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PATTERNS IN NATURE
Outline the historical development of the cell theory, in particular, the contributions of
Robert Hooke and Robert Brown.
Things to consider:
- What does outline mean?
- Underline key words.
- Understand what the question is asking before you write your answer.
Their have been many scientific contributions towards the development of the cell
theory. Of importance were the contributions of Robert Hooke. Robert Hooke began
to use the compound microscope in 1665. The compound microscope had already
been invented by Hans and Zacharias Janssen in 1590. It was in 1665 that Hooke
observed the first cells. He did this by observing thin slices of cork and describing the
boxes filled with air as cells. Robert Brown also made significant contributions
towards cell theory. Brown identified and described the nucleus of a plant cell in
1827. These contributions are significant in the development of cell theory as it
enabled scientists to further research and develop techniques to prove that all
organisms are composed of cells.
Describe evidence to support the cell theory.
Things to consider:
- What does describe mean?
- Creative way to present answer???
- Be succinct.

SUPPORTING THE CELL THEORY
EVIDENCE
DESCRIPTION
1665 Discovery cells in cork.
 Robert Hooke used a compound
microscope to describe little
boxes of air, which in turn he
called cells.

1676 Discovery of
microorganisms.


1827 Discovery of nucleus in
plants.

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1838 Discovery of cell
replication.

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1879 Proof of cells dividing.

Leeuwenhoek identifies
microorganisms in pond water
which he views using a
microscope.
Robert Brown discovers and
describes the nucleus in plant
cells.
Schwann views single yeast cells
budding and producing new cells.
This leads to the conclusion that
all cells are the building blocks of
life and subsequently mitosis.
Flemming uses a biological stain
to view cells. He discovers that
cells divide supporting Virchow’s
hypothesis.
The above evidence supports cell theory as it shows the gradual steps as to the final
conclusion that all living things contain cells, which in turn replicate. (Mitosis)
Use available evidence to assess the impact of technology, including the development
of the microscope on the development of the cell theory.
Things to consider:
- What does assess mean?
- What does impact mean?
- Relate the development of the microscope to cell theory
Technology has had a huge effect on the development of cell theory. In particular was
the development of the light microscope. The light microscope was developed and
refined over hundreds of years from the initial stages where Italian monks invented
glass magnifying spectacles, to that of the current day light compound microscope. It
was through the invention of the light microscope and the work of various scientists
including Hooke, Brown, Schwann and Flemming that the hypothesis that all
organisms contained cells was proven, and hence cell theory was established.
Therefore by the work of Hooke discovering cells using the microscope, Brown
identifying and describing the nucleus using a microscope, Schwann witnessing yeast
budding and producing new cells using a microscope and Flemming using biological
stains to view mitosis using a microscope further supports cell theory as well as how
technology has affected the development of cell theory.
Discuss the significance of technological advances to developments in the cell theory.
Things to consider:
- What does discuss mean?
- Underline key words
- Be succinct
There have been many technological advancements which have led to further
developments in cell theory. In chronological order they are:
TECHNOLOGICAL ADVANCE 1: The development of the light microscope:
The light microscope was developed over hundreds of years. It enabled Hooke to
identify the first cells, which in turn led to further discoveries by Brown, Schwann
and Flemming. Therefore establishing and proving cell theory.
TECHNOLOGICAL ADVANCE 2: The use of a biological stain:
The use of the biological stain has enabled scientists to make further discoveries about
cells and their function. Biological stains stain certain parts of the cell and highlight
their structure. It was the work of Flemming who first used a stain in 1879 to view
cells dividing that further supports cell theory.
TECHNOLOGICAL ADVANCE 3: The use of oil immersion:
Oil immersion was developed so that scientists could view extremely small cells such
as bacteria. Through oil immersion cell theory has been further supported.
TECHNOLOGICAL ADVANCE 4: The development of the electron microscope:
The electron microscope was developed due to the low magnification and clarity of
the light microscope. The electron microscope was fully developed in 1939 and has
enabled scientists to view cells in more detail. This therefore supports and proves cell
theory.
Identify cell organelles seen with current light and electron microscopes.
Things to consider:
- What does identify mean?
- Be succinct
The cell organelles which can be seen with the current light microscope are;
chloroplasts, nucleus and vacuoles. The cell organelles that can be seen with the
current electron microscope are; nucleus, chloroplasts (plastids), vacuoles,
mitochondria, golgi body (apparatus) lysosomes, ribosomes and the endoplasmic
reticulum.
Describe the relationship between the structure of cell organelles and their function.
Things to consider:
- What does describe mean?
- Think of a creative way to formulate an answer…..table??
ORGANELLE
NUCLEUS
STRUCTURE/FUNCTION
The nucleus is a dark large spherical structure which contains
DNA and RNA. The DNA in particular is responsible for cell
structure and chemical activity within the cell.
