract insects
Attract insects
Attract insects
Sticky or spiky pollen Stick to insects
Anthers inside flower Insects brush against
Stigma inside flower Insects brush against
Sticky stigma
Pollen sticks to it
Feature
Function
Dull, small petals
No scent
No nectar
No need to attract insects
No need to attract insects
No need to attract insects
Large amount of pollen Lots of pollen wasted
Light, smooth pollen
Long anthers which
hang outside flower
Long stigmas which
hang outside flower
Feathery stigmas
To be blown in the wind
easily
To allow pollen to be blown
away
To catch drifting pollen
To catch drifting pollen
• If a pollen grain of the correct species lands
on the stigma of a flower, the pollen grain
germinates.
• A pollen tube grows from the pollen grain
down towards the ovule.
• The nucleus of the pollen grain then travels
down the tube to join with the nucleus of the
ovule.
• This meeting of the two nuclei is called
fertilisation.
• This results in the formation of a seed which
contains the embryo plant.
• After fertilisation the female parts
of the flower develop into a fruit.
• The ovary wall becomes the fleshy
part of the fruit and the ovules
become the seeds.
• Seeds are dispersed away
from each other and the
parent plant to reduce
competition.
• The three main methods of seed dispersal are:
1.
Wind – seeds usually have wings
or parachutes to carry them away.
2.
Animal Internal – brightly coloured,
juicy fruits which contain seeds with indigestible coats,
seeds eaten by animals and seed passes out of animal’s
body.
3.
Animal External – fruits have hooks which
attach to fur of passing animals.
4.
Self Explosive – fruits who’s seeds disperse themselves.
Now complete the seed dispersal cut out exercise!
(You may wish to show a video of ‘dispersal of seeds’)
• Now complete the plant life cycle cut
outs.
• You may wish to show a video of the
plant life cycle.
• Plants can reproduce by 2 methods:
- Sexual Reproduction
Involves 2 parents and the production of
sex cells. Pollination and fertilisation must
take place followed by seed dispersal and
germination.
- Asexual Reproduction
Involves only 1 parent. It is a very quick
method of reproduction and does not
depend on pollination, fertilisation etc. New
plants are formed from outgrowths of buds
from the parent plant. All new plants are
identical to parent.
(a) Bulbs
• A bulb contains thick
fleshy leaves full of
stored food which is
stem
used for the growth of
a new plant.
• During the summer new
bulbs are formed
Fleshy leaves
attached to the old store food
parent bulbs. These
new bulbs give rise to
new plants.
roots
• Examples –Daffodils, &
onions
(b) Tubers
During the summer,
some plants
produce swollen
underground stems
as a food store. If
planted, these will
lead to new plants.
Examples –
potatoes, carrots &
Crocus.
(c) Runners
• Some plants produce
side shoots from the
parent plant which
trails along the
surface of the soil.
• These shoots may
develop roots and
eventually become
detached from the
parent.
Asexual
Reproduction
Sexual
Reproduction
Advantages
•Young plant has its
own food store or
recieves food and
water from parent.
•Fast process,
pollination plays no
part.
•Different
Characteristics
inherited from each
parent producing
variety amongst
offspring.
•Plants are well
distributed which
means less competition
for light, water etc.
Disadvantages
•Lack of variety – poor
ability to adapt to
environmental changes
and lack of resistance
to disease.
•Overcrowding as
offspring surround
parent. Leads to
competition for light,
•Slow process
•Many seeds may not
germinate.
• A clone is a group of cells or
organisms which are genetically
identical to each other.
• Also known as artificial propagation.
• It makes use of asexual reproduction
in order to propagate plants.
• 2 methods are
-Grafting
-Cuttings
1. Grafting
• A small branch of a
chosen plant is cut and
the end trimmed and
tapered.
• A slit is done in the
stem of the well
established plant and
the tapered end of the
branch is inserted into
the slit.
• If the graft ‘takes’,
then both will grow as
one plant.
• Used to produce fruit.
2. Cuttings
•Young, fast growing shoots are cut from a parent plant
with a sharp knife.
•The cutting is dipped into rooting powder to encourage
root growth.
•Cutting is then planted into moist soil.
• Quick method of producing large
numbers of new plants.
• Particular varieties that are required
can be produced easily.
• Allows people to save rare plant that
are threatened by extinction.
• All the plants are uniform i.e. they
are clones.
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(c) Making Food
• Plants need a transport system to get
water and minerals from the soil up to the
leaves and to move sugar from
photosynthesis around the plant
• The transport system consists of bundles
of tubes running up and down the plant
(vascular bundles)
Xylem
Carry water from the soil up to the
leaves where the water is needed for
photosynthesis
Demonstrating the site of water movement in a plant
• Cut a piece of celery
and place it into a
beaker of red dye
until next day.
• Observe what
happened.
Before
After
Xylem
• Xylem vessels are hollow dead tubes.
• Their walls are strengthened and
thickened with lignin.
• The lignin also helps support the plant
• Minerals from the soil are also
carried in the xylem
Phloem
• Phloem (sieve) tubes carry sugar (food)
around the plant.
– Phloem Cells are alive
– They have (sieve) plates to let
the sugar through.
– The companion cells at the side
provides energy for the
transport of the sugar.
Vascular Bundles
• In the plant xylem and phloem are grouped very
close together. They are arranged in
structures called vascular bundles.
• The positioning of these vascular bundles in
roots and stems is different.
Activity – label the diagram of a vascular bundle.
Vascular Bundles
Root – Cross Section
Epidermis
Cortex
Xylem
Phloem
Stem – Cross section
Phloem
Xylem
Epidermis
Photosynthesis
•
Photosynthesis is the process where
green plants (producers) make their own
food.
• The food they make is a carbohydrate
called glucose sugar.
• The plant can use the glucose in 3 ways:
1. Stored for later use as starch
2. Used in the process of respiration
3. Used for structural carbohydrates e.g.
cellulose for making cell walls.
Testing for Photosynthesis
•
Glucose manufactured in the process of photosynthesis can be stored as starched. We can
test for starch using iodine solution following the steps outlined below.
Exp 1 – To show light is needed
• Light energy is trapped by the chlorophyll within
the chloroplasts of green plants. Photosynthesis
cannot occur in the dark. You will test 2 plants
for the presence of starch. One plant will be put
in the dark and the other will be exposed to
light.
Result
Condition
Colour
Starch
present?
Plant in light
Plant in dark
Conclusion
Plants need _________ in order to make _________.
