I know there’s been a thread made previously but I thought I’d try and make a list of some answers based on that so they’re all in one place
Fully aware some are probs wrong but I’ll edit it with peoples suggestions, let me know (but be nice haha). I’ve also not been able to remember all the questions and it’s not in order, so please let me know if you remember any other questions and I’ll add them on
I have about 70 marks worth here, the paper was out of 91 so I’m definitely missing some questions
Succession 4 marker
- Pioneer species colonises, adapted to hostile conditions
- Changes abiotic conditions as broken down by saprobionts, creates soil/humus which retains water
- Means next species can colonise as conditions less hostile, die and decomposed by saprobionts, more humus
- Repeats. At any stage, new species can be introduced that makes conditions less favourable for previous species, outcompetes them.
- Eventually climax community, most stable the ecosystem can support
3 marks worth of trophic maths
- There was a 1 marker, I got 0.155%
- 2 marker was to do with the zebras, it was 177? Not sure
IAA: 2 marker on why remove shoots
Why keep lid closed (2 marks)
- Prevent contamination
- Stop evaporation
- Keep oxygen concentration constant in all Petri dishes
Why add glucose (2 marks)
3 marker on what if roots instead/describe and explain results
- higher concentration of IAA means greater increase in shoot length
- caused as IAA stimulates cell elongation in shoots
- but in roots it inhibits cell elongation, so if roots were used higher concentration would mean less growth
1 marker on serial dilution
Stupid pH graph 4 marker
- I think I put that contraction had less force in both rabbits and mice at 12 and 22, but not at 32 so pH does decrease muscle contraction at lower temperatures but not at higher
- I’ve seen people say that the fact a stats test wasn’t used would get you a mark
Why decreased calcium ions inhibits muscle contraction (3 marks)
- calcium ions bind to a protein attached to tropomyosin, cause it to change shape, pull tropomyosin out of actin-myosin binding site exposing it
- so that myosin heads can bind, forms actin myosin cross bridge, pull actin over myosin causing muscle to contract as sarcomere shortens
- so if calcium ions are decreased, tropomyosin blocks binding sites, less contraction
- calcium also activates ATP hydrolyse (ATP -> ADP + Pi), energy used for contraction, so if less calcium then less energy
Inheritance question:
Why is body colour not on X chromosome
Why you know black is recessive(? I think)
3 marker on find phenotypes
- I got 1:1:1:1 ratio
2 marks hardy Weinberg equation
48%
Insulin - role of glucagon (2 marks)
Why does inhibiting adenylate Cyclase reduce glucose concentration (3 marks)
5 marker on estimating population (sunningdew or whatever)
Why is it advantageous for sunningdews to digest insects in nutrient deficient soil (2 marks)
Tick box 1 marker on photosynthesis
- bottom one
2 marker on photoionisation
Light hits chlorophyll, electrons become excited, leave chlorophyll and move to higher energy level, move down ETC
What is a DNA probe (2 marks)
- single stranded base sequence complementary to desired gene with label attached
How is DNA cut (2 marker)
- Restriction endonuclease, cuts DNA at specific palindromic recognition sequences (recognition sites)
How long is DNA 2 marker
- I got 3.42
Suggest why there are more bands than just 4 2 marker
Gel electrophoresis 1 marker on which volunteers
- I got 3,4,5
Application 15 marker:
3 marker on why myelin sheath being broken causes muscle paralysis
3 marker on why Huntington can lead to irregular heartbeat
3 marker on role of epistasis on Huntington’s being later in life
2 marker on why trials don’t show cure
- Only over 4 months
- Only 36(?) individuals
2 marker on why injected into spine and not taken orally
- would be digested by digestive enzymes
- short diffusion pathway to cells where it would be most effective as Huntingtin produced here, drug has effect quicker
2 marker on something else