Question 1
Topic-: 6.2
(a) Topic- 6.2 (leaf structure)
(b) Topic- 6.2 (leaf structure)
(c) Topic- 8.2 (water uptake)
(d) Topic- 19.3 (nutrient cycles)
Fig. 1.1 is a photomicrograph of a cross-section of part of a leaf.
(a) (i) State the letter in Fig. 1.1 that identifies where:
gas exchange is controlled ……………………………
most photosynthesis occurs ……………………………
spongy mesophyll cells are found. ……………………………
(ii) Draw a circle on Fig. 1.1 to identify a vascular bundle.
(iii) Translocation occurs in the vascular bundle.
State the names of two substances that are only moved by translocation.
1 ……………………………………………………………………………………………………………………….
2 ……………………………………………………………………………………………………………………….
(b) Explain how xylem vessels are adapted for their functions.
…………………………………………………………………………………………………………………………………
(c) Describe how water moves through a plant from the soil to the air spaces in a leaf.
…………………………………………………………………………………………………………………………………
(d) Explain why plants need nitrate ions.
…………………………………………………………………………………………………………………………………
▶️Answer/Explanation
1(a) (i) L ;
N ;
M ;
(ii) circle drawn around a vascular bundle ;
(iii) sucrose ;
amino acids ;
1(b) any three from:
thick walls ;
containing lignin ;
(lignin for) support (of vessel / tube) / AW ;
no cell contents ;
cells joined end to end / forming long continuous tube / no cross-walls ;
to transport water ;
AVP ;
1(c) any four from:
(water enters) root hair cells, by osmosis through the (root) cortex (cells) to xylem (in the root) ;
a column of water molecules moves up (the stem in xylem) / AW water molecules are held together by forces of attraction (between the molecules) / ref. to cohesion ;
(water) diffuses / moves, out (of xylem in the leaf) into mesophyll cells ;
(water) evaporates (from surface of mesophyll cells) into the air spaces ;
1(d) any two from:
needed to make amino acids ;
(amino acids) to make proteins ;
(proteins) for growth ;
Question 2
Topic-: 16.6
(a) Topic- 16.6 (sexually transmitted infections)
(b) Topic- 14.3 (hormones)
(c) Topic-18.3 (selection)
(a) Chlamydia is a sexually transmitted infection (STI) that is caused by a bacterium.
Fig. 2.1 shows the number of chlamydia cases in a country in 2018.
(i) Calculate the percentage decrease in the number of chlamydia cases between the age groups 20–24 and 25–29.
Give your answer to two significant figures.
……………………………………………….%
(ii) Describe how the spread of STIs, such as chlamydia, can be controlled.
………………………………………………………………………………………………………………………….
(b) Chlamydia can damage the reproductive system.
(i) State the name of the part of the female reproductive system that produces oestrogen.
…………………………………………………………………………………………………………………….
(ii) Describe the role of oestrogen at puberty.
………………………………………………………………………………………………………………………….
(c) Complete the sentences about drug resistance and genetic variation by writing a suitable word or phrase in the spaces provided.
Bacteria can be killed by drugs called …………………………………. . The development of strains of bacteria that are resistant to these drugs is an example of …………………………………. selection.
Resistant strains of bacteria have gene mutations that enable them to survive drug treatment.
Gene mutations are caused by random changes in the …………………………………. of bases in DNA and result in the formation of new …………………………………. in the bacteria. Mutation rates can be increased by …………………………………. radiation and some chemicals.
In animals and plants, another source of genetic variation is a type of nuclear division called …………………………………. .