The _________ of light is converted to __________
energy, which is contained in this food they make.
Exp 2 – To show CO2 is needed
You will test 2 plants, one which is exposed to CO2 in the air
and the other which has been exposed to a chemical called
soda lime which absorbs CO2.
Results
Condition
Colour
Starch
present?
CO2 present
CO2 absent
Conclusion
Plants require __________ ___________ in order to carry out
photosynthesis.
Exp 3 To show chlorophyll is needed
For photosynthesis to occur the plant must have
choroplasts. Chloroplasts contain a green pigment
called chloropyll, which traps light energy. A type of
plant called a variegated plant has both green and
white parts.
Part
Results
Colour
Starch present?
Green part
White part
Conclusion
Photosynthesis only occurs in _________parts of the plant
because it contains __________. This chlorophyll is
needed for photosynthesis because it traps the energy
from sunlight and coverts it into chemical energy to
power the process of photosynthesis.
Photosynthesis Summary
• Photosynthesis is the process where ________
_________ make their own food _______.
Photosynthesis occurs in _________ where
_________ traps light energy. _________
__________ gas is also required. A by product of
photosynthesis is Oxygen gas.
Word Equation
Carbon dioxide +water
(Raw materials)
light
chloropyhll
Glucose + Oxygen
(Product)
(By-product)
Limiting Factors
• A limiting factor is a factor when in
short supply can slow down or limit
the rate of photosynthesis.
• Photosynthesis can be limited by
-Carbon Dioxide concentration
-Light intensity
-Temperature
Elodea Bubbler Experiment
• An experiment can be set up to
measure the rate of photosynthesis.
• Elodea is an aquatic plant. When
placed in water, this plant under the
conditions suitable for photosynthesis
will release oxygen bubbles.
• The number of oxygen bubbles
released can be used to determine the
rate of photosynthesis.
The effect of light intensity on the rate of photosynthesis.
Units of light
Number of oxygen
bubbles released per
minute
• Use multimedia science school and look
at how CO2 and light intensity can limit
the rate of photosynthesis.
• Graph your results.
Leaf structure
• The structure of a leaf is suited to its function.
Tissues of a leaf
• Upper Epidermis – consists of a waxy cuticle which prevents
water from evaporating from the leaf surface.
• Palisade (mesophyll) cells – many column shaped cells full of
chloroplasts. This is the site of photosynthesis.
• Spongy mesophyll cells – the cells here also have
chloroplasts and photosynthesis may occur if light reaches
this layer. There are many air spaces in this layer to allow
gases into and out of the leaf.
• Veins- these contain both xylem and phloem.
• Lower epidermis – Have same cells as upper epidermis but
also contain pores called stomata. Each stomata is
surrounded by 2 guard cells which open and close the
stomata.
Stomata
• Stomata are tiny pores
found on the under
surfaces of a leaf.
• They are involved in gas
exchange.
• During the day, they open
to allow carbon dioxide to
enter for photosynthesis
to take place and to allow
exit of oxygen.
• During the night, the
stomata are closed to
conserve energy and
photosynthesis cannot take
place in the dark.
Open
- Day
Closed
-Night
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Animal Survival
Reproduction
Water and
Waste
Responding to the
Environment
Click on the topic you want to revise
Reproduction
Sexual Reproduction
• Reproduction is the production of new
members of a species. For a species to
survive it must produce enough young
to replace those lost through old age,
disease etc.
• Humans produce sex cells (sexual
reproduction) or GAMETES which join
together at FERTILISATION.
Reproduction in humans
• The male gametes in humans are called
sperm.
Sperm
• The sperm are made in the testes.
Reproduction in humans
• The female sex cells in humans are
called ova.
Ovum
• The ova are made in the ovary.
Male Reproductive organs
Sperm duct: takes
sperm from testicle
to vagina
Testes: produce
sperm
Penis: deposits sperm in
vagina
Female Sex Organs
Vagina
Where sperm are
deposited
Female Sex Organs
Uterus
Where baby
develops
Vagina
Female Sex Organs
Ovary
Where ova
are produced
Uterus
Vagina
Female Sex Organs
Oviduct
Connects ovary
to uterus
Uterus
Ovary
Vagina
Human reproduction
• The sperm and ova each carry half the
genetic information to construct a new
human being.
• The sperm reaches the egg by
swimming towards it.
Zygote –fertilised ovum
Fertilisation
• Fertilisation takes place in the oviduct.
• The sperm’s nucleus enters the egg with
fuses with the egg nucleus.
• The resulting cell is called a zygote
• The zygote then divides as it travels to
the uterus where the embryo implants
into the uterus wall.
• After 8 weeks – when all major structures
have formed – the embryo is known as a
foetus.
• It will develop here for 9 months.
Development in the Uterus
• During gestation the developing embryo is
protected in the uterus by amniotic fluid in an
amniotic sac.
• Its mouth and nose are not used for feeding
or breathing at this time
• Instead the embryo is attached by its
umbilical cord to the placenta. Which allows it
to receive food and oxygen from its mothers
blood
• The placenta allows blood of mother
and baby to come into close contact.
• Urea and carbon dioxide moves from
baby to mother by diffusion
• Oxygen and food move from mother to
baby
• In the placenta mother & baby’s blood
never mix
• The placenta is a large disc with fingerlike villi which project into the uterus
wall.
• The villi provide a large surface area for
diffusion
• Maternal and foetal blood are only
separated by thin membranes so
diffusion is able to take place.
Internal Fertilisation
• Fertilisation takes place when the sperm
and ova meet.
• In land animals this takes place in the
oviduct of the female.
• The sperm are released during
copulation in a fluid which allow the
sperm to swim towards the ovum.
External Fertilisation
• Aquatic animals release sperm and eggs
directly into the water.
• To increase the chance that some
sperm will reach the eggs many animals
have a courtship ritual.
– Eg stickleback: males perform zig-zag
dance to attract females. Femlae lays eggs
in a nest and male deposits eggs on top.
Protecting Embryos
• Few species of fish
protect their embryos.
• Instead the embryos
develop in a protective
covering with a food
store – YOLK.
• This yolk provides the
developing embryo and
young fish with food.
Care of Young - Fish
• After hatching many young fish receive
no parental care and are also eaten.
• Fish therefore produce large numbers of
sperm & eggs to ensure that:
– Some eggs are fertilised
– Some embryos survive development.
