Download Unit One Cell Biology Powerpoint

Unit One: Cell Biology
S3 CFE Biology
Units:
• Cell Biology – now till October
• Multicellular Organisms – October – Feb
• Life on Earth – February onwards
S3 Biology Course Unit 1
How is the course assessed?
There will be an end of topic test at the
end of Unit 1 and Unit 2. This will test
your knowledge of the unit and your
problem solving (calculations, %, line/bar
graphs).
S3 Biology Course Unit 1
Course Work
As well as the tests, there are three
pieces of course work to do:
Unit 1: Practical investigation
Unit 2: Short Scientific Report
Unit 3: Research Assignment
S3 Biology Course Unit 1
Key area 1: Cell structure
Learning objectives:
• Identify and name the structures in a plant
cell
• Identify and name the structures in an animal
cell
• State the functions of the structures found
in plant and animal cells
• Be able to work out the size of a cell
S3 Biology Course Unit 1
Prior Knowledge
From CSI Speyside you should know:
• That cells are the basic unit of all living
things
• How to use the microscope
• Some parts of animal and plant cells and
what their role in the cell is.
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Examining plant cells
Your teacher will remind you how to make
a microscope slide.
Look at the onion cells under the x10 lens
and draw what you can see in your
jotter.
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X 40
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Collect
and label
this
diagram
of a plant
cell
Typical plant cell
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Functions
Use page 19 of the N5 textbook to find out
what the following parts of the cell do:
Nucleus
Cell membrane Cytoplasm
Cell wall
(Sap) Vacuole
Chloroplast
Ribosome
Mitochondria
Display this in your jotter as a table or list.
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Examining animal cells
Your teacher will show you how to make a
slide of your cheek cells.
Using x 10 magnification draw what you
can see.
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X 100
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Collect
and label
this
diagram
of an
animal cell
Typical animal cell
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Common structures
Make two columns in your jotter:
Plant and Animal
Cells
Plant cells
Only
Fill in which cell parts should go in each
column.
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Just how tiny are cells?
“How big?”
This link will show you how tiny cells are.
Cells can be seen more clearly using a
microscope.
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Magnification
Total magnification is
worked out by
multiplying the
eyepiece lens
magnification by
the objective lens
magnification.
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Eyepiece
Lens
Objective
Lens
Copy and complete this table
Eyepiece lens
magnification
Objective lens
magnification
X 10
X4
Total
magnification
X 10
X 100
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Working out the size of a cell
Field of view = 2 mm
The field of view is the
area you can see down the
microscope.
Field of view
Number of cells
Length
= of each cell
(mm)
e.g. 2 ÷ 5 = 0.4 mm
So each cell
measures 0.4 mm.
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Field of view = 2 mm
Collect a version
of this diagram.
Your teacher will
tell you how
many cells to
draw in the
circle.
Calculate the
length of your
cell in
millimetres (mm).
Swap with other
and calculate the
length of their
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Key area 2: Cell membrane and
Transport
Learning objectives:
• Describe what the cell membrane is
made of
• Describe what is meant by “diffusion”
• Explain how the process of diffusion
occurs across the cell membrane
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Prior Knowledge
From Science in everyday life you should
know:
• The three states of matter are – solid,
liquid and gas.
• The particles behave in different ways
depending on if they are in a solid, liquid
or gas.
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How are particles arranged?
Solid
Liquid
Gas
Copy this table. Using a circle to show the
particles – fill in the space to show how the
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particles
areCourse
arranged.
How are particles arranged?
Solid
Liquid
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Gas
How to liquids and gases move?
Your teacher will take you outside (or to
the auditorium) to pretend to be
particles.
Based on what you did, write a couple of
sentences describing how particles of
liquid or gas move.
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The cell membrane in close up
Copy this diagram
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The cell membrane is made of lipids and
proteins.
The lipids are arranged in a double layer.