PLASTIDS
The plastids are a group of organelles which include
chloroplasts, chromoplasts and leucoplasts. Chloroplasts are
cylindrical in structure and contain grana. The grana contain
chlorophyll which is responsible for photosynthesis.
Chromoplasts contain colours for fruit and flowers. Leucoplasts
store starch.
MITOCHONDRIA Mitochondria are sausage shape structures which contain tiny
membranes called cristae. The angle of the cristae enables a
larger surface area which in turn increases surface area. The
main function of mitochondria is cellular respiration and the
production of ATP.
ENDOPLASMIC
ER is a series of flattened sacs, tubules and membranes. The
RETICULUM
cells chemical activity takes part in the ER as well as the
transport of nutrients and the removal of wastes.
RIBOSOMES
Ribosomes are found all throughout cells They are seen as tiny
black dots. Their main function is protein synthesis.
GOLGI BODIES
Specialised areas of ER. Semi circle arrangement of
membranes. On the end of theses membranes are tiny vesicles.
These vesicles transport substances to the cell membrane. Other
functions include the sorting of proteins. (Transport within the
cell.)
LYSOSOMES
Tiny vesicles (sacs) which destroy any foreign material entering
the cell.
VACUOLES
Large fluid filled sacs which contain water, salts and other
molecules. Provides support for the cell.
Perform a first-hand investigation to gather first-hand information using a light
microscope to observe cells in plants and animals and identify nucleus, cytoplasm,
cell wall, chloroplast and vacuoles.
Things to consider:
- What does perform mean?
- Underline key words.
- Ensure you know how to use a microscope (refer to class notes)
- Ensure you know how to prepare a wet mount (refer to class notes)
- Ensure you know how to prepare a stained slide (refer to class notes)
REFER TO PAGE 107 – 108 OF THE SCIENCE TEXT BOOK.
Process information from secondary sources to analyse electron micrographs of cells
and identify mitochondria, chloroplasts, Golgi bodies, lysosomes, endoplasmic
reticulum, ribosomes, nucleus, nucleolus and cell membranes.
Things to consider:
- What are electron micrographs?
- What does identify mean?
- Ensure you obtain/observe a micrograph with all of the above stated
organelles.
MITOCHONDRIA
CHLOROPLAST
GOLGI BODY AND LYSOSOMES
Identify that there is movement of molecules into and out of cells.
There is movement of molecules in and out of cells. However this is restricted by the
cell membrane also known as the phospholipid bilayer. This layer is selectively
permeable, which means it only allows certain molecules in and out of the cell.
Describe the current model of membrane structure and explain how it
accounts for the movement of some substances into and out of cells.
Things to consider:
- Describe means to provide characteristics or features of.
- Explain means to relate cause and effect
- Firstly give features of the fluid mosaic model structure.
- Then explain how these features account for the movement of
some substances into and out of cells.
The main structures of the fluid mosaic model include glycolipids,
cholesterol, carbohydrates, glycoproteins, phospholipids and proteins.
These structures in turn all have a specialised function. These functions
account for the movement of some substances into and out of cells.
- The phospholipid bilayer acts as a barrier to ions, polar substances
and large molecules. Water is an exception because it easily travels
through the bilayer.
- The proteins allow substances such as amino acids to pass through
the membrane. Their pore allows substances to pass through the
membrane.
- The carbohydrate molecule projects towards the extracellular fluid.
Its main role is to reject foreign cells and molecules away from the
cell. It is also expected to accept cells or molecules recognised as
its own. This recognition phase is mainly undertaken by the
glycoprotein.
Identify that there is movement of molecules into and out of cells.
Things to consider:
- Identify means to recognise and name
- This question is a low order question meaning it will only require a
short answer
There is movement of molecules into and out of cells. Molecules move
into and out of cells by active or passive transport. This process of
transport is related to diffusion. Diffusion is the movement of a substance
from where it is more concentrated to an area of less concentration.
Perform a first-hand investigation to model the selectively permeable
nature of a cell membrane.
OBSERVING DIFFUSION
AIM:
To observe and describe an example of diffusion.
MATERIALS:
 2 Beakers
 Straw
 Potassium Permanganate
METHOD:
1. Label one beaker “cold” and the other “hot,” then three-quarters fill
each with cold and hot water, as labelled. Put the beakers where
they can be left undisturbed. Wait five minutes to let the contents
settle.
2. Using the straw, carefully position a crystal at the bottom of each
beaker as shown below. Try not to disturb the water as the straw is
withdrawn.
RESULTS:
Draw a diagram of each beaker and use shading to show the differences
in colour intensity of the solutions for:
- the changes you observe over half an hour in both beakers
- the changes you observe in the next lesson
Compare the processes of diffusion and osmosis.