– Some fish survive to reproduce
1000 Eggs
1000000 Sperm
100 Fertilised Eggs
50 Young Fish
5 Adult Fish
Care of Young - Mammals
• Because mammals have internal
fertilisation fewer eggs and sperm need
to be produced.
• The embryo is then protected in the
uterus by the amniotic fluid and
nourished via the placenta.
• Newborn mammals are protected by
their parents and fed with milk from the
mothers mammary glands.
• Young mammals are more likely to
survive to adulthood so fewer need to
be produced.
Reproduction
Sexual Reproduction
• Reproduction is the production of new
members of a species. For a species to
survive it must produce enough young
to replace those lost through old age,
disease etc.
• Humans produce sex cells (sexual
reproduction) or GAMETES which join
together at FERTILISATION.
Reproduction in humans
• The male gametes in humans are called
sperm.
Sperm
• The sperm are made in the testes.
Reproduction in humans
• The female sex cells in humans are
called ova.
Ovum
• The ova are made in the ovary.
Male Reproductive organs
Sperm duct: takes
sperm from testicle
to vagina
Testes: produce
sperm
Penis: deposits sperm in
vagina
Female Sex Organs
Vagina
Where sperm are
deposited
Female Sex Organs
Uterus
Where baby
develops
Vagina
Female Sex Organs
Ovary
Where ova
are produced
Uterus
Vagina
Female Sex Organs
Oviduct
Connects ovary
to uterus
Uterus
Ovary
Vagina
Human reproduction
• The sperm and ova each carry half the
genetic information to construct a new
human being.
• The sperm reaches the egg by
swimming towards it.
Zygote –fertilised ovum
Fertilisation
• Fertilisation takes place in the oviduct.
• The sperm’s nucleus enters the egg with
fuses with the egg nucleus.
• The resulting cell is called a zygote
• The zygote then divides as it travels to
the uterus where the embryo implants
into the uterus wall.
• After 8 weeks – when all major structures
have formed – the embryo is known as a
foetus.
• It will develop here for 9 months.
Development in the Uterus
• During gestation the developing embryo is
protected in the uterus by amniotic fluid in an
amniotic sac.
• Its mouth and nose are not used for feeding
or breathing at this time
• Instead the embryo is attached by its
umbilical cord to the placenta. Which allows it
to receive food and oxygen from its mothers
blood
• The placenta allows blood of mother
and baby to come into close contact.
• Urea and carbon dioxide moves from
baby to mother by diffusion
• Oxygen and food move from mother to
baby
• In the placenta mother & baby’s blood
never mix
• The placenta is a large disc with fingerlike villi which project into the uterus
wall.
• The villi provide a large surface area for
diffusion
• Maternal and foetal blood are only
separated by thin membranes so
diffusion is able to take place.
Internal Fertilisation
• Fertilisation takes place when the sperm
and ova meet.
• In land animals this takes place in the
oviduct of the female.
• The sperm are released during
copulation in a fluid which allow the
sperm to swim towards the ovum.
External Fertilisation
• Aquatic animals release sperm and eggs
directly into the water.
• To increase the chance that some
sperm will reach the eggs many animals
have a courtship ritual.
– Eg stickleback: males perform zig-zag
dance to attract females. Femlae lays eggs
in a nest and male deposits eggs on top.
Protecting Embryos
• Few species of fish
protect their embryos.
• Instead the embryos
develop in a protective
covering with a food
store – YOLK.
• This yolk provides the
developing embryo and
young fish with food.
Care of Young - Fish
• After hatching many young fish receive
no parental care and are also eaten.
• Fish therefore produce large numbers of
sperm & eggs to ensure that:
– Some eggs are fertilised
– Some embryos survive development.
– Some fish survive to reproduce
1000 Eggs
1000000 Sperm
100 Fertilised Eggs
50 Young Fish
5 Adult Fish
Care of Young - Mammals
• Because mammals have internal
fertilisation fewer eggs and sperm need
to be produced.
• The embryo is then protected in the
uterus by the amniotic fluid and
nourished via the placenta.
• Newborn mammals are protected by
their parents and fed with milk from the
mothers mammary glands.
• Young mammals are more likely to
survive to adulthood so fewer need to
be produced.
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Water & Waste
• Our bodies gain water in 3 different ways:
• Drinking fluids
• Eating foods
• Chemical reactions – e.g. respiration
• Our bodies lose water in 4 different ways:
• Urine
• Faeces
• Breathing
• Sweating
Water Balance
• To ensure that the water concentration
of our bodies always stays the same:
Water Gain = Water
Loss
The Kidneys
The kidneys have 2 main
functions.
– Maintaining water balance.
– Getting rid of poisonous waste
substances, such as urea, from
the body.
Urea
• Urea is a poisonous waste product formed
from of protein & amino acids digestion.
• It is made in the liver and travels to the
kidneys in the blood where it is filtered
from the blood
• If not removed its build up causes death!
How the Kidneys Work
• Each kidney is made up
of about 1 million tiny
tubes called
NEPHRONS which
filter the blood and then
reabsorb the useful
substances.
How the kidneys work
• Blood from the renal artery enters a knot of
capillaries called the GLOMERULUS.
• The blood is under high pressure and all
small molecules such as water, salt, glucose &
urea are forced out of the blood and into the
BOWMANS CAPSULE.
• The filtered small molecules make up glomerular
filtrate and passes into the nephron.
• Useful substances such as glucose, water & salt
are reabsorbed into the capillaries from the Loop
of Henle.
• The urea and excess water & salt are passed
into the COLLECTING DUCT.
• This is passed along the URETER and stored in
bladder as URINE.
• Urine leaves the body via the URETHRA.
Water
Regulation
• The kidneys regulate water, but this is controlled
by the brain.
• The brain produces ANTI-DIURETIC
HORMONE (A.D.H.) which controls the amount
of water reabsorbed by the kidney nephrons.
• Different amounts of ADH are produced to suit
the varying water conditions of the body,
ensuring water balance is maintained.
Role of ADH
Water content of
blood too low
Salt eaten or
much sweating
Brain releases
much ADH
Too much
water drunk
Water content of
blood normal
High volume of
water passes
into blood
High volume of
water reabsorbed
by kidney
Small volume of
concentrated urine
passed to the bladder
Water content of
blood too high
Brain releases
little ADH
Low volume of
water passes
into blood
High volume of dilute
urine passed to the
bladder
Low volume of
water reabsorbed
by kidney
High Water Conc. In Blood
• Less ADH released from brain
• Less water reabsorbed from the
nephron into the blood
• High quantity of dilute urine produced
• Water conc. of blood returns to normal
Low Water Conc. In Blood
• Lots of ADH released from the brain.
