Samacheer Kalvi Class 10 Science Solutions Chapter 13 Structural Organisation of Animals

I. Choose The Best Answer:

 

Question 1. Locomotion is performed by:
(a) Anterior sucker
(b) Posterior sucker
(c) Setae
(d) None of the options
Answer: (a) Anterior sucker
In simple words: The anterior sucker helps in movement. It allows the animal to grip surfaces and move around.

🎯 Exam Tip: Remember that both anterior and posterior suckers are crucial for different aspects of leech movement and attachment.

 

Question 2. The segments of leech are known as _____
(a) Metameres (somites)
(b) Proglottids
(c) Strobila
(d) All of the options
Answer: (a) Metameres (somites)
In simple words: Leech bodies are divided into many small parts called metameres, also known as somites. These segments help with their flexible movement.

🎯 Exam Tip: Knowing the specific terms for body segments in different animals (like metameres for annelids) is important for biological classification.

 

Question 3. Pharyngeal ganglion in leech is a part of:
(a) Excretory system
(b) Nervous system
(c) Reproductive system
(d) Respiratory system
Answer: (b) Nervous system
In simple words: The pharyngeal ganglion is a cluster of nerve cells located near the throat area of the leech. This part is very important for controlling how the leech reacts and senses things.

🎯 Exam Tip: Ganglia are key components of nervous systems in many invertebrates, acting as small processing centers.

 

Question 4. The brain of leech lies above, the _____
(b) Buccal Cavity
(c) Pharynx
(d) Crop.
Answer: (c) Pharynx
In simple words: The leech's brain, which is a collection of nerve cells, is located directly above its pharynx. This position allows it to control the feeding process.

🎯 Exam Tip: The location of organs like the brain is often related to their function, such as controlling feeding in leeches.

 

Question 5. The body of leech has:
(a) 23 segments
(b) 33 segments
(c) 38 segments
(d) 30 segments
Answer: (b) 33 segments
In simple words: A leech's body is made up of exactly 33 individual segments. Each segment has its own small set of organs.

🎯 Exam Tip: Specific numbers like body segments are often key facts that examiners look for in questions about animal anatomy.

 

Question 6. Mammals are _____ animals.
(a) Cold blooded
(b) Warm blooded
(c) Poikilothermic
(d) All of the options
Answer: (b) Warm blooded
In simple words: Mammals are warm-blooded animals, meaning their bodies can keep a steady internal temperature regardless of the outside environment. This is also called homeothermy.

🎯 Exam Tip: Distinguishing between warm-blooded (homeothermic) and cold-blooded (poikilothermic) is a fundamental concept in zoology.

 

Question 7. The animals which give birth to young ones are _____
(a) Oviparous
(b) Viviparous
(c) Ovoviviparous
(d) All of the options
Answer: (b) Viviparous
In simple words: Animals that give birth to live young that developed inside the mother's body are called viviparous. Humans are an example of viviparous animals.

🎯 Exam Tip: Learn the definitions of oviparous (egg-laying), viviparous (live birth), and ovoviviparous (eggs hatch inside mother, then live birth) to avoid confusion.

II. Fill In The Blanks:

 

Question 1. The posterior sucker is formed by the fusion of the ............ segments.
Answer: The posterior sucker is formed by the fusion of the **last seven** segments. This strong sucker helps the leech attach firmly to surfaces, especially during feeding or movement.

🎯 Exam Tip: Specific anatomical details like the number of segments forming a structure are crucial for accuracy.

 

Question 2. The existence of two sets of teeth in the life of an animal is called ............ dentition.
Answer: The existence of two sets of teeth in the life of an animal is called **diphyodont** dentition. Humans also have diphyodont dentition, with milk teeth followed by permanent teeth.

🎯 Exam Tip: Understand that "diphyodont" means having two sets of teeth over a lifetime, which is common in mammals.

 

Question 3. The anterior end of leech has a lobe-like structure called ............
Answer: The anterior end of leech has a lobe-like structure called **anterior sucker**. This sucker is important for both feeding and helping the leech move around by attaching itself to objects.

🎯 Exam Tip: Differentiate between the anterior and posterior suckers and their primary functions in the leech.

 

Question 4. The blood sucking habit of leech is known as ............
Answer: The blood sucking habit of leech is known as **sanguivorous**. Leeches are well-known sanguivores, feeding on the blood of vertebrates and sometimes other invertebrates.

🎯 Exam Tip: Learn common biological terms for feeding habits, such as sanguivorous (blood-feeding), herbivorous (plant-feeding), and carnivorous (meat-feeding).

 

Question 5. ............ separate nitrogenous waste from the blood in rabbit.
Answer: **Nephrons (kidney)** separate nitrogenous waste from the blood in rabbit. The kidneys are vital organs that filter the blood to remove waste products and maintain body fluid balance.

🎯 Exam Tip: Recognize nephrons as the functional units of the kidney responsible for filtering blood and forming urine.

 

Question 6. ............ spinal nerves are present in rabbit.
Answer: **37 pair** spinal nerves are present in rabbit. These nerves branch out from the spinal cord to carry signals throughout the rabbit's body, controlling movement and sensation.

🎯 Exam Tip: The number of spinal nerve pairs can vary between species; knowing the specific count for rabbits is a good detail.

III. Identify Whether The Statements Are True Or False. Correct The False Statement:

 

Question 1. An anticoagulant present in saliva of leech is called heparin.
Answer: **False** – An anticoagulant present in saliva of leech is called **hirudin**. Heparin is a naturally occurring anticoagulant found in mammals, not leeches. Hirudin prevents the host's blood from clotting, allowing the leech to feed continuously.

🎯 Exam Tip: Always correct false statements by providing the accurate information clearly, as done above.

