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2024 AQA AS LEVEL BIOLOGY EXAM WITH 100% VALID ANSWERS
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2024 AQA AS LEVEL BIOLOGY EXAM WITH 100% VALID ANSWERS
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2024 AQA AS LEVEL BIOLOGYEXAM WITH 100% VALID
ANSWERS
What are the lifestyle factors that can affect your chances of getting cancer?
- CORRECT-ANSWERS1) smoking
2) excessive exposure to sunlight
3) excessive alcohol intake
What are the two ways pathogens cause disease? - CORRECT-ANSWERS1)
production of toxins
2) cell damage
What are the three ways a pathogen can damage hosts cells? - CORRECT-
ANSWERS1) rupturing them to release nutrients inside them
2) breaking down nutrients inside the cell for their own use. This starves and
eventually kills the cell.
3) replicating inside the cells and bursting them when they're released
Describe the test for reducing sugars - CORRECT-ANSWERSAdd benedicts
and heat
if the sample contains reducing sugars = will turn red
Describe the test for non-reducing sugars - CORRECT-ANSWERS1) boil with
hydrocholric acid and neutralise with sodium hydrogencarbonate.
2) carry out the benedicts test as if you would for the reducing sugars test.
Describe the test for starch - CORRECT-ANSWERS1) Add iodine dissolved in
potassium iodide solution
2) if there is starch = will turn a blue-black colour
Explain the effect of temperature on enzymes. - CORRECT-ANSWERS1) The
rise in temperature makes the enzymes molecules vibrate more
2) If the temperature goes above a certain level, this vibration breaks some
of the bonds that hold the enzyme in shape
3) The active site changes shape and the enzyme and subtrate no longer fit
together
4) At this point, the enzyme in denatured
, Explain the effect of PH on enzymes - CORRECT-ANSWERS1) All enzymes
have an optimum PH value
2) Above and below the optimum PH, the H + and OH - ions can mess up the
ionic and hydrogen bonds that hold the enzymes tertiary structure in place.
3) The active site changes shape, so the enzyme is denatured
Explain the effect of substrate concentration on enzymes. - CORRECT-
ANSWERS1) the higher the substrate concentration, the faster the reaction.
2) More substrate molecules means a collision between substrate and
enzyme is more likely
3) This only happens until the saturation point, when there are too many
substrates, all active sites are full and adding more makes no difference
Explain What a competitive inhibitor is - CORRECT-ANSWERS1) Competitive
inhibitors compete with the substrate to bind to the active site but no
reaction takes place.
2) Instead they block the active site so that no subtrate molecule can fit in it
3) If theres a high concentration of the inhibitor, it'll take up nearly all the
active sites and hardly any of the substrate will get to the enzyme.
Explain what a non-competitive inhibitor is. - CORRECT-ANSWERS1) non-
competitive inhibitor molecules bind to the enzyme away from its active site
2) This causes the active site to change shape so the substrate molecules
can no longer bind to it.
3) They dont compete with the substrate molecules to bind to the active site
because they are a different shape.
4) increasing the concentration wont make any difference - enzyme activity
will still be inhibited.
Explain the function of the:
1) plasma membrane
2) nucleus
3) lysosome
4) ribosome - CORRECT-ANSWERS1) regulates the movement of substances
in and out of the cell
2) The pores allow substances to move between the nucleus and cytoplasm,
the nucleolus makes ribosomes.
3) Contains digestive enzymes. These are kept seperate from the cytoplasm
by the surrounding membrane and can be used to digest invading cells or to
break down worn out components of cell.
4) The site where proteins are made.
Explain the functions of:
1) endoplasmic recticlum
2) golgi apparatus
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