2024 Past paper

i. Cytoplasm: Jelly-like fluid that holds organelles and is the site of many cellular activities. (0.5)
ii. Mitochondria: Produces energy (ATP) through cellular respiration. (0.5)
iii. Rough Endoplasmic Reticulum: Synthesizes and transports proteins (due to ribosomes attached). (0.5)
iv. Nucleus: Contains DNA; controls the cell’s activities. (0.5)

2. Differentiate between osmosis and diffusion: (2)

  • Osmosis is the movement of water molecules across a semi-permeable membrane from a region of low solute concentration to high solute concentration.

  • Diffusion is the movement of molecules (solutes or gases) from an area of high concentration to low concentration without needing a membrane.

3. Categories of tissue:
i. Covering and lining organs: Epithelial tissue (1)
ii. Supporting and binding tissues: Connective tissue (1)

4. Four constituents of blood and one function of each: (2)

  • Red blood cells (erythrocytes): Carry oxygen.

  • White blood cells (leukocytes): Fight infection.

  • Platelets (thrombocytes): Help blood clotting.

  • Plasma: Transports nutrients, hormones, and waste.

5. Where are:
i. Lymphocytes matured: Thymus gland (1)
ii. Erythrocytes formed: Red bone marrow (1)

6. Two components of gastric juice and their function: (2)

  • Hydrochloric acid (HCl): Kills bacteria and activates pepsin.

  • Pepsin: Breaks down proteins into peptides.

7. Function and production of bile: (2)

  • Function of bile: Emulsifies fats (breaks them into small droplets).

  • Produced in: The liver.

8. Enzyme and digestion products:
i. Carbohydrate digestion enzyme: Amylase → End-product: Maltose (later glucose). (1)
ii. Protein digestion enzyme: Pepsin → End-product: Peptides (later amino acids). (1)

9. Type of marrow:
i. Spongy bone: Red bone marrow (1)
ii. Compact bone: Yellow bone marrow (1)

10. Difference between endocrine and exocrine glands: (2)

  • Endocrine glands: Release hormones directly into the bloodstream (no ducts).

  • Exocrine glands: Release their products (e.g., enzymes, sweat) into ducts.

11. Hormones:
i. Thyroid gland: Produces thyroxine, which regulates metabolism. (1)
ii. Pancreas: Produces insulin, which lowers blood sugar levels. (1)

12. Definitions:
i. Antigen: A foreign substance that triggers an immune response. (1)
ii. Antibody: A protein produced by the immune system to neutralize antigens. (1)

13. Definitions:
i. Ovulation: Release of an egg (ovum) from the ovary. (1)
ii. Implantation: Attachment of the fertilized egg to the lining of the uterus. (1)

14. Homeostasis definition: (2)

  • Homeostasis is the maintenance of a stable internal environment in the body, despite external changes (e.g., regulating body temperature, pH, glucose levels).

SECTION B

Question 1

1. Locations and Functions:
i. Lymph node: Found along lymphatic vessels (e.g., neck, armpits); filters lymph and traps pathogens. (1)
ii. Lacteal: Found inside villi of the small intestine; absorbs fats and transports them into the lymphatic system. (1)

2. How the skin regulates heat: (2)

  • When too hot: Blood vessels dilate (vasodilation) to increase heat loss; sweat glands release sweat to cool the body through evaporation.

  • When too cold: Blood vessels constrict (vasoconstriction) to retain heat; hairs stand up (piloerection) to trap air for insulation.

3. Diagram of skin (important labels):

  • Sebaceous gland

  • Adipose tissue (in the hypodermis)

  • Arrector pili muscle

  • Hair follicle
    (If you want, I can draw a labeled diagram for you — just ask!)

Question 2

1. Definitions:
i. Nephron: The functional unit of the kidney that filters blood to form urine. (1)
ii. Osmoregulation: The control of water and salt balance in the body. (1)

2. Two hormones produced by ovaries and functions: (2)

  • Oestrogen: Promotes development of female secondary sexual characteristics and thickens the uterus lining.

  • Progesterone: Maintains the uterus lining for implantation.

3. Functions in male reproductive system:
i. Epididymis: Stores and matures sperm. (1)
ii. Prostate: Produces fluid that nourishes and protects sperm. (1)
iii. Urethra: Transports semen and urine out of the body. (1)
iv. Testes: Produce sperm and testosterone. (1)

Question 3

1. Lipid digestion: (2)

  • Enzyme: Lipase

  • Secreted by: Pancreas

  • End-product: Fatty acids and glycerol

2. Terms and locations:
i. Absorption: The movement of nutrients from the digestive tract into the bloodstream; mainly in the small intestine. (2)
ii. Assimilation: The incorporation of absorbed nutrients into body cells for use; occurs throughout body tissues. (2)

3. Diagram of four layers of the alimentary canal:

  • Mucosa (innermost)

  • Submucosa

  • Muscularis externa

  • Serosa (outermost)
    (I can also draw this diagram for you if you like.)

4. Functions of the skeleton: (2)

  • Support the body

  • Protect vital organs

  • Allow movement (attachment for muscles)

  • Produce blood cells (in marrow)

5. Explanations:
v. Periosteum: A membrane covering bones that nourishes and protects them. (1)
vi. Ligament: Connects bone to bone. (1)
vii. Tendon: Connects muscle to bone. (1)
viii. Synovial joint: A freely movable joint lubricated by synovial fluid. (1)

6. Name the four bones labeled A-D:
(Without the diagram, I can't name exactly, but usually it would be something like:

  • A: Femur (thigh bone)

  • B: Humerus (upper arm bone)

  • C: Tibia (shin bone)

  • D: Radius (forearm bone))