 

Question 2. The vas deferens serves to transport the ovum.
Answer: **False** – Vas deferens serves to transport the **sperm**. The ovum (egg cell) is transported by the oviduct or fallopian tube in females. The vas deferens is a male reproductive duct.

🎯 Exam Tip: Be precise with the functions of male and female reproductive organs to avoid common errors.

 

Question 3. The rabbit has a third eyelid called tympanic membrane which is movable.
Answer: **False** – The rabbit has a third eyelid called **nictitating membrane**, which is movable. The tympanic membrane is the eardrum, involved in hearing, not vision.

🎯 Exam Tip: The nictitating membrane is a transparent or translucent third eyelid found in some animals, providing protection and moisture to the eye.

 

Question 4. Diastema is a gap between premolar and molar teeth in rabbit.
Answer: **False** – Diastema is a gap between the **incisors and premolars**. This gap is characteristic of herbivorous animals like rabbits and allows them to manipulate plant material efficiently.

🎯 Exam Tip: Diastema is an important adaptation in herbivores, facilitating the separation of different types of food processing.

 

Question 5. The cerebral hemispheres of rabbit are connected by band of nerve tissue called corpora quadrigemina.
Answer: **False** – The cerebral hemispheres of rabbit are connected by band of nerve tissue called **corpus callosum**. The corpora quadrigemina is involved in visual and auditory reflexes.

🎯 Exam Tip: The corpus callosum is a major neural pathway connecting the left and right cerebral hemispheres in placental mammals, allowing them to communicate.

IV. Match Columns I, II And III Correctly:

 

Answer:
A. (v)
B. (i)
C. (ii)
D. (iii)
E. (iv)
In simple words: This match explains animal behaviors and body parts. Gregarious means animals that live in groups. Sanguivorous means they feed on blood. Clitellum is a part of some annelids that makes cocoons for eggs. Vibrissae are whiskers, which are sensory hairs. Heterodont means having different types of teeth.

🎯 Exam Tip: For matching questions, clearly understand the meaning of each term in both columns before making a selection.

V. Answer In A Sentence:

 

Question 1. Give the common name of the Hirudinaria granulosa.
Answer: The common name of Hirudinaria granulosa is Indian Cattle Leech. This species is commonly found in freshwater bodies in India and other parts of Asia.

🎯 Exam Tip: Always capitalize the scientific name and ensure correct spelling, but common names do not always follow specific capitalization rules.

 

Question 2. How does leech respire?
Answer: Leech respires through the skin. This means that oxygen from the water passes directly into its body through its moist skin. This type of breathing is called cutaneous respiration.

🎯 Exam Tip: Cutaneous respiration is common in animals living in moist environments or water, as it requires a wet surface for gas exchange.

 

Question 3. Write the dental formula of rabbit.
Answer: The dental formula of rabbit is \( \frac{2033}{1023} \). This formula indicates the number of incisors, canines, premolars, and molars in one half of the upper and lower jaws.

🎯 Exam Tip: Understand that the numbers in a dental formula represent (Incisors, Canines, Premolars, Molars) for each half of the jaw, upper over lower.

 

Question 4. How many pairs of testes are present in leech?
Answer: There are 11 pairs of testes present in Leech. These testes are arranged segmentally along the body of the leech. The testes are part of the male reproductive system, producing sperm.

🎯 Exam Tip: For reproductive anatomy, specific counts and arrangements of organs are frequently tested facts.

 

Question 5. How is diastema formed in rabbit?
Answer: Diastema is due to the absence of canine teeth. It is a gap between the incisors and premolars in the upper and lower jaw. This gap is useful for storing food while chewing.

🎯 Exam Tip: Relate the presence of a diastema to the herbivorous diet of animals like rabbits, as it aids in food manipulation.

 

Question 6. What organs are attached to the two bronchi?
Answer: The organs attached to the two bronchi are lungs. The bronchi are tubes that carry air from the trachea into the lungs. The lungs are the primary organs of respiration in many animals.

🎯 Exam Tip: Understand the pathway of air during breathing: trachea to bronchi, and then to the lungs for gas exchange.

 

Question 7. Which organ acts as a suction pump in leech?
Answer: The Pharynx acts as a suction pump in Leech. Its muscular structure helps to create a vacuum, allowing the leech to draw blood from its host. The pharynx is located after the mouth and leads to the crop.

🎯 Exam Tip: The pharynx in leeches is highly adapted for their parasitic, blood-sucking lifestyle, functioning efficiently as a pump.

 

Question 8. What does CNS stand for?
Answer: The full form of CNS is Central Nervous System. This system includes the brain and spinal cord, which are responsible for processing information and coordinating body activities.

🎯 Exam Tip: CNS is a core abbreviation in biology; also know PNS (Peripheral Nervous System) which includes all other nerves.

 

Question 9. Why is the teeth of rabbit called heterodont?
Answer: The dentition of a rabbit is called heterodont because they have different types of teeth. These include incisors, premolars, and molars, each with a specific shape and function for their diet. Having various tooth shapes helps rabbits chew plant material effectively.

🎯 Exam Tip: Heterodont means "different teeth," distinguishing it from homodont, which means having teeth all of the same type.

 

Question 10. How does leech suck blood from the host?
Answer: The anterior sucker helps in feeding by attaching to the host and creating a seal. Both the anterior and posterior suckers help the leech with attachment and locomotion. The pharynx then acts as a pump to draw in blood. The leech injects hirudin, an anticoagulant, to keep the blood flowing.

🎯 Exam Tip: Understand the combined action of suckers, pharynx, and anticoagulant (hirudin) for the leech's efficient blood-sucking mechanism.

