15 extra multiple-choice questions for Structural Organisation of Animals (10th Standard Science, Samacheer Kalvi), beyond the ones printed in the textbook — each with the correct option highlighted and a clear, worked explanation. Free to read in English and Tamil.
Q1
To which order does the Indian cattle leech (Hirudinaria granulosa) belong?
- A. GnathobdellidaCorrect
- B. Lagomorpha
- C. Rhynchobdellida
- D. Oligochaeta
Explanation. The Indian cattle leech belongs to the phylum Annelida, class Hirudinea, and order Gnathobdellida.
Q2
Which segments of the body of a leech constitute the clitellar region?
- A. 1st to 5th segments
- B. 6th to 8th segments
- C. 9th to 11th segmentsCorrect
- D. 12th to 22nd segments
Explanation. In leeches, segments 9, 10, and 11 form the clitellar region, which is responsible for cocoon formation during reproduction.
Q3
Where is the female genital pore situated in the body of a leech?
- A. Mid-ventrally between the 2nd and 3rd annuli of the 10th segment
- B. Mid-ventrally between the 2nd and 3rd annuli of the 11th segmentCorrect
- C. Dorsally on the 26th segment above the posterior sucker
- D. Ventrally on the 5th segment near the buccal cavity
Explanation. The female genital pore lies mid-ventrally between the second and third annuli of the 11th segment, whereas the male genital pore lies on the 10th segment.
Q4
Which tissue lies beneath the longitudinal muscles and fills the coelomic space around the gut in leeches?
- A. Parenchyma tissue
- B. Botryoidal tissueCorrect
- C. Epithelial tissue
- D. Collenchyma tissue
Explanation. Botryoidal tissue lies beneath the longitudinal muscular layer of a leech and fills the entire body cavity around the alimentary canal.
Q5
What is the primary function of the substance hirudin secreted by the salivary glands of a leech?
- A. Digestion of complex carbohydrates in the crop
- B. Prevention of blood coagulation during feedingCorrect
- C. Neutralization of stomach acids in the host
- D. Destruction of bacterial cells inside the host blood
Explanation. Hirudin is an anticoagulant secreted in leech saliva that prevents host blood from clotting while the leech feeds.
Q6
How many main longitudinal haemocoelic channels are present in the circulatory system of a leech?
- A. Two
- B. Three
- C. FourCorrect
- D. Six
Explanation. The blood vascular system in a leech is replaced by four longitudinal haemocoelic channels: one dorsal, one ventral, and two lateral channels.
Q7
How many pairs of nephridia are present in a leech for excretion, and in which segments are they located?
- A. 11 pairs, located in segments 12 to 22
- B. 17 pairs, located in segments 6 to 22Correct
- C. 23 pairs, located in segments 1 to 23
- D. 33 pairs, located in all body segments
Explanation. Leeches possess 17 pairs of nephridia that open to the exterior through nephridiopores from the 6th to the 22nd segments.
Q8
In leeches, how many pairs of testes sacs are present and in which body segments are they located?
- A. 1 pair in the 11th segment
- B. 5 pairs in segments 6 to 10
- C. 11 pairs in segments 12 to 22Correct
- D. 17 pairs in segments 6 to 22
Explanation. In leeches, there are 11 pairs of testes sacs situated from the 12th to the 22nd segments.
Q9
What are the tactile hairs present on either side of the upper lip of a rabbit called?
- A. Pinnae
- B. VibrissaeCorrect
- C. Cilia
- D. Flagella
Explanation. Vibrissae, commonly known as whiskers, are sensitive tactile hairs projecting outward from both sides of the upper lip in rabbits.
Q10
Which anatomical structure separates the thoracic cavity from the abdominal cavity in rabbits?
- A. Pericardium
- B. Pleura
- C. DiaphragmCorrect
- D. Corpus callosum
Explanation. A muscular transverse partition called the diaphragm separates the thoracic cavity from the abdominal cavity, which is a characteristic feature of mammals.
Q11
Which of the following represents the correct dental formula for an adult rabbit?
- A. \(\frac{2033}{1023}\)Correct
- B. \(\frac{1023}{2033}\)
- C. \(\frac{2123}{2123}\)
- D. \(\frac{3142}{3143}\)
Explanation. The dental formula of a rabbit is \(I\frac{2}{1}, C\frac{0}{0}, PM\frac{3}{2}, M\frac{3}{3}\), which is written as \(\frac{2033}{1023}\). Canines are completely absent.
Q12
In rabbits, which specialized digestive structure contains bacteria that help in the digestion of cellulose?
- A. Crop
- B. Stomach
- C. CaecumCorrect
- D. Rectum
Explanation. The caecum is a thin-walled sac at the junction of the small and large intestine containing symbiotic bacteria that assist in digesting cellulose.
Q13
In the brain of a rabbit, what connects the right and left cerebral hemispheres?
- A. Corpus callosumCorrect
- B. Corpora quadrigemina
- C. Pons varolii
- D. Infundibulum
Explanation. The right and left cerebral hemispheres of a mammalian brain are connected by a transverse band of nerve tissue called the corpus callosum.
Q14
How many pairs of cranial nerves are present in the peripheral nervous system of a rabbit?
- A. 10 pairs
- B. 12 pairsCorrect
- C. 31 pairs
- D. 37 pairs
Explanation. In rabbits, the peripheral nervous system consists of 12 pairs of cranial nerves arising from the brain and 37 pairs of spinal nerves from the spinal cord.
Q15
Which pair of accessory glands is present in the female reproductive system of a rabbit?
- A. Prostate gland and seminal vesicle
- B. Cowper's gland and perineal glandCorrect
- C. Bartholin's gland and thyroid gland
- D. Adrenal gland and pituitary gland
Explanation. Cowper's glands and perineal glands are the accessory glands associated with the female reproductive system of a rabbit.
Frequently asked questions
How many MCQs are there in Structural Organisation of Animals?
This chapter has 15 book-back multiple-choice questions, each with the correct answer and a step-by-step explanation.
Are these 10th Standard Science MCQs free to practise online?
Yes. Every question, answer and explanation here is free, and you can also take them as a timed practice test.
Where can I find the Structural Organisation of Animals book-back answers?
The correct option for each question is highlighted on this page with a worked explanation, plus a quick answer-key summary at the top.
