Question 1
(a) Topic: 7.2 (digestive system)
(b) Topic: 7.3 (physical digestion)
(c) Topic: 7.3 (physical digestion)
(a) Fig. 1.1 shows part of the human digestive system.
(i) Using label lines and the letters shown, identify on Fig. 1.1:
• the organ that produces bile and label it A
• the organ that stores bile and label it B.
(ii) Describe physical digestion.
(iii) State the names of two places where physical digestion occurs in the body.
1 ……………………………………………………………………………………………………………………….
2 ……………………………………………………………………………………………………………………….
(b) Bile is involved in fat digestion.
(i) Complete the sentences about fat digestion.
Bile is released into the ………………………………………… in the digestive system. Bile increases the surface area of fats and oils. This is called ………………………………….. . This increase in surface area increases the rate of ………………………………………… digestion using the enzyme ………………………………………… .
(ii) State the names of the products of fat digestion.
(c) Explain the role of bile in the breakdown of protein by trypsin.
▶️Answer/Explanation
1(a) (i) liver labelled A ;
gall bladder labelled B ;
(ii) the breakdown of food into (smaller) pieces ;
without chemical change to the food molecules ;
(iii) mouth ;
stomach ;
small intestine / duodenum ;
1(b) (i) small intestine / duodenum ;
emulsification ;
chemical ;
lipase ;
(ii) fatty acids and glycerol ;
1(c) (bile) is alkaline and so neutralises the mixture (from the stomach) / (bile) neutralises the (named) acidic mixture (from the stomach) provides, optimum / suitable, pH (for trypsin activity) ;
Question 2
(a) Topic: 1.3 (features of organisms)
(b) Topic: 8.4 (translocation)
(c) Topic: 8.4 (translocation)
Aphids are arthropods.
Aphids insert their mouthpieces into the phloem in the stem of a plant to feed.
An aphid is shown in Fig. 2.1.
(a) (i) Identify two features visible in Fig. 2.1 that can be used to classify an aphid as an insect.
1 ……………………………………………………………………………………………………………………….
2 ……………………………………………………………………………………………………………………….
Fig. 2.2 is a diagram of a cross-section of a dicotyledonous stem.
(ii) State the letter in Fig. 2.2 that identifies the structure from which aphids feed.
…………………………………………………………………………………………………………………….
(iii) State the names of two nutrients transported in the phloem.
1 ……………………………………………………………………………………………………………………….
2 ……………………………………………………………………………………………………………………….
(b) Scientists investigated the effect of temperature on the rate of translocation.
The data are shown in Table 2.1.
Calculate the percentage change in rate of translocation between 15 °C and 30 °C.
Give your answer to three significant figures.
……………………………………………….%
(c) Fig. 2.3 shows a potato plant growing in the spring and then in the summer.
(i) Explain how translocation changes between spring and summer in the potato plant shown in Fig. 2.3.
Use the terms source and sink in your answer.
(ii) New tubers form on the potato plant in the summer. These tubers are genetically identical.
Identify the type of reproduction that the potato plant is using to form the tubers.
…………………………………………………………………………………………………………………….
▶️Answer/Explanation
2(a) (i) any two from:
three pairs of legs ;
three (named) body, parts / segments ;
one pair of antennae ;
(ii) M ;
(iii) amino acids and sucrose ;
2(b) 134(%)
2(c)(i) any four from:
in spring
the (growing) shoot is the sink and the, tuber / potato, is the source glucose / sucrose needed for, respiration / growth or amino acids / protein, for growth ;
in summer
the leaves are the source and the, tuber / potato, is the sink leaves photosynthesise to, produce glucose / starch or leaves photosynthesise to transfer (light) energy (to chemical energy) ;
general:
(correctly named) sources are part of the plants that release sucrose / glucose / amino acids ;
(correctly named) sinks, use / store, sucrose / glucose / amino acids / starch / protein ;
the source and sink are different in spring and summer ;
(ii) asexual ;
Question 3
(a) Topic: 16.6 (sexually transmitted infections)
(b) Topic: 10.1 (diseases and immunity)
(a) HIV can be transmitted from mother to infant.
Describe how the risk of a mother transmitting HIV to their infant can be reduced.
(b) (i) Scientists investigated the effect of breastfeeding on the chance of infants getting an infection.
They studied two groups of 100 infants. One group was breastfed and one group was not breastfed.
Table 3.1 shows the data.
Using the data in Table 3.1, describe the effect of breastfeeding on the chance of getting an infection.
(ii) State the name of a blood cell involved in the immune response.
(iii) Describe how infants can gain passive immunity.
(iv) Describe how immunity gained by vaccination differs from passive immunity.