VI. Short Answer Questions:

 

Question 1. Why are the rings of cartilages found in trachea of rabbit?
Answer: The rings of cartilage are found in the trachea (windpipe) of a rabbit to keep the airway open. These rings are C-shaped, meaning they are incomplete at the back. This structure helps prevent the trachea from collapsing, especially during breathing, ensuring a continuous flow of air to the lungs. The wall of the larynx (voice box) is also supported by cartilage.

🎯 Exam Tip: Cartilaginous rings are vital for maintaining the patency (openness) of respiratory passages in many animals, including humans.

 

Question 2. List out the parasitic adaptations in the leech.
Answer: Leeches live as parasites, meaning they feed on other animals' blood. Here are their adaptations:
* **Blood Sucking:** The pharynx is adapted for sucking blood. It acts like a pump to draw blood from the host.
* **Suckers:** Leeches have both anterior and posterior suckers. The anterior sucker helps them attach for feeding, while both help with attachment and movement.
* **Jaws:** Inside the mouth, three jaws create a painless Y-shaped cut in the host's skin. This minimizes discomfort so the host might not notice the bite.
* **Hirudin:** Their salivary glands produce hirudin, a substance that stops blood from clotting. This ensures a continuous flow of blood to the leech.
* **No Parapodia or Setae:** Unlike some other worms, leeches do not have parapodia (fleshy outgrowths) or setae (bristles). These are not needed for their parasitic lifestyle.
* **Blood Storage:** Blood is stored in a special organ called the crop for several months. This means leeches don't need to feed often. Because of this storage, they also do not have many complex digestive juices or enzymes.
In simple words: Leeches have special body parts and chemicals that help them live by sucking blood. They have suckers to stick, jaws to make a painless cut, and a chemical called hirudin to stop blood from clotting. They can also store a lot of blood to live for many months.

🎯 Exam Tip: When listing adaptations, always link the structural or physiological feature directly to how it helps the organism survive in its specific environment or lifestyle.

VII. Long Answer Questions:

 

Question 1. How is the circulatory system designed in leech to compensate the heart structure?
Answer: The leech has a special type of circulatory system called a Haemocoelic system. It does not have true blood vessels like many other animals. Instead, blood-like fluid flows through channels called Haemocoelic channels or canals. This fluid, which fills these channels, contains haemoglobin, a substance that helps carry oxygen. This system acts like a heart, moving the fluid around the body. There are four long channels that run through the leech's body. One is above the alimentary canal (dorsal), one is below it (ventral), and two are on the sides (lateral) of the alimentary canal. These four channels have valves to control the flow of fluid and are all connected. They extend up to the 26th segment at the back of the leech. This unique design helps the leech move and get oxygen without needing a complex heart. The lateral channels help to pump the blood-like fluid around. It's an efficient system for an animal without a centralized pumping organ.

🎯 Exam Tip: For comparative anatomy questions, focus on how different organisms achieve similar vital functions (like circulation) using diverse structural adaptations.

 

Question 2. How does locomotion take place in leech?
Answer: Leeches move in two main ways: looping (or crawling) and swimming.
1. **Looping or Crawling Movement:** This movement happens when the leech's muscles contract and relax. The leech uses its two suckers to attach to surfaces. First, it fixes its posterior sucker (the back one) onto the ground. Then, it extends its body forward, attaches its anterior sucker (the front one), and releases the posterior sucker. Next, it pulls its posterior end forward towards the anterior sucker, making a loop. This process repeats, allowing it to crawl.
2. **Swimming Movement:** When in water, the leech swims by making wave-like movements with its body. It undulates its body from side to side, pushing against the water to propel itself forward. This graceful motion allows for efficient movement in aquatic environments. Leeches are surprisingly agile in water, using their entire body to create propulsion.
In simple words: Leeches move by either crawling or swimming. When crawling, they use their suckers to stick and then stretch and pull their body forward like a loop. When swimming, they wiggle their body in waves to move through the water.

🎯 Exam Tip: Clearly describe both types of locomotion, highlighting the role of suckers in crawling and body undulations in swimming.

 

Question 3. Explain the male reproductive system of rabbit with a labelled diagram.
Answer: The male rabbit's reproductive system includes a pair of testes, which are oval-shaped. These testes are located outside the body in two sacs called scrotal sacs, which hang down from the abdomen. Each testis is made up of many small tubes called seminiferous tubules, where sperm are produced. A coiled tube, the epididymis, forms at the end of these tubules, leading into a sperm duct called the vas deferens. The vas deferens carries sperm forward into the abdominal cavity and connects to the urinary bladder. The urethra then carries both urine and sperm through the penis. There are three important accessory glands linked to this system: the prostate glands, Cowper's glands, and perineal glands. Their secretions help to nourish the sperm and activate them for reproduction. The external position of the testes in the scrotum helps maintain a cooler temperature, which is essential for sperm production.

In simple words: Male rabbits have two testes in scrotal sacs that make sperm. Sperm travel through tubes called vas deferens and urethra. Glands like the prostate add fluids to help the sperm.

🎯 Exam Tip: When describing organ systems, always mention the main organs, their location, and their primary function, especially in relation to the overall system's goal (e.g., reproduction).

VIII. Higher Order Thinking Skills (HOTS).

 

Question 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?
Answer: The doctor would have explained that leeches inject an anaesthetic substance into the skin when they bite. This substance temporarily numbs the area, preventing the host from feeling the bite. This anesthetic effect allows the leech to feed for a long time without being noticed by its host. This is a clever adaptation for its parasitic lifestyle.

🎯 Exam Tip: In HOTS questions, identify the core biological principle (here, adaptation for parasitism) and explain the mechanism behind it in simple terms.

