Biology 0610/43 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.
Plants are sensitive to light.
(a) Fig. 1.1 shows a sequence of diagrams for two young plant seedlings. The seedlings were first grown in pots with light from all directions and then placed into boxes.
• Seedling A was placed in a box with light entering from one side only.
• Seedling B was placed in a box with no light.
seedling
soil water
A A
B B
Fig. 1.1
Complete Fig. 1.1 by drawing seedling A and seedling B, in the boxes, to show the expected direction of their growth after one week. [2]
(b) Plants are also sensitive to gravity.
(i) Define the term sensitivity.
…… [2]
(ii) Explain the role of plant hormones in gravitropism.
…… [4]
(iii) Gravitropism enables plants to survive in their environment.
Explain how gravitropism enables a plant to survive.
…… [2]
(c) Reflexes in animals are also an example of sensitivity.
(i) Describe how reflexes in animals differ from sensitivity in plants.
…… [2]
(ii) The pupil reflex is an example of a reflex that occurs in the eye. The eye is a sense organ.
Define the term sense organ.
…… [2]
[Total: 14]
Mark scheme
1(a) seedling A bending towards the light ; 2
seedling B with taller shoot than original (growing straight up) ;
1(b)(i) the ability to detect stimuli, in the internal / external environment ; 2
to make appropriate, responses ;
1(b)(ii) any four from: 4
1 auxin (is a plant hormone) ;
2 auxin made in (root / shoot) tip (only) ;
3 auxin, diffuses (through the plant) ;
4 auxin, is unequally distributed / (more) auxin accumulates lower
parts ;
5 (auxin) stimulates cell elongation ;
6 shoots, grow away from / against, gravity / negative (tropic)
response OR roots, grow towards / with, gravity / positive (tropic)
response ;
7 AVP ;
1(b)(iii) any two from: 2
(roots / plants growing down) anchor the plant / AW ;
(roots / plants growing down are more likely) to reach, water / (named)
minerals ;
(shoots / plants) growing up are more likely) to reach light ;
(shoot or plant has better) access to (named) pollinators ;
1(c)(i) any two from: 2
(reflexes) respond faster ; ora
(reflexes) use, (electrical) impulses / neurons / nerves / nervous
system ;
(reflexes) are shorter lived ; ora
(reflexes) are not a growth response ; ora
AVP ;
1(c)(ii) groups of receptor cells ; 2
responding to specific stimuli ;
(a) A person ate a meal containing starch and fat.
Fig. 2.1 shows some events that occurred after ingesting this meal.
P absorption of nutrients in the villi
Q assimilation of fatty acids in the liver
R breakdown of large food particles by the teeth
S movement of small food particles through the oesophagus
T secretion of amylase from the salivary glands
Fig. 2.1
Put the events in Fig. 2.1 into the correct sequence. One has been done for you.
R
[2]
(b) The stomach lining contains cells that secrete proteins.
(i) State the names of two cell structures that are involved in making or secreting proteins.
1 ……
2 ……
[2]
(ii) State the name of one component of gastric juice and describe its functions.
[3]
(iii) There are goblet cells in many parts of the alimentary canal.
State the substance that goblet cells secrete.
…… [1]
(c) Emulsification of fats occurs in the alimentary canal.
(i) Describe the process of emulsification of fats.
…… [2]
(ii) State the name of the organ in the alimentary canal where fats are emulsified.
…… [1]
(iii) State the name of the structure in the villi where digested fats are absorbed.
…… [1]
[Total: 12]
Mark scheme
2(a) 2 one mark for T before S
R T S; P Q; one mark for P before Q
2(b)(i) any two from: 2
nucleus ;
ribosomes ;
rough endoplasmic reticulum ;
vesicles ;
mitochondria ;
cell membrane ;
AVP ;
2(b)(ii) component: 3
hydrochloric acid ;
functions:
(acid) creates optimum pH for, (stomach) enzymes / pepsin
/ protease ;
(acid) kills (harmful) microorganisms / denatures enzymes (of
microorganisms) ;
OR
component:
pepsin / protease ;
functions:
protein amino acids ;
ref. to chemical digestion (by enzymes) or to allow soluble
molecules / amino acids, to be absorbed ;
pepsin digests, bacteria / pathogens ;
OR
component:
water ;
functions:
acts as a solvent / AW ;
OR
AVP ;;
2(b)(iii) mucus ; 1
2(c)(i) (mix with) bile ; 2
breaks up of large fat globules (into smaller fat globules) ;
increases surface area (of fat globules) ;
AVP ; e.g. water enables dispersion of (smaller) fat globules
2(c)(ii) small intestine / duodenum ; 1
2(c)(iii) lacteal ; 1
(a) Fig. 3.1 is part of a food web in a rainforest.
