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Howlers - Summer 2018

I lost quite a lot of this material when Windows decided to shut down my laptop without giving me the opportunity to check all my current files were saved.


Why heat stress leads to a decrease in the light-independent reaction

The LDR produces the fuel for the LIR

Increased temperature denatures the enzymes that break down ATP into ADP and Pi in the chemiosmotic theory

Less CO2 will be formed

The light doesn't convert to energy

Too much heat leads to too many electrons being excited

Why a decrease in the activity of the enzyme rubisco would limit the rate of photosynthesis

Rubisco is used to bind 2 3-C compounds back together

How alterations to tumour suppressor genes can lead to the development of tumours

If there's uncontrollable cell division of mutated DNA then it'll cause the development of tumours

If there is a mutation in the amino acid that codes for a protein ...

mRNA formed may not be translated correctly

A mutated gene may be dividing uncontrollably

How you would determine the mean percentage cover for beach grass on a sand dune

Count how many metres of beach grass there was and add them together

Divide the total area of the sand dunes to 10m x 10m quadrats At each quadrat measure the % cover by using the 1m x 1m divisions

Use a statistical test after calculating the mean

I would use a random quadrat

Succession explained

Beach grass is growing, possibly a pioneer spishy

Conditions are initially harsh and inhospital

The population dies due to lack of biotic and abiotic factors

Beach grass is the initial successor

Trees were successful successors of Beach Grass

How the drug furosemide causes an increase in the volume of urine produced

This allows water to be fully absorbed

Sodium and chloride ions are solvents which would decrease the water potential

How dopamine stimulates the production of nerve impulses in postsynaptic neurones

This acts as a domino to activate the next action potential

Dopamine travels down the axon

How GABA inhibits postsynaptic neurones

This means that when a real synapse is occurring it has to be larger than usual

GABA prevents a chemiosmotic gradient from forming which means that the vesicles crossing the synaptic cleft do not fuse with the postsynaptic neurone

Chloride ions depolarise the membrane so neurotransmitters cannot bind to post synaptic receptors

It inhibits postsynaptic neurones by using charged chloride ions as a bridge, which acts as an insulator and therefore inhibits it

Due to the chloride ions being negatively charged, they would try to move to a more positive side

Chloride ions would prevent an influx of sodium ions from entering

Cl- ions cause Na+ ions to diffuse out

So the post synaptic neurone needs to do more to allow the impulse across the synapse

Entry of chloride ions is negative in itself

This prevents the chemical impulse from changing into an electrical impulse

This stops the synapse from taking place

This means that the impulse is no longer attracted to the next synapse because that is also negatively charged

Why people with red-green colour blindness are unable to distinguish between red and green, and also between other colours

Rod cells are all connected to one bipolar cell

Cone cells are unable to absorb pigment

The rod cells are not able to see a lot of visual

Red-green colour blindness blurs the colours together

The IPS cell is a steam cell

Gene therapy could be a waist of money

Red and green are opposite colours and people struggle to distinguish between them

How iPS cells could correct red-green colour blindness

Pluripotent stem cells are able to develop into any human cell. Therefore they could be developed into rod cells that allow for photosynthetic pigments to be coded for that allow for red-green sight

Reasons why iPS cells could have advantages over the use of gene therapy to correct red-green colour blindness

In gene therapy the offspring of the patient cannot choose whether they have the treatment or not, which is an ethical problem

Cone cell would have working photosynthetic pigment

Cells could multiply by mitosis when dying

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