Things to consider:
- What does compare mean?
- What is the best way to present our data?
- The best way to present our data would most likely be in the form of a
table.

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
DIFFUSION
The process by which
substances move from an
area of high concentration to
an area of low concentration.
The difference in
concentration between two
areas is usually due to the
fact of a barrier.
This barrier is known as the
concentration gradient.
No cellular energy is needed.
The energy within the
molecules is suffice for the
molecules to move from
either side of the
concentration gradient.
An example of diffusion is
carbon dioxide leaving the
blood stream and into the
lungs.
OSMOSIS
 Osmosis is the process of
water crossing a semipermeable membrane.
 This means that the
difference between diffusion
and osmosis is that osmosis
is concerned with water
crossing the gradient and
diffusion is concerned with
molecules crossing the
gradient.
Compare prokaryotic cells to eukaryotic cells.
PROCARYOTIC
 Earliest type of cells
 Do not contain a nucleus nor
any membrane bound
organelles.
 All substances for cell
function are found in the
cytoplasm.
EUCARYOTIC
 Contain a nucleus and
membrane enclosed
organelles
 Multicellular
 Examples include plant and
animal cells.
 Unicellular
 Contain only ribosomes.
 Examples include bacteria.
OBSERVING OSMOSIS
AIM:
To model the function of a cell membrane
METHOD:
1. Three-quarters fill the gas jar with water and add iodine/potassium
iodide solution until the water is dark brown.
2. Moisten the dialysis tubing and tie a very tight knot in one end.
Insert the stem of the thistle funnel into the other end and fasten it
firmly with the rubber band.
3. Pour starch solution through the thistle funnel into the dialysis bag
until the bag is full and the starch level is 2-3cm up the stem of the
funnel. Make sure that there are no air bubbles trapped in the bag.
Rinse the outside of the bag and funnel with water to remove any
traces of starch.
4. Mark the level of starch on the funnel stem and then suspend the
apparatus as shown in Figure 2. Let the apparatus stand
undisturbed for 30 to 60 minutes.
RESULTS:
Draw large and accurate ‘before’ and ‘after’ diagrams of your apparatus.
Note the liquid level in the funnel stem. Label the diagrams fully.
DISCUSSION:
1. From your results, what is the evidence that some of these
molecules have moved through the dialysis bag? On your diagrams
indicate in which direction there has been a net (overall) movement
of each type of molecule.
2. Suggest a reason why some molecules have moved through the
dialysis bag while others have not.
3. Is there any evidence that there has been a net movement of water
into the dialysis bag? Explain how you decided whether such a
movement occurred.
4. Based on your observations, and referring to your text book if
necessary, write down a definition of osmosis.
CONCLUSION:
This experiment modelled the movement of water in living cells. In your
conclusion consider the following:
- What did the dialysis bag represent in this model?
- What did the starch solution represent?
- From your observations, explain how water enters living cells.
Discussion answers:
1. Evidence should include:
- Change of colour. (Black = starch and iodine have reacted)
- The volume of the dialysis bag
- The volume in the gas jar
2. Main reason would be due to the fact that the dialysis bag is
selectively permeable to certain substances. E.G. larger molecules
would not be able to permeate through the bag
3. Evidence to suggest that there has been some net movement of
water into the bag would include the volume in the bag as well as
the volume in the gas jar. (Water molecules attached to iodine
molecules)
4. Osmosis is the diffusion of water across a semi-permeable
membrane
Explain how the surface area to volume ratio affects the rate of movement
of substances into and out of cells
Things to consider:
- What does “explain” mean?
- What is surface area to volume ratio?
- How does this affect the movement of substances in and out of
cells?
Firstly the surface area to volume ratio is the amount of surface area of an
object compared to its apparent volume. This definition can be linked to
cells and how surface area to volume ratio affects the rate of movement
of substances into and out of cells. Cells obtain nutrients and release
waste through their membrane through diffusion. This covers the whole
surface area of the cell. The cell carries out important chemical reactions
(metabolism) within the volume of the cell. It is important that a cell has
a large surface area to volume ratio because then there is enough surface
area to supply the volume with nutrients as well as the diffusion of wastes
out of the cell to keep the cell in working order and alive.
Perform a first-hand investigation to demonstrate the effect of surface
area to volume ratio on rate of diffusion
AIM:
To investigate the relationship between the surface area to volume ratio
of an object, the rate of diffusion of a substance into it, and the
relationship between surface area and rate of reaction.
METHOD:
1. Accurately cut the jelly sheets into blocks as indicated by your
table.
2. Half fill the beaker with sulphuric acid.
3. Add the blocks to the beaker and gently stir. Watch until the first
block goes completely clear then proceed to the next step
immediately
4. Remove all the blocks from the acid. Rinse in water and pat them
dry. Working quickly cut them in half and measure in millimetres
the depth of the clear layer in each.
