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Exam Questions Biology ­ AQA Unit 1
Advantages and limitations of using a TEM microscope.
Advantages =high resolution, small objects seen and wavelength of electrons is short. Disadvantages
involve preparation may cause artefacts, thin specimen needed, not 3d, no colour and a vacuum is
Explain how a high rate of gas exchange in a fish is maintained.…read more

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Vaccines protect people against disease, explain how?
Vaccines contain a weakened strain of the pathogen. This allows a primary response from your
immune system to occur. Memory cells are then created, so the next time your infected you will not
have the primary symptoms of the disease, your immune system will rid of the pathogen before you
even notice.…read more

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What is atheroma and how may it cause myocardial infarction?
Atheroma is fatty material/cholesterol in the walls of the artery; it can cause an increased risk of
thrombosis (clotting) and aneurysms. It can block the coronary artery which takes glucose and oxygen
to the heart and respiring cells. Less oxygen means less respiration and less energy, the heart muscle
is unable to respire efficiently. This can cause a heart attack.…read more

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Many different substances enter and leave a cell by crossing its cell surface membrane. Describe
how substances can cross a cell surface membrane?
Facilitated diffusion, the net movement of molecules from an area of high to low concentration with
the aid of carrier proteins. By osmosis, the net movement of water molecules from a high to low
water potential across a partially permeable membrane.…read more

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Testing for non-reducing sugars?
A few steps are needed first. You must add HCL to the sample and heat it in a water bath. You must
then neutralise the solution by adding sodium hydrocabonate. You then proceed with the normal test
of adding benedict's solution, heating in water bath again and look for colour change.
Test for starch?
Add iodine to the sample; wait to see if the sample colour turns blue-black
Sucrose and lactose digestion, explain the processes.…read more

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TEM microscope.
As on previous page, there are more limitations than advantages. The advantages are electrons have
short wavelength, the resolution is high and small objects can be visible. The limitations are that there
needs to be a vacuum present, it produces no colour images, only 2d, artefacts can be made during
preparation, and a thin specimen is also required.
Optical Microscopes.
No vacuum needed, colour image, light used, high resolution. The limitations are however only 2d,
low magnification and light is always needed.…read more

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Smooth endoplasmic?
Has the same structure as rough except no ribosomes on outer surfaces. It synthesis, stores and
packages lipids and carbs.
Golgi Apparatus?
This transports materials across the cell surface membrane using vesicles. It forms lysomes, secretes
carbs, and produces secretory enzymes.
Break down and digest dead organelles. They also release enzymes to break down foreign
pathogens.…read more

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What is active transport?
Active transport is the net movement of molecules from an area of low concentration to an area of
high concentration using ATP and carrier proteins.
What is the purpose of villi?
Villi are finger like projections in the folds of the small intestine; they increase the surface area which
aids better absorption of digested foods.
Explain the transport of glucose into the cell?
Sodium ions are pumped out the cell using ATP from respiration.…read more

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Describe the structure of a cholera bacterium cell?
Cholera bacterium is prokaryote it does not have a nucleus or a nuclear envelope as well as no
membrane bound organelles, eg mitochondria. It has small ribosomes only as well as a capsule and
flagella and cell wall.
Describe inhalation?
This is where air is drawn into the lungs. The external intercostal muscles contract and the internal
costal muscles relax. This causes the chest to move up and out and the diaphragm to flatten and
contract.…read more


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