(a) The mineral ion iron is a component of a balanced diet. People who do not get enough iron from their diet can develop anaemia. Fig. 7.1 shows the percentage of children with anaemia in four countries in the year 2000 and in the year 2015.
Describe the data shown in Fig. 7.1.
(b) Mineral ions are part of a balanced diet. State three other components of a balanced diet.
(c) Some crop plants have been genetically modified to improve their nutritional value.
(i) State the meaning of the term genetic modification.
(ii) Describe two examples of genetic modification in crop plants, other than improving their nutritional value.
(iii) State two reasons why bacteria are often used for genetic modification.
▶️ Answer/Explanation
Ans:
(a) The graph shows:
- Countries A and C saw decreases in childhood anaemia (e.g., Country A dropped from ~30% to ~15%).
- Country B had an increase (from ~10% to ~15%).
- Country D remained unchanged (~5%).
This suggests improved nutrition in A and C but worsening in B.
(b) Three other diet components:
- Carbohydrates (energy source)
- Proteins (growth/repair)
- Vitamins (e.g., vitamin C for immunity)
(c)(i) Genetic modification (GM) involves altering an organism’s DNA to introduce new traits (e.g., inserting genes for pest resistance).
(c)(ii) GM examples:
- Herbicide-resistant crops (e.g., Roundup Ready soybeans)
- Pest-resistant crops (e.g., Bt cotton produces insecticidal proteins)
(c)(iii) Bacteria are used because:
- They reproduce rapidly, speeding up research.
- They can express complex proteins (e.g., human insulin).
(a) Some bacteria have had human genes inserted into them. The bacteria are said to be genetically modified.
(i) Describe what is meant by the term gene.
(ii) One human protein that is made by genetically modified bacteria is insulin. State the role of insulin in the human body.
(iii) Describe one other use of genetically modified organisms.
(iv) State two reasons why bacteria are useful for genetic modification.
(b) State two ways in which bacterial cells are different from plant cells.
▶️ Answer/Explanation
(a)(i) A gene is a segment of DNA that codes for a specific protein or polypeptide. It determines inherited traits.
(a)(ii) Insulin regulates blood glucose levels by promoting glucose uptake into cells and storage as glycogen.
(a)(iii) Genetically modified organisms (GMOs) are also used to create pest-resistant crops (e.g., Bt cotton) or enhance nutritional value (e.g., Golden Rice with vitamin A).
(a)(iv) Bacteria are useful for genetic modification because:
1. They reproduce rapidly, allowing quick production of desired proteins.
2. They can express complex human proteins (e.g., insulin).
(b) Differences between bacterial and plant cells:
1. Bacteria have circular DNA, while plant cells have linear DNA in a nucleus.
2. Bacteria lack membrane-bound organelles (e.g., mitochondria, chloroplasts).