5. Record results in table.
RESULTS:
BLOCK
NUMBER
1
2
3
Block
Dimensions
(mm)
20 x 20 x 20
20 x 20 x 10
20 x 20 x 5
3
2
1
Order of
clearing
Depth of clear
part of block
(mm)
Student answers Student answers
Student answers
Surface area
(mm2)
2400
1600
1200
Volume (mm3)
8000
4000
2000
Surface area to
volume ratio
(SA÷V)
0.3:1
0.4:1
0.6:1
QUESTIONS:
1. What causes the blocks to become clear?
2. Which block was first to go clear
3. From your observations of the other two blocks, predict which
would be next to go clear. Explain your prediction.
4. Which block in your table had the largest surface area to volume
ratio?
5. Does the size of a block influence the rate at which acid diffuses
into it? Refer to surface area and volume in your answer.
ANSWERS:
1. A chemical reaction occurs whereby the sulphuric acid diffuses
into the jelly. This in turn reacts with the sodium hydroxide and the
phenolphthalein to turn the block clear.
2. Block number three
3. Block number two. This is due to the fact that it has a greater
surface area to volume ratio to that of block one, which in turn
means block two would have a greater reaction rate.
4. Block number three had the largest surface area to volume ratio
5. The size of the block does influence its rate of diffusion. This is
evident in the results. The results showed that block three which
had the largest surface area to volume ratio obviously had the
quickest diffusion as the block went clear the quickest out of the
two.
Identify some examples that demonstrate the structural and functional
relationships between cells, tissues, organs and organ systems in
multicellular organisms.
Brainstorm activity.
Things to consider:
- What does identify mean?
- What is the question asking?
- Can we think of any examples?
THE EXAMPLE WE USED WAS WRITTEN IN CLASS.
(CARDIOVASCULAR SYSTEM)
Distinguish between autotrophs and heterotrophs in terms of nutrient
requirements.
Things to consider:
- What does distinguish mean?
- What are autotrophs and heterotrophs?
- Nutrient requirements: Nutrients they need to survive.
Autotrophs are organisms that make their own food. They make their
food by trapping energy from another system. For example plants make
their own food in the process of photosynthesis. Bacteria on ocean floors
make their own food through chemosynthesis. Autotrophs are different to
that of heterotrophs because heterotrophs can not make their own food.
Heterotrophs have to rely on other organisms to make their food. For
example humans eat meat.
Identify the materials required for photosynthesis and its role in
ecosystems.
Things to consider:
- What does identify mean?
- Name the materials required
- How does this help ecosystems?
The materials required for photosynthesis include:
- Water
- Carbon Dioxide
- Sun Light
- chloroplasts
The role of photosynthesis in ecosystems is to produce energy and food
for plants to survive; this in turn can feed other heterotrophic organisms.
E.G. Cows eating grass.
Identify the general word equation for photosynthesis and outline this as
a summary of a chain of biochemical reactions.
Things to consider:
- What is the meaning of identify?
- The word equation for photosynthesis
- What does outline mean?
- What are biochemical reactions?
The word equation for photosynthesis can be seen on page
Firstly the term biochemical refers to the chemistry of living matter. In
this case we are talking about plants and how they undergo
photosynthesis. For photosynthesis to occur plants need the following,
carbon dioxide, water, sun light and chlorophyll. The chlorophyll “traps”
the sunlight in the plant cells; this then reacts with the two reactants
carbon dioxide and water. Once this reaction has taken place a product of
oxygen and glucose has been produced.
Plan, choose equipment or resources and perform first-hand
investigations to gather information and use available evidence to
demonstrate the need for chlorophyll and light in photosynthesis
As a class we need to design an experiment which will address the
following questions:
Is chlorophyll necessary for starch production?
Is light necessary for starch production?
Things to consider:
- What results can be expected?
- How will the actual results be recorded?
- Are any controls needed?
- Are their any problems with the design
PART A:
AIM:
To determine if chlorophyll and light are necessary for starch production.
EQUIPMENT (Apparatus)
 Plants
 Dark cupboard
 Sunlight
 Iodine solution
 100ml beaker
METHOD:
1. Water both plants with 100ml of water
2. Put one plant into a dark cupboard for the weekend
3. Place the other plant in direct sunlight for the weekend.
4. Record any observations you see in the plants.
RESULTS:
Describe any changes between the two plants.
PART B: Testing a leaf for starch
METHOD:
1. Using a Bunsen burner bring 75ml of water to the boil. Then turn
off the Bunsen.
2. Place leaves to be tested into the water. When the leaves are limp
remove them with forceps and place in evaporating dish.
3. Using the forceps put the softened leaves into a test tube of alcohol.
4. Place this test tube into the beaker of water and place on the hot
plate. The alcohol should start to turn green.
