Year 2 content- Exam questions in mock that I missed:

Following the release of acetylcholine into a neuromuscular junction, a muscle contraction occurs.

Describe the sequence of events following the release of acetylcholine that lead to a contraction.

Do not include details following the release of calcium ions in the myofibrill

Bonus: take a minute to think about what the question is asking first before you answer.

This question essentially asks you to describe the process by which acetylcholine diffuses across cleft, binds and causes an influx of calcium ions. The question is more about synaptic transmission rather than muscle contraction.

1. Acetylcholine diffuses across synaptic cleft

2. attaches to receptors on sarcolemma

3. Sodium ion channels open and sodium ions enter leading to depolarisation/action potential.

4. Calcium ions released by sarcoplasmic reticulum.

Answer ends here, nothing following the release of calcium.

Hardy weinberg question gives you: 19% grey bodied flies, dominant allele (G). What percentage are heterozygous?

What do I need to remember for when it is a dominant allele?

The % given is BOTH heterozygous Gg and homozygous dominant GG. So 2pq+p2.

You have to first find out what q2 is and take it from there.

P values. What are the rules? When is it significant and when is it not?

In biology unless stated otherwise, the p-value is typically considered significant if it is less than 0.05. This indicates a less than 5% probability that the observed differences are due to chance.

if the result of the test is higher than 0.05 then the difference isn’t statistically significant and the result is due to chance.

How do you create a 10-3 solution using a 10-1 stock solution and distilled water? (serial dilution)

10-1 has a value of 0.1 (its literally standard form you know this) so the 10-3 solution 0.001 which =1/100. So it needs to be diluted by a factor of 100.

To create a 10-3 solution from a 10-1 stock solution, dilute 1 part of the 10-1 stock solution with 9 parts of distilled water to obtain a 10-2 solution. Then, take 1 part of the 10-2 solution and dilute it with 9 parts of distilled water to achieve the 10-3 solution.

List some control variables to consider in an experiment investigating the effect of a hormone solution on plant growth

-temperature

-same species

-same age

-thickness of stem

-volume of solution

-length of time

List some precautions to be taken to ensure that estimated populations from mark release recapture

Marks must still be visible upon second capture so that recaptured can be identified

Must be a time delay so the captured can spread across the whole population.

Marking must not be toxic or visible to predators so it doesn’t affect survival.

What process adds ammonium to soil other than ammonification?

proteins/amino acids broken down into ammonium ions by saprobionts

How does aerating the soil by ploughing affect the fertility of the soil?

Makes the conditions aerobic so denitrification does not occur so more usable nitrates in the soil so fertility increases

What is the process of the light independent reaction?

-carbon dioxide reacts with ribulose bisphosphate to produce a 6 carbon molecule

-this is broken down to produce 2 molecules of glycerate 3 phoshate

-GP is reduced to produce triose phoshate

-using NADP

-Using energy from ATP

-triose phosphate is then converted to glucose or to ribulose bisphosphate to continue the calvin cycle.

Describe the process of glycolysis

-glycerol is made more reactive by the addition of inorganic phosphate molecules from atp hydrolysis. Produces 6C molecule.

-this molecule is split into two molecules of TRIOSE PHOSPHATE

-TP is oxidised and the electrons are donated to NAD to produce 2 molecules of reduced NAD

-Dephosphorylation occurs and 4 molecules of atp produced by substrate level phosphorylation.

-pyruvate is produced

What is the role of saprobionts in the nitrogen cycle?

-they use enzymes to decompose proteins, dna, rna into ammonia in a process called ammonification

• saprobionts are fungi or bacteria and only carry out ammonification

What technique estimates dry biomass?

Calorimetry

Why is ATP a suitable energy source for CELLS?

-energy is released in small amounts so energy is released by atp hydrolysis in small amounts- important as it prevents the cell from overheating causing thermal death.

-it can be rapidly resynthesised

-hydrolysed quickly so is a rapid energy source.

Why is farming and eating crops more efficient than farming and eating animals?

-energy is lost from animals between feeding levels

-energy is lost via respiration and faeces is less in plants

How can a mutation of tRNA anticodon cause a mitochondrial disease?

• anticodon change causes different amino acid to be coded for and being incorporated into protein.

• tertiary structure of protein changed

• protein was required in krebs cycle so no atp produced

How do you word a statistical test significance answer? eg it was significant

what must you NOT say

the DIFFERENCES are significant

must NOT say the results are significant

Instead of amount what should you say

• volume

• concentration

• mass

• weight

• intensity (eg light intensity)