Biology 0610/42 October/November 2020: question paper and mark scheme
Cambridge IGCSE Biology (0610), Paper 4 Theory (Extended), October/November 2020. Read both free below, or download them. Done the paper? Get it marked by AI against this mark scheme.
(a) Sensitivity is one of the characteristics of life. The eye is one of the major sense organs of vertebrates.
(i) Define the term sensitivity.
…… [2]
(ii) Define the term sense organ.
…… [2]
(b) Accommodation (focusing) is one of the functions of the eye.
Fig. 1.1 is a diagram of an eye that is focusing on a distant object.
retina ciliary muscle
X
suspensory ligaments
Fig. 1.1
(i) State the name of the part of the retina labelled X.
…… [1]
Fig. 1.2 is an incomplete diagram of an eye that is focusing on a near object.
Fig. 1.2
(ii) Complete Fig. 1.2 by drawing the shape of the lens and the light rays from the object to the retina. [3]
(iii) Describe the roles of the ciliary muscles and suspensory ligaments in focusing on a distant object, as shown in Fig. 1.1.
…… [3]
(c) The eye also controls the amount of light that enters the pupil.
Fig. 1.3 shows an eye in low light and in bright light.
eye in low light eye in bright light
Fig. 1.3
Describe the changes that occur in the eye when the light becomes bright, as shown in
Fig. 1.3.
…… [3]
(d) The change shown in Fig. 1.3 occurs automatically without thought.
State the name given to this type of action.
…… [1]
[Total: 15]
Mark scheme
1(a)(i) (the ability to) detect stimuli (in the internal / external environment) ; 2
to make (appropriate) responses ;
1(a)(ii) groups of receptor cells ; 2
responding to specific stimuli ;
1(b)(i) fovea ; 1
1(b)(ii) lens drawn with correct shape and position ; 3
light rays are shown refracted in, cornea / lens ;
light rays focused on fovea ;
1(b)(iii) (ciliary) muscles relax ; 3
suspensory ligaments are, taut / tight / tense / are pulled / AW ;
so ligaments pull on lens ;
lens is, thin(ner) / flatter / less convex / elliptical shape / stretched ;
light is refracted less ;
1(c) idea that size of pupil, decreases / constricts / gets smaller ; 3
iris in the correct context ;
circular muscles (of iris) contract ;
radial muscles (of iris) relax ;
ref to antagonistic muscles ;
1(d) reflex / involuntary ; 1
Fig. 2.1 is a vertical section of a human molar tooth and surrounding structures.
A
B
C
D
Fig. 2.1
(a) State the names of the parts labelled A to D on Fig. 2.1.
A ……
B ……
C ……
D ……
[4]
(b) Describe and explain the function of molar teeth.
…… [3]
(c) Fig. 2.2 is an X-ray of decay in a molar tooth.
decayed molar tooth
Fig. 2.2
Explain how tooth decay occurs.
…… [4]
[Total: 11]
3 Fig. 3.1 is a food web for a forested area in Central America.
great horned owl
jaguar bobcat
long-tailed weasel nine-banded armadillo hooded skunk
red harvester ants termites collared peccary lowland tapir
muhly grass Peruvian feather grass
Fig. 3.1
(a) Complete Table 3.1 using information from Fig. 3.1.
Table 3.1
trophic level description example from Fig. 3.1
herbivore
producer
feeds on tertiary consumers
secondary consumer
[4]
(b) Fig. 3.2 shows the flow of energy through a food chain. The size of each box represents the energy available in each trophic level, numbered 1, 2, 3 and 4.
solar energy
respiration trophic level 1
trophic level 2
respiration trophic level 3
Z respiration trophic level 4
Fig. 3.2
(i) State the term given to the group of organisms represented by Z in Fig. 3.2.
…… [1]
(ii) Explain, with reference to Fig. 3.2, why food chains usually have fewer than five trophic levels.
