Secondary 1 Science Life Sciences Quiz

Secondary 1 Science Quiz - Life Sciences (Answer Key)

Total Marks: 40

Section A: Multiple Choice [5 marks]

1. B. Mitochondrion [1 mark] Marking note: Mitochondrion is an organelle. A is a cell, C is an organ, D is a tissue.

2. C. 400× [1 mark] Marking note: Total magnification = eyepiece × objective = 10× × 40× = 400×

3. C. Microvilli [1 mark] Marking note: Microvilli are finger-like projections that increase surface area for absorption.

4. B. Solubility in the solvent [1 mark] Marking note: Different components have different solubilities, causing them to travel different distances.

5. C. Both mitochondria and chloroplasts [1 mark] Marking note: Chloroplasts for photosynthesis, mitochondria for cellular respiration.

Section B: Short Answer Questions [10 marks]

6. [3 marks total] (a) Controls what enters and leaves the cell / selective permeability [1 mark] (b) Controls cell activities / contains genetic material/DNA [1 mark] (c) Site of photosynthesis / contains chlorophyll [1 mark]

7. [2 marks] Working: Actual length = Image length ÷ Magnification = 24 mm ÷ 400 = 0.06 mm = 0.06 × 1000 = 60 μm [1 mark for working, 1 mark for correct answer with units]

8. [2 marks - any two of the following] (a) Plant cells have cell wall, animal cells do not [1 mark] (b) Plant cells have chloroplasts, animal cells do not [1 mark] Accept: Plant cells have large vacuole, animal cells have small/no vacuole

9. [3 marks] Organelle → Cell → Tissue → Organ → Organ System [1 mark each]

Section C: Applied Knowledge [10 marks]

10. [1 mark - any one of the following]

• Requires small sample size
• Quick/fast method
• Can separate multiple components simultaneously
• Sensitive technique Accept other reasonable advantages

11. [2 marks] Red blood cells need to carry maximum amount of haemoglobin [1 mark] Having no nucleus provides more space for haemoglobin [1 mark] Accept: More flexible to pass through narrow blood vessels

12. [2 marks] If iodine solution is added to plant cells, then the cells will turn blue-black [1 mark] because plant cells contain starch which reacts with iodine [1 mark] Accept other testable hypotheses about starch in plant cells

13. [2 marks] Light microscope [1 mark] Because it allows observation of living specimens without killing them / electron microscopes require dead specimens [1 mark]

14. [3 marks] Peel a thin layer of onion skin [1 mark] Place on microscope slide with a drop of water [1 mark] Cover with coverslip, avoiding air bubbles [1 mark] Accept: Add stain like iodine for better visibility

Section D: Structured Questions [15 marks]

15. [4 marks total] (a) Flagellum / Chloroplast [1 mark] Accept either structure

(b) Flagellum: Movement/locomotion [1 mark] Chloroplast: Photosynthesis [1 mark] Award mark based on structure identified in part (a)

(c) Photosynthesis using chloroplasts to make glucose from carbon dioxide and water [1 mark] Cellular respiration using mitochondria to break down glucose [1 mark]

16. [4 marks total] (a) [2 marks - any two of the following] (i) Wear protective gloves / Use in ventilated area [1 mark] (ii) Keep away from flames / Avoid skin contact [1 mark] Accept other appropriate safety precautions

(b) Different pigments have different solubility in the solvent [1 mark] More soluble pigments travel further up the paper [1 mark]

17. [4 marks total] (a) Working: Image length = Actual length × Magnification = 1000 μm × 200 = 200,000 μm = 200 mm [1 mark for working] Answer: 200 mm [1 mark]

(b) Muscle cells contain many mitochondria [1 mark] This provides energy (ATP) needed for muscle contraction [1 mark]

18. [4 marks total] (a) If temperature increases, then the rate of diffusion will increase [1 mark] because higher temperature gives particles more kinetic energy [1 mark]

(b) Independent variable: Temperature [1 mark] Dependent variable: Rate of diffusion / Time taken for colour to spread [1 mark]

19. [3 marks total] Structure differences: Root hair cells have long projections/root hairs, palisade cells are rectangular with many chloroplasts [1 mark] Function differences: Root hair cells absorb water and minerals from soil, palisade cells carry out photosynthesis [2 marks]

20. [3 marks total] (a) Muscle cells and nerve cells [1 mark] Muscle cells need many mitochondria for contraction energy, nerve cells need fewer for signal transmission [1 mark] Accept other suitable cell types with appropriate explanations

(b) Light microscope has limited resolution/magnification to clearly see individual mitochondria [1 mark] Accept: Mitochondria are too small to see clearly with light microscope

Marking Guidelines:

• Award marks for scientifically accurate answers even if wording differs slightly
• For calculations, award method marks even if final answer is incorrect
• Accept alternative correct answers not listed in this scheme
• Deduct marks for incorrect units where specified