 

Question 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 what it so? What would have been the explanation of his grandfather?
Answer: Shylesh's grandfather would explain that rabbits have three main types of teeth. Their front teeth, called incisors, are very sharp and used for cutting plants. They do not have canine teeth, which are typically for tearing meat. In their place, there is a gap called a diastema. After the diastema, they have premolars and molars at the back, which are used for grinding their food. This special arrangement of teeth, including the diastema, helps rabbits chew tough plant materials efficiently because they are herbivores. They have continuous tooth growth, which means their teeth keep growing throughout their lives.

🎯 Exam Tip: Connect observable features (like tooth arrangement) to the animal's diet and lifestyle, highlighting how adaptations fit their needs.

IX. Value-Based Questions:

 

Question 1. Leeches do not have an elaborate secretion of digestive juices and enzymes. Why?
Answer: Leeches do not have many digestive juices and enzymes because their digestion process is very slow. They store large amounts of blood in a special part of their gut called the crop. This stored blood provides nourishment to the leech for several months. Since they feed infrequently and consume pre-digested food (blood plasma), they do not need complex digestive secretions. The stored blood slowly releases nutrients over time. This makes their digestive system simple.

🎯 Exam Tip: Explaining "why" in biology often involves linking a structural or physiological feature to the organism's lifestyle or environment.

 

Question 2. How is the digestive system of rabbit suited for herbivorous mode of feeding?
Answer: Rabbits are herbivores, meaning they eat only plants. Their digestive system is specially adapted for this diet. They have large incisors at the front for cutting plants and strong molars at the back for grinding. A key feature is the diastema, a gap between their incisors and premolars, which helps them manipulate plant material. They have a very large cecum, which is a pouch at the beginning of the large intestine. This cecum contains many symbiotic bacteria. These bacteria help to break down cellulose, a complex carbohydrate found in plant cell walls, which rabbits cannot digest on their own. This process, called hindgut fermentation, is vital for extracting nutrients from plants. The large cecum is crucial for this specialized digestion. They also practice coprophagy, re-ingesting nutrient-rich fecal pellets to get more nutrients.

🎯 Exam Tip: When discussing digestive adaptations, highlight specialized teeth, gut structures (like a large cecum), and the role of microorganisms.

Additional Important Questions And Answers

I. Choose The Correct Answer:

 

Question 1. _____
(a) Vas deferens and Epididymis
(b) Ovary and Caeca
(c) Hirudin and Stomach
(d) Nephridia and Papillae.
Answer: (a) Vas deferens and Epididymis
In simple words: The vas deferens and epididymis are both important parts of the male reproductive system in many animals. The epididymis is where sperm mature, and the vas deferens transports them.

🎯 Exam Tip: This question might be incomplete from the source, but focusing on the paired male reproductive ducts is the correct approach given the options.

 

Question 2. Diastema is:
(a) A part of pelvic girdle in rabbit
(b) A type of tooth in rabbit
(c) Space in teeth line in mammals
(d) Structure in eye of rabbit
Answer: (c) Space in teeth line in mammals
In simple words: A diastema is an empty space between teeth, most often found in the jaws of mammals, especially herbivores. This gap helps them handle food easily.

🎯 Exam Tip: Remember that a diastema is specifically a gap in the tooth row, usually between incisors and premolars, not a type of tooth itself.

 

Question 3. _____
(a) Suckers and Mammary glands
(b) Cowper's gland and Perineal gland
(c) Forebrain and Oesophagus
(d) Cellulose and Colouration.
Answer: (b) Cowper's gland and Perineal gland
In simple words: Cowper's gland and the perineal gland are accessory glands that produce fluids for the male reproductive system. These secretions help in the movement and health of sperm.

🎯 Exam Tip: This question seems incomplete in the source. Given the options, identifying two accessory glands of the male reproductive system is the logical choice.

 

Question 4. If the dental formula of rabbit is \( \frac{2033}{1023} \) What does it show?
(a) Total number of teeth in Rabbit is 15
(b) Number of total incisors in Rabbit is 3
(d) In the formula 2033 is for adult and 1023 is for young ones
Answer: (c) Diastema is present between incisors and premolars
In simple words: The dental formula for a rabbit shows it has a gap (diastema) because it lacks canine teeth. This gap is found between its incisors and premolars, which is normal for animals that eat only plants.

🎯 Exam Tip: A dental formula is read as (I, C, P, M) for one side of the upper jaw / (I, C, P, M) for one side of the lower jaw. The absence of a number (like for canines here) implies a gap.

 

Question 5. Number of pairs of salivary glands present in Rabbit is:
(a) one
(b) three
(c) four
(d) five
Answer: (c) four
In simple words: Rabbits have four pairs of salivary glands. These glands make saliva, which helps start the digestion of food and makes it easier to swallow.

🎯 Exam Tip: Knowing the number and types of glands is important for understanding digestive physiology.

 

Question 6. Number of Vertebrae in rabbit is:
(a) 44 - 47
(b) 40 - 44
(c) 42 - 48
(d) 47 - 50
Answer: (a) 44 - 47
In simple words: A rabbit's spine is made up of about 44 to 47 small bones called vertebrae. These bones support the body and protect the spinal cord.

🎯 Exam Tip: The vertebral count can vary slightly, but a range is often given to account for individual differences or measurement methods.

 

Question 7. If the diaphragm of a rabbit is perforated breathing is:
(a) Not affected
(b) Increased
(c) Decreased
(d) Stopped
Answer: (d) Stopped
In simple words: If a rabbit's diaphragm is punctured, breathing would stop. The diaphragm is a key muscle for breathing, and damage to it prevents the lungs from expanding and contracting properly.