• Lots of water reabsorbed from the nephron
into the blood.
• Low volume of concentrated urine is
produced
• Water conc. of the blood returns to normal
Kidney Failure
• If the both kidneys stop working because of
disease or damage, then unless treated, the
person will die.
• To prevent death a patient must undergo
– Kidney transplant
– Kidney dialysis
Kidney Dialysis
• Blood is passed from the body into a dialysis
machine.
• The machine filters out harmful substances
such as urea and salt.
• The purified blood is passed back into the
blood.
• This keeps a person alive but is very
time consuming:
– 4 x 12 hour sessions per week
Kidney Transplant
• A kidney from a donor is transplanted into the
body.
• This donor kidney filters & purifies the blood
allowing the patient to lead a normal life.
• There is a danger of rejection and suitable
donors are not always easily found.
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Responding to the Environment
Animal Survival
• Animals respond to changes (stimuli) in their
environment.
• The way in which the animal responds will affect its
chances of survival.
• Responses to environmental stimuli can be studied
using a choice chamber.
• There are many stimuli in the environment e
– moisture
– smell
– sound
– taste
– Light
– chemicals
– vibration
– pH
• Some example of stimuli and
responses are:
– Blowfly maggots and woodlice
move away from light to escape
predators.
– Paramecium move towards acid
because their prey organism,
bacteria, produce acid.
– Woodlice move towards
moisture to prevent drying out.
Rhythmical Behaviour
• Occurs at regular intervals.
• A stimulus which causes rythmical behavior is called a trigger
stimulus.
– Daily (circadian):
• The trigger stimulus is darkness or daylight.
• Such as sleep and feeding patterns – to make use of the
daylight or the darkness.
• Examples of night active organisms are bats and owls, and
day active organisms are cows and sheep.
• Tidally:
– The trigger stimulus is the tide
rising and falling.
– Sea anemones come out of
their protective jelly-like body
at high tide to feed on the
plankton.
– Crabs feed along the shoreline
at low tide when there is a lot
of debris.
• Once a year.
– The trigger stimulus can be the days lengthening or
shortening.
– Geese migrate to Islay in the autumn and to Greenland in
the spring.
– Sheep and cows breed in the autumn to make sure the
young are born in the spring when there is plentiful food.
Biorhythms
• Recurring behaviour patterns occur in
humans – most physical & mental
activity occur during daytime.
• When these patterns get disturbed on
long distance air flights across time
zones, this give rise to “Jet Lag”.
Tidal Changes
• Tidal movement occurs twice daily – i.e.
2 high tides and 2 low tides in 24 hours.
Rhythmical Behaviour in Shore Crabs
• The shore crab regulates its period of activity to
coincide with the movement of the tide.
• The shore crab is found in rock pools where it
feeds on prey at low tide
Annual Changes
• During summer the number of
daylight hours (daylength) is
greater than in winter.
Annual Changes
• In response to increasing / decreasing
day length some animal may:
– Breed – ensures young are born when
there are favourable conditions.
– Migrate – move to an area where the
conditions (food / weather) are better.
– Hibernate – allows animals to survive
extreme conditions.
Hibernation
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Biosphere
Go Back to Main Menu
Biosphere
Investigating an
Ecosystem
Control and
Management
How it Works
Click on the Sub-topic you want to revise
Investigating an ecosystem
• Find out and write down definitions of
the following words associated with
the biosphere:
• Ecosystem
• Habitat
• Community
• Population
• There are certain factors which affect
lives of all the members of a community.
• Factors relating to living things are
called biotic factors and include:
– Food availability
– Disease
– Competition
• Non-living factors are called abiotic
factors and include
–
–
–
–
Temp.
Rainfall
Light intensity
pH
Sampling techniques
• Studying an ecosystem involves
– Finding out what plants and animals live
there
– Finding out how many of them live there
– Finding out why they live there
• Samples are taken to help investigate
an ecosystem. Here are some common
sampling techniques….
• Using a quadrat:
– Rectangular unit with a known
area such as 1m2
– Used to estimate numbers of
plants or slow moving animals
– Example: Estimating no. of
thistles in a field
• Quadrat placed at random and
number of thistles in quadrat
counted. Repeated several
times.
• Average number per square
metre is calculated.
• Area of whole field measured
• Estimate of total number of
thistles in field calculated
• Tree beating:
– A stick is used to give a tree
branch a few sharp taps.
– Small animals drop onto a tray
held below.
– This should be repeated by
beating several different
branches for average results.
– A tray with large sides should
be used to minimise animals
escaping
• Pitfall trap:
– Container in dug into ground to
trap animals that are active at
soil surface.
– Several traps should be set up.
– Errors could include animals
eating each other or birds eating
animals from the traps.
– Traps should be disguised as
much as possible
• Netting:
– Net is moved rapidly
through the water catching
animals which are quickly
transferred to jars.
– Must be repeated many
times
– Fine mesh should be used
to stop small animals
escaping.
Keys
• Used to identify organisms while sampling.
• 2 types
– Paired statement
– branch
1.
Has green coloured body ......go to 2
Has purple coloured body ..... go to 4
2.
Has 4 legs .....go to 3
Has 8 legs .......... Deerus octagis
3.
Has a tail ........ Deerus pestis
Does not have a tail ..... Deerus magnus
4.
Has a pointy hump ...... Deerus humpis
Does not have a pointy hump.....go to 5
5.
Has ears .........Deerus purplinis
Does not have ears ......Deerus deafus
Unidentified organism
Has a green coloured body
Has 4 legs
Has a tail
Does not have a tail
Deerus pestis
Deerus m agnus
Has a purple coloured body
Has 8 legs
Has a pointy hump
Deerus octagis
Deerus hum pis
No pointy hump
Has ears
No ears
Deerus purplinis
Deerus deafus
Measuring abiotic factors
• Light intensity:
– Light meter is held with sensor
panel pointed towards source to be
measured
– Reading is taken when pointer stops
moving
– Possible errors
• Casting a shadow over meter while
taking reading.
• Changing weather such as cloud cover.
All measurements should be taken at
same time of day.
• Moisture:
– Probe of moisture
meter is pushed
fully into soil.
– Reading taken
when pointer stops
moving.
– Possible errors:
• Probe not dry at
start. Probe should
be wiped before
every use.
• Organisms can only survive in an
ecosystem if certain abiotic factors
suited to their needs are present
there.