▶️Answer/Explanation
2(a) (i) (–)59(%) ;
(ii) any four from:
abstain from sexual contact ;
condoms / femidom ;
testing / screening ;
contact tracing ;
education (about, risks / how it is transmitted / prevention) ;
use of antibiotics ;
no sharing of needles ;
using screened blood for transfusions ;
vaccination ;
AVP ;
2(b) (i) ovary ;
(ii) any three from:
secondary sexual characteristics ;
start of, the menstrual cycle / AW ;
hips widen ;
growth of breasts ;
growth of, pubic / body, hair ;
AVP ;
2(c) antibiotics ;
natural ;
sequence ;
alleles ;
ionising ;
meiosis ;
Question 3
Topic-: 10.1
(a) Topic- 1.3 (genetic modification)
(b) Topic- 10.1 (diseases and immunity)
(c) Topic- 10.1 (diseases and immunity)
(d) Topic- 10.1 (diseases and immunity)
(a) Fig. 3.1 shows the structure of the pathogen that causes cholera.
(i) State the name of the kingdom that includes the pathogen shown in Fig. 3.1.
…………………………………………………………………………………………………………………….
(ii) Table 3.1 shows some of the names, functions or uses, and identifying letters of the parts labelled in Fig. 3.1.
Complete Table 3.1.
(b) Describe how a person becomes infected with cholera.
…………………………………………………………………………………………………………………………………
(c) People with cholera can become very dehydrated.
Explain how cholera causes dehydration.
…………………………………………………………………………………………………………………………………
(d) Vaccination can help to prevent the spread of diseases such as cholera.
Outline the process of vaccination and explain how it can prevent the spread of diseases.
…………………………………………………………………………………………………………………………………
▶️Answer/Explanation
3(a) (i) prokaryote ;
(ii)
3(b) drinking contaminated water / AW ;
3(c) any four from:
1) cholera / bacterium / pathogen, produces a toxin ;
2) (toxin) causes secretion of chloride ions ;
3) into lumen / small intestine ;
4) (loss of ions) increases / AW, water potential within cell ; ora
5) water moves out of cells / blood ;
6) down water potential gradient / from high to low water potential ;
7) (out) by osmosis / through the partially permeable membranes ;
8) (causing) diarrhoea / watery faeces / AW ;
9) resulting in loss of water (from the body) ;
3(d) any six from
1) ref. to active / long-term, immunity ;
2) vaccine contains weakened / dead / AW, bacteria / pathogen ;
3) ref. to antigens of pathogen ;
4) (antigen) stimulates an immune response ;
5) lymphocytes make antibodies ;
6) antibodies bind to, antigen ;
7) ref. to, specificity / complementary (shape to antigen / pathogen) ;
8) ref. to forming memory cells ;
9) ref. to mass vaccination (programmes) ;
10) person to person transmission interrupted / AW ;
11) AVP ;
Question 4
Topic: 14.1
(a) Topic- 14.1 (coordination and response)
(b) Topic- 14.1 (coordination and response)
(c) Topic- 14.1 (coordination and response )
(a) Complete the sentence about the mammalian nervous system.
The ………………………………………….. nervous system consists of the brain and spinal cord and the ………………………………………….. nervous system consists of the nerves outside the brain and spinal cord
(b) Fig. 4.1 shows the parts of a reflex arc.
(i) Put the parts listed in Fig. 4.1 into the correct sequence, and write the letters in the boxes.
Two have been done for you.
(ii) State two stimuli that are detected by the skin.
1 ……………………………………………………………………………………………………………………….
2 ……………………………………………………………………………………………………………………….
(iii) The pupil reflex controls the amount of light that enters the eye.
State the name of an effector in the pupil reflex.
…………………………………………………………………………………………………………………….
(c) Describe and explain how impulses are only passed in one direction from one neurone to the
next.
