10th Science - Book Back Answers - Biology Unit 13 - English Medium Guides

 

SSLC / 10th - Science - Book Back Answers - Biology Unit 13 - English Medium

Tamil Nadu Board 10th Standard  Science - Biology Unit 13: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 13 – Biology from the Tamil Nadu State Board 10th Standard  Science textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

    We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

    By going through this material, you’ll gain a strong understanding of Biology Unit 13 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

• 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following 
• 2 Mark Questions: Answer briefly 
• 3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 10 students! Prepare well and aim for top scores. Thank you!

Topic: Structural Organisation of Animals

I. Choose the correct Answer

1. In leech locomotion is performed by:

(a) Anterior sucker

(b) Posterior sucker

(c) Setae

(d) None of the above

Answer Key:

(a) Anterior sucker

 

2. The segments of leech are known as _____.

(a) Metameres (somites)

(b) Proglottids

(c) Strobila

(d) All the above.

Answer Key:

(a) Metameres (somites).

 

3. Pharyngeal ganglion in leech is a part of:

(a) Excretory system

(b) Nervous system

(c) Reproductive system

(d) Respiratory system

Answer Key:

(b) Nervous system

 

4. The brain of leech lies above, the _____.

(a) Mouth

(b) Buccal Cavity

(c) Pharynx

(d) Crop.

Answer Key:

(c) Pharynx

 

5. The body of leech has:
(a) 23 segments
(b) 33 segments
(c) 38 segments
(d) 30 segments
Answer Key:
(b) 33 segments

 

6. Mammals are animals.

(a) Cold blooded

(b) Warm blooded

(c) Poikilothermic

(d) All the above

Answer Key:

(b) Warm blooded

 

7. The animals which give birth to young ones are _____.

(a) Oviparous

(b) Viviparous

(c) Ovoviviparous

(d) All the above.

Answer Key:

(d) All the above

 

II. Fill in the blanks

1. The posterior sucker is formed by the fusion of the ………. segments.
2. The existence of two sets of teeth in the life of an animal is called ……….. dentition.
3. The anterior end of leech has a lobe-like structure called ………..
4. The blood sucking habit of leech is known as ………..
5. ………. separate nitrogenous waste from the blood in rabbit.
6. ……… spinal nerves are present in rabbit.
Answer Key:
1. last seven
2. diphyodont
3. anterior sucker
4. sanguivorous
5. Nephrons (kidney)
6. 37 pair

 

III. State whether the following statements are true or false. correct the statement if it is false.

1. An anticoagulant present in saliva of leech is called heparin.
2. The vas deferens serves to transport the ovum.
3. The rabbit has a third eyelid called tympanic membrane which is movable.
4. Diastema is a gap between premolar and molar teeth in rabbit.
5. The cerebral hemispheres of rabbit are connected by band of nerve tissue called corpora quadrigemina.
Answer Key:
1. True
2. False – Vas deferens serves to transport the sperm.
3. True
4. False – The gap between the incisors and premolars.
5. False – The cerebral hemispheres of rabbit are connected by band of nerve tissue called corpora corpus callosum.

IV.  Match the following  

Organs	Membranous Covering	Location
Brain	pleura	abdominal cavity
Kidney	capsule	mediastinum
Heart	meninges	enclosed in thoracic cavity
Lungs	pericardium	cranial cavity

Answer Key:

Organs	Membranous Covering	Location
Brain	meninges	cranial cavity
Kidney	capsule	abdominal cavity
Heart	pericardium	enclosed in thoracic cavity
Lungs	pleura	mediastinum

 

 

V.  Answer in a sentence

1. Give the common name of the Hirudinaria granulosa.
Answer Key:
The common name of Hirundinaria granulosa is Indian Cattle Leech.
 
2. How does leech respire?
Answer Key:
Leech respire through the skin.
 
3. Write the dental formula of rabbit.
Answer Key:
The dental formula of rabbit is $\frac{\mathbf{2033}}{\mathbf{1023}}$
 
4. How many pairs of testes are present in leech?
Answer Key:
There are 11 pairs of testes are present in Leech.
 
5. How is diastema formed in rabbit?
Answer Key:
Diastema is due to the absence of canine. It is a gap between incisors and premolars in the upper jaw and lower jaw.
 
