biology paper 2

Question 1

define homeostasis

Answer 1

the regulation of conditions inside the body

Question 2

what is negative feedback

Answer 2

it counteracts change in the body

Question 3

what is a synapse

Answer 3

a connection between two neurones

Question 4

3 main components of the brain

Answer 4

cerebral cortex
medulla
cerebellum

Question 5

3 ways to study the brain

Answer 5

patients with brain damage
electrical stimulation
mri scans

Question 6

what happens when bright light meets the eye

Answer 6

the iris reflex, circular muscles in the iris contract and radial muscles relax.

Question 7

how is hyperopia treated

Answer 7

using a convex lens

Question 8

how is myopia treated

Answer 8

using a concave lens

Question 9

what happens when you are too cold

Answer 9

hairs stand up
no sweat produces
blood vessels supplying skin capillaries constrict
you shiver

Question 10

blood level too high/too low?

Answer 10

too high - insulin added to blood

too low - glucagon released, makes liver turn glycogen into glucose

Question 11

what do kidneys filter out of the blood

Answer 11

urea, iona and water

Question 12

what is an auxin

Answer 12

plant hormone which controls growth in response to phototropism and geotropism

Question 13

name some other plant hormones

Answer 13

gibberellin - controls dormancy and grows larger fruits

ethene - ripening of fruit

Question 14

what is dna

Answer 14

long molecules of chromosomes

Question 15

what is dna made up of

Answer 15

nucleotides, containing 4 bases, A, C, G and T

Question 16

what is mRNA

Answer 16

carries the code to make proteins from the DNA in the nucleus to the ribosome

Question 17

what is a gamete and how are they produced

Answer 17

sex cells, produced by meiosis

Question 18

what does meiosis produce

Answer 18

cells which have half the normal number of chromosomes