…… [4]
(c) Intensive livestock production can be damaging to natural ecosystems.
Fig. 3.3 shows intensive farming of chickens.
Fig. 3.3
(i) Describe the negative impact on an ecosystem of the intensive production of livestock, such as chickens.
…… [3]
(ii) Forests are cleared for farmland. Deforestation can lead to a loss of soil (soil erosion).
Explain the effects of soil erosion on ecosystems.
…… [3]
[Total: 15]
Mark scheme
2(a) A enamel ; 4
B dentine ;
C pulp / pulp cavity / nerve / sensory neurone / capillaries / blood
vessels ;
D gum ;
2(b) mechanical / physical, digestion ; 3
crushes food / chewing / grinds food / breaks food into smaller
pieces ;
increases surface area of food ;
for (named) enzyme action / chemical digestion ;
AVP ; e.g. mix food with saliva
2(c) (named) food remains on teeth ; 4
bacteria, use / breakdown, sugars / carbohydrate / sweet foods ;
respiration ;
acid is produced ;
acid, dissolves / erodes / destroys / wears away / AW, enamel ;
dentine is exposed / AW ;
dentine, softer / dissolves more rapidly (than enamel) ;
AVP ; e.g. decay reaches nerve endings leading to pain
3(a) 4 one mark per correct row
trophic level description example from Fig. 3.1
herbivore feeds on, (named parts of) collared peccary
plants / producers / / lowland tapir
/ autotrophs / red harvester ants
/ termites ;
producer makes own food muhly grass
/ photosynthesis / Peruvian feather
/ autotrophic grass ;
quaternary feeds on tertiary consumers great horned owl ;
/ 4° / fourth
/ 4th,
consumer
secondary gets energy from / feeds on, long-tailed weasel
consumer primary consumers / bobcat / jaguar
/ herbivores / nine-banded
armadillo
/ hooded skunk ;
3(b)(i) (named) decomposers ; 1
3(b)(ii) 1 idea that small percentage of energy from sun is ’fixed’ by 4
photosynthesis ;
2 most energy from sun not available / reference to wrong
wavelength / AW ;
3 energy is lost, between / within, trophic levels / along food chain ;
4 ref. to 10% energy transfer / ORA ;
5 ref. to material that is, inedible / not digestible / egested / not
absorbed / not consumed ;
6 energy lost, in respiration / heat / movement / (named) metabolic
process ;
7 ref. to energy loss to (named) decomposers ;
8 ref. to (small) total percentage reaching fourth trophic level ;
or
not enough energy (in fourth trophic level) to support, 5th / another,
level ;
9 would be very small population of predators in fifth trophic
level / (population of) predators in fifth trophic level unlikely to
survive ;
10 fifth trophic level may be parasites which are very small ;
3(c)(i) 1 effect of waste (faeces and urine) on, waterways / crops ; 3
2 disease spreading to, wild populations / humans ;
3 use of antibiotics and (spread of) antibiotic resistance ;
4 use of pesticides ;
5 loss of biodiversity ;
6 release of, (named) greenhouse gases / carbon emissions ;
7 named consequence ; e.g. climate change / global warming
8 providing food for livestock requires monocultures ;
9 deforestation / habitat loss ;
10 idea that livestock production is an inefficient use of, crop
plants / energy ;
11 AVP ; e.g. use of hormones and effect on wild populations
/ feminisation of fish
3(c)(ii) 1 silting of rivers ; 3
2 landslides / mudslides ;
3 soil does not absorb (rain)water / increased risk of flooding ;
4 increased rate of evaporation / land is exposed to drying ;
5 desertification / decreased soil water ;
6 reduction in transpiration ;
7 reduction in cloud formation ;
8 change in rainfall patterns ;
9 plants cannot grow (well) ;
10 idea that loss of anchorage for plants ;
11 idea of reduced (soil) fertility / increased leaching / AW ;
12 loss of, habitat / places where organisms live / described ;
13 disruption to food chain(s) / described ;
14 endangered / extinction / migration of, species ;
15 less, nutrient / nitrogen / carbon, recycling ;
16 AVP ; e.g. dust storms
(a) Yeast cells have many structures in common with a plant cell.
