Biology Questions and Answers – Animals – Organs and Organ System – 1

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This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Animals – Organs and Organ System – 1”.

1. Which of the following is a common Indian earthworm?
a) Pheretima
b) Periplaneta
c) Blatta
d) Hirudina
View Answer

Answer: a
Explanation: The common Indian earthworms are Pheretima and Lumbricus. The earthworm is a reddish-brown terrestrial invertebrate that inhabits the upper layer of the moist soil.
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2. How can we trace earthworms?
a) Colour
b) Smell
c) Predator
d) Worm castings
View Answer

Answer: d
Explanation: During day time, earthworms live in burrows made by burrowing and swallowing the soil. In the gardens, they can be traced by their faecal deposits known as worm castings.

3. How can we distinguish the ventral surface of the earthworm by their dorsal surface?
a) Presence of setae
b) Presence of hair
c) Presence of genital pores
d) Presence of oil glands
View Answer

Answer: c
Explanation: The ventral surface of the body of the earthworm can be distinguished by the dorsal surface by the presence of genital openings or pores. The genital openings in the earthworm help in cross-fertilisation and pores help in removal of the wastes generated in the body.
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4. In how many regions, is the body of earthworm divisible?
a) One
b) Two
c) Three
d) Four
View Answer

Answer: c
Explanation: The body of the earthworm is divisible into three prominent regions-
i. Preclitellar segment
ii. Clitellar segment
iii. Postclitellar segment.

5. Segments 18-19 are called as clitellar segments.
a) True
b) False
View Answer

Answer: b
Explanation: The first body segment is called as the peristomium which contains the mouth. In a mature worm, segments 14-16 are covered by a prominent dark band of glandular tissue called the clitellum.
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6. How many spermathecal apertures are present in an earthworm?
a) Two
b) Four
c) Six
d) Eight
View Answer

Answer: d
Explanation: Four pairs or eight spermathecal apertures are situated on the ventrolateral sides of the intersegmental grooves, i.e., 5-9 segments. A single female genital pore is present in the mid-ventral line of 14th segment.

7. In which of the following segments, setae are present?
a) First segment
b) Second segment
c) Clitellar segments
d) Last segment
View Answer

Answer: b
Explanation: In each body segment, except the first, last and clitellum, there are rows of S-shaped setae, embedded in the epidermal pits in the middle of each segment. Setae can be extended or retracted. Their principal role is in locomotion.
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8. The body wall of an earthworm is made up of how many muscle layers?
a) One
b) Three
c) Two
d) Five
View Answer

Answer: c
Explanation: The body wall of the earthworm is covered externally by a thin non – cellular cuticle below which is the epidermis, two muscle layers – circular and longitudinal and an innermost coelomic epithelium.

9. What is the characteristic feature of the intestine of an earthworm?
a) Setae
b) Clitellum
c) Glans
d) Typhlosole
View Answer

Answer: d
Explanation: The characteristic feature of the intestine of an earthworm is the presence of internal median fold of dorsal wall called typhlosole. Typhlosole helps in increasing the effective area of absorption for food and minerals. These structures are present after the 26th segment except for the last 23rd-25th segments.
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10. Earthworm consists of an open type of circulatory system.
a) True
b) False
View Answer

Answer: b
Explanation: The earthworm exhibits a closed type of blood vascular system, consisting of blood vessels, capillaries and heart. Due to the closed circulatory system, blood is confined to the heart and the blood vessels.

11. In which of the following segments are the blood glands of an earthworm present?
a) 2, 3 and 4
b) 3, 4 and 5
c) 4, 5 and 6
d) 5, 6 and 7
View Answer

Answer: c
Explanation: In earthworm, blood glands are present on the 4th, 5th and 6th segments. They produce blood cells and haemoglobin which is directly dissolved in blood plasma as their blood does not have any respiratory pigment.

12. How many types of nephridia are present in the earthworm?
a) One
b) Two
c) Three
d) Four
View Answer

Answer: c
Explanation: The excretory organs of earthworm occurs as segmentally arranged coiled tubules called nephridia. They are of three types –
i. Septal nephridia
ii. Integumentary nephridia
iii. Pharyngeal nephridia.

13. Which of the following structures represent the nervous system of an earthworm?
a) Ganglia
b) Notochord
c) Vertebral column
d) Brain
View Answer

Answer: a
Explanation: Nervous system of the earthworm is represented by ganglia arranged segment-wise on the ventral paired nerve cord. The nerve cord on the anterior region bifurcates, laterally encircling the pharynx and joins the cerebral ganglia dorsally to form a nerve ring.

14. What type of fertilization is exhibited by an earthworm?
a) Internal and cross-fertilization
b) External and cross-fertilization
c) Internal and self-fertilization
d) External and self-fertilization
View Answer

Answer: b
Explanation: The type of fertilization exhibited by earthworm is External and cross-fertilization. Fertilisation and development occur within the cocoons which are deposited in the soil. Development of earthworms is direct, i.e., there is no larva formation.

15. What are earthworms commonly called as?
a) Friends of farmers
b) Souls of farmers
c) Enemies of farmers
d) Gods for the farmers
View Answer

Answer: a
Explanation: Earthworms are commonly called as friends of farmers because they make burrows in the soil and make it porous which helps in respiration and penetration of the developing plant roots. The process of increasing fertility of the soil by the earthworms is called vermicomposting.

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