G10 BIO OPENER TERM 3 2026 MS

MARKING SCHEME

GRADE 10 BIOLOGY

TERM 3 OPENER EXAM 2026

Question 1

a) Any two valid contributions, 1 mark each: diagnosis/prevention/treatment of diseases; development of medicines/vaccines; improved nutrition; public-health education; disease surveillance. (2)

b) i. Independent variable — temperature. (1)

ii. Dependent variable — enzyme reaction rate/activity, measured using reaction time/end point. (1)

iii. Controlled variable — any valid one, e.g. enzyme concentration, substrate concentration, pH, volume of reagents. (1)

c) i. Percentage decrease = ((80 − 25) / 80) × 100 = (55/80) × 100 = 68.75%. Award 1 mark for correct difference 55 s; 1 mark for correct percentage. (2)

ii. 40°C; it has the shortest reaction time (25 s), hence the highest rate. (1)

d) Any two: wear goggles/gloves; use a test-tube holder; handle hot apparatus carefully; keep chemicals away from skin/eyes; follow reagent instructions; use a heat source in a ventilated area. (2)

Question 2

a) Diagram labels: 1 Cell wall; 2 Nucleus; 3 Large central vacuole; 4 Chloroplast. Accept cell membrane where indicated at the inner boundary. 1 mark each. (4)

Expected labelled diagram.

b) Nucleus — controls cell activities/contains genetic material. Cell membrane — selectively controls movement of substances into and out of the cell. Chloroplast — site of photosynthesis/contains chlorophyll. 1 mark each. (3)

c) Any two: long extension gives large surface area; thin wall gives short diffusion distance; many mitochondria provide ATP for active uptake of mineral ions; large vacuole helps maintain water potential gradient. 1 mark each. (2)