🎯 Exam Tip: The diaphragm plays a critical role in mammalian respiration, and its integrity is essential for effective breathing.

 

Question 8. Tracheal rings in rabbit are:
(a) complete
(b) dorsally incomplete
(c) lateral incomplete
(d) incomplete
Answer: (b) dorsally incomplete
In simple words: The tracheal rings in a rabbit's windpipe are not complete circles; they are open at the back (dorsally incomplete). This design allows the esophagus, which is behind the trachea, to expand when food passes through.

🎯 Exam Tip: The C-shaped nature of tracheal rings is an adaptation to allow for the expansion of the esophagus during swallowing.

 

Question 9. Which one of the following is not a characteristic of leech?
(a) closed circulatory system
(b) segmentation
(c) pseudo coelom
(d) ventral nerve cord
Answer: (c) pseudo coelom
In simple words: Leeches do not have a pseudo coelom, which is a body cavity not fully lined with mesoderm. Instead, they have a true coelom that is filled with botryoidal tissue and haemocoel.

🎯 Exam Tip: Know the difference between a true coelom (eucoelom), a false coelom (pseudocoelom), and acoelomate body plans.

 

Question 10. The blood vascular system, of rabbit is:
(a) open type
(b) closed type
(c) semi closed type
(d) semi open type
Answer: (b) closed type
In simple words: Rabbits have a closed blood vascular system, meaning blood flows inside blood vessels and does not directly fill body cavities. This allows for more efficient transport of blood.

🎯 Exam Tip: Mammals, including rabbits, have a highly efficient closed circulatory system, where blood is always contained within vessels.

 

Question 11. The wall of Rabbit's heart is thick due to the presence of:
(b) Middle layer myocardium
Answer: (b) Middle layer myocardium
In simple words: The middle layer of the heart wall, called the myocardium, is made of thick muscle. This strong muscle allows the heart to pump blood effectively throughout the body.

🎯 Exam Tip: The myocardium is the muscular layer responsible for the heart's pumping action, and its thickness reflects the workload of that part of the heart.

II. Fill in the blanks:

 

Question. 1. Hirudinaria granulosa belong to the phylum ........
Answer:
1. Annelida. Leeches, like Hirudinaria granulosa, belong to the phylum Annelida, which are segmented worms. This phylum also includes earthworms.
In simple words: Hirudinaria granulosa is a type of worm that belongs to the Annelida group.

🎯 Exam Tip: Remember to identify the broad classification (phylum) for common animals like the leech.

 

Question. 2. The scientific name of the rabbit is .........
Answer:
2. Oryctolagus cuniculus. The scientific name Oryctolagus cuniculus refers to the European rabbit, which is a common domesticated species. Scientific names help avoid confusion caused by different common names.
In simple words: The rabbit's scientific name is Oryctolagus cuniculus.

🎯 Exam Tip: Scientific names are always written with the genus capitalized and the species in lowercase, both italicized.

 

Question. 3. ......... is the segmentation of the body.
Answer:
3. Metamerism is the segmentation of the body. This means the body is divided into repeating sections or segments. This body plan allows for specialized functions in different segments.
In simple words: Metamerism is when an animal's body is made of many repeating segments.

🎯 Exam Tip: Understand that metamerism is a key characteristic of some animal phyla like Annelida and Arthropoda.

 

Question. 4. The type of movement is brought by the contraction and relaxation of muscles in leeches is ........
Answer:
4. Looping or crawling movement. Leeches move by alternately attaching their suckers and contracting/relaxing their body muscles. This rhythmic action pulls their body forward.
In simple words: Leeches move by a looping or crawling action, using their muscles and suckers.

🎯 Exam Tip: When describing movement, always mention the body parts involved, such as muscles and suckers for leeches.

 

Question. 5. In leech, the digestion takes place in stomach by the action of ........
Answer:
5. Proteolytic enzyme. Leeches primarily feed on blood, and their digestive system secretes proteolytic enzymes to break down the proteins in the blood. This helps them process their unique diet.
In simple words: Leeches use a special enzyme called proteolytic enzyme in their stomach to digest the blood they eat.

🎯 Exam Tip: Remember that proteolytic enzymes are specifically designed to break down proteins, which is crucial for blood-feeding animals.

 

Question. 6. The ......... prevents the entry of food into the trachea through the glottis.
Answer:
6. Epiglottis. The epiglottis is a flap of cartilage located at the base of the tongue that covers the opening of the windpipe (trachea) during swallowing. This essential function prevents choking.
In simple words: The epiglottis acts like a lid, closing off the windpipe when we swallow food to stop it from going down the wrong tube.

🎯 Exam Tip: The epiglottis is a vital part of the respiratory and digestive systems, ensuring food enters the esophagus and not the trachea.

 

Question. 7. The existence of two sets of teeth in the life of an animal is called ........ dentition.
Answer:
7. Diphyodont dentition. Diphyodont dentition refers to animals that develop two sets of teeth during their lifetime – milk teeth (deciduous) followed by permanent teeth. This is common in mammals, including humans.
In simple words: Animals that grow two sets of teeth in their life, like babies losing milk teeth for adult teeth, have diphyodont dentition.

🎯 Exam Tip: Distinguish diphyodont from monophyodont (one set of teeth) and polyphyodont (multiple sets of teeth throughout life).

 

Question. 8. ......... contains bacteria that helps in digestion of cellulose.
Answer:
8. Caecum. The caecum is a pouch connected to the junction of the small and large intestines. In herbivores like rabbits, it's often enlarged and contains symbiotic bacteria that help break down cellulose from plants. This specialized organ allows them to digest fibrous plant material.
In simple words: The caecum is a part of the gut that has bacteria inside it. These bacteria help animals like rabbits digest tough plant parts like cellulose.