The proteins are in a patchy
arrangement. Some stick all the way
through making channels called “pores”.
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Diffusion
What happens to
the smell when
you spray perfume
in one corner of
the room?
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Gas or liquid particles are constantly
moving and bumping into each other.
This means that they spread out from
an area where there are lots of
particles to an area where were are no
particles.
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This process is called diffusion.
Diffusion is the movement of
molecules of a substance from an
area of high concentration to an
area of low concentration until
they are evenly spread.
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Diffusion through a membrane
Starch
Water
Visking
tubing
Starch +
Glucose
solution
In bag
In water
at the
start
In water
after 20
mins
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Glucose
Take a small sample of the water from around
the test tube. Test for starch and sugar
Test
for
starch
2. Add 4
drops of
IODINE
1. Put sample on
tray
Test for
sugar
BOILING
WATER
3. If starch is present it goes
from brown to black
2. Add 4
drops of
BENEDICTS
SOLUTION
3. If sugar is present it goes from
blue to orange
1. Put sample in test tube – IN a
beaker of BOILING WATER
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Conclusion:
Glucose molecules can diffuse through
Visking tubing but starch molecules
cannot.
Explanation:
Visking tubing is a selectively permeable
membrane.
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A Selectively Permeable
Membrane
A selectively permeable membrane
contains tiny holes through which only
tiny molecules can diffuse.
Cell membranes are also selectively
permeable.
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They control the movement of substances
in and out of cells.
Small molecules which can diffuse
through a selectively permeable
membrane are:
oxygen
glucose
water
carbon dioxide
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Large molecules which cannot diffuse
through are:
Starch
Protein
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Substances which can and
cannot diffuse into or out of
cells
Starch
Carbon
dioxide
Glucose
Protein
Oxygen
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Why is diffusion important?
Diffusion is essential to living things. All
cells need to take in food (e.g. glucose
and amino acids) and oxygen.
These are used for respiration (see later
in this unit) to produce energy.
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Key area 3: Making new cells
Learning objectives:
• Explain that cells must divide to increase the
number of cells in an organism.
• State the cell division is controlled by the
nucleus.
• Explain why the original cells must divide to
produce two identical daughter cells.
• Describe the main stages of mitosis.
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Prior knowledge
From CSI Speyside you should know:
• The nucleus of the cell contains
chromosomes.
• Chromosomes are a set of instructions
which tell the cell how to work.
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What is cell division?
• Cell division is how an organism makes new
cells for growth, development and repair.
• In cell division one cell divides to make
two new cells.
• The two new cells are called daughter
cells and they are identical to the original
cell.
• In unicellular organisms cell division is a
way of reproducing.
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Inside the nucleus
Nucleus contains 46 chromosomes.
These carry information.
Each piece of information is packaged
on a gene.
e.g. gene with information for eye colour
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Chromosome complement
Humans have 46 chromosomes in every nucleus
inside every body cell.
This is called our chromosome complement
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The importance of the
chromosome complement
• The chromosome complement contains
all of the codes needed by each cell.
• It must be copied exactly for each new
cell in cell division so that none of the
codes (which are the cell’s instructions)
are left out.
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Stage 1
•nucleus containing long
uncoiled chromosomes.
•each chromosome doubles
to form to identical
chromatids.
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doubles
1 chromosome
1 chromosome made of
two chromatids
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Stage 2
•each chromosome becomes
thicker – forming a short
coiled chromosome (made of
two chromatids).
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centromere –
holds 2
chromatids
together.
shortens
and coils
1 long uncoiled
chromosome made of
two chromatids
1 short coiled
chromosome made of
two chromatids
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Stage 3
•the chromosomes line up at
the equator of the cell.
•a spindle forms and attaches
at the centromeres.
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Stage 4
N pole
•the chromatids are pulled
apart and move to different
poles.
S pole
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Stage 5
•a nuclear membrane forms
around each group of
chromatids – now called
chromosomes.
