iGCSE Biology (0610)-21.3 Genetic modification - iGCSE Style Questions Paper 4

Question

Golden rice is a type of rice that has been genetically modified to contain a nutrient called beta-carotene.
Fig. 6.1 shows the genetic modification process used to produce golden rice.

Genetic Modification Process of Golden Rice

(a) Using the information in Fig. 6.1, complete the sentences to describe how rice is genetically modified to contain beta-carotene.
The part labelled A in the bacterial cell is a …………………………………………… .
Part A is extracted and cut using a ………………………………………….. enzyme forming
…………………………………………….. ends.
The part labelled B is the ………………………………………….. that codes for the production of
beta-carotene.
The enzyme used to cut part A is also used to cut part B from the plant DNA.
Part B is inserted into the part labelled A using the enzyme …………………………………… .
This forms the part labelled C, which is called a ………………………………………………….. .
Part C is put into a bacterium. The bacterium is taken up by rice plant cells, giving them the
ability to produce beta-carotene.
Tissue culture is a form of …………………………………………………….. reproduction that is used to
produce many identical rice plants producing beta-carotene for commercial use.

(b) Apart from structural features, state two reasons why bacteria are useful for genetic modification.

(d) Beta-carotene is required to produce vitamin A, which is essential for eye function.
State the nutrient required to prevent:
– scurvy
– rickets

▶️ Answer/Explanation

Solution

(a)

The part labelled A in the bacterial cell is a plasmid.
Part A is extracted and cut using a restriction enzyme forming sticky ends.
The part labelled B is the gene that codes for the production of beta-carotene.
The enzyme used to cut part A is also used to cut part B from the plant DNA.
Part B is inserted into the part labelled A using the enzyme (DNA) ligase.
This forms the part labelled C, which is called a recombinant (plasmid).
Tissue culture is a form of asexual reproduction that is used to produce many identical rice plants producing beta-carotene for commercial use.

Explanation: The process involves extracting a plasmid (A), cutting it with a restriction enzyme to create sticky ends, inserting the beta-carotene gene (B) using DNA ligase, and forming a recombinant plasmid (C). Tissue culture ensures mass production of identical GM rice plants.

(b) Any two from:
– Reproduce rapidly
– No ethical/welfare issues
– Ability to make complex molecules
– Easy to maintain or store / don’t take up too much space
– Share a genetic code with other organisms

Explanation: Bacteria are ideal for genetic modification due to their fast reproduction, simplicity, and lack of ethical concerns compared to higher organisms.

(c) Any three from:
1. Additional nutrient content may be too small to be effective.
2. Seeds may be expensive for farmers to purchase.
3. Farmers cannot save seeds for future planting.
4. Potential unknown health risks to consumers.
5. Risk of cross-contamination with wild rice.
6. Reduction in biodiversity or genetic diversity.
7. Consumer resistance to GM products due to ethical concerns.

Explanation: While GM rice like golden rice addresses vitamin A deficiency, it poses economic, ecological, and health-related challenges.

(d)
– Scurvy: vitamin C
– Rickets: vitamin D / calcium

Explanation: Scurvy is caused by vitamin C deficiency, while rickets results from insufficient vitamin D or calcium, affecting bone development.

Question

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.

(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.

(vi) Describe two ways animal cells differ from bacterial cells.

(c) Crop plants such as soya can also be genetically modified.
Discuss the advantages and disadvantages of genetic modification of crop plants.

▶️ Answer/Explanation

Solution

(a)(i) Inheritance refers to the transmission of genetic information from parents to offspring, ensuring the continuity of traits across generations.

(a)(ii) Blood clotting involves platelets triggering the conversion of soluble fibrinogen into insoluble fibrin, forming a mesh that traps blood cells to stop bleeding.

(b)(i) A: Restriction enzyme; B: DNA ligase. These enzymes cut and join DNA strands, respectively, enabling genetic modification.

(b)(ii) Using the same restriction enzyme ensures complementary sticky ends, allowing human DNA and plasmid to bind seamlessly.

(b)(iii) C represents the recombinant plasmid, which contains the inserted human gene.

(b)(iv) Stirring ensures uniform distribution of nutrients and oxygen, promoting optimal bacterial growth and protein production.

(b)(v) Bacteria are useful because they reproduce rapidly and can be genetically manipulated easily, making them efficient for biotechnological applications.

(b)(vi) Animal cells have a nucleus and mitochondria, while bacterial cells lack these organelles and possess circular DNA.

(c) Advantages of GM crops include increased yield and pest resistance, while disadvantages involve ethical concerns and potential ecological disruption.

Final Answers:

(a)(i) transmission of genetic information from generation to generation ;

(a)(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;

(b)(i) A: restriction enzyme ; B: (DNA) ligase ;

(b)(ii) forms sticky ends ; (sticky) ends will be complementary ;

(b)(iii) recombinant plasmid ;

(b)(iv) ensure even / uniform, distribution (of contents / AW) ;

(b)(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 ;

(b)(vi) animal cells have a nucleus ; mitochondria ; linear DNA ; no cell wall ; no plasmids ; AVP ;

(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 ;

iGCSE Biology (0610)-21.3 Genetic modification – iGCSE Style Questions Paper 4

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