anaconda jaguar
iguana frog
monkey grasshopper fruit bat
coconut tree banana plant
Fig. 3.1
(i) Complete Fig. 3.2 using the information in Fig. 3.1.
The first one has been done for you.
the number of different producers 2
the number of different secondary consumers
the number of different trophic levels in the food web
how many different trophic levels monkeys feed at
Fig. 3.2
[3]
(ii) Sometimes anacondas are able to kill and eat jaguars.
Using the information in Fig. 3.1, state the name of the highest possible trophic level of an anaconda that eats a jaguar.
…… [1]
(iii) Explain why the population of anacondas is always smaller than the population of fruit bats in the food web shown in Fig. 3.1.
Use the concept of energy flow in your answer.
…… [3]
(b) (i) A giant rat was discovered in a natural rainforest on Vangunu Island. Scientists wanted to determine if it was a new species.
Explain how scientists can use tissue samples to classify this rat.
…… [2]
(ii) Giant rats eat coconuts.
Coconuts are grown as a monoculture for human consumption.
Suggest how monocultures of crop plants can result in the extinction of some animals.
…… [3]
[Total: 12]
Mark scheme
3(a)(i) 3
the number of different producers 2
the number of different secondary consumers 5;
the number of different trophic levels in the food web 4;
how many different trophic levels monkeys feed at 2;
3(a)(ii) fifth (trophic level) / (trophic level) 5 / quaternary consumer ; 1
3(a)(iii) any three from: 3
1 fruit bats are at a lower trophic level (than anaconda) ; ora
2 idea that energy transfer along a food chain is inefficient ; e.g. respiration / egestion / uneaten
3,4 named examples of causes of inefficient energy flow between parts / excretion / movement
trophic levels ;;
3(b)(i) any two from: 2
ref. to use of extracted DNA / protein (from tissue) ;
(determination of) DNA / base / amino acid, sequences ;
DNA / sequences / amino acids / genes, compared with, other (known)
species / organisms / ancestors / DNA databases ;
3(b)(ii) any three from: 3
loss of habitat / described ;
addition of (named polluting) chemicals ;
human animal conflict ;
(the crop is often an) introduced species ;
loss of biodiversity or loss of, suitable / variety of, food sources ;
outbreaks / spreading, of diseases / pests / plagues ;
AVP ;
Yeast is an example of a single-celled fungus.
(a) The population of yeast can be estimated by using a light microscope to view a small sample of yeast cells in a modified microscope slide.
There is a square chamber, with a specific volume, cut into the microscope slide and a grid to make it easier to count the number of cells.
Fig. 4.1 shows a diagram of the modified microscope slide. It also shows part of a light microscope with the modified microscope slide filled to the top with a sample of yeast cells.
grid
chamber
Fig. 4.1
The length of the sides of each small square in the grid in the modified microscope slide is
200 μm. The depth of the chamber is 100 μm. There is a total of 25 small squares in the grid.
Each small square in the grid has an average of 52 yeast cells.
Calculate the concentration of yeast cells per mm3.
Space for working.
…… cells per mm3
[3]
(b) A small sample of yeast cells and 19 g per dm3 of sugar were added to a fermenter. The population size of live yeast cells and the concentration of the sugar in the fermenter were calculated every day for 10 days.
The results are shown in Fig. 4.2 and Fig. 4.3.