•the cytoplasm begins to
divide.
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Stage 6
•two daughter cells each
containing the same
numbers of chromosomes as
the original cell.
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1
6
5
2
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4
3
2
1
Collect this diagram of cell
division.
6
3
Write a sentence describing
what is happening at each
stage of the process. Use
page 41-42 to help.
4
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5
Key area 4: Producing proteins
Learning objectives:
• State that proteins are made of
different sequences of amino acids.
• Describe some of the main functions of
proteins.
• Describe the structure of DNA.
• Explain how the DNA helps the cell to
make different proteins.
S3 Biology Course Unit 1
Prior knowledge
From Science in Medicine you should
know:
• Proteins are large molecules made up
from 21 different amino acids.
From CSI Speyside you should know:
• Chromosomes are made of a molecule
called Deoxyribonucleic acid (DNA).
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Proteins
Proteins are large molecules made by
joining small subunits called amino acids
together.
There are 21 different amino acids.
Different proteins have different
combinations of the amino acids.
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The amino acid chains can then fold into
different shapes which allow the
proteins to do different jobs in the cell.
Antibody
Keratin (hair)
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Cell membrane pore
What makes organisms different?
Organisms differ because they
have different genes.
 Humans have human genes
 Gerbils have gerbil genes
 Bananas have (yes, you’ve
guessed it) banana genes!
Nobody else in the whole world
has the same DNA as you!
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Genetic information
• The nucleus of living cells contain
chromosomes which are made up of a
string of genes.
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Chromosomes and their genes are made of a
molecule called DNA
DNA stands for
deoxyribonucleic
acid.
Each chromosome
is a very long molecule
of tightly coiled DNA.
The DNA molecule
looks like a
twisted ladder this
spiral shape is
called a
DOUBLE HELIX
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DNA bases
The double helix ‘ladder’ of a DNA molecule
is held together by ‘rungs’ made from pairs
of chemicals called bases.
A
C
G
T
There are four types
of bases, and they are
usually identified by
their initials.
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Base pairs hold the two strands of the DNA
helix together.
C
G
A
T
C
G
A
T
It is the sequence of these bases along a
DNA molecule that forms the genetic code.
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The genetic code
Every three bases in the DNA (codon)
tells the cell which amino acid to use to
help build proteins.
TATCGGTACGTA
Alanine
Glycine
Proline
DNA sequence
Cysteine
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Amino
acids
joined
together
in protein
Translating the DNA code
Your teacher will give each group a DNA
sequence.
Divide the sequence into groups of three
(codons) then use the chart to work out
which coloured bead you will need.
Put the beads in order based on your
sequence.
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1st
position
3rd
position
2nd position
T
C
A
G
T
Yellow
Green
Red
Blue
T
Yellow
Green
Red
Blue
C
Yellow
Green
Red
Blue
A
Yellow
Green
Red
Blue
G
C
Light Blue
White
Pink
Red
T
Light Blue
White
Pink
Red
C
Light Blue
White
Pink
Red
A
Light Blue
White
Pink
Red
G
A
White
Green
Light Blue
Blue
T
White
Green
Light Blue
Blue
C
White
Green
Red
Blue
A
Pink
Green
Red
Green
G
G
STOP
Blue
Yellow
Pink
T
STOP
Blue
Yellow
Pink
C
Pink
Yellow
Yellow
Pink
A
Pink
Yellow
Yellow
Pink
G
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Use this chart to
help you to build
your final protein
Key area 5: Enzymes
Learning objectives:
• State that enzymes are found in all cells
and speed up chemical reactions.
• Explain why enzymes are described as
“specific”
• Give examples of “building up” and
“breakdown” enzymes and explain what
they do.
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Prior knowledge
From Science In Medicine you should
know:
• The digestion of starch in your mouth
was carried out by a substance in your
saliva called an enzyme.
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Catalysts
A catalyst speeds up a chemical reaction,
but is unchanged in the process and can
be used over and over again.
