2018 p2

Question 1

How does iris make pupil size smaller

Answer 1

it contracts

Question 2

describe how reflex action works

Answer 2

-receptor detects stimulus
-generates electrical impulse
-sensory neurone conducts impulse to spinal cord
-synapse between neuronesl
-chemical crosses synapse
-chemical stimulates impulse in relay neurone
-then chemical impulse conducted to motor neurone
-effector carries out response
-muscle contracts or gland secretes chemical

Question 3

how does more co2 in atmosphere increase temperature

Answer 3

co2 traps heat in atmosphere

Question 4

Give 2 effects of increase in global air temp on living organisms

Answer 4

higher yield, loss of habitat

Question 5

Why are the coords for a quadratic random

Answer 5

to avoid bias

Question 6

guve 3 environmental dactors that affect growth of plants

Answer 6

-temp
-lightintensity
-soil ph

Question 7

2 advantages of asexual reproduction

Answer 7

-only need 1 parent
-offspring is genetically identical
-faster than sexual reproduction

Question 8

Explain advantages of sexual reproduction in plants

Answer 8

-genetic variation in offspring
-better adapted to survive
-can colonise new area by seed dispersal
-many offspring so higher probability some will survive

Question 9

How does distribution of auxin effect gravotropism

Answer 9

-uneven distribution of auxin
-causes top (side with more auxin) to grow faster than bottom (side with more auxin)

Question 10

what is the use of gibberellin

Answer 10

promote seed germination

Question 11

give a use of ethene

Answer 11

reduce time taken for food to ripen

Question 12

how does bacteria decay organic matter

Answer 12

-digestion
-respire aerobically using oxygen
-with lowers oxygen concentration in water
-reduced energy supply causes death of fish

Question 13

why dies a change in an amino acid in an enzyme molecule stop the enzyme working

Answer 13

different protein is made, active site is changed, so substrate does not bind

Question 14

Describe selective breeding

Answer 14

-find female with desired traits
-and male with desired traits
-breed the female with best features and male with best features
-select the best offspring then repeat over several generations

Question 15

list classification groups

Answer 15

Kingdom, Phylum, Class, Order, Family, Genus, Species

Question 16

Describe evolutions of same animal to different species

Answer 16

-isolation of different populations
-habitat variation between them
-genetic variation from mutation
-better adapted to survive will survive and reproduce, passing on genes
-eventually cannot produce fertile offspring with other populations