• This effects the distribution of
organisms in any ecosystem.
• For example:
– Daisies only grow in areas of high light
intensity so they can carry out
photosynthesis and would therefore be
found in open areas and not in the shade
of larger plants eg. Trees.
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How it works
• All energy in an ecosystem comes from sun.
• Green plants are called producers as they
make their own food.
• Other plants and animals are called
consumers as they eat to obtain energy.
– Primary consumer: animal that eats plants
– Secondary consumer: eats the primary consumer
• Energy is passed between organisms
– When a primary consumer eats a plant, energy is
transferred from plant to animal.
• Energy flow in an
ecosystem can be
shown as a food
chain or food web.
• A food chain always
starts with a
producer and each
arrow indicates the
direction of energy
flow.
• In most ecosystems
the energy flow is
shown by several
interlinked food
chains. This is called
a food web.
• Energy is lost at each link in a food
chain or web.
– predators will not eat every part of
their prey so not 100% of energy will be
passed on.
– Animals use energy for warmth and
movement throughout their lives. This
energy is not passed onto predators.
• Since energy is lost at every arrow,
smaller food chains/webs are more
efficient.
• The numbers of
each species in a
chain can be shown
as a pyramid. There
are always more
producers, followed
by the primary
consumers and so
on.
• Animals higher up
in the chain are
larger and tend to
need more energy
to survive.
• A pyramid of biomass shows the
biomass of each species in a chain.
• The producers have the highest,
followed by the primary consumers
and so on.
Disturbing a food web
• Removing a species from a
food web effects the
population of other species
around it.
• If the rabbits were
removed from the web,
which species would be
effected?
• Would their numbers
increase, decrease or stay
the same?
• The smaller the web, the
more severe the effect.
Population growth
• Growth rate of a species depends on birth and
death rates.
• If births exceed deaths then the population will
increase and vice versa.
• Population size is regulated by:
–
–
–
–
–
Food/water supply
Space
Predators
Toxic wastes
Disease
• These factors prevent uncontrolled population
growth.
• The first curve shows
unlimited growth
without any regulating
factors.
• The second shows a
more realistic growth
curve.
Predator-prey relationships
• The graph shows that
as prey numbers
increase, predator
numbers shortly follow
and vice versa.
• Notice how the prey
numbers are always
higher since they are
lower down in the food
chain.
Competition
• Arises when two or more members of the
same community need the same resource
which is in short supply.
• Green plants compete for light, water, soil
nutrients etc.
• Animals compete for water, food, shelter,
mates etc.
• Weaker individuals lose out and often die.
Stronger, successful competitors survive
to breed and pass on their favourable
genes.
Nutrient cycles
• Nutrients are substances needed by living
things to stay alive and grow ex. nitrogen,
oxygen and water
• When an organism dies, chemicals present
in its body are released back into the
ecosystem by decomposing bacteria and
fungi (saprophytes).
• These nutrients then become available for
use by living things in the ecosystem
• This takes the form of a cycle
Nutrients in
living organisms
Excretion
and death
Absorption by
living things
Nutrients in
enviroment available
for use
Nutrients in
dead bodies and
wastes
Decomposition by
bacteria and fungi
Nitrogen cycle
• All living things need N to make protein however
plants and animals cannot make use of it directly.
• Some plants absorb N form the soil as nitrates. They
have swellings on their roots called nodules which
contain N fixing bacteria.
• Animals must take in protein in their diet.
Nitrogen
gas in air
Nitrogen in
animals
(protein)
Nitrogen
in plants
(protein)
Nitrogen in
dead bodies
and wastes
(urine etc)
Nitrogen in
nitrates in
soil
Nitrogen in ammonium
compounds in soil
Nitrogen in
nitrites in
soil
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Control and management
Pollution
Part of enviroment
Source of
pollution
Example
Possible control
Air
Industry/coal fired
power stations
SO2
Scrubbing fumes
before release
Car exhausts
CO and lead
Filters /unleaded
petrol
Land
Homes and cars
Rubbish and car parts
Recycling/ burying
/burning
Fresh water
industry
mercury /paper
fibres
Recycling
homes
sewage
Decomposition by
bacteria
agriculture
Fertilisers/pesticides
Reduced use
Oil tankers
oil
Decomp. by
bacteria/burning
Nuclear power
stations
Radioactive waste
Buried in lead
containers/other
fuels
Sea
• A closer look….
– SO2: agggravates respiratory
conditions and causes leaf
damage to plants.Lichens are
especially sensitive and will
not grow where air is polluted
with this gas (cities).
– Nuclear power: used in some power
stations to generate electricity.
Radioactive waste is harmful for many
years and if released causes leukaemia
and other cancers.
– Fossil fuels: gases
such as SO2 react
with water and O2 in
the clouds and form
acid rain. Plants are
damaged and soil pH
effected. Fish may
also die.
Organic pollution
• A source of fresh water pollution is
untreated sewage:
o Micro-organisms in the sewage use it as an
energy source (food)
o They multiply rapidly
o They use up the oxygen in the water for their
respiration
o Organisms that require oxygen cannot survive.
o Organisms that don’t require oxygen flourish
o These are called indicator species as there
presence tells about polltution levels.
All the organisms in the above diagram are indicator species for oxygen levels.
Management
• Human beings manage the environment to produce
materials to meet our needs.
• Sometimes this management, if not well thought
out and researched, can lead to problems.
• Grazing too many cattle on poor land
o
o
o
o
Plants are killed right down to the roots
The soil isn’t held together
Erosion of the soil occurs
Leading to desertification
• Trees are cut down for ski runs
o Water flows down the hillside with no trees to stop it
o Mudslides bury the ski resorts at the bottom of the
slopes.
• DDT is an powerful insecticide and in
small doses doesn’t affect animals or
plants.
o In 1950s onwards sprayed on crops to
reduce insect damage.
o Harmless to animals in the concentrations
that were sprayed but whenever a small
mammal eats plants covered in DDT is gets
a small dose that remains in its body so
over many meals the levels begin to build
up
o Eating only a few such small mammals is
lethal to a predator.
o Many birds of prey died during the 50s and
60s of DDT poisoning
o Even today DDT is still detectable in the
environment.
o It was banned in the UK and the USA in
the 70s
Control
• Agriculture and forestry industries carry out
many practices to control the ecosystem to make
it more productive.
