paper 2 exam q

Question 1

explain one reason why there is an increase in blood flow to muscles during exercise (2)

Answer 1

during exercise muscles require MORE oxygen for respiration

Question 2

explain how crop rotation increases nitrate levels in the soil (3)

Answer 2

leguminous plants are planted that have nitrogen fixing bacteria in the root nodules which fix nitrogen gas

Question 3

explain the effects of type 2 diabetes in the body (3)

Answer 3

blood glucose levels are high because cells are resistant to insulin so the liver does not convert glucose into glycogen

Question 4

explain why the body temperature of the iguana affects its oxygen consumption (3)

Answer 4

chemical reactions are increased at higher temperatures. more respiration occurs. so more respiration requires more oxygen

Question 5

describe how stomata open? (3)

Answer 5

the guard cells take in water by osmosis and become turgid

Question 6

the top of a leaf has no stomata, the bottom of the leaf has a lot. explain why this is an advantage to the plant. (2)

Answer 6

there is no stomata on the upper surface to reduce water loss. stomata on the lower surface allow for gas exchange

Question 7

an iguana pants to cool down. explain how this helps it cool down. (2)

Answer 7

panting causes water loss. causing evaporation so temperature is reduced

Question 8

explain the role of vasodilation in thermoregulation (4)

Answer 8

vasodilation acts to cool the body down. more blood flows near the surface of the skin. less blood flows through the shunt valve. causing increased thermal energy loss.

Question 9

explain how nitrate ions were absorbed by seedlings (3)

Answer 9

by the root hair cells by active transport against the concentration gradient

Question 10

3 seedlings are put in different concentrations of fertiliser. explain why there are changes in lengths of the seedlings (2)

Answer 10

nitrates are needed to make proteins. the largest amount of growth can be seen in the highest concentration of nitrates

Question 11

explain why farmers use peas and beans in their crop rotation cycle (3)

Answer 11

to increase the nitrate levels in the soil. nitrogen fixing bacteria live in the root nodules of these plants. nitrogen fixing bacteria make nitrates from the nitrogen in the air.

Question 12

explain why women over 50 are less likely to ovulate (2)

Answer 12

women over the age of 50 have low oestrogen levels. high levels of oestrogen are needed to release LH. a surge of LH is needed for ovulation to occur.

Question 13

explain why women are less likely to menstruate after the age of 60 (2)

Answer 13

low levels of oestrogen stops the uterus lining from building up

Question 14

explain how the release of adrenaline can help improve the performance of an athlete (4)

Answer 14

adrenalin acts to increase heart rate so there is increased blood flow which causes the release of glucose form glycogen

Question 15

explain how marram grass is adapted to live in hot, dry, windy conditions (6)


Answer 15

grass is flexible so does not break in windy conditions
good root structure prevents being uprooted in the wind
leaf is rolled to trap air inside
thick waxy cuticle to prevent water loss by evaporation
no stomata on the upper surface to prevent water loss
long thing leaves to reduce wind damage

Question 16

explain the benefit to plants of having root hair cells (2)

Answer 16

increases surface area for absorption of more mineral ions

Question 17

explain one adaption of a root hair cell that increases the absorption of water and mineral ions (2)

Answer 17

has a large surface area, to increase rate for absorption

Question 18

explain why a waxy cuticle is important for a pine leaf (2)

Answer 18

it surrounds the leaf to prevent water loss

Question 19

give another method of measuring light intensity rather than calculating it (1)

Answer 19

use a light meter

Question 20

counting bubbles to find how much gas collected is not the best method. explain how you could improve this method (2)

Answer 20

use a gas syringe to collect and measure the gas produced to reduce the errors that could be made as bubbles have different sizes

Question 21

explain the use of auxins in the production of plants and fruit

Answer 21

used in selective weed killers
target broad leafed plants
kills the weed but not the crop
added to the ends of cutting to stimulate growth of roots

Question 22

explain the use of gibberellins in the production of fruit and plants

Answer 22

to stimulate germination in dormant seeds
imitates breakdown of starch
stimulate flower and fruit formation
sprayed onto plants before pollination
stimulate the development of seedless fruits

Question 23

explain the use of ethene in the production of fruit and plants

Answer 23

fruit ripening
unripe fruit is harvested
ethene is added so fruit ripens for selling

Question 24

temperature increased from 8am to 1pm. explain why this affected the size of the stomata (2)

Answer 24

the stomata get smaller because the guard cells lose water

Question 25

the number of WBC in a sample was 40. the acceptable range was 2 to 5. explain why the doctor concluded that the person had an infection (2)

Answer 25

WBC were above the normal range. indicating pathogens were present.

Question 26

describe how the blood flows through the heart and the lungs to leave the heart through the aorta. (6)

Answer 26

blood flows from vena cava to atrium
into the ventricle through the valve
pumped through the pulmonary artery
through the valve to the lungs
from the lungs back to heart through pulmonary vein
into left atrium, left ventricle, through a valve, valves prevent backflow
back to the aorta

Question 27

white clawed crayfish cannot live in rivers with low conc of oxygen. explaining how eutrophication can cause the population of white clawed crayfish to decrease. (3)

Answer 27

eutrophication causes oxygen levels to decrease. because nitrates levels in water is increased. causing an overgrowth in algae which blocks the sunlight from reaching the plants in the water so they die and are decomposed by microorganisms for respiration.

Question 28

describe what happens to urea as the blood passes through a dialysis machine

Answer 28

blood is filtered in the dialysis machine. urea moves out of the blood into the machine by diffusion

Question 29

explain how the blood entering the nephron of the kangaroo rat is filtered to remove excess sodium ions and water (3)

Answer 29

ultrafiltration occurs in the glomerulus where the liquid part of the blood is passed to the Bowmans capsule. reabsorption takes place as it travels through the proximal convoluted tubule into the Loop of Henle. urine production occurs in the collecting duct and excess fluid and sodium ions are removed.

Question 30

explain how shivering helps regulate body temp (3)

Answer 30

shivering stop body temp from falling. due to increased muscle contraction that generates heat from respiration/ friction