5. Remove the leaves when they are pale and place them into an
evaporating dish.
6. Rinse the leaves in the hot water that is still in your beaker and
place them in an evaporating dish.
7. Cover each leaf with iodine/potassium iodide solution and allow
them to stand for a minute.
RESULTS
1. Write an account of what you observed during this experiment.
2. Compare the two sets of results. Were there any differences? If so
what were they?
3. State why it was safer to burn the alcohol on the hot plate 170
4. Rather then the Bunsen burner.
5. Why are chlorophyll and light required for photosynthesis to
occur?
CONCLUSION
From your investigations, are chlorophyll and light necessary for starch
formation?
Explain the relationship between the organisation of the structures used
to obtain water and minerals in a range of plants and the need to
increase the surface area available for absorption.
Things to consider:
- What does explain mean?
- Simplify the question. For example know what the question is
asking before writing an answer.
- Underline key words
- Remember to use scientific terms.
- Refer back to question
Plants are simple in their nutritional requirements. They only require
water and minerals. Water enters the plant by osmosis while minerals are
mainly absorbed through active transport. There are many different
groups of plants which in turn means there are many different ways to
absorb water and nutrients. Firstly there are monocot plants. These plants
have a fibrous root network. These fibrous roots increase the surface area
for the absorption of water and mineral ions. The second group of plants
are dicotyledons. This group of plants have a main tap root as well as
roots that branch off. This system in turn increases the surface area
available leading to greater water and mineral ion absorption. The third
group of plants is a symbiotic relationship between a fungus and the
plant. Mycorrhizae consist of a large network of fungal threads which
surround the root hairs of plants. Water and minerals are absorbed
through the fungal cells as well as the plant roots. The plant receives
water from the mycorrhizae in return for nutrients. This symbiotic
relationship increases the surface area for the absorption of water and
minerals.
Explain the relationship between the shape of leaves, the distribution of
tissues in them and their role.
Things to consider:
- What does explain mean?
- Simplify the question so you understand what the question is
asking.
- Underline key words
- Remember to use scientific terms
- Refer back to the question
The leaves of many plants are flat and thin, this increases the surface area
for light absorption. Palisade mesophyll cells are packed just below the
upper cuticle of the leaf. These cells are packed with chloroplasts which
enhances photosynthesis. Next in line are the spongy mesophyll cells.
These cells are surrounded by air spaces filled with carbon dioxide and
oxygen. Gas is exchanged in the leaves through tiny holes called
stomates. Therefore the shape of the leaf as well as photosynthetic leaf
cells maximise the surface area for photosynthesis to occur. The
chloroplasts also play an important role in increasing surface area for
photosynthesis. They are a large organelle structure which contain
thylakoids and granum. Thylakoids contain large amounts of chlorophyll
which traps the sunlight. The thylakoids are stacked upon one another and
are called granum (grana). The light reactions of photosynthesis take
place in the grana. The arrangement of the grana increases the surface
area and hence increases the efficiency of photosynthesis.
AIM:
To determine if the surface area of calcium carbonate will affect the rate
of reaction.
EQUIPMENT:
Marble chips, calcium carbonate powder, dilute HCl, test tubes with
stoppers and side arms, test tubes, lime water, 10ml measuring cylinder,
electronic balance and test tube rack.
METHOD:
1. Pour 10mL of HCl into 2 test tubes with side arms and place them
in the test tube rack.
2. Pour 10mL of lime water into 2 plain test tubes and place them in
the test tube rack.
3. Collect a marble chip. Weigh the marble chip and record its
weight.
4. Collect some calcium carbonate powder. Weigh the calcium
carbonate and make sure it is the same weight as the marble chip.
5. Connect your test tubes as indicated below.
6. At the same time place both the powder and marble chip into their
respective HCl test tubes.
7. Observe the two tubes and the reactions taking place.
8. The lime water should turn a murky colour indicating the presence
of carbon dioxide and a reaction taking place
9. Record which substance reacted the fastest.
RESULTS
Weight of marble chip: _______________
Weight of calcium carbonate powder: ____________________
Observations:
Describe the role of teeth in increasing the surface area of complex foods
for exposure to digestive chemicals
Things to consider:





What does describe mean?
Simplify the question
Underline key words
Be succinct
Refer back to the question
The role of teeth in mammals is to break down food and to increase the
surface area of this food so that enzymes can break down this food. The
human mouth consists of four types of teeth incisors, canines, pre-molars
and molars. There are a total of eight incisors in the human mouth. Their
specialised function is cutting and biting. Canines are situated next to the
incisors. They are used for ripping and tearing food. Premolars and molars
are situated to the back of the human mouth. These teeth are used for
grinding and crushing food. This set of human teeth therefore increases the
surface area of complex foods which in turn increases their chances of being
exposed to digestive chemicals. Herbivorous mammal’s teeth are very
different to that of humans. Premolars and molars are the main type of tooth
in a herbivore. These types of teeth break down food by crushing and
grinding. This aids herbivores as plant food contains cellulose which can
only be broken down by excessive grinding and crushing. Therefore the role
of the herbivores teeth is to break down plant material to increase the surface
area of complex food which in turn exposes this food to digestive chemicals.
