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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
needed.

Explain how a high rate…

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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…

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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…

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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…

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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…

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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…

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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.

Lysomes?

Break down and digest dead organelles.…

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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…

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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…

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