Paper 42 2021

Question 1

Name 3 parts of the small inestine

Answer 1

ileum
villi in ileam
duadenum

Question 2

Describe how active transport differs from diffusion. [4]

Answer 2

membrane for active transport uses (chemical) energy

energy from, the cell / respiration / mitochondria

(substances move) against concentration gradient / low to high concentration

using / AW, proteins / carriers (in membranes)

Question 3

Explain the importance of the microvilli in small intestine [2]

Answer 3

idea of more (cell) membrane / large surface (area)

allow, increased rate of / fast, absorption (of nutrients)

Question 4

Goblet cells provide protection for the epithelial cells that line the intestine.

State the name of the protective substance produced by goblet cells

Answer 4

mucus

Question 5

Goblet cells provide protection for the epithelial cells that line the intestine

Suggest why a protective substance is necessary in the intestines. [3]

Answer 5

to protect the intestine from) bacteria pathogens

protects intestine from enzmes and self digestion

protects fom hydrochloric acid

Question 6

Describe the roles of lacteals in the centre of each villus 2

Answer 6

absorbs, fats / fatty acids (and glycerol)

transports, fats / fatty acids, into, lymphatic vessels

Question 7

identify the level of organisation of gall bladder

Answer 7

organ

Question 8

identify the level of organisation of endoplasmic reticulum

Answer 8

cell structure

Question 9

identify the level of organisation of intestinal epithelium

Answer 9

tissue

Question 10

identify the level of organisation of the ileum

Answer 10

organ

Question 11

refer to question 1 f
State what conclusions can be made about the enzymes in the fungal extract and give evidence from Fig. 1.3 to support your conclusions. [7]

Answer 11

conclusions
1 fungal extract contains amylase and pectinase ;
6 D / fungal extract, in both Petri dishes has clear zones (MP1) ;

2 clear zone is where substrate has been, digested / broken down ;
7 no staining in clear zones shows that enzyme was active (MP2) ;

5 extract has, higher concentration of / more, amylase than pectinase ;
10 clear zone in, D / with fungal extract, is larger in the plate containing starch than in the plate containing pectin (MP5) ;

13 no clearance / no breakdown / no change, with water

Question 12

refer to question 1 f

The investigation was repeated but at 5°C instead of at 27°C. Predict the effect of the lower temperature on the results

Answer 12

(same pattern but) smaller / no, clear zones

Question 13

Define the term chromosome. 2

Answer 13

(thread-like structure) molecule, of DNA ;

contains, genes / alleles / genetic information or material ;

Question 14

refer to question 2 a
Suggest why the scientist placed a bag around flower 1.

Answer 14

prevent pollination (from another flower or plant) / to prevent (other) pollen landing on stigma

Question 15

refer toquestion 2 a

Explain how sexual reproduction results in the variation that the scientist discovered in the offspring plants. 2

Answer 15

different, combinations of, maternal and paternal chromosomes

fusion of gametes with different, genotypes or alleles

Question 16

Explain how the chromosome number is maintained from one generation to the next 2

Answer 16

meiosis halves the number of chromosomes

diploid, number is restored at fertilisation

Question 17

define phenotype 2

Answer 17

observable feature of an organism

phenotype of an organism depends on the genotype

Question 18

define Genotype

Answer 18

genetic make-up of an organisms in terms of alleles present

Question 19

refer to question 2 b i

Answer 19

PRPR ;
PRPW ;
PRPR,
PRPW,
PWPW

Question 20

refer to question 2b

State the type of inheritance that is shown by petal colour in C. japonica.

Answer 20

codominance

Question 21

Fig. 3.1 shows the changes in the concentrations of the hormones FSH and LH during a menstrual cycle.

Suggest the target organ for FSH.

Answer 21

ovary

Question 22

State how FSH reaches its target organ [1]

Answer 22

plasma / blood (vessels)

Question 23

what does FSH stand for

Answer 23

Follicle-stimulating hormone

Question 24

what does LH stand for

Answer 24

Luteinizing hormone

Question 25

Describe the relationship shown by the two hormones in Fig. 3.1 [3]

Answer 25

2 both hormones reach a peak at, day 14 / the same time / the same day ;
3 LH starts increasing before FSH ;
4 LH has a higher concentration than FSH at, the peak / day 14 ;

Question 26

Describe the roles of FSH in the menstrual cycle. 4

Answer 26

any four from:
1 FSH stimulates, development of follicles (in ovary) ;

2 FSH stimulates, development of, ovum

3 FSH stimulates, production of oestrogen (from ovary) ;
4 (FSH and) LH (surge) stimulates, ovulation

Question 27

Describe the changes that occur in the lining of the uterus during one menstrual cycle. [3]