20
20
18
18
16
16
14
concentration 12
14 of sugar
/concentration g per dm3 12
10 of sugar
/ g per dm3 10
8
8
6
6
4
4
2
2
0
0 1 2 3 4 5 6 7 8 9 10
0 time / days
0 1 2 3 4 5 6 7 8 9 10
Fig. 4.2time / days
population size of live yeast cells population size of live yeast cells
0 1 2 3 4 5 6 7 8 9 10 time / days
0 1 2 3 4 5 6 7 8 9 10 time / days
Fig. 4.3
(i) Draw an X on Fig. 4.3 to indicate the position of the lag phase. [1]
(ii) Complete the line on Fig. 4.3 to show the expected change in the population size of live yeast cells from day 3 to day 10. [2]
(iii) Describe and explain the changes in the concentration of sugar in the fermenter over the
10-day period.
…… [5]
(c) Explain why it is important that there is a tube in the fermenter that allows gases to escape.
…… [2]
[Total: 13]
Mark scheme
4(a) 3 apply ecf from one step to the next
conversion from μm to mm ; MP1 e.g. (200 μm) = 0.2 (mm)
calculation of volume (of each grid square) ; MP2 e.g. 0.2 × 0.2 × 0.1 = 0.004 (mm3)
calculation of final answer =13 000 (cell per mm3) ; MP3 e.g. 52 yeast cells × 25 grid squares gives a
total of 1300 yeast cells in a volume of 0.1 mm3
(which is the total volume of grid (0.004 × 25 = 0.1
mm3)) multiple 1300 by 10 to convert to yeast
cells per mm3
4(b)(i) X on Fig. 4.3 on / near, solid line between 0 and up to 1 day ; 1
4(b)(ii) line drawn on Fig 4.3, increasing from day 3, more slowly / level ; 2
line drawn on Fig 4.3 showing any decrease (in population) at end of
candidate’s line ;
4(b)(iii) any five from: 5
sugar concentration decreases faster between day 6 and 9 ; ora
no change in sugar concentration / stops decreasing, from day 9 ;
the yeast population affects the sugar concentration ;
(yeast use sugar) in respiration ;
release energy ;
rate of sugar decrease is slow, at first / in lag phase, because there
are few yeast cells ; ora
ref. to dead yeast (after day 9) / death phase / AW ;
AVP ; e.g. ethanol build up / change in pH, could kill the yeast / some
sugar leftover so it is not a limiting factor
4(c) carbon dioxide (produced by respiration) ; 2
(gas) pressure will increase / AW ;
Fig. 5.1 shows a photomicrograph of a sperm cell reaching an egg cell.
Fig. 5.1
(a) (i) Complete the sentence:
A nucleus containing a single set of unpaired chromosomes in a sperm is called a
…… nucleus. [1]
(ii) State where, in the female reproductive system, the event shown in Fig. 5.1 occurs.
…… [1]
(iii) Describe what happens from the event shown in Fig. 5.1 until an embryo is formed.
…… [4]
(b) Some people use fertility drugs and in vitro fertilisation (IVF) to have children.
Outline the use of fertility drugs and the process of IVF.
…… [6]
[Total: 12]
Mark scheme
5(a)(i) haploid ; 1
5(a)(ii) oviduct ; 1
5(a)(iii) any four from: 4
ref. to acrosome / (digestive) enzymes, are released (from sperm) ;
jelly coat is digested (by enzymes) ;
fusion of nuclei (of gametes) / fertilisation ;
to form a (diploid) zygote ;
jelly coat hardens (after fertilization) ;
zygote moves, along oviduct / towards uterus ;
cell division / mitosis (after formation of zygote) ;
AVP ; e.g. use of energy stores from egg cell (for mitosis)
5(b) any six from: 6
use of fertility drugs:
1 FSH / LH (are used in fertility treatment) ;
2 taken / injected, during early stage of menstrual cycle ;
3 (FSH) stimulates follicles to, develop / mature ;
4 (fertility drugs) stimulate, the ovaries / production of oestrogen ;
5 (LH / FSH) stimulates, ovulation / described ;
6 AVP ;
process of IVF:
7 collect / extract, eggs ;
8 collect / extract, sperm ;
9 use of donor, eggs / sperm ;
10 fertilisation / described / IVF, outside the body / in a dish / in a
laboratory ;
11 embryo development in dish / AW ;
12 screening of embryos ;
13 inserting embryos into uterus ;
14 give mother progesterone after inserting embryos (to maintain
lining) ;
15 AVP ; appropriate ref. to surrogate mothers or multiple
embryos / zygotes, could lead to multiple births
(a) Researchers investigated four different insecticides to determine how effective they were at removing three different species of insects, A, B and C, from crop plants.