Explain the relationship between the length and overall complexity of
digestive systems of a vertebrate herbivore and a vertebrate carnivore with
respect to:
- the chemical composition of their diet
- the functions of the structures involved
Things to consider:




What does explain mean?
Simplify the question so that you understand what the question is
asking
Underline key words
Use scientific terminology
The digestive systems of vertebrate herbivores and vertebrate carnivores
are very different. Herbivores eat plant material which contains cellulose.
Cellulose is a good source of nutrients for herbivores. The problem for
herbivores is that cellulose is broken down by the enzyme cellulase,
which is not part of the herbivores digestive system. To overcome this
problem herbivores have a symbiotic partnership with bacteria and
protozoa. These microbes are present in the herbivores long caecum. The
caecum provides a large surface area for bacterial enzymes to digest
cellulose and to release the nutrients into the small intestine. The
herbivore then digests the rest of their food.
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
Kangaroo’s have two stomachs first stomach to digest cellulose.
Ruminants large group of animals which have a four chambered
stomach to digest cellulose:
- 1st chamber the rumen moistens and churns up the food.
- 2nd chamber the reticulum breaks down cellulose with bacterial
cellulases and forms a round ball called a cud.
- 3rd chamber omasum further digestion of the cud
- 4th chamber abomasum acts as a stomach similar to that of any
other mammal.

Food passes to intestine for further digestion.
Identify data sources, gather, process, analyse and present information from secondary
sources and use available evidence to compare the digestive systems of mammals, including a
grazing herbivore, carnivore and a predominantly nectar feeding animal
Things to consider:
-
-
What does identify, gather, analyse, present and compare mean?
Simplify the question
Be succinct
Underline key words
http://babcock.cals.wisc.edu/downloads/de_html/images/en1_digestion1.gif
http://www.onedreamdesign.com/canine/pic/digestiveplate1cpy.jpg
DOG
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COW
Mostly feed on
meat.
Eating is rapid as
well as the
digestion of the
meat
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Most of their time
eating grass.
Grass processed by
a four chambered
stomach.
Main nutrient is
cellulose which is
broken down by
cellulase
HONEY POSSUM
 Mainly eat nectar
and pollen
 Pollen containing
protein, carbs and
lipids.
 Nectar being
sugary
 2 chambered
stomach where
pollen and nectar
are stored
 No caecum
 Specialised
function is the
tongue and roof of
their mouth.
Compare the roles of respiratory, circulatory and excretory systems
Things to consider:
- What does compare mean
- Simplify the question
- Use scientific terminology
RESPIRATORY
-This system consists of
the lungs and the
structures within the lungs
to maintain our breathing
- The main gases involved
in respiration are called
oxygen and carbon dioxide
- The exchange of these
gases are known as
“gaseous exchange”
- Therefore the main role
of the respiratory system is
to help organisms to breath
as well as the exchange of
gases in and out of the
body
CIRCULATORY
- This system consists
mainly of the heart and
blood vessels
- The heart pumps
oxygenated blood around
the body.
- Deoxygenated blood
returns to the heart.
- Therefore the main role
of the circulatory system is
to pump blood around the
body.
EXCRETORY
- This system consists
mainly of the kidneys,
urethra, ureter and the
urinary bladder
- The main function of the
kidneys is to filter the
blood. During filtration
nutrients for the body are
returned to the body while
waste converts to the form
of urine.
- Waste passes into the
ureter and then into the
urinary bladder.
- When the urinary bladder
is full the urine is then
passed out of the body.
- Therefore the main
function of the excretory
system is to filter the blood
through the kidney’s and
to excrete waste as urine
Identify and compare the gaseous exchange surfaces in an insect, a fish, a frog and a
mammal
Things to consider:
- What does identify and compare mean?
- Simplify the question so you know what it is asking
- Be succinct
- Use scientific language
IDENTIFY
COMPARE
To perform gaseous
The fish opens its mouth, lowering the buccal
FISH
exchange fish have
cavity floor. The water flows in. Fish then
gills.
closes its mouth. Pressure of inside mouth
increases. This pressure squeezes the water.
The water then subsequently flows over the
gills and out via the operculum. Fine tubes
next to the capillary network pick up oxygen
from the water while carbon dioxide is
removed from the blood stream and out into
the water.