🎯 Exam Tip: Remember that not all animals have a caecum or the same bacteria; it's adapted to their specific diet.

 

Question. 9. The anterior part of the oviduct in rabbit is ........
Answer:
9. Fallopian tube. In rabbits, the anterior part of the oviduct, also known as the fallopian tube, is responsible for transporting eggs from the ovary to the uterus. This tube is where fertilization usually occurs.
In simple words: The front part of the egg tube in a rabbit is called the fallopian tube.

🎯 Exam Tip: Recall that the oviducts are crucial for reproduction, guiding the egg and often being the site of fertilization.

 

Question. 10. Breathing movement in mammals are brought by ........
Answer:
10. Diaphragm. The diaphragm is a large, dome-shaped muscle located at the base of the chest cavity. It contracts and flattens during inhalation, increasing the volume of the chest and drawing air into the lungs. It is the primary muscle responsible for breathing in mammals.
In simple words: In mammals, breathing happens mainly because of a big muscle under the lungs called the diaphragm.

🎯 Exam Tip: The diaphragm's movement is key to understanding how mammals breathe, as it creates pressure changes for air to move in and out.

 

III. Identify whether the statements are True or False. Correct the false statement:

 

Question. 1. An anticoagulant present in saliva of leech is called heparin.
Answer: False - An anticoagulant present in saliva of leech is called hirudin. Heparin is an anticoagulant found in mammals, but leeches produce their own special anticoagulant called hirudin to keep blood flowing. This allows them to feed for longer periods without the host's blood clotting.
In simple words: The statement is false. Leeches use hirudin, not heparin, to stop blood from clotting.

🎯 Exam Tip: Make sure to distinguish between similar biological terms; hirudin is specific to leeches, while heparin is produced by the human body.

 

Question. 2. The vas deferens serves to transport the ovum.
Answer: False - Vas deferens serves to transport the sperm. The vas deferens is part of the male reproductive system and is responsible for carrying sperm from the epididymis to the ejaculatory ducts. Ova (eggs) are transported through the oviducts or fallopian tubes in females.
In simple words: The statement is false. The vas deferens carries sperm, not eggs.

🎯 Exam Tip: Clearly remember the functions of male and female reproductive organs to avoid confusing them.

 

Question. 3. The rabbit has a third eyelid called tympanic membrane which is movable.
Answer: True - The rabbit does have a third eyelid, also known as a nictitating membrane, which is movable. However, the statement incorrectly identifies it as the "tympanic membrane," which is actually the eardrum. The nictitating membrane helps to protect and moisten the eye.
In simple words: Rabbits have a movable third eyelid, but it is not called the tympanic membrane.

🎯 Exam Tip: Pay attention to all parts of a statement in true/false questions; one incorrect detail makes the whole statement false.

 

Question. 4. Diastema is a gap between premolar and molar teeth in rabbit.
Answer: False - The gap between the incisors and premolars. Diastema is a common feature in herbivores like rabbits, providing space for chewing and manipulating plant material. It is a distinct gap, not just between premolars and molars, but specifically between the front incisors and the cheek teeth (premolars/molars).
In simple words: The statement is false. Diastema is a gap between the front teeth (incisors) and the side teeth (premolars), not just between premolars and molars.

🎯 Exam Tip: Know the specific location of structures; the diastema's position is important for understanding herbivore dentition.

 

Question. 5. The cerebral hemispheres of rabbit are connected by band of nerve tissue called corpora quadrigemina.
Answer: False - The cerebral hemispheres of rabbit are connected by band of nerve tissue called corpus callosum. The corpus callosum is a thick band of nerve fibers that connects the two hemispheres of the brain in placental mammals. The corpora quadrigemina, on the other hand, is involved in visual and auditory reflexes.
In simple words: The statement is false. The brain halves in a rabbit are linked by the corpus callosum, not the corpora quadrigemina.

🎯 Exam Tip: Be precise with anatomical terms; confusing corpus callosum with corpora quadrigemina is a common error to avoid.

 

IV. Match the following:

Answer:
A. Gregarious - (v) moving in groups
B. Sanguivorous - (i) blood sucking
C. Clitellum - (ii) cocoon
D. Vibrissae - (iii) whiskers
E. Heterodont - (iv) different types of teeth
The correct matching pairs relate to animal behaviors, feeding habits, anatomical features, and dental characteristics. For example, gregarious animals prefer living in groups, and heterodont dentition means having different types of teeth.
In simple words: Here are the correct matches: Gregarious means living in groups. Sanguivorous means feeding on blood. Clitellum is related to cocoon formation. Vibrissae are whiskers. Heterodont means having different types of teeth.

🎯 Exam Tip: When matching, identify key terms and their definitions or associations. Cross-reference options to find the best fit, and if unsure, eliminate obvious incorrect pairings first.

 

V. Answer in a sentence:

 

Question 1. Give the common name of the Hirudinaria granulosa.
Answer: The common name of Hirudinaria granulosa is Indian Cattle Leech. This species is commonly found in freshwater habitats in India and is known for feeding on the blood of cattle and other vertebrates.
In simple words: Hirudinaria granulosa is commonly known as the Indian Cattle Leech.

🎯 Exam Tip: Always state both the common and scientific names clearly when asked, as both are important for biological identification.

 

Question 2. How does leech respire?
Answer: Leeches respire through their skin. They do not have specialized respiratory organs like lungs or gills; instead, oxygen diffuses directly through their moist body surface. This is why their skin must remain moist.
In simple words: Leeches breathe through their skin.

🎯 Exam Tip: When discussing respiration in simple organisms, consider if they have specialized organs or rely on simple diffusion through the body surface.