They tested different concentrations of each insecticide to find the minimum dosage required to remove 95% of each insect population in two hours.
Each insecticide had the same cost per gram.
The results are shown in Table 6.1.
Table 6.1
minimum dosage required species of / mg per dm3 insect insecticide 1 insecticide 2 insecticide 3 insecticide 4
A 3 51 5 58
B 31 27 2 75
C 10 2 3 65
(i) Use the information in Table 6.1 to decide which one of the four different insecticides and which dosage would be the best choice for removing insects A, B and C from a field of crop plants.
Explain your choices.
insecticide …… dosage ……
explanation ……
[3]
(ii) Discuss factors, other than dosage, that should be considered to prevent the insecticide damaging the environment.
…… [3]
(b) (i) Describe the advantages to farmers of using insecticides.
…… [2]
(ii) Farmers also use other chemicals on their crop plants.
State the names of chemicals, other than insecticides, that are used by farmers on crop plants and explain their benefits.
…… [3]
(c) Insecticides are often made from chemicals that occur naturally in plants. Tobacco plants are one example of this.
(i) Suggest why having a natural insecticide is an adaptive feature of plants.
…… [1]
(ii) Describe why people find it difficult to stop smoking tobacco.
…… [2]
(iii) State the names of two diseases that can be caused by smoking tobacco.
1 ……
2 ……
[2]
(iv) State the name of the component of tobacco that can damage alveoli.
…… [1]
[Total: 17]
Mark scheme
6(a)(i) insecticide: 3 ; 3
dosage: 5 (mg per dm3) ;
explanation: insecticide 3 has lowest dosage required to remove all
insects species ;
6(a)(ii) any three from: 3
factor to consider discussion points
1 toxicity (of the 7 importance of (named) pollinators
insecticide) ; (in ecosystem) ;
8 potential creation of insecticide-
resistant ‘super’ bugs ;
2 persistence (of
9 harms other (named) non-target
insecticide) / how
species / damages food
quickly it breaks
chains / pollutes environment
down / biodegradable ;
/ described ;
3 presence of non-target
species in the
environment ;
4 prevailing 10 avoid spread into non-target
environmental areas ;
/ climatic conditions ;
5 method of application ;
6 other valid factor ; e.g. 11 relevant corresponding discussion
frequency of application point ;
6(b)(i) any two from: 2
fewer insects, eat / damage crops / AW ;
improved (quality / yield) of crops / AW ;
prevents spread of diseases (carried by insects) ;
AVP ; quick effect (to the treatment) / application is easy / not labour
intensive
6(b)(ii) 3 max 2 from chemical column
table rows indicate paired mark points
chemical benefit
magnesium ; for chlorophyll / photosynthesis ;
more, growth / yield ;
nitrates ; for, amino acids / (to synthesize) A fertilisers once as an alternative if no named
proteins ; ions given
more, growth / yield ;
carbon dioxide ; increased photosynthesis ;
more, growth / yield ;
water ; prevent wilting ; ref. to turgor / ref.
to dissolving solutes ;
herbicides ; reduced (named) competition with
weeds ;
2,4 D / (synthetic)
more, growth / yield ;
plant hormones ;
AVP ;; e.g. other relevant benefit ;;
valid chemicals or e.g. more , growth / yield
ions such as
phosphate
/ potassium
/ fungicide reduced competition with
fungi / prevent disease
6(c)(i) reduced predation / improve chance of survival / increased 1
fitness / AW ;
6(c)(ii) any two from: 2
(tobacco) contains nicotine ;
(nicotine) is addictive ;
ref. to withdrawal symptoms ;
6(c)(iii) any two from: 2
COPD ;
lung cancer ;
coronary heart disease / CHD ;
AVP ; e.g. gum disease / bronchitis
6(c)(iv) any one from: 1
tar ;
dust particles / AW ;
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Biology 0610/43 for October/November 2020 is out of 40 marks, with 1 hour 15 minutes to answer it.
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