6. What organs are attached to the two bronchi?
Answer Key:
The organs attached to the two bronchi are lungs.
 
7. Which organ acts as a suction pump in leech?
Answer Key:
The Pharynx acts as a suction pump in Leech.
 
8. What does CNS stand for?
Answer Key:
The full form of CNS is Central Nervous System.
 
9. Why is the teeth of rabbit called heterodont?
Answer Key:
The dentition of rabbit is called heterodont, as they have different types of teeth (Incisors, premolars and molars).
 
10. How does leech suck blood from the host?
Answer Key:
The Anterior sucker helps in feeding, while both the suckers, help in attachment and locomotion.

 

VI. Short answer questions

1. Why are the rings of cartilages found in trachea of rabbit?
Answer Key:
The wall of larynx which serves as the voice box is supported by 4 cartilaginous plates. When the air passes the vocal cord, it vibrates resulting in sound production.

2. List out the parasitic adaptations in the leech.
Answer Key:
Leeches lead a parasitic mode of life, by sucking the blood of vertebrates. The adaptations are
• Blood is sucked by the pharynx.
• Anterior and Posterior Suckers are provided, by which the animal attaches itself to the body of the host.
• The three Jaws, inside the mouth, causes a painless Y – shaped wound in the skin of the host,
• The salivary glands produce Hirudin, which does not allow the blood to coagulate. So, the continuous supply of blood is maintained.
• Parapodia and Setae are absent.
• Blood is stored in the crop. It gives nourishment to the leech for several months. So there is no elaborate secretion of the digestive juices and enzymes.

 

VII. Long answer questions

1. How is the circulatory system designed in leech to compensate the heart structure?
Answer Key:
The circulation in Leech is Haemocoelic system. There are no true blood vessels. The blood vessels are replaced by channels called Haemocoelic channels or canals, filled with blood like a fluid. The coelomic fluid contains Haemoglobin.
There are four longitudinal channels. One channel lies above (dorsal) to the Alimentary canal, one below (ventral) to the Alimentary canal. The other two channels lie on either (lateral) side of the Alimentary canal, which serves as a heart and have inner valves. All the four channels are connected together posteriorly in the 26th segment. Thus the circulatory system is designed in Leech to compensate the heart structure.
 
2. How does locomotion take place in leech?
Answer Key:
1. Looping or Crawling movement : Looping movement is brought about by the contraction and relaxation of muscles. The two suckers serve for attachment during movement. The animal fixes its posterior sucker on the substratum.
2. Swimming movement : The animal swims in the water by undulating movements of the body.
 
3. Explain the male reproductive system of rabbit with a labelled diagram.
Answer Key:
The male rabbit has a pair of testes. They are oval in shape. They are kept in two sacs called scrotal sacs hanging down from the abdomen. Each testes is formed of numerous fine tubules called seminiferous tubules. A coiled tubule called epididymis is formed at the end of seminiferous tubules. Epididymis lead into the sperm duct called vas deferens. The vas deferens run forward and enters abdominal cavity through urinary bladder. The urethra runs back and passes into the penis. There are three accessory glands associated with the male reproductive system. They are prostate glands, cowper’s gland and perineal glands. Their secretion nourishes and activates the reproduction.

VIII. HOT questions

1. Arjun is studying in the tenth standard. He was down with fever and went to meet the doctor. As he went to the clinic he saw a patient undergoing treatment for severe leech bite. Being curious, Arjun asked the doctor why leech bite was not felt as soon as it attaches to the skin? What would have been the reply given by the doctor?
AnswerKey:
The doctors would have replied that the leeches inject an anaesthetic substance, that prevents the host from feeling their bite.

2. Shylesh has some pet animals at his home. He has few rabbits too, one day while feeding them he observed something different with the teeth. He asked his grandfather, why is it so? What would have been the explanation of his grandfather?
Answer Key:
The rabbit has three types of teeth – Incisors are front teeth used for cutting, premolar and molar are used for grinding. Canine is absent as rabbit are herbivores. The gap between the incisor and premolar is called diastema. It helps in mastication and chewing of food in herbivores animal.

 

IX.  Value based questions

1. Leeches do not have an elaborate secretion of digestive juices and enzymes. Why?
Answer Key:
The digestion in leeches in very slow. So, the blood stored in the crop gives nourishment to the leech for several months. So there is not elaborate secretion of digestive juices and enzymes.

2. How is the digestive system of rabbit suited for herbivorous mode of feeding?
Answer Key:
Rabbit are herbivores which feed on plants. The plant contain cellulose which need cellulose to digest. The laccum of Rabbit contain large number of symbiotic bacteria that helps in digestion of cellulose.