Mocks Flashcards
Explain how inhibitory synapses causes hyperpolarisation of the membrane?
How it prevents another action potential from happening straight away?
-Neurotransmitter binds to and opens Cl- channels on post synaptic membrane and triggers K+ channels to open
-Cl- moves in and K+ moves out via facilitated diffusion
-P.D becomes more negative - hyper-polarisation
-Decreases likelihood of action potential as more Na+ needed for depolarisation
How are products of light dependent reactions used in light-independent reaction
-Products = ATP and reduced NADP
-GP is reduced into Triose Phosphate (TP) by NADPH (which is oxidised and turns into NADP)
-This process requires energy that is provided for by ATP
-ATP provides energy for the regeneration of RuBP from Triose Phosphate (TP)
How to tell if grey fly heterozygous
-Cross with black fly
-Observe phenotypic ratio of
Offspring
-If any black offspring produced, fly heterozygous.
-If all grey offspring, fly must be homozygous
why is it not x-linked
If x-linked, any female offspring inherits dominant allele for grey body from father, and will be grey-bodied, but black-bodied female offspring present
How can sampling be used to estimate the number of fat hen plants in the whole field
1) random sampling - make axis with tape measures
2) use random number generators to make coordinates to place quadrats
3)count numbers of plants in each one
3) Repeat at least 10 times so it is representative of area
4) calculate mean number of plants per quadrat
5) Convert this to number of plants per m2 and multiply by area of field
why decrease potato production
Interspecific competition
Nitrate ion conc decreases as wild hen plant use most of it
Less light for photosynthesis
Fat hen plant is 2m tall so blocks sunlight
This causes the wild hen plants to outcompete the potato cells decreasing the production/population size of potato plants
describe and explain relationship between IAA concentration growth rate and cell plasticity
Higher concentration, greater growth and plasticity
It was explain so would have to say higher IAA conc → more cell elongation → higher plasticity etc
-Plasticity started to decrease at one point which is very likely due to the cell wall being at the point of bursting open
Serial dilution
1 part solution to 9 parts water mix
Then repeat
Control of heart rate
Myogenic - initial stimulus for contraction initiated in the heart itself
1. SAN sends electrical impulse causes both r + L atria to contract at the same time
2. Electrical Impulse travels from SAN to AVN. Band of Non conductive tissue prevents the impulse from being directly passed from atria to ventricles
3. There is a slight delay before the AVN sends out an impulse to allow atria to empty so ventricles fill up before they contract
4. Electrical impulse Conducts through the bundle of His which branches off into Purkyne tissue.
5. Wave of excitation causes ventricles to contract simultaneously from the bottom up
causes of phenotypic diversity
-Mutations resulting in different alleles
-Crossing over during meiosis resulting in new combinations of alleles
-Independent Segregation
Why is it advantageous to be able to camouflage based on surroundings?
Camouflage prevents predation
More likely to survive, reproduce fertile offspring with advantageous allele.
Disruptive selection with sympatric speciation
-Same habitat/geographical location
-Mutation causes dark/light colour or nocturnal/daytime behaviour
-So the two groups don’t interact and no gene flow
-So offspring inherit different alleles
-Allele frequency of the two groups change
-Reproductive isolation
-Over many generations the two groups can no longer interbreed to produce fertile offspring
Disruptive selection - extreme traits favoured not middle
Dark geckos able to hide from predators during the day, while pale geckos would be seen so they are active at night to avoid being seen during the day
Evaluate points against:
-Whether they could interbreed to produce fertile offspring was not tested
-Pale geckos on walls and dark geckos on trees so different habitats in same ecosystem = geographic isolation so possibly allopatric speciation
How has new technology allowed for rapid comparison of genes?
-Can happen with a computer so don’t have to manually investigate
-Mitochondria genes can be identified by analysing amino acid sequence.
-DNA code universal so can find DNA sequence.
-Since you work backwards from mRNA, there are no introns so it’s faster.
-The closer the similarities between a DNA sequence, the more closely related the species are.
Geckos - capture and recapture precautions and formula
Precaution - marking doesn’t cause harm (harm only not enough for mark - needs survival) to geckos or affect chance of reproduction
marking also shouldn’t impede movement to ensure random mixing
Ensure marking does not come off so results are accurate
Ensure geckos have to time to fully (uniformly) disperse before second sample taken.
No deaths or births
No immigration/ emigration
Population size= (number of geckos in sample 1 x number in sample 2)/ number marked in sample 2
Population
-All the individuals of one species
-In one area at one time
-That can interbreed to make fertile offspring
Species richness
Number of different species
Mutation for shorter polpeptide
-Deletion mutation
-Removes base, frame shift
-Codon could code for diff AA
-Change in tertiary structure
-Shorter AA chain, stop codon reached faster
Why might change still occur if at climax community
-Predator prey fluctuations
-Immigration
-Death
-Interspecific comp
Climax community
Constant - flat on graph
Wildlife choice chamber control variables
Light humidity temper
Why a vaccine would not be effective against HIV
-T helper cells so you would need to destroy T helper cells - Causes harm, and jeopardises immune system
- High rate/frequency of mutations
-HIV exhibits antigen variability
-HIV can be dormant in body for years
Why would the following antibiotic no s not work against HIV? Antibiotic 1 affects the coiling of double- stranded DNA Antibiotic 2 affects murein
1 - HIV is an RNA virus and it is it single-stranded
2 -HIV does not have a murein cell wall (or a cell wall at all) HIV is acellular
Relationship of an organisms surface area to volume ratioand metabolic rate
-Small mammal has a higher SA to Vol ratio than a large mammal
-This means that heat is lost more easily from small mammal
-So needs relatively high metabolic rate in order to generate enough heat to maintain a constant body temp
What gives fish high SA for gas exchange
Gill filaments and lamallae