Fig. 4.1 is a drawing of a yeast cell.
A B
C
cell wall
D
Fig. 4.1
(i) State the names of the cell structures labelled A and D on Fig. 4.1.
A ……
D ……
[2]
(ii) State the functions of the cell structures labelled B and C on Fig. 4.1.
B ……
C ……
[2]
(iii) State the name of one structure that is found in plant cells but is absent in yeast cells.
…… [1]
(b) Yeast is used in the production of ethanol to manufacture a type of biofuel.
Fig. 4.2 is a flow chart of the process.
maize plants
extraction of starch from maize
enzyme S
maltose
enzyme T
glucose process U in anaerobic conditions
ethanol carbon dioxide
Fig. 4.2
(i) State the names of enzymes S and T.
S ……
T ……
[2]
(ii) Yeast is used in process U. Complete the balanced chemical equation for anaerobic respiration in yeast.
…… ……C2H5OH + ……
[2]
(iii) Suggest the advantages of using biofuels instead of fossil fuels.
…… [3]
(iv) Carbon dioxide may be collected from process U and sold for use in glasshouses.
Explain why carbon dioxide is used in glasshouses.
…… [4]
[Total: 16]
Mark scheme
4(a)(i) A (rough) endoplasmic reticulum ; 2 A ribosomes
D (sap) vacuole ;
4(a)(ii) B / nucleus – one from: 2
store of, DNA / chromosomes / genetic information / genetic
material / genes ;
controls / regulates, (reactions / protein synthesis in) the cell ;
C / mitochondrion – one from:
(aerobic) respiration ;
releases / provides, energy ;
4(a)(iii) chloroplast ; 1 A starch grain
4(b)(i) S – amylase ; 2
T – maltase ;
4(b)(ii) C6H12O6 ; 2
2 (C2H5OH) + 2CO2 ;
4(b)(iii) 1 conserves fossil fuels ; 3
2 idea that fossil fuels are a finite resource / fossil fuels are not
renewable / biofuels are renewable ;
3 maize / plants, uses carbon dioxide (from the atmosphere) ;
4 ref to photosynthesis ;
5 idea that so balancing the carbon dioxide in, exhausts
/ emissions / AW ;
6 less likely to cause acid rain ;
7 ref to global warming / climate change / (enhanced) greenhouse
effect ;
8 uses waste from crops for energy ;
9 AVP ; e.g. reduces dependency on fossil fuels from other countries
4(b)(iv) 1 carbon dioxide is required for photosynthesis ; 4
2 (more carbon dioxide =) faster / maximum / optimum, rate of
photosynthesis ;
3 (more carbon dioxide) more, glucose / starch / organic molecules, is
produced ;
4 carbon dioxide (concentration) is a limiting factor ; ora
5 prevents concentration falling below that of atmosphere / AW ;
6 ref. to more, growth / yield / profit ;
(a) The activities of the ovaries and the uterus are regulated by the hormones FSH, LH, oestrogen and progesterone during the menstrual cycle.
Complete Table 5.1 to show the sites of production and the roles of these four hormones.
Table 5.1
target hormone site of production role organ
FSH pituitary gland ovary
LH pituitary gland ovary
oestrogen uterus stimulates growth of the lining of the uterus
progesterone uterus
[5]
(b) Fig. 5.1 shows the changes in the lining of the uterus of a human female.
thickness of the lining of the uterus
0 7 14 21 28 7 14 day of menstrual cycle
Fig. 5.1
Describe the changes in the lining of the uterus between days 0 and 28 of the menstrual cycle.
between days 0 and 7 ……
between days 7 and 28 ……
[3]
(c) Some people are infertile.