• These practices effect the ecosystem and must
therefore be managed sensibly.
o Overgrazing: plants cannot re-grow and poor soil/sand
begins to replace fertile soil.
o Fertilisers/pesticides: cause pollution and may enter
food chain. Use should be minimum or replace with
biodegradable alternatives.
o Cash crops: Poor countries use land to grow crops for
export (coffee) instead of crops to feed the population.
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Biotechnology
Living Factories
Problems with
Profit and Waste
Reprogramming Microbes
Biotechnology
Sub-topic 3
Genetic Engineering
• Bacteria posses one circular chromosome
• They may also possess smaller circles of chromosomal
material called plasmids
• The genes needed to control the bacterial cell
functions are found on the chromosome & plasmids
• Scientists can now transfer pieces of
chromosomes from one organism (e.g.
human) to another organism (e.g.
bacterium).
• This process is called genetic engineering.
• The altered bacterium (reprogrammed
bacterium) can mass produce the new
substance which can be useful to mankind.
Identify & extract desired gene
Extract & open plasmid
Insert gene into plasmid
Insert altered plasmid into bacterium
Allow plasmid and bacterium to multiply and
produce gene product
Extract & purify gene product
Advantages of genetic engineering
• It is less expensive than traditional
methods.
• The chemical coded for by the gene is
produced in very large quantities.
• The chemical is very pure. The process is
much faster than traditional methods.
Products of genetic engineering
Product of genetic
engineering
Medical Application
Insulin
Given to diabetics who do
not make enough insulin
naturally to control blood
sugar levels
Given to children who do not
produce enough GH to
prevent reduced growth &
dwarfism.
Human Growth Hormone
Factor VIII
Required for blood clotting.
Need for Insulin
• Insulin is a hormone that controls blood
sugar levels.
• People who have diabetes do not make
enough insulin by the pancreas. As a result
they cannot control the level of sugar in
their blood.
• Diabetics used to use insulin from cattle
and pigs to stay alive.
• This insulin was not exactly like human
insulin and caused allergic reactions.
• Now it is possible to use genetically
engineered insulin which is identical to
human insulin.
Biological Detergents
• Biological detergents contain enzymes
made by bacteria which digest the
stains on the clothes like enzymes in
your gut digest food.
• Non-biological enzymes do not contain
enzymes.
Advantages of Biological Detergents
• They completely remove difficult
stains such as blood and egg.
• Effective at low temperatures (e.g
40ºC). Saves money on fuel costs and
prevents damage to delicates like silk
or wool.
Antibiotics
 An antibiotic is a naturally occurring
chemical produced by one type of microorganism (e.g. a fungus) which stops the
growth of another micro-organism e.g.
bacteria.
 The first antibiotic to be discovered was
Penicillin by Alexander Fleming in 1928.
Alexander Fleming noticed no bacteria grew around the
area of the fungus (antibiotic.) He concluded that the
fungus was producing a substance that was preventing
bacterial growth. This substance was penicillin.
• If a micro-organism’s growth is
prevented by an antibiotic, the
microbe is said to be sensitive to the
antibiotic.
• If the antibiotic has no effect, the
microbe is said to be resistant.
Antibiotics work by
• Destroying the bacterial cell walls
• Bursting bacterial cell membranes
• Stopping chemical reactions in the
bacterial cells.
Range of Antibiotics
• A range of antibiotics is needed in the
treatment of bacterial diseases because:
- No one antibiotic is effective against all types
of bacteria.
- Some people are allergic to a certain antibiotic.
- Strains of bacteria are constantly emerging
that are resistant to one or more antibiotics. If
several antibiotics are available, there is a good
chance that at least one will be effective
against the bacterial strain.
Immobilisation
• An immobilsed cell or enzyme is one
which has been trapped inside a jelly
bead.
• Yeast cells and enzymes can be
trapped in this way.
jelly coat
yeast + enzyme
Advantages of Immobilisation
•
•
•
After the reaction the beads can be
washed and re-used.
Saves money (enzymes are
expensive)
Bead easily separated from product
(e.g. by filtering)
Making Immobilised Cells
• Using a clean syringe, put 4ml sodium
alginate into a beaker
• Using a clean syringe, add 6ml of yeast
suspension to the same beaker, and mix
well with a glass rod.
• Draw up the mixture into a clean syringe.
• Put 50ml of Calcium chloride solution into a
new beaker and drop by drop release the
contents of the syringe into it.
• The beaker now contains some jelly
beads with immobilised (trapped)
yeast cells which can be used again.
• Beads can be separated from the
liquid by filtration.
Beads
can be
re-used
Continuous Flow Processing
•
Raw materials can be added to immobilised
enzymes and a product can be obtained at the
end of the fermenter vessel.
•
This is a continuous process
•
Very large quantities of product are
produced quickly and cheaply in a continuous
process.
•
There is no need to separate the product
from the enzyme that produced it.
•
The enzyme (which is probably expensive)
gets used for a long time and is not lost in the
process.
•
There is no need for frequent cleaning of the
fermenter vessel as in a batch process.
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Subtopic 1:
Introduction
Biotechnology is…….
•
The use of micro-organisms, such as
bacteria or yeast, or biological
substances, such as enzymes, to
perform specific industrial or
manufacturing processes.
Yeast cells
• Yeast is a single
celled fungus.
Cell wall
cytoplasm
Cell membrane
nucleus
Aerobic & Anaerobic Respiration.
• Respiration is the process which
releases energy from food (glucose).
• When this process happens in the
presence of oxygen, it is called
Aerobic respiration.
• When this process happens in
absence of oxygen, it is called
Anaerobic respiration.
• Yeast cells use sugar as their source of
energy (food).
• In the absence of oxygen they change this
sugar into Carbon dioxide and alcohol
(ethanol).
• This process also releases some energy.
Sugar
yeast
CO2 + Alcohol + Energy
• This process is also known as Alcoholic
fermentation.
Uses of Yeast Cells
1.
Baking
•
Alcoholic fermentation is an essential
stage in bread making.
When the bread dough is left in a warm
place for a few hours, the yeast changes
the small amount of sugar into CO2 gas
and alcohol.
The CO2 bubbles get trapped in the
dough making it rise.
The alcohol evaporates during the baking
process.
•
•
•
2. Brewing
•
•
•
•
•
This is the production of beer.
In beer production, yeast uses the sugar
called maltose from Barley grains.
Hops is also added to flavour the beer.
The barley grains are allowed to
germinate and the starch in them slowly
changes into maltose by the enzyme
amylase. This is called Malting. (work
sheet)
Sugar
(Maltose)
yeast
CO2 + alcohol (beer) + energy
• The brewer is interested in the
alcohol content and the Carbon
dioxide gas is what gives beer its
‘fizz’.