…………………………………………………………………………………………………………………………………
▶️Answer/Explanation
4(a) first gap: central and second gap: peripheral ;
4(b) (i)
(ii) any two from:
touch ;
temperature ;
AVP ;
(iii) circular / radial, muscle ;
4(c) total of five from:
1) only the first neurone releases neurotransmitters ;
2) only the second neurone has (complementary) receptors ;
max four from:
3) ref. to neurotransmitter (molecules) ;
4) (neurotransmitter is released) from vesicles ;
5) into the synaptic gap ;
6) the junction between the neurones is the synapse ;
7) (neurotransmitter molecules) diffuse (across the gap) ;
8) ref. to receptors are complementary in shape (to neurotransmitter) ;
9) (neurotransmitter molecules) bind with receptors (on the next neurone) ;
10) impulse is then stimulated (in the next neurone) ;
Question 5
Topic: 17.4 (monohybrid inheritance)
(a) Topic-17.4 (monohybrid inheritance)
(b) Topic- 17.4 (monohybrid inheritance)
The gene for red-green colour vision is on the X chromosome.
There are two alleles for this gene:
• The allele for normal colour vision is represented by the letter B.
• The allele for red-green colour blindness is represented by the letter b.
Fig. 5.1 shows a pedigree chart for a family in which some of the members are red-green colour-blind.
(a) Explain why all of the male children of parent 1 and parent 2 are red-green colour-blind.
…………………………………………………………………………………………………………………………………
(b) Parent 4 is a female who has normal colour vision and is heterozygous for red-green colour blindness.
Complete the genetic diagram to determine the probability that the offspring of parent 3 and parent 4 would be red-green colour-blind.
probability of offspring having red-green colour blindness ………………………………………………..
▶️Answer/Explanation
5(a) any two from:
parent 2, is homozygous recessive / has two alleles (for red-green colour blindness) ;
only parent 2 can provide the X chromosome for male children ;
males only have one X chromosome and they only need one recessive allele (to be red-green colour blind) ;
red-green colour blindness is a sex-linked characteristic ;
5(b) parental genotypes: parent \(3 X^{b}Y\) and parent \(4X^{B}X^{b}\) ;
gametes: \(X^{b}\) , Y/O/- and \(X^{B}\) , \(X^{b}\) ;
probability: \(\frac{0.5}{50}%\) ;
Question 6
Topic: 21.2
(a) Topic- 21.2 (biotechnology)
(b) Topic- 21.2 (biotechnology)
(c) Topic- 21.2 (biotechnology)
Penicillin can be produced in fermenters.
(a) State the name of the type of organism that produces penicillin.
……………………………………………………………………………………………………………………………
(b) Fig. 6.1 shows the change in biomass of the organism that produces penicillin, when grown in a fermenter under controlled conditions.
State the name of the growth stages of the organism, shown by the letters X, Y and Z in Fig. 6.1.
X ……………………………………………………………………………………………………………………………..
Y ……………………………………………………………………………………………………………………………..
Z ……………………………………………………………………………………………………………………………..
(c) Fig. 6.2 is a diagram of a fermenter containing the organisms that produce penicillin.
(i) Explain why air is supplied to the fermenter shown in Fig. 6.2.
………………………………………………………………………………………………………………………….
(ii) Explain why the temperature in the fermenter must be controlled.
………………………………………………………………………………………………………………………….
(iii) State the role of the paddles in the fermenter.
………………………………………………………………………………………………………………………….
(iv) Other than penicillin, state the names of two commercial products that can be made using fermenters.
1 ……………………………………………………………………………………………………………………….
2 ……………………………………………………………………………………………………………………….
▶️Answer/Explanation
6(a) fungus / fungi ;
6(b) X: lag (phase)
Y: log (phase) / exponential (phase)
Z: stationary (phase)
6(c) (i) organisms need oxygen ;
for (aerobic) respiration ;
(ii) any three from:
respiration, produces heat ;
ref. to enzymes (in organisms) ;
(enzymes are) denatured by excess heat to keep (the fermenter) at the optimum (temperature) for maximum yield of product ;
AVP ;
(iii) any two from:
ref. to mixing / stirring ;
ensure even / uniform, distribution of, oxygen / air / nutrients / fungi ;
ensure even / uniform, temperature / pH, (in all parts of the fermenter) ;
(iv) any two from:
insulin ;
mycoprotein ;
AVP ;