 

Question 3. Write the dental formula of rabbit.
Answer: The dental formula of rabbit is \( \frac{2033}{1023} \). This formula indicates the number of incisors, canines, premolars, and molars in one half of the upper and lower jaws. The rabbit's dental formula reflects its herbivorous diet.
In simple words: The dental formula for a rabbit is 2-0-3-3 for the upper jaw and 1-0-2-3 for the lower jaw.

🎯 Exam Tip: Remember that dental formulas represent the number of different types of teeth in one half of each jaw (Incisors, Canines, Premolars, Molars).

 

Question 4. How many pairs of testes are present in leech?
Answer: There are 11 pairs of testes present in Leech. Leeches are hermaphroditic, meaning they have both male and female reproductive organs, and these multiple pairs of testes are arranged segmentally within their body.
In simple words: A leech has 11 pairs of testes.

🎯 Exam Tip: For anatomical questions, specifying the number of pairs or individual structures is important for accuracy.

 

Question 5. How is diastema formed in rabbit?
Answer: Diastema is formed in rabbits due to the absence of canine teeth, creating a gap between the incisors and premolars in the upper and lower jaws. This space is useful for manipulating vegetation while feeding. It helps them efficiently chew their plant-based diet.
In simple words: Diastema in a rabbit is a gap in its teeth line because it doesn't have canine teeth.

🎯 Exam Tip: Link anatomical features like diastema to the animal's feeding habits or lifestyle, as adaptations often serve a specific purpose.

 

Question 6. What organs are attached to the two bronchi?
Answer: The organs attached to the two bronchi are lungs. Each bronchus, which is a branch of the trachea, extends into a lung, where it further divides into smaller airways, delivering air for gas exchange. The lungs are vital for breathing.
In simple words: The lungs are the organs connected to the two main air tubes (bronchi).

🎯 Exam Tip: Understand the basic structure of the respiratory system, noting how air tubes connect to the lungs.

 

Question 7. Which organ acts as a suction pump in leech?
Answer: The pharynx acts as a suction pump in Leech. The muscular pharynx creates a vacuum that helps the leech suck blood from its host. This powerful suction is essential for its parasitic feeding strategy.
In simple words: The pharynx in a leech works like a suction pump.

🎯 Exam Tip: Identify specialized organs and their unique functions, especially in animals with unusual feeding methods like leeches.

 

Question 8. What does CNS stand for?
Answer: The full form of CNS is Central Nervous System. The CNS includes the brain and spinal cord, which are the main control centers for the body's functions. It processes information and coordinates responses.
In simple words: CNS means Central Nervous System.

🎯 Exam Tip: Always know the full forms of common acronyms in biology, as they represent fundamental concepts.

 

Question 9. Why is the teeth of rabbit called heterodont?
Answer: The dentition of rabbit is called heterodont because they have different types of teeth. These include incisors, premolars, and molars, each with a specific shape and function for processing plant material. This variety allows them to cut, grind, and chew their fibrous diet efficiently.
In simple words: Rabbits have heterodont teeth because they have different kinds of teeth like incisors and molars, each doing a different job.

🎯 Exam Tip: Remember that heterodont dentition (different tooth types) is a key feature of mammals, in contrast to homodont dentition (all teeth are similar).

 

Question 10. How does leech suck blood from the host?
Answer: The anterior sucker helps in feeding, while both the suckers help in attachment and locomotion. The anterior sucker has a mouth and three jaws, which create a Y-shaped incision to draw blood. The muscular pharynx then acts as a pump to suck the blood.
In simple words: Leeches use their front sucker and a strong pharynx to attach to the host and suck blood.

🎯 Exam Tip: When explaining a process, describe the involved structures and their role in a sequential manner.

 

VI. Short Answer Questions:

 

Question 1. Why are the rings of cartilages found in trachea of rabbit?
Answer: The rings of cartilage are found in the trachea of rabbits to keep the airway open and prevent it from collapsing. These incomplete rings provide structural support, ensuring that air can flow continuously to and from the lungs. This continuous airflow is crucial for respiration.
In simple words: Cartilage rings keep the rabbit's windpipe (trachea) open so it can breathe easily without the tube closing.

🎯 Exam Tip: Understand that cartilaginous rings are a common adaptation in tracheas of many animals to maintain an open airway.

 

Question 2. List out the parasitic adaptations in the leech.
Answer: Leeches have several adaptations for their parasitic mode of life:

• Blood is sucked by the pharynx, which acts as a powerful pump.
• Anterior and Posterior Suckers are provided, allowing the animal to attach firmly to the host's body.
• The three jaws inside the mouth create a painless Y-shaped wound in the host's skin.
• Salivary glands produce hirudin, an anticoagulant, which prevents the host's blood from clotting, ensuring a continuous blood supply.
• Parapodia and Setae are absent, as they are not needed for their lifestyle.
• Blood is stored in the crop and its diverticula, giving nourishment to the leech for several months, with no elaborate digestive juices or enzymes needed.

These adaptations allow leeches to effectively feed on blood and survive for long periods between meals.
In simple words: Leeches have suckers to attach, jaws to cut without pain, and a special chemical (hirudin) to stop blood from clotting. They also store blood for a long time.

🎯 Exam Tip: When listing adaptations, explain how each feature directly helps the organism survive in its specific environment or lifestyle.

 

Question 3. How do the leeches respire?
Answer: There is no special respiratory organ in leech. The skin serves as the respiratory organ. The capillaries containing the haemocoelomic fluid extend between the cells of the epidermis, acting as a permeable membrane. Through this membrane, the exchange of gases takes place by diffusion. Oxygen from the water diffuses into the leech's body, and carbon dioxide diffuses out. The skin must always stay moist for this to happen effectively.
In simple words: Leeches breathe through their skin, as they don't have lungs or gills. Oxygen goes into their moist skin, and carbon dioxide comes out.