In living things, catalysts are known as
enzymes.
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If cells did not have enzymes in their
cytoplasm, then the chemical reactions
which happen in our cells would happen
so slowly that life would be impossible!
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An example of an enzyme:
CATALASE
Hydrogen peroxide (H2O2) is a liquid
similar to water (H2O), but with one
extra oxygen.
Over a long period of time hydrogen
peroxide naturally breaks down into
water and oxygen.
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The word equation for this reaction is:
Hydrogen peroxide
water + oxygen
This process can be sped up using an
enzyme.
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Into each test tube – measure out 5 ml of
Hydrogen peroxide AND 5 drops of
detergent.
CAUTION!!
Hydrogen
peroxide is a
dangerous
chemical.
Safety goggles
must be worn!!
1. Add nothing
2. Potato
3. Carrot
4. Liver
Leave for 10 minutes.
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1
height of the foam bubbles.
Estimating the catalase activity
of different food groups
Aim:
Dependent variable:
Independent variable:
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Test tube contents
Height of foam (mm)
Nothing – “CONTROL”
Potato
Carrot
Liver
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Conclusion
Only the plant and animal tissues speed up
the breakdown of hydrogen peroxide.
This is because the cells contain catalase.
Catalase is an enzyme found in living
cells.
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Catalase
Hydrogen peroxide
water + oxygen
The tissue which contained the most
catalase was ______________.
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Breakdown and Building Up
Catalase is an enzyme involved in chemical
breakdown.
“Breakdown” means chopping up larger
molecules into smaller molecules.
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Other enzymes do the opposite – the
build large molecules from smaller
molecules.
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An example of a “Build up”
enzyme: Phosphorylase
Glucose-1-phosphate is a chemical made
by plants during photosynthesis. It is
stored in plant cells be converting it
into a large molecule called starch.
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Phosphorylase
Phosphorylase
Glucose-1-phosphate
Starch
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Substrates and products
The substrate is the substance the
enzyme works on.
The product is the substance the enzyme
makes.
Enzyme
Substrate
Product
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Enzyme
Substrate
Catalase
Phosphorylase
Amylase
Pepsin
Lipase
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Product
How enzymes work
Enzymes are made of protein. This
protein has a special shape which is
unique to each enzyme.
Enzyme
Active site
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Substrate
Enzyme
The active site is the correct shape to fit the
substrate.
Substrate
Turned into
the products
Enzyme
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Substrate
Enzyme
Other substrates are the wrong shape to
fit in the active site of the enzyme.
Therefore the enzyme will only work with
one substrate. This is described as being
SPECIFIC.
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“Specific”
When talking about enzymes, SPECIFIC
means that the ENZYME WILL ONLY
WORK WITH ONE SUBSTRATE.
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One enzyme = one substrate
5 ml Starch
3 ml Water
5 ml Starch 5 ml Starch 5 ml Starch
3 ml Amylase 3 ml Pepsin 3 ml Lipase
Put in waterbath for 10 minutes. Test all 4 test-tubes with
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Benedict’s Solution
Investigating the specificity of
enzymes
Aim:
Dependent variable:
Independent variable:
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Results
Sugar present?
Starch + water
Starch + amylase
Starch + Pepsin
Starch + Lipase
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Conclusion
The test-tube containing Starch and
Amylase had the most sugar.
This shows that only Amylase can convert
starch to sugar.
Amylase is said to be SPECIFIC to starch.
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Investigation
Design an experiment to investigate:
“Factors affecting the enzyme activity
using the catalase enzyme”
Carry out and write up this experiment –
your teacher will give you advice.
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Factors affecting the enzyme
activity using the catalase
enzyme
Aim:
Dependent variable:
Independent variable:
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Key area 6: Respiration
Learning objectives:
• State what cells use energy for.
• State the summary word equation for
aerobic respiration.