▶️Answer/Explanation
3(a) any two from:
(mother) takes HIV medication ;
reduce / do not, breastfeed ;
C(aesarean) section / AW ;
correct description of how a mother could avoid getting HIV, during pregnancy / while breastfeeding ;
AVP ; e.g. testing or screening of pregnant mothers for HIV
3(b) (i) any two from:
(breastfeeding) reduces the chance of a, gastroenteritis / bronchitis infection/ ora ;
(breastfeeding) does not change / causes a (small) change in the chance of influenza / conjunctivitis / bronchitis, infection similar / less, (total) chance of infections in breastfed infants than in not breastfed infants / ora suitable data manipulation ;
(ii) white blood cell / phagocyte / lymphocyte ;
(iii) any four from:
(passive immunity) involves antibodies that are acquired from, another individual / outside the body ;
(antibodies pass from mother to infant) when breastfeeding / AW ;
(antibodies pass from mother to, fetus / infant) across the placenta ;
infants need regular antibodies from the mother to maintain passive immunity ;
infants need different antibodies to gain passive immunity to different pathogens / infants only get passive immunity to the specific pathogen for which the mother has antibodies ;
AVP ; e.g. antibodies / (anti)serum, given (by injection)
(iv) any three from:
ref. to active immunity ;
idea that person makes their own antibodies ;
exposure to, antigen / weakened pathogen, stimulates (immune) response ;
memory cells are produced ;
long lasting / long-term (immunity) / ora ; active immunity is not immediate / slower response than passive immunity/ ora ;
Question 4
(a) Topic: 12.3 (anaerobic respiration)
(b) Topic: 14.3 (hormones)
Human muscle cells use anaerobic respiration during vigorous exercise.
(a) (i) State the word equation for anaerobic respiration in humans.
(ii) Compare the process of anaerobic respiration to aerobic respiration in human muscle cells.
(b) An athlete runs a race which lasts 60 seconds.
Fig. 4.1 shows the heart rate and breathing rate of the athlete during the race and as he recovers after the race.
(i) The rate of breathing increases during the race in response to a change detected by the body.
Identify the stimulus in this response and state the organ that detects the stimulus.
stimulus ……………………………………………………………………………………………………………..
organ …………………………………………………………………………………………………………………
(ii) Using the information in Fig. 4.1, calculate the rate of decrease in heart rate from 125 seconds to 260 seconds as the athlete recovers.
…………………………… beats per minute per second
(iii) Explain the results shown in Fig. 4.1 from 60 seconds until 420 seconds.
▶️Answer/Explanation
4(a) (i) glucose lactic acid ;
(ii) any three from:
anaerobic respiration occurs without oxygen / ora ;
anaerobic respiration releases less energy (per glucose molecule) / ora ;
anaerobic respiration produces lactic acid whereas aerobic produces carbon dioxide and water ;
anaerobic respiration does not occur in the mitochondria / ora ;
both types of respiration use glucose ;
4(b) (i) stimulus: increased / concentration, of carbon dioxide ;
organ: brain ;
(ii) 0.5(33 333) (beats per minute per second) ;
(iii) any six from:
1) heart rate and breathing rate, peaked / at highest level, (immediately) as the race ends / at 60 s / AW ;
2) only aerobic respiration occurs / anaerobic respiration no longer required (after race / from 60 s) / ora ;
3) less muscle contraction (than during race) / ora ;
4) less energy required (than during race) / ora ;
5) decreased need for (delivery of), oxygen / glucose or removal of (less) carbon dioxide, from blood / to muscle (cells) / ora ;
6) no more / less, adrenaline is released (after race / from 60 s) / ora ;
7) heart rate returns to, resting rate / pre-race level (during the 6 minutes / by 420 s / end) ;
8) not enough oxygen was supplied (to muscles) during race ;
9) (resulted in) oxygen debt ;
10) lactic acid (had been) produced / accumulated, in muscle / blood ;
11) lactic acid, (aerobically) respired / converted to glucose ;
12) (lactic acid) broken down / removed, in the liver ;
13) (removal of lactic acid) requires (extra) oxygen ;
14) (therefore) breathing rate, stays high for short time after race / not yet returned to, resting rate / pre-race level (during the 6 minutes / by 420 s / end) ;
Question 5
(a) Topic: 17.4 (monohybrid inheritance)
(b) Topic: 17.4 (monohybrid inheritance)
(c) Topic: 17.4 (monohybrid inheritance)
(d) Topic: 17.4 (monohybrid inheritance)
Feather colour in some breeds of chicken is an example of codominance in birds.
In this example, a chicken with white feathers and a chicken with black feathers can breed to produce offspring that have white feathers and black feathers.
The allele for black feathers is \(F^{B}\) and the allele for white feathers is \(F^{W}\).
Fig. 5.1 is a pedigree diagram of a family of chickens.
(a) State the type of variation that is caused by genes only.
