FEB MOCK

Question 1

Describe how meiosis leads to genetic variation in the gametes produced (2)

Answer 1

Produces non-identical gametes due to independent assortment

crossing over between non-sister chromatids

Question 2

Explain how vesicles are involved in the successful fertilisation of an egg cell by only one sperm (2)

Answer 2

cortical granules fuse with egg cell surface membrane

releasing enzymes that thicken the zona pellucida

Question 3

Explain why some genes show linkage and others show sex-linkage (3)

Answer 3

there are more genes then there are chromosomes
Linkage refers to genes located on the same chromosome
sex-linkage refers to genes on the sex chromosomes

Question 4

State what is meant by the Q10 temperature coefficient (1)

Answer 4

The ratio of the rate of an enzyme reaction taking place at temperatures differing by 10 degrees Celsius

Question 5

Devise an investigation to determine Q10 for an extract of lipase (5)

Answer 5

Use two water baths with a temperature difference of 10 degrees Celsius
provide triglyceride in excess
use a fixed concentration of lipase eg 1moldm
measure concentration of triglyceride every 30 seconds for 4 minutes
calculate initial rate of reaction
determine Q10 - T+10+rate at T

Question 6

Give two biotic factors that could affect the number of bird species in an observed forest (2)

Answer 6

Food availability

Interspecific competition

Question 7

Describe how forests can be managed as a sustainable resource (2)

Answer 7

replant trees that have been cut
replace them with seeds
remove old seeds

Question 8

explain the impact of cutting down trees of climate change (4)

Answer 8

less photosynthesis
more co2 remains in the atmosphere
co2 is a greenhouse gas and traps heat
more energy in atmosphere raises atmospheric temperature

Question 9

where does the krebs cycle take place (1)

where does oxidative phosphorylation take place (1)

Answer 9

Matrix

cristae

Question 10

Name three molecules needed for aerobic respiration that can move into the mitochondria (3)

Answer 10

pyruvate
oxygen
reduced NAD

Question 11

Explain why the outer mitochondrial membrane is impermeable to H+ ions (4)

Answer 11

to stop H+ ions diffusing out of mitochondria
maintains high conc of H+ ions in intermembrane space
hydrogen ions can move down conc gradient by chemiosmosis

Question 12

explain why the production of fibres from nettles is more sustainable than fibres produced from crude oil (3)

Answer 12

nettle plants can be regrown, they are renewable
crude oil is not renewable, will run out
Clothes made from nettle fibres are biodegradable

Question 13

state what is meant by the term bacteriostatic (1)

Answer 13

substance which can inhibit growth of bacteria

Question 14

explain why antibiotics that bind to ribosomes of bacteria can affect protein production (3)

Answer 14

ribosome shape is altered
mRNA is prevented from binding to ribosome
translation can not occur
protein not synthesised

Question 15

Describe how HIV particles are able to enter T helper cells (3)

Answer 15

Glycoproteins (GP120) on the surface of the virus
bind to CD4 receptors on the surface of T helper cells
viral envelope fuses with cell membrane of T helper cell

Question 16

explain why the destruction of T helper cells causes the symptoms of AIDS (4)

Answer 16

Lack of T helper cells reduces cytokine production
reduces activation of B cells
reducing antibody production
increases risk of opportunistic infections

Question 17

discuss how anthropogenic climate change can affect the growth of plants in polar and temperate regions of climate zones (6)

Answer 17

Currently growth is greater in temperate region than polar
increase in temp could increase growth in both regions
rate of photosynthesis increases with temperature so growth could continue to increase
increase is likely to be greater in polar regions which have a lower temperature
photosynthesis and therefor growth may be limited by light intensity