• Explain when animal cells might use
anaerobic respiration.
• State the summary word equation for
anaerobic respiration
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Prior knowledge
In Science in Medicine you learned that:
• Cells get energy from this chemical
reaction:
sugar + oxygen
energy + carbon + water
dioxide
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Why do cells need energy?
Maintain body
temperature
Making
larger
molecules
Cells use
energy from
respiration
to…
Growth and
repair of
cells
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Make your
muscles
work
Carry out
chemical
reactions
Which foods have the most
energy?
Different types of food contain different
amounts of energy.
The three main food groups are:
• Carbohydrates
• Proteins
• Fats
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Estimating the energy content of
foods
Aim:
Dependent variable:
Independent variable:
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Your teacher will demonstrate how to set up and
carry out this experiment safely.
NUTRIENT
EXAMPLE
WATER TEMPERATURE (ºC)
At start
Carbohydrate
Sucrose
Protein
Gelatine
Fat or oil
Sunflower
Oil
After burning
food
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%
Increase
Conclusion:
Most energy in the body comes from
breakdown of carbohydrates.
Carbohydrates are made of the sugar
glucose.
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Aerobic respiration
Aerobic respiration means “with air” and
is happening in you body now.
Glucose
Oxygen
Comes from
breakdown
of your
food
Breathed in
by your
lungs
38 energy
molecules
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Carbon
dioxide
Breathed
out by your
lungs
Water
What happens if you do heavy
exercise?
During sports your muscles run out of
oxygen because they are working so
hard the heart and lungs cannot keep up
sufficient supply.
When this happens anaerobic respiration
occurs.
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Anaerobic respiration
Glucose
Comes from
breakdown
of your
food
2 energy
molecules
Lactic
Acid
Builds up in your
muscles making
them painful
Anaerobic respiration only produces 2
energy molecules compared with the 38
produced by normal aerobic respiration.
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Key area 7: Photosynthesis
Learning objectives:
• State that photosynthesis is the process
used by plants – where carbon dioxide and
water is used to produce sugar and oxygen.
• Identify and describe the role of the cells
in a leaf.
• State the summary word equation for
photosynthesis.
• Describe how you can measure the rate of
photosynthesis and name one factor which
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affects the rate of photosynthesis.
Prior knowledge
You should know from the Planet Earth
unit:
• Plants produce their own food from
sunlight.
• This process happens in the leaves.
• This process requires a chemical called
chlorophyll.
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Collect
and label
this
diagram
of a leaf
Leaf Structure
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Part
Function
Upper and lower
Layer of cells on top and bottom
Epidermis
of leaf which protect the leaf.
Palisade Mesophyll These cells contain loads of
chloroplasts. Site of
photosynthesis
Spongy Mesophyll This layer has air spaces to
allow diffusion of gases in the
leaf
Stomata
Pores on underside of leaf to
allow gases to enter or leave.
Made of two guard cells.
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Photosynthesis
Photosynthesis occurs in the palisade
mesophyll cells.
These cells contain chloroplasts.
Chloroplasts contain a green pigment
called chlorophyll which traps light
energy from the sun.
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Carbon
dioxide
Enters leaf
through the
stomata
water
Light
energy
Chlorophyll
Glucose
Enters
plant
through the
root
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Oxygen
Is a waste
product
which exits
the leaf
through the
stomata
What happens to the glucose?
Use page 84 of the text book to complete
this diagram:
Glucose
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Measuring the rate of photosynthesis
How fast photosynthesis
occurs can be
estimated by counting
the number of bubbles
of oxygen produced
each minute.
Your teacher will show
you how to set up this
experiment.
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Measuring the effect of light
intensity on the rate of
photosynthesis
Aim:
Dependent variable:
Independent variable:
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Distance from the light
(cm)
Number of oxygen
bubbles produced in
______ minutes
0
10
20
30
40
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Conclusion:
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2
1
3
6
4
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5
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