Gaseous exchange in
The tracheae distribute oxygen to and collect
INSECT
an insect occurs
carbon dioxide from body cells. This system
through a set of tiny
has the advantage of having a small surface
holes called spiracles.
area exposed to the atmosphere while having
These spiracles are
a large internal surface area for maximum gas
connected to a network exchange.
of tubes called
tracheae.
Gaseous exchange
The skin of a frog has a well developed blood
FROG
occurs in two ways.
supply. Oxygen from the air diffuses into the
The skin and the lungs. skin and is transported by the blood to the
heart, and sent all around the body. Gaseous
exchange also occurs in the lungs whereby
oxygen is passed in and out by the pumping
movement of the buccal cavity and
opening/closing of the nostrils
Air passes through the mouth/nostrils down
MAMMAL Gaseous exchange
occurs through the
the trachea and into the lungs. Alveoli
lungs.
provide large surface area for gas exchange.
Oxygen diffuses from the alveoli into the
blood stream. Carbon dioxide diffuses back
into the lungs from the blood stream and is
breathed out.
Explain the relationship between the requirements of cells and the need for transport
systems in multicellular organisms (pg 89, 90)
Things to consider:
- What does explain mean
- What is the question asking?
- Be succinct and use scientific terms
Multicellular organisms need transport systems as they transport important nutrients
such as amino acids, carbon dioxide and oxygen to cells. For example a transport
system in the human body is the cardiovascular system. This system transports blood
around the body. The blood contains oxygen. This oxygen is transported to cells. The
oxygen enters the cells by diffusion. The oxygen is then used by the mitochondria to
perform a process known as cellular respiration. Therefore it is evident that
multicellular organisms need transport systems as they allow certain substances to
travel to and from cells.
Outline the transport system in plants including: (pg 86, 87, 88, 95, 96, 97)
-
root hair cells
xylem
phloem
stomates and lenticels
Things to consider:
-
What does outline mean?
Underline key words and determine what they mean.
Be succinct and use scientific terminology in your answer.
Plants have many transport systems which aid in water absorption, nutrient absorption
and gas exchange. The following structures are transport systems within plants; root
hair cells, xylem, phloem, stomates and lenticels. Root hair cells are small structures
within plants. They increase the surface area which therefore increases the absorption
of water and minerals. Xylem are tube like structures. Xylem can be strengthened by a
woody structure called lignin. Xylem transport water and dissolved mineral salts. The
process starts in the root hairs. Water and mineral salts pass through the root hairs into
root tissue and into the xylem. Water and mineral salts then pass through the xylem
into the leaves where some of it is used for photosynthesis while most of the water is
transpired. Phloem is a tube like structure that carries mainly glucose around the
plant. Glucose can be converted into other substances such as starch and sucrose. The
movement of nutrients within the phloem is called translocation. If a substance is to
be returned to a previous location it is called retranslocation. Stomates and lenticels
have a similar function within a plant. They are both involved in gas exchange.
Stomates are tiny pores in the leaves which aid in the sucking up of water as well as
releasing oxygen into the air and taking in carbon dioxide for photosynthesis. In larger
plants there are also gaps in the bark which allows gas diffusion. These gaps are filled
with parenchyma cells, which in turn are called lenticels. These lenticels allow easy
diffusion of gases in and out of plants.
Compare open and closed circulatory systems using one vertebrate and one
invertebrate as examples.
-
What does compare mean?
Underline key words
Make sure you include a vertebrate and invertebrate as an example.
VERTEBRATE




Vertebrates have a closed
circulatory system.
This means that the blood stays
within the blood vessels.
Materials diffuse in and out of the
blood vessels via the capillaries.
The lymphatic system collects
excess fluid from around the cells
and transports it to the
bloodstream. Lymphatic system is
closed.
INVERTEBRATE




Invertebrates have an open
circulatory system.
Invertebrate’s blood is at low
pressure and is pumped directly
into the main cavity.
Blood is collected by valves and
drained back to the heart.
The small size of invertebrates
allows them to function with a
relatively inefficient circulatory
system.
Use available evidence to discuss, using examples, the role of technologies, such as
the use of radioisotopes in tracing the path of elements through living plants and
animals. (Text book page 97. Dot point page 49, 50)
Things to consider:
- What does discuss mean?
- Simplify the question to know all the terms in the question
- Be scientific, key words etc
Radioactive forms of certain elements can be utilised in the production of radioactive
isotopes. These radioactive isotopes aid scientists as they are capable of tracing
certain biochemical pathways. The radioactive isotope acts much the same as the nonradioactive isotope in the biochemical pathway to be tested.
For example:
Autoradiography is a technique used by scientists to trace the movement of certain
substances around a plant. It involves the following steps:
 Carbon – 14 a radioactive isotope, is added to plant to observe the movement
of carbon in the process of photosynthesis.