3. Wine Making
•
•
•
•
Also depends on alcoholic fermentation
by yeast.
This time, yeast uses sugar found in
grapes.
The grapes are first crushed to release
their fruit juice rich in sugar.
Wine yeast is then added which changes
the sugar in the fruit juice into alcohol
and CO2.
• As the alcohol concentration builds
up, the yeast cells die and drop to the
bottom of the fermentation tank.
• Once the wine has cleared, it is
filtered and bottled.
Sugar
Alcohol + CO2 + energy
(From
grapes)
(Wine)
Ideal Conditions
Commercial brewers and distillers control the
conditions for the yeast carefully:
• Temperature – temperature of fermenter
controlled by thermostat.
• Cleanliness – before each batch is
produced the fermenter cleaned to kill
bacteria.
• Food supply – starch converted to sugar
for yeast by germinating barley grains.
Batch Processing
• In a batch process the manufacturer takes
the raw materials and produces the
product in a single process.
• After the process has come to an end, the
fermenter is emptied and the useful
product is separated from the microbes.
• Fermenter is cleaned out and process is
repeated using new batch of raw materials.
Lactic Acid Formation
• Milk is rich in sugar, protein and fat and is
a good food source for bacteria.
• When milk sours, bacteria in the milk feed
on the sugar in milk called Lactose and
convert it into Lactic Acid. (Lactic Acid
Fementation)
• Lactose
Lactic Acid
• The lactic acid formed by the
bacteria lowers the pH of the milk,
resulting in the molecules of milk
protein to coagulate (clump together)
to make yoghurt.
Cheese Making
• Milk is heated (pasteurised) to kill most
micro-organisms.
• Special cheese making bacteria added to
convert lactose into Lactic Acid.
• Enzyme called Rennin added to spearate milk
into curds and whey.
• Whey is discarded.
• Curds cut into blocks and mixed with salt.
• Cheese packed onto moulds and left to ripen.
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Problems & Profit with Waste
Biotechnology
Untreated Sewage
• Raw or untreated sewage contains organic
material and bacteria.
• Theses bacteria feed on the organic waste
using aerobic respiration.
• In fresh water oxygen levels fall.
• Nitrates & phosphates may be added to the
water causing algae to grow (bloom).
• Many fresh water animals die through lack of
oxygen.
• Fresh water pollution
• Indicator species graph
• Disease is spread when untreated sewage
leaks into public water supplies.
• Contamination of drinking water can result in
disease – dysentery, typhoid, cholera - and
sometimes death.
• This can happen after floods, earthquakes
or with badly designed sewage systems.
Untreated Sewage
Sewage Treatment
• Sewage is broken down by a variety of
different micro-organisms, feeding on the
different organic material, to products
harmless to the environment.
• Oxygen is required by the aerobic microorganisms to feed on the organic waste – this
is provided by compressed air.
Sewage Works
Sewage Treatment
Sewage Treatment
• Sewage is first filtered to remove large
particles and rubbish.
• The sewage is allowed to settle – the solids
fall to the bottom (SLUDGE) and the liquid
(EFFLUENT) rises to the top.
• The sludge is treated and bacteria produce
METHANE gas – the sludge can then be
disposed of on land or at sea.
• The sludge contains bacteria that can be used to
digest organic material in the effluent – ACTIVATED
SLUDGE.
• Bacteria can be used in BIOLIGICAL FILTRATION or
the ACTIVATED SLUDGE process to completely break
down all organic material.
• The effluent can then be released back into
freshwater.
• Virtual Sewage - a trip through San Diego's sewage
system
Chemical Oxygen Demand
• Any untreated sewage that is released into
freshwater contains organic material.
• Bacteria feed on this, using up oxygen in the
water – the oxygen they need to use is called
the CHEMICAL OXYGEN DEMAND.
• Sewage treatment reduces the COD of
effluent.
Sterile Technique
• When working with mircoorganisms it is important to
ensure that you do not contaminate the environment
or your experiment .
• Work surfaces must be disinfected before starting an
experiment.
• Hands should be washed and gloves and lab coats
worn.
Sterile Technique
•
•
•
•
•
•
Heat wire loop in flame to kill micro-orgs.
Allow loop to cool.
Collect sample of organism to be cultured.
Transfer sample to agar plate.
Heat loop in flame to kill micro-orgs.
Seal and label agar plate.
Microbes and Decay
• When a plant or animal dies its tissues
decay due to the actions of saprophytes
- microbes such as bacteria & fungi.
• These decomposers use the dead animal or plant
material as a food source to obtain energy.
• At the same time they release nutrients back into the
environment to be used again
The Carbon Cycle
The Carbon Cycle
• CO2 is used by plants in photosynthesis to
make carbohydrates.
• Animals eat plants to obtain carbohydrates
and make other carbon compounds.
• Plants and animals release CO2 during
respiration
• Dead organic matter from plants & animals
contain carbon compounds.
• Decomposers feed on this organic matter
during respiration – releasing CO2 as a waste
product.
• Some organic matter may be changed into
coal over millions of years.
• When this is burned CO2 is released.
The Nitrogen Cycle
Denitrification
N2 in the air
Nitrogen
Fixing
Nitrogen
Fixing
Nitrogen in animal protein
N in plant protein
N in waste &
dead organisms
Decomposers
N in ammonia
Nitrification
N in NITRATES
Lightning
N in NITRITES
The Nitrogen Cycle
• In your own words describe how nitrogen can
be recycled through plants, animals and the
environment.
• Include :
– The chemical compounds formed
– The microorganisms involved
– Nitrogen fixing
– Denitrification
Advantages of Upgrading Waste
• Micro-organisms can change the
chemicals in waste into other chemical
substances containing energy or protein
• Upgrading low value waste into high
value products is usually inexpensive
and reduces costs of waste disposal
and pollution
Fuels from Micro-organisms
• Methane gas is produced when microbes feed
anerobically on sewage
• Alcohol is produced when yeast feed
anaerobically on sugar
Glucose
YEAST
Alcohol + Carbon dioxide + Energy
• These fuels are renewable and therefore
unlimited
Protein from Waste
• Bacteria grow rapidly under ideal conditions
producing lots of protein
• Certain bacteria can be grown & dried to
produce single celled protein
• This can be used to make animal feeds
• Some fungi produce mycoprotein which can
be used to form meat like products for
humans – e.g. Quorn
Industry
Waste
Microbe
Product
Cheese
Whey
Yeast
Protein for
cattle feed &
vitamins
Crisp manuf.
