and National 5 Biology Questions and
Answers | Latest Version | 2025/2026 |
Correct & Verified
Describe what happens to enzyme activity when temperature increases beyond the optimum.
✔✔The enzyme activity decreases because the enzyme becomes denatured and its active site
changes shape.
Explain why stomata are mostly found on the underside of a leaf.
✔✔To reduce water loss by evaporation due to lower exposure to sunlight.
Define osmosis.
✔✔Osmosis is the movement of water molecules from a region of higher water concentration to
a region of lower water concentration through a selectively permeable membrane.
Suggest a reason why white blood cells increase during an infection.
✔✔To fight off pathogens by producing antibodies or engulfing bacteria.
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, Predict what would happen to a plant cell in a solution with very low water concentration.
✔✔The cell would lose water and become plasmolysed.
Compare mitosis and meiosis in terms of chromosome number.
✔✔Mitosis produces cells with the same number of chromosomes as the parent cell, while
meiosis halves the chromosome number.
Identify one structure that is found in plant cells but not in animal cells.
✔✔Chloroplast
Calculate the number of cells produced after four rounds of mitotic division starting from one
cell.
✔✔Sixteen cells
Explain the role of insulin in the body.
✔✔Insulin lowers blood glucose levels by promoting the uptake of glucose into cells and storage
as glycogen in the liver.
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