 The plant uses the radioactive isotope carbon – 14 in the process of
photosynthesis.
 The movement of the carbon – 14 isotope can be traced by using an
autoradiograph. This is similar to when we have an x – ray. The
autoradiograph is produced by placing the plant against photographic film.
The areas of the plant that are dark in nature is where carbon – 14 has built up.
Other examples of radioisotopes include:
Thallium – 201: Used to detect damaged heart tissue after a heart attack. The isotope
will only accumulate in normal undamaged heart tissue. This enables doctors to
determine how much of the heart tissue was damaged during the heart attack.
Technetium – 99: This radioactive isotope emits gamma radiation and is useful in
scintigraphy, (method used to examine organs to diagnose cancer and other diseases).
USE OF THALLIUM – 201
(http://www.drdo.org/pub/techfocus/jun2000/image/401.jpg)
USE OF TECHNETIUM – 99 (http://www.ndteducational.org/images/Brandenburg_Figure1.jpg)
Perform a first-hand investigation of the movement of materials in xylem or phloem
(This will be completed first lesson back)
Things to consider:
- Performing means?
- Know how to write an aim, method, discussion, results, hypothesis etc
AIM:
To observe the movement of dye in the xylem and phloem of a piece of celery.
HYPOTHESIS:
I believe…..I think…..
MATERIALS:
 Food dye
 250ml beaker
 Celery
 Water
METHOD: PART A
1. Pour approximately 100-150ml of water into a 250ml beaker.
2. Pour the same amount of water into another beaker, this time add five drops of
food dye to the water. Add more dye if necessary.
3. Place a stalk of celery into the beaker with the plain water.
4. Place a stalk of celery into the beaker with the water and dye.
5. Leave the celery overnight. (Till Friday)
PART B:
1. Take your celery and cut a cross section
2. Observe the xylem and phloem, and the movement of the dye.
3. Cut a thin section of the celery and prepare a wet mount slide of the celery and
view under the microscope.
4. Draw your observations.
RESULTS:
Drawing of your specimen. Indicate the xylem, phloem and any other observations on
your diagram.
CONCLUSION:
Write a conclusion to this experiment.
Identify mitosis as a process of nuclear division and explain its role
http://www.cellsalive.com/mitosis.htm
Things to consider:
- What does identify mean?
- What does explain mean?
- Know mitosis is nuclear division
- Be succinct and use scientific language
Mitosis is the duplication of chromosomal DNA followed by a cell division that
results in two smaller daughter cells being formed, which are identical to the parent
cell. Mitosis is an important process for all organisms. It is responsible for growth as
well as tissue repair. Mitosis also plays an important role in asexually reproducing
organisms. In this process mitosis transmits DNA codes from one cell generation to
the next.
Identify the sites of mitosis in plants, insects and mammals (Text page 104, 105, 106.
Dot point book page 51)
Things to consider:
- What does identify mean?
- Underline key words
- Make sure you answers for plants, insects and mammals
- Use scientific terminology
Plants, insects and mammals are constantly undergoing mitosis in order for growth
and repair of tissue. In plants mitosis occurs just behind the root cap, just below the
shoot tip, buds along the stem and roots and in the cambium, which lies between the
xylem and phloem. Insects have various stages in which they undergo mitosis. When
a larva changes into a pupa, groups of cells form into discs. These discs are the sites
for cell division and mitosis. New cells are produced here for growth and for the pupa
to turn into an adult insect. Mammals undergo mitosis for growth and repair. The
main sites for mitosis in mammals include the bone marrow and skin.
Explain the need for cytokinesis in cell division (Text book page 103, 104. Dot point
page 51)
Cytokinesis is the division of the cytoplasm and occurs during the telophase stage of
mitosis. In animal cells the cytoplasm constricts to the centre, breaks, and then forms
into two cells. In plants there is no constriction. A cell plate is formed instead. The
plate is a double membrane with a space between the two layers. The process of
cytokinesis is important during mitosis as the cells stabilise the internal concentration
of materials which is essential to produce two functioning cells.
Identify that nuclei, mitochondria and chloroplasts contain DNA
-
Know the meaning of identify
Simple question, answer should be short and straight to the point.
Cells contain many organelles. These organelles enable the cell to function efficiently.
The organelles that contain DNA are the nuclei, mitochondria and chloroplasts.
Use available evidence to perform a first-hand investigation and gather first hand
data to identify and describe factors that affect the rate of transpiration.
Refer to aim, materials and method on page 116 of the text book. FACTORS
AFFECTING THE RATE OF TRANSPIRATION
Perform a first - hand investigation with a microscope to gather information from
prepared slides to describe the sequence of changes in the nucleus of plant or animal
cells undergoing mitosis.
Refer to aim, materials and method on page 117 of the text book.
IDENTIFICATION OF MITOTIC PHASES