(b) State all the possible genotypes of chicken 2 and chicken 7 in Fig. 5.1.
chicken 2 ………………………………………………………………………………………………………………….
chicken 7 ………………………………………………………………………………………………………………….
(c) Complete the genetic diagram to show the results of a cross between chicken 5 and chicken 6 in Fig. 5.1.
offspring genotypes ……………………………………………………………………………………………..
expected offspring phenotype percentage ………………………………………………………………
(d) State one example of codominance in humans.
▶️Answer/Explanation
5(a) discontinuous ;
5(b) chicken 2 – \(F^{B}\)\(F^{B}\) and \(F^{B}\)\(F^{W}\) ;
chicken 7 – \(F^{W}\)\(F^{W}\) and \(F^{B}\)\(F^{W}\) and \(F^{B}\)\(F^{B}\) ;
5(c) phenotypes: (5)(male) black and white (feathers) × (6)(female) black (feathers) ;
parental genotypes: \(F^{B}\)\(F^{W}\) × \(F^{B}\)\(F^{B}\) ;
gametes: \(F^{B}\) , \(F^{W}\) \(F^{B}\) , \(F^{B}\) ;
offspring genotypes: \(F^{B}\)\(F^{W}\), (\(F^{B}\)\(F^{W}\)) and \(F^{B}\)\(F^{B}\), (\(F^{B}\)\(F^{B}\)) ;
offspring phenotype percentage: 50(%) black and white and 50(%) black ;
5(d) (ABO) blood group / AVP ;
Question 6
(a) Topic: 17.1 (chromosomes,genes and proteins)
(b) Topic: 9.4 (blood)
(c) Topic: 21.3 (genetic modifications)
(d) Topic: 21.3 (genetic modifications)
Some blood-clotting disorders can be inherited.
(a) (i) Describe what is meant by the term inheritance.
(ii) Describe the process of blood-clotting.
(b) Genetic modification has been used to produce human proteins.
One protein made in this way is factor VIIa which is used to treat some blood clotting disorders.
Fig. 6.1 shows part of the process.
(i) State the names of enzyme A and enzyme B in Fig. 6.1.
A ……………………………………………………………………………………………………………………….
B ……………………………………………………………………………………………………………………….
(ii) Explain why it is important that enzyme A is used to cut both the human DNA and the plasmid.
(iii) State what the letter C in Fig. 6.1 represents.
(iv) Explain why the contents of the fermenter in Fig. 6.1 are stirred constantly.
(v) Bacteria can be used to make complex molecules.
Describe two other reasons why bacteria are useful in biotechnology.
1 ……………………………………………………………………………………………………………………….
2 ……………………………………………………………………………………………………………………….
(vi) Describe two ways animal cells differ from bacterial cells.
1 ……………………………………………………………………………………………………………………….
2 ……………………………………………………………………………………………………………………….
(c) Crop plants such as soya can also be genetically modified.
Discuss the advantages and disadvantages of genetic modification of crop plants.
▶️Answer/Explanation
6(a)(i) transmission of genetic information from generation to generation ;
(ii) any four from:
involves platelets ;
fibrinogen converted to fibrin ;
(fibrinogen is) soluble to insoluble (fibrin) / fibrin is insoluble ;
(fibrin) forms a, mesh AW ;
traps blood cells ;
AVP;
6(b) (i) A: restriction enzyme ;
B: (DNA) ligase ;
(ii) forms sticky ends ;
(sticky) ends will be complementary ;
(iii) recombinant plasmid ;
(iv) ensure even / uniform, distribution (of contents / AW) ;
(v) any two from:
presence of plasmids ;
few / no, ethical concerns (in use of bacteria) ;
rapid reproduction rate ;
reproduce asexually / offspring are genetically identical ;
small / do not need much space ;
simple requirements to, grow / keep / AW ;
same, genetic code / AW, as other organisms ;
AVP ;
(vi) animal cells have
a nucleus ;
mitochondria ;
linear DNA ;
no cell wall ;
no plasmids ;
AVP ;
6(c) total of four from:
max three advantages from:
increased, yield / quantity ;
increased nutritional, quality / content ;
reduced use of fertiliser ;
decrease damage from pests ;
resistance to (insect) pests / (crops) produce insecticide / reduced use of insecticides ;
resistance to, herbicides ;
resistance to disease ;
resistance to, salinity / cold / drought / AW ;
max three disadvantages from:
(genetically modified) seeds / plants, cost more (to farmer / consumer) ;
(genetically modified) seeds, are sterile / need to be bought for each new crop ;
(modified) genes may transfer into other (nearby) plants by cross pollination / AW ;
ethical / religious, concerns about altering natural genomes / of consumers ;
disruption of food chain by pest losing food source ;
reduced genetic variability (of the crop) / (crop) less able to adapt to a change in the environment ;