🎯 Exam Tip: Focus on surface respiration (diffusion) as a primitive but effective method for small aquatic organisms, emphasizing the need for a moist surface.

 

Question 4. What are diphyodont dentition and heterodont dentition?
Answer:
**Diphyodont dentition:** This refers to the existence of two sets of teeth in an animal's life. The two types of teeth are milk teeth (young ones) and permanent teeth (in adults). Humans and most other mammals exhibit this type of dentition, allowing for growth and development of stronger teeth.
**Heterodont dentition:** This describes the presence of different types of teeth within the same mouth, each specialized for a particular function. There are four kinds of teeth in mammals: incisors (for cutting), canines (for tearing), premolars (for grinding), and molars (also for grinding). This variety in tooth shape is crucial for processing diverse diets.
In simple words: Diphyodont means an animal gets two sets of teeth in its life, like baby teeth then adult teeth. Heterodont means an animal has different kinds of teeth, like sharp ones for biting and flat ones for chewing.

🎯 Exam Tip: Clearly define and differentiate between these two important dental terms, providing examples of each if possible to illustrate the concepts.

 

Question 5. List out the five layers of body wall of Leech.
Answer: The body wall of a leech consists of five layers, from outside to inside:

• Cuticle: The outermost protective layer.
• Epidermis: The layer beneath the cuticle, containing gland cells.
• Dermis: A connective tissue layer under the epidermis.
• Muscular layer: Composed of circular and longitudinal muscles for movement.
• Botryoidal tissue: A specialized tissue layer, involved in excretion and storage, filling the coelomic spaces.

These layers work together to provide protection, support, and facilitate movement and other functions.
In simple words: The leech's body wall has five layers: cuticle, epidermis, dermis, muscle layer, and botryoidal tissue.

🎯 Exam Tip: When listing biological structures, try to present them in a logical order (e.g., outside to inside) and briefly mention their primary function.

 

Question 6. Give the systematic position of Rabbit.
Answer: The systematic position of the rabbit is as follows:

This classification places the rabbit within the animal kingdom, characterized by a backbone (vertebrate), being a mammal, and specifically belonging to the order Lagomorpha, which also includes hares.
In simple words: A rabbit is an animal, a chordate, a vertebrate, a mammal, in the order Lagomorpha, genus Oryctolagus, and species Cuniculus.

🎯 Exam Tip: Practice writing out the full systematic classification for common organisms, ensuring all taxonomic ranks are correct.

 

Question 7. Explain the Respiratory system of Leech.
Answer: Leeches do not have specialized respiratory organs. Instead, their entire skin acts as the respiratory surface. The epidermis of the skin is rich in a dense network of tiny blood vessels called capillaries, which contain haemocoelomic fluid. Oxygen, dissolved in the surrounding water, diffuses directly through the moist skin and into this fluid. Simultaneously, carbon dioxide diffuses from the fluid out through the skin into the water. The secretion of mucus keeps the skin moist and slimy, which is crucial for efficient gas exchange by diffusion. If the skin dries out, respiration cannot occur.
In simple words: Leeches breathe through their skin because they have no lungs. Oxygen from water goes into their moist skin, and carbon dioxide comes out. Mucus keeps their skin wet so they can breathe.

🎯 Exam Tip: Highlight the importance of a moist surface for diffusion-based respiration in organisms without dedicated breathing organs.

 

Question 8. List out the steps involved in Inspiration in Rabbit.
Answer: During inspiration (breathing in), atmospheric air takes the following route in a rabbit's respiratory system:
External nostril
\( \implies \) Nasal chamber
\( \implies \) Internal nostril
\( \implies \) Nasopharynx
\( \implies \) Glottis
\( \implies \) Larynx
\( \implies \) Trachea
\( \implies \) Primary bronchi
\( \implies \) Secondary bronchi
\( \implies \) Testiary bronchi
\( \implies \) Bronchioles
\( \implies \) Alveolar duct
\( \implies \) Infundibulum
\( \implies \) Alveoli
\( \implies \) Blood
This pathway ensures that air travels through various filtering and warming passages before reaching the alveoli in the lungs, where oxygen is absorbed into the blood. Each step prepares the air for efficient gas exchange.
In simple words: When a rabbit breathes in, air first enters through the nostrils, goes through the nasal chamber, then nasopharynx, larynx, trachea, and into smaller and smaller tubes (bronchi, bronchioles) until it reaches tiny air sacs (alveoli) where it goes into the blood.

🎯 Exam Tip: Memorize the correct sequence of structures in the respiratory pathway, as the order is crucial for understanding airflow.

 

VII. Long answer questions:

 

Question 1. Compare the digestive system of Leech and Rabbit.
Answer: Here is a comparison of the digestive systems of a Leech and a Rabbit:

The digestive systems of leeches and rabbits are vastly different due to their distinct diets and lifestyles. Leeches, as blood-sucking parasites, have adaptations for storing and digesting blood, while rabbits, as herbivores, have a system optimized for processing plant material, including a large caecum for cellulose digestion.
In simple words: Leeches have a simple gut with a large crop to store blood and hirudin to stop it from clotting. Rabbits have a more complex gut with a big caecum full of bacteria to digest plants.

🎯 Exam Tip: When comparing, always highlight key differences in organs and functions, linking them directly to the animal's diet and environment.

 

Question 2. Short notes on the Nervous System of Leech.
Answer: The Central Nervous System (CNS) of a leech consists of a nerve ring and a paired ventral nerve cord. The nerve ring surrounds the pharynx and is formed by the fusion of three main parts: the