Answer 27

1 loss / thinning, of lining (of uterus), during first week
2 thickening of, lining (of uterus), during second week
3 thickness of lining remains constant, in the last two weeks if no fertilisation ;

Question 28

Oral contraceptives are a method of birth control taken by women. Outline how the hormones in contraceptives act as a method of birth control. [4]

Answer 28

1 (contraceptives contain) progesterone (with oestrogen) ;
2 decreases secretion / prevents release, of FSH / LH ;
3 prevents, development / maturation of, follicles / eggs / ova ;
4 prevents ovulation / described

Question 29

refer to figure 4.1

what conducts impulses to central nervous system (CNS)?

state letter on fig

Answer 29

afferent, neurone V

Question 30

refer to figure 4.1

what conducts impulses to an effector

state letter on fig

Answer 30

motor neurone Y

Question 31

refer to figure 4.1

conducts impulses only within the CNS

state letter on fig

Answer 31

relay neurone X

Question 32

refer to figure 4.1

detects / senses, stimulus / change in temperature

state letter on fig

Answer 32

receptor U

Question 33

refer to figure 4.1

contracts / causes movement / carry out response

state letter on fig

Answer 33

biceps / muscle / effector Z

Question 34

Fig. 4.2 shows the structure of the synapse at W on Fig. 4.1.

Describe how an impulse travels across the synapse shown in Fig. 4.2. 5

Answer 34

1 vesicles move towards end of, pre-synaptic neurone / axon / AW ;
2 vesicles fuse with (pre-synaptic) membrane ;
3 neurotransmitter diffuses across, synapse / gap / synaptic cleft ;
4 neurotransmitter binds to receptor, on post-synaptic neurone ;
5 impulse (generated) in post-synaptic neurone ;

Question 35

State examples of a reflex action that occurs in the eye. 6

Answer 35

blinking / pupil reflex / iris reflex / accommodation / corneal reflex / tear reflex

Question 36

State two factors that affect the volume of urine produced in the human body

Answer 36

any two from: water / fluid / liquid, intake ; exercise / activity level ; sweating ; temperature ; salt / salty food, intake ; quantity of urea produced / concentration of urea in blood ; (named) drug ; (named) medical condition ;

Question 37

Nitrogen is an important element for organisms. In a livestock farm, waste from animals contains protein. This waste is often spread on farmland as a fertiliser. Describe how the nitrogen in protein is recycled in the soil into a form that plants can absorb and use. [6]

Answer 37

any five from:
1 protein, broken down decomposed, to amino acids ;
2 ammonification
3 amino acids converted to, ammonium (ions) / NH4+ ;
4 ammonium (ions) convert to nitrate (ions)
5 nitrification / nitrifying bacteria ;
6 plants, absorb nitrate (ions) (and ammonium ions)

Question 38

Waste from livestock farms often pollutes water courses, such as streams and rivers, leading to a reduction in biodiversity. Explain how the pollution of water courses by animal waste leads to a reduction in biodiversity [6]

Answer 38

any six from:
1 eutrophication ;
2 increased growth of, plants / producers / algae ;
3 plants / producers, compete with each other for light / AW

reasons for reduction in biodiversity:
8 death of, fish / invertebrates (due to lack of dissolved oxygen) ;
9 decrease in, food / energy, available in, ecosystem / AW ;
11 ref to aerobic respiration (in either section)

Question 39

Enzymes are catalysts. Define the term catalyst. [2]

Answer 39

(substance) that increases the rate of (chemical) reactions ; not changed, during / by, the reaction ;

Question 40

Fig. 6.1 shows diagrams of three enzymes and eight different substrates.

State the letter of the substrate that will be broken down by enzyme 1.

Answer 40

T

Question 41

Fig. 6.1 how do you know T is broken down b 1 [2]

Answer 41

T) fits into, enzyme ;
active site has a complementary shape (to T)

Question 42

what reaction does maltase catylise

Answer 42

breakdown of maltose to glucose

Question 43

what reaction does protease catylise

Answer 43

breakdown of proteins to amino acids

Question 44

what reaction does lipase catylise

Answer 44

breakdown of fats to fatty acids and glycerol

Question 45

what reaction does lactase catylise

Answer 45

breakdown of lactose to simpler sugars

Question 46

what reaction does( DNA) ligase catylise

Answer 46

insertion of a short length of DNA into a plasmid

Question 47

what reaction does restriction enzyme catylise

Answer 47

digests, DNA molecules

Question 48

Describe the roles of LH in the menstrual cycle. [2]

Answer 48

1 (FSH and) LH (surge) stimulates, ovulation
2. Stimulates corpus luteum/ release, of progesterone