Question

Which one of the following correctly describes the location of some body parts on the earthworm pheretima?

• A. two pairs of accessory glands in 16-18 segments
• B. two pairs of testes in the 10th and 11th segments
• C. one pair of ovaries attached at the intersegmental septum of the 14th and 15th segments
• D. four pairs of spermathecae in 4-7 segments

Answer 1

The correct option is B

two pairs of testes in the 10th and 11th segments

The correct option is B.

Explanation of the correct option:

1. Earthworms are hermaphrodites, meaning they have both testes and ovaries in the same body.
2. There are two pairs of testes.
3. One pair is housed in the tenth segment, while the other pair is housed in the eleventh segment.
4. The testes are lobed, white structures.
5. A testes sac surrounds each testis.
6. The lobules of each testis contain spermatogonia cells.
7. For copulation, the testis generates sperm.

Explanation of the incorrect option:

Option A:

1. When investigating the anatomy of a male earthworm, it can be noticed that the 18th segment of the earthworm's body has a pair of male genital pores.
2. Each pore can be found on both sides.
3. These are beneficial throughout the copulation procedure.

Option C:

Between segments 14 and 16, the clitellum is a prominent black strip of glandular tissue.

Option D:

Four pairs of spermathecae are placed ventral laterally in each of the sixths, seventh, eighth, and ninth segments.

Final Answer: Two pairs of testes in the 10th and 11th segments correctly describe the location of some body parts on the earthworm pheretima.