This set of Zoology Objective Questions and Answers focuses on “Animals Structural Organisations – Earthworm – 3”.
1. Which of the following does the nervous system of the earthworm not contain?
a) Nerve ring
b) Nerve cord
Explanation: The nervous system of the earthworm contains ganglia arranged on the nerve cord. It is present on the ventral side of the body. The nerve ring is present on the dorsal side. It is made of the nerve cord and cerebral ganglia.
2. At which of these segments does the nerve cord of the earthworm divide into two parts?
a) 5th, 6th
b) 8th, 9th
c) 3rd, 4th
d) 11th, 12th
Explanation: The nerve cord of the earthworm bifurcates or divides into two parts at the 3rd and 4th segments. It then encircles the pharynx and forms the nerve ring by combining with the cerebral ganglia.
3. Which of these statements is true about nerve ring?
a) It has only sensory function
b) It has only motor function
c) It is present on the dorsal side
d) It is present on the ventral side
Explanation: The nerve ring is present on the dorsal side of the body of the earthworm. It is made of the nerve cord which combines with the cerebral ganglia. The nerve ring has both sensory and motor functions.
4. Which of these is not a function of the sensory system of earthworms?
a) Visualize food
b) Distinguish light intensities
c) Detect vibrations
d) React to chemical stimuli
Explanation: The sensory system of earthworm lacks eyes. Hence, the earthworm cannot visualize its food. However, it contains receptor cells which helps it to detect vibrations, changes in light intensities and allows it to react to chemical stimuli.
5. Which of these statements regarding the sensory system of earthworm is false?
a) Eyes are absent
b) The sense organs are located posteriorly
c) Taste receptors are present
d) Receptor cells help to detect vibrations
Explanation: The sense organs of the earthworm are located on the anterior side of the body. Eyes are absent. It contains taste receptors or chemoreceptors. The receptor cells allow the earthworm to detect vibrations and changes in light intensity.
6. How many testes does Pheretima possess?
Explanation: Pheretima or earthworm possesses 4 testes, that is, two pairs. They are present in the 10th and 11th segment. The earthworm is hermaphrodite. Hence, it also possesses female reproductive structures.
7. The common prostate and spermatic duct of earthworms is known as ________
a) vasa deferentia
b) vasa efferentia
Explanation: Vasa deferentia is the common prostate and sperm duct of earthworms. Vasa efferentia is absent. Spermathecae store spermatozoa during copulation. Oviduct is a part of the female reproductive system.
8. What is the role of spermathecae?
a) Sperm is produced here at the time of mating
b) It is an accessory organ
c) It is vestigial
d) It stores spermatozoa during mating
Explanation: The spermathecae stores spermatozoa during mating. Four pairs of spermathecae are present in earthworms. They occur in segments 6 to 9. It is not an accessory organ. It is not a vestigial organ.
9. How many ovaries are present in an earthworm?
Explanation: The earthworm possesses one pair, that is, two ovaries. They are attached at the septum between the 12th and 13th segments. Egg cells or ova are formed which subsequently get fertilized to zygotes during fertilization.
10. Larvae are formed during the development of earthworms. True or false?
Explanation: Larvae are not formed during the development of earthworms. Hence, the development of earthworms is direct as young worms are formed directly without an intermediate larval stage.
11. In earthworms, ovarian funnels open into the ______
b) female genital pore
Explanation: In the body of earthworms, the ovarian funnels are present below the ovaries. The ovarian funnels open up into the oviduct and join together. They lead to an opening on the ventral side known as the female genital pore.
12. What is exchanged during mating in earthworms?
Explanation: Spermatophores are exchanged between two earthworms during mating. Spermatophores are packs of sperm. They exchanged between the gonadal openings of the mating earthworms.
13. Where does fertilization occur for the earthworm?
d) Female genital pore
Explanation: Fertilization occurs in the cocoon. The cocoons are produced by the gland cells of the clitellum. The cocoons contain egg cells, mature sperm and nutritive fluid to ensure proper fertilization and subsequent development of the embryo.
14. Using earthworms to increase soil fertility is called ______
Explanation: Using earthworms to increase soil fertility is called vermicomposting. Sericulture is associated with silkworms; apiculture is associated with bees and pisciculture is associated with fish. They have industrial importance.
15. Which of these statements is true about earthworm?
a) They are harmful for agriculture
b) They are used as fishing bait
c) They decrease soil fertility
d) They cannot live in burrows
Explanation: Earthworms are very beneficial for agriculture and increase soil fertility. They aerate the soil by creating burrows in which they live. They are known as ‘friends of farmers’. Earthworms are also used as fishing bait.
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