BIOLOGY

Question 1

What is the name of layer A?

Answer 1

B

Question 2

(ii) Explain the function of the spaces between the cells in layer B(spongy mesophyll)

Answer 2

to allow gas exchange so co2 can enter the cells

Question 3

(iii) Explain the function of part C (stomata)

Answer 3

stomata which allows gas exchange and allows water vapour to leave

Question 4

Xerophytes are plants adapted to live in very dry conditions.
State two differences between the leaf structure of a xerophyte and the leaf
structure shown in Figure 1

Answer 4

less/reduced surface area
fewer stomata
cuticle is thicker

Question 5

Hedgehogs eat slugs and earthworms. Slug pellets were used to kill the slugs. Explain how killing the slugs would affect the population of earthworms in
this garden.

Answer 5

population of earthworms will decrease because more earthworms will be eaten by hedgehogs

Question 6

(iii) Describe a method that could be used to estimate the population of slugs in
the garden.

Answer 6

use a 1m^2 square and count the number of slugs then multiply it out but the m^2 of the guarden

Question 7

(b) Explain how cabbages, earthworms and squirrels contribute to the carbon cycle.

Answer 7

they all release co2 through respiration, cabbages take in co2 for photosynthesis

Question 8

(i) State two ways this method could be improved to make the results for these
three organisms more comparable.

Answer 8

same mass of organisms

use a control

Question 9

(ii) Describe a suitable control for this investigation (three test tubes)

Answer 9

same equipment without any live organisms

Question 10

(i) Explain why the result for the germinating peas is different from the result for the dried peas.

Answer 10

germinating peas produce co2

Question 11

(ii) How was the carbon dioxide produced in this investigation?

Answer 11

B - when glucose is broken down in the presence of oxygen

Question 12

(c) Explain why cellular respiration is essential for living organisms.

Answer 12

to release energy for movement

Question 13

(a) State two variables that would need to be controlled in this investigation. (three test tube)

Answer 13

size/volume of flask

volume of water

Question 14

(ii) Compare the trends shown in the data for flask 1 and flask 2.

Answer 14

flask 1 and 2 decrease in tempature but the temp in flask one decreases faster than in flask 2

Question 15

(c) Explain how sweating helps to cool the body.

Answer 15

sweat is released onto skin and is evaporated transferring heat

Question 16

(d) Which part of the brain controls internal body temperature?

Answer 16

C - hypothalamus

Question 17

(e) Explain why it is important to control the internal temperature of the human body

Answer 17

at high tempature enzymes will denature

Question 18

(a) (i) Water enters a plant through root hair cells.

Root hair cells have

Answer 18

C - a large surface area and thin cell walls

Question 19

(ii) Explain how water in the root is transported to the leaves of the plant.

Answer 19

through the root through osmosis up the xylem

Question 20

b) How is sucrose transported from the leaves to other parts of the plant?

Answer 20

C - by translocation through the phloem

Question 21

(i) Name the cells that change the size of stomata

Answer 21

guard cells

Question 22

(ii) Describe the trend shown in Figure 7.

Answer 22

increase in size until 8am then decreases till 6pm

Question 23

(iii) The temperature increased from 8 am to 1 pm.

Explain why this affected the size of the stomata

Answer 23

stomata gets smaller as it gets warmer due to the guard cells losing water

Question 24

A doctor analysed the results and asked the person to have further tests for type 2 diabetes. Give a reason why the doctor came to this conclusion.

Answer 24

excess of glucose

Question 25

(ii) Explain why the doctor also concluded that the person had a kidney infection.

Answer 25

protein levels were above normal range meaning bacteria present

Question 26

(b) Describe how a student could test a sample of urine for the presence of protein.

Answer 26

do a biuret test and if it is purple protein is present

Question 27

(c) Describe the route taken by urine from the kidney until it leaves the body.

Answer 27

through the ureters to the bladder then through the urethra and out of the body

Question 28

(d) Urine contains urea. State how urea is formed in the human body.

Answer 28

breakdown of amino acids in the liver

Question 29

Name the endocrine gland that produces FSH.

Answer 29

pituitary gland

Question 30

(ii) During this therapy, a woman takes a clomiphene tablet each day for the first five days of her menstrual cycle. Describe the changes that would happen inside the ovaries during the first five days of this treatment.

Answer 30

eggs will mature and oestrogen is released

Question 31

Which hormone causes ovulation?

Answer 31

A - LH

Question 32

During clomiphene therapy, the woman has a blood test on day 20 of the menstrual cycle. The blood test shows a high level of progesterone. Explain the cause of this high level of progesterone on day 20 of the menstrual cycle.

Answer 32

day 20 is after ovulation meaning the corpus lutem produces progesterone

Question 33

Hormones are also used as a method of contraception. Explain why taking high levels of oestrogen and progesterone in the combined contraceptive pill reduces the chance of pregnancy.

Answer 33

stops production of LH so ovulation is prevented

Question 34

(i) Compare the effect of heart rate on stroke volume of the person who has
trained for a marathon with the person who has not trained for a marathon.

Answer 34

stroke volume of person who has trained is higher.

as heart rate increases for the person who has trained for the marathon stroke volume increases

Question 35

cardiac output equation

Answer 35

cardiac output = heart rate x stroke volume

Question 36

Blood from the body enters the heart through the vena cava. Describe how this blood flows through the heart and lungs to leave the heart through the aorta. Include references to the chambers of the heart and the relevant valves in your answer.
(6)

Answer 36

Blood flows from vena cava into the right atrium
• Into the right ventricle
• Through valve
• And is pumped into the pulmonary artery
• Through valve to the lungs
• From the lungs back to the heart through the pulmonary vein
• Into the left atrium
• Into the left ventricle
• Through valve
• And is pumped into the aorta
• Through valve
• valves prevent backflow

Question 37

(i) Explain why these alveoli have the internal structure shown in Figure 10.

Answer 37

many air sacs which increases the surface area

Question 38

How does oxygen move across the alveolar membrane into the capillary?

Answer 38

C - by diffusion

Question 39

Describe how Figure 11 illustrates movement of molecules across a membrane.

Answer 39

molecules are moving down the concentration gradient until it is equal on both sides

Question 40

Explain, using Fick’s law, the factors that affect the diffusion rate of molecules into
and out of cells. (6)

Answer 40

Fick’s law
• rate of diffusion is proportional to surface area and
concentration difference
• and inversely proportional to the thickness of the
membrane
Surface area
• as surface area increases the rate of diffusion also
increases
• as there are more places for diffusion to happen faster
Concentration difference
• the larger the difference in concentration inside the
cell to outside the cell
• the faster the rate of diffusion
Thickness of the membrane
• the thicker the membrane
• the slower the rate of diffusion
as the diffusion distance is greater