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Secondary 4 Combined Science Biology Practice Paper 1

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TuitionGoWhere Practice Paper - Combined Science Biology Secondary 4

TuitionGoWhere Practice Paper (AI) — Version 1 of 5

Subject: Combined Science Biology
Level: Secondary 4
Paper: Practice Paper (Topic: Cells Biomolecules)
Duration: 1 hour
Total Marks: 40
Name: ___________________________
Class: ____________
Date: ____________

Instructions:

This practice paper contains 20 questions on the topic of Cells Biomolecules.
Section A: Questions 1–8 (1 mark each, total 8 marks)
Section B: Questions 9–15 (2–3 marks each, total 16 marks)
Section C: Questions 16–20 (3–4 marks each, total 16 marks)
Write your answers in the spaces provided.
Use pen and show working where required.

Section A (8 marks)

1. State the process by which oxygen from the surroundings reaches a muscle cell. [1]

2. Name the organelle that is the site of aerobic respiration in a cell. [1]

3. State one difference between the cell wall of a plant cell and the cell membrane of an animal cell. [1]

4. Name the biomolecule that is made up of amino acids. [1]

5. State the term for the movement of water molecules from a region of high water potential to a region of low water potential through a partially permeable membrane. [1]

6. Identify the cell shown below.

Diagram for Q6 (SEC4 Combined Sci Bio)

Generated diagram for Q6.

Cell: ____________________ [1]

7. Name the carbohydrate that plants store as a reserve food substance. [1]

8. State the process by which glucose enters a red blood cell down its concentration gradient through a carrier protein. [1]

Section B (16 marks)

9. Table 1 shows the number of mitochondria in three cell types.

Cell type	Number of mitochondria per cell
Skin epithelial cell	200
Skeletal muscle cell	2500
Red blood cell	0

Explain why skeletal muscle cells have more mitochondria than skin epithelial cells. [2]

10. A student investigates the movement of glucose across the cell membrane of intestinal epithelial cells. Explain the process involved and one factor that affects its rate. [3]

11. Describe how the structure of a plant cell wall helps the plant. [2]

12. The diagram below shows a cell placed in a concentrated sugar solution.

Diagram for Q12 (SEC4 Combined Sci Bio)

Generated diagram for Q12.

State what happens to the cell and explain why. [2]

13. Name two biomolecules that contain carbon, hydrogen and oxygen only, and state one function of each. [2]

14. Suggest why a liver cell has more ribosomes than a fat storage cell. [2]

15. The table below shows the result of testing a food sample with two reagents.

Test	Reagent	Colour after test
A	Benedict's solution	Brick red
B	Biuret solution	Purple

State the biomolecule present in the food sample based on each test. [2]

Test A: ____________________
Test B: ____________________

Section C (16 marks)

16. Describe in detail how a molecule of oxygen present in the air breathed into the lungs reaches a cell in the heart muscle. Name the structures involved. [4]

17. A cell is placed in a solution with a higher solute concentration than its cytoplasm.

(a) State the type of solution. [1]
(b) Explain what happens to an animal cell in this solution. [2]
(c) State one difference in the result for a plant cell. [1]

18. Explain the difference between diffusion and active transport. Include in your answer whether energy is needed and the direction of movement. [3]

19. Table 2 shows the mass of biomolecules in 100 g of three foods.

Food	Carbohydrate (g)	Protein (g)	Fat (g)
A	2	20	15
B	75	8	2
C	10	30	25

(a) Which food is best for a person needing to build muscle? Give a reason. [2]
(b) Calculate the total mass of biomolecules in Food C. [1]
(c) State one role of fat in the body. [1]

20. A student says: "Enzymes are proteins that speed up reactions and are not changed by the reaction." Explain whether this statement is correct using two points. [3]

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Answers

TuitionGoWhere Practice Paper — Combined Science Biology Secondary 4 (Answers)

Version: 1 of 5
Topic: Cells Biomolecules
Total Marks: 40

Section A Answers

1. Diffusion [1]
Teaching note: Oxygen moves from high concentration in alveoli to low concentration in muscle tissue fluid by diffusion, a passive process needing no energy.

2. Mitochondrion (or mitochondria) [1]
Teaching note: Aerobic respiration releases energy as ATP and occurs in the mitochondria, the "powerhouse" of the cell.

3. Cell wall is made of cellulose and is rigid; cell membrane is made of phospholipid and protein and is flexible. [1]
Accept any one clear difference.
Teaching note: Plant cells have a rigid cellulose wall outside the membrane for support; animal cells lack this.

4. Protein [1]
Teaching note: Proteins are polymers of amino acids linked by peptide bonds.

5. Osmosis [1]
Teaching note: Osmosis is passive movement of water across a partially permeable membrane down a water potential gradient.

6. Animal cell [1]
Teaching note: The diagram shows no cell wall and a nucleus, typical of an animal cell.

7. Starch [1]
Teaching note: Plants store excess glucose as starch in leaves, stems and roots.

8. Facilitated diffusion [1]
Teaching note: Glucose uses carrier proteins but moves down its gradient without energy, so it is facilitated diffusion.

Section B Answers

9. [2]

Skeletal muscle cells contract to move the body and need large amounts of ATP. [1]
Mitochondria produce ATP by respiration, so more mitochondria are present where energy demand is high. [1]
Marking: 1 mark for link to energy need, 1 mark for mitochondria–ATP link.

10. [3]

Glucose moves by facilitated diffusion through carrier proteins. [1]
It moves down its concentration gradient from intestine to blood. [1]
Factor: higher glucose concentration gradient increases rate; or more carriers increase rate. [1]
Teaching note: Facilitated diffusion is passive; carriers help large molecules cross.

11. [2]

Made of cellulose, rigid and strong. [1]
Supports plant, keeps shape, prevents bursting in water. [1]

12. [2]

Cell becomes plasmolysed (membrane pulls from wall). [1]
Water leaves vacuole by osmosis to the stronger sugar solution outside. [1]

13. [2]

Carbohydrate (e.g., glucose) — energy source. [1]
Fat (lipid) — energy store / insulation. [1]
Accept starch, glycogen for carbohydrate.

14. [2]

Liver cells make many proteins (e.g., enzymes). [1]
Ribosomes synthesise proteins, so more are needed than in fat storage cells. [1]

15. [2]

Test A: reducing sugar (glucose). [1]
Test B: protein. [1]
Benedict's brick red = reducing sugar; Biuret purple = protein.

Section C Answers

16. [4]

Oxygen enters alveoli in lungs. [1]
Diffuses across alveolar wall into capillary blood. [1]
Binds haemoglobin, transported via pulmonary vein → left atrium → left ventricle → aorta → coronary artery. [1]
Diffuses into heart muscle cell mitochondrion. [1]
Marking: 1 mark per clear stage with structure named.

17. [4]
(a) Hypertonic solution. [1]
(b) Animal cell loses water by osmosis, shrinks (crenates). [2]
(c) Plant cell becomes plasmolysed, not burst. [1]

18. [3]

Diffusion: passive, no energy, high to low concentration. [1.5]
Active transport: needs energy (ATP), low to high concentration. [1.5]

19. [4]
(a) Food A or C (high protein); reason: protein builds muscle. [2]
(b) 10 + 30 + 25 = 65 g. [1]
(c) Energy reserve / insulation / protect organs. [1]

20. [3]

Correct: enzymes are proteins and speed up reactions. [1.5]
Correct: enzymes are not used up / not changed permanently. [1.5]