Artificial insemination (AI) and in vitro fertilisation (IVF) are two methods of fertility treatment.
These two methods are outlined in Fig. 5.2.
artificial insemination
collection of sperm
washed sperm
in vitro fertilisation collection of eggs collection of sperm washed sperm
eggs and sperm mixed together
embryo
transfer of growth of embryos in freezing of embryos culture dish spare embryos
not to scale
Fig. 5.2
Describe the similarities and differences between the two processes of fertility treatment shown in Fig. 5.2.
…… [6]
[Total: 14]
Mark scheme
5(a) 5
hormone site of target role
production organ
FSH pituitary ovary (stimulates) development
gland of egg or ovum / ref. to
secretion of oestrogen ;
LH pituitary ovary (stimulates) ovulation
gland / ref. to secretion of
progesterone (and
oestrogen) ;
oestrogen ovary ; uterus stimulates growth of the
A placenta lining of the uterus
progesterone ovary ; uterus maintains / AW, the lining
A placenta of the uterus ;
5(b) days 0–7: 3
decrease in thickness ;
decreases quickest between days 0 and 3 ;
days 7–28:
increase in thickness ;
remains at same thickness from day, 21 / 22 / 23 ;
5(c) 6
similarities differences A ora
1 treatment with fertility drugs ; 10 ovulation occurs in AI ;
2 (fertility drugs) encourage, 11 fertilisation in AI occurs
follicle production / egg inside the body / in IVF it
development ; occurs in, a Petri dish or
outside the body or AW ;
3 intercourse does not occur ; 12 eggs removed (from ovary)
in IVF ;
4 collection of sperm (from a 13 embryo starts development
donor) ; outside body in IVF / embryo
inserted into uterus in IVF ;
5 washing of sperm ; 14 excess / surplus, embryos
produced in IVF ;
6 fertilisation 15 embryo selection possible in
or fusion of, gametes / egg IVF ;
and sperm ;
7 lining of uterus must develop ; 16 frozen / stored, embryos in
IVF ;
8 implantation occurs
(naturally) ;
9 A as a similarity or as a way
IVF differs from AI
increase chances of multiple,
births / babies ;
Fig. 6.1 is a diagram of DNA.
Key: base pair base A
Fig. 6.1
(a) (i) State the letter of the base that pairs with A.
…… [1]
(ii) State the letters of the other bases in DNA.
…… [1]
(b) Outline the roles of DNA in a cell.
…… [2]
(c) Fig. 6.2 shows a plant tissue in which cells are dividing by mitosis.
K
J
H
Fig. 6.2
(i) Cell H in Fig. 6.2 is about to divide by mitosis.
State what happens to the chromosomes in cell H before mitosis takes place and state why it is necessary.
…… [2]
(ii) Cell K is about to divide into two cells.
State the structures that will form between the nuclei so that the cell divides into two cells.
…… [2]
(iii) Cell J in Fig. 6.2 is an example of a diploid cell.
State what is meant by the term diploid.
…… [1]
[Total: 9]
Mark scheme
6(a)(i) T; 1
6(a)(ii) C and G ; 1
6(b) 1 store of, genetic information / genetic make-up / genes / AW ; 2
2 DNA / genes / alleles / genetic information / base sequence, codes
for / makes, (named) proteins ;
3 sequence of bases in DNA codes for sequence of, amino acids ;
4 transfer of information to daughter cells (during mitosis) ;
5 DNA copied as mRNA ;
6 AVP ;
6(c)(i) each chromosome is, duplicated / replication / doubled / copied ; 2
to maintain the same number of chromosomes OR so all cells have the
same genetic information / cells are all genetically identical ;
6(c)(ii) cell membrane ; 2
cell wall ;
AVP ;
6(c)(iii) (a diploid cell has) two sets of chromosomes ; 1
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Biology 0610/42 for October/November 2020 is out of 80 marks, with 1 hour 15 minutes to answer it, across 6 questions.
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