Starch
Fungus
Mycoprotein
for humans
Gas & Oil
Methanol
Bacteria
Protein for
animal feed
Sugar
Molasses
Yeast & fungi
Vinegar &
Alcohol
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Inheritance
Variation
What is
Inheritance
Genetics and Society
Inheritance
Genetics and Society
Selective Breeding
• Selective Breeding is the method used by
man for thousands of years to change the
characteristics of animals & plants to make
them more suited to our needs.
• Only organisms showing desired
characteristics are allowed to breed, hopefully
passing on the desirable characteristics
Afghan Hound
Greyhound
Chihuahua
Newfoundland
http://www.pbs.org/wgbh/nova/dogs/world.html
Selective Breeding
• This process may be controlled by hand
pollinating plants or artificially
inseminating animals.
• This process is slow and many
generations may be needed before
significant improvement is seen.
Selective Breeding
• Examples of ‘Improved’ characteristic
– Increased milk yield in cattle
– Increased meat production in cattle
– Leaner meat in cattle
– Disease resistance in crops eg wheat
Mutation
• A mutation is a change in the number or
structure of chromosomes in an organism.
• Mutations occur naturally but are rare.
• Some mutations are of benefit to the
organism but many are harmful.
• Mutation rates may be increased by exposure
to Mutagenic Agents such as:
– X Rays
Ultra Violet Light
– Mustard Gas
Colchicine
Useful Mutations
Extra sets of chromosomes
occurring in fruit such as
apples, pears, strawberries,
etc. can lead to increased
fruit size and increased
yield. These plants are called
POLYPLOIDS
Amniocentesis
• Mutations in humans can be detected before
birth by amniocentesis
• A needle is used to withdraw a small amount
of amniotic fluid from around the baby
• Cells from the baby can then be ‘grown’ and
the number and structure of chromosomes in
the nucleus can be examined for mutations
e.g Downs Syndrome – Trisomy 21 ( 3 copies
of chromosome 21 instead of 2).
Down’s Syndrome Karyotype
Three copies of chromosome 21
Species
• A species is a group of living organisms that
are so similar to one another that they are
able to interbreed and produce fertile
offspring.
• E.g. Red deer are an example of a species.
Individual red deer can vary in size and
colour. However, all red deer adults are able
to interbreed and produce fertile offspring.
• Horses and Donkeys may look alike but they
do not belong to the same species as their
Red Deer Hind
Red Deer Stag
(Female)
(Male)
Red Deer Fawn
is the
offspring. The
Fawn will grow
into a Fertile
Adult.
Male Horse
Female Donkey
Young Mule is
the offspring
but is Infertile
(can’t breed)
Variation
• Members of the same species look
similar to one another but are not
exactly the same.
• There are small differences between
everyone in this class.
– E.g. height, weight, eye colour, shoe size.
• These small differences are called
VARIATION
• Continuous variation can be measured
across a range from smallest to largest
and can usually be plotted on a line
graph or histogram
– E.g. height, weight, shoe size
• Discontinuous variation can be observed
and falls into definite groups which can
be plotted on a bar graph
– E.g. eye colour, blood group, hair colour
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What is Inheritance?
Inherited Characteristics
• Inherited characteristics are passed on
in genes from one generation to the
next during sexual reproduction
Genes and Genotype
• A gene is a unit of heredity, found on
chromosomes, that controls an
inherited characteristic
• The complete set of genes possessed
by an organism is known as its
genotype
• The phenotype is what characteristics
an organism possesses as a result of its
genotype
• Genes may have more than one form,
eg the eye colour gene may be brown,
blue, green etc.
• The different forms of a gene are
known as alleles
• Every body cell has two copies of each
gene because it has two sets of each
chromosome
• Gametes have one copy of each allele
• If an organism inherits two copies of
the same allele it is said to be
homozygous
• If an organism inherits two different
alleles it is said to be heterozygous
• Alleles may be dominant or recessive
• A dominant allele is always expressed in
the organisms phenotype if it is present
in the genotype
Brown
Eye
Gene
Blue
Eye
Gene
Brown
Eyes
• A recessive allele is only expressed in
the organisms phenotype if it inherits
two copies of the recessive allele
Blue
Eye
Gene
Blue
Eye
Gene
Blue
Eyes
• A monohybrid cross is a genetic cross
where one characteristic is studied
– E.g hair colour, eye colour
• Parents who always produce offspring
that have an identical characteristic
when they interbreed are said to be
true breeding
Monohybrid Crosses
• P = parent
• F1 = first filial generation - the offspring
produced by crossing the two original
parents
• F1 cross = a cross involving two
members of the F1
• F2 = second filial generation - the
offspring of the F1 cross
Parents Phenotype
Parents Genotype
Gametes
F1 Genotype
F1 Phenotype
F1 Cross
F1 Gametes
Punnet square
F2 Genotypes & ratios
F2 Phenotypes & ratios
Observed ‘v’
Predicted Results
• When a monohybrid cross is carried out
the actual results that you obtain are
not always the results which you
expected
• This is because fertilisation is a random
process involving the element of chance
• Producing large numbers of offspring
gives more reliable results.
Backcrosses
• When an organism shows a dominant
trait you cannot know if it is
homozygous or heterozygous for that
trait.
– E.g. in mice – black fur =
BB or Bb
brown fur = bb
• A backcross is when you cross an
organism of unknown genotype with a
recessive organism to find out whether
it is homo or heterozygous.
Black fur x Brown fur
fur
BB?
X
bb
F1
Black fur
x
brown
Bb?
x
bb
All Bb
1 Bb : 1bb
All Black
Half black
Half brown
Sex Chromosomes
• Human body cells contain 23 pairs of
chromosomes.
• One pair - the sex chromosomes –
determine the sex of an individual.
• Females = XX
• Males = XY
Egg mother cells can only pass X chromosomes
to egg cells.
XX
X
X
Sperm mother cells give half the sperm X chromosomes
and half Y chromosomes
XY
X
Y
If an X egg is fertilised by an X sperm a
girl is formed.
X
X
XX
If an X egg is fertilised by an Y
sperm a boy is formed.
X
Y
• There is a 1 in 2 chance that an egg will
be fertilised by an X sperm and a 1 in 2
chance the egg will be fertilised by a Y
sperm.
• This gives a sex ratio of 1 male : 1
female in the population as a whole
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