▶️ Answer/Explanation
Detailed solution
(a) The completed table is as follows:
| Letter | Name of Structure | Function |
|---|---|---|
| C | scrotum | contains / protects / holds testes |
| F | prostate gland | produces seminal fluid |
| A | urethra | transports urine and sperm |
| E | sperm duct / vas deferens | transports sperm (to urethra) |
Explanation:
Based on the diagram in Fig. 6.1:
- A (Urethra): The tube running through the penis that carries both urine (from the bladder) and sperm (from the sperm ducts) out of the body.
- C (Scrotum): The sac of skin that holds the testes (D) outside the main body cavity to maintain a lower temperature for optimal sperm production.
- E (Sperm duct): The tube that carries sperm from the testis towards the urethra.
- F (Prostate gland): The gland located just below the bladder that secretes fluid which nourishes and protects sperm, forming part of the semen.
(b)
Testosterone
Explanation: Testosterone is the primary male sex hormone produced by the testes. During puberty, rising levels of testosterone cause secondary sexual characteristics, such as the enlargement of the larynx which results in the voice deepening.
(c)
Any three of the following adaptive features:
- Flagellum / Tail: Enables the sperm to swim (motility) to reach the egg for fertilization.
- Mitochondria: Located in the mid-piece, they release energy (via aerobic respiration) required for swimming.
- Acrosome: A vesicle at the tip of the head containing enzymes (e.g., hyaluronidase) that digest the jelly coat/outer layers of the egg cell to allow penetration.
- Haploid nucleus: Contains half the genetic material (23 chromosomes in humans) to fuse with the haploid egg nucleus, restoring the diploid condition in the zygote.
- Streamlined shape: Reduces resistance/friction to facilitate faster swimming.