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Help on AQA Biology(B) Module 4

Hi, can anyone help me answer the following questions please.

1) Explain why the reduction in coenzyme A, due to gene mutation, leads to a reduction in depolarisation in the neurones to muscles. (5 marks)

2) Explain the role of calcium ions in the muscles during ventricular systole. (4 marks)

3) Describe how an eye focuses when it shifts from a long distance view to a short-distance view. (6 marks)

4) Suggest reasons to explain how geological isolation of a species of lizards results in two species with different chemical reactions in respiration.

5) Describe and explain how the process of meiosis results in multiple alleles on a chromosome in a chromatid pair.

6) Explain why people suffering from diabetes mellitus A are less able to control their temperature and suffer from heat stroke.

Thank you. I would grately appreciate your help if you could answer at least one question from above. Thanks again.

Reply 1

JOYEESANG

Anyone able to answer these questions?

Reply 2

Botticello

I know the answers, but I have to go out in a minute, so bear with me when I've got a spare 15 minutes later, OK?

Reply 3

Excalibur

I don't do AQA so these may not be the textbook answer, but.....

1) Explain why the reduction in coenzyme A, due to gene mutation, leads to a reduction in depolarisation in the neurones to muscles. (5 marks)

Well, acetylcholinesterase breaks down acetylcholine into acetate and choline at the synapse. Acetyl coenzyme A is then needed to combine with choline and resynthesise Ach. Thus if coenzyme A is deficient, the synapse would have less neurotransmitter, so transmits less impulses and therefore less depolarisation. I think.

2) Explain the role of calcium ions in the muscles during ventricular systole. (4 marks)

Errr.... I guess this is to do with calcium ions in the synapse and the AVN etc? I've never done Ca in relation to ventricular systole so you might want to wait until an AQA person comes along.

3) Describe how an eye focuses when it shifts from a long distance view to a short-distance view. (6 marks)

Well when the eye looks at closer objects the lens becomes more biconvex (fatter), as the ciliary muscles contract and the suspensory muscles slacken. The rounder cornea therefore refracts the light rays at a steeper angle and the eye can focus. This process is called accommodation.

4) Suggest reasons to explain how geological isolation of a species of lizards results in two species with different chemical reactions in respiration.

Err... evolution? Different environmental conditions, different selection pressures, perhaps different oxygen levels determining aerobic or anaerobic respiration etc? Don't know really!

5) Describe and explain how the process of meiosis results in multiple alleles on a chromosome in a chromatid pair.

In prophase I chiasmata (cross-over) forms between the homologous pairs, so that the alleles from the parents mix around. Not sure if that's what the question is asking though.

And sorry to be extremely pedantic, but don't you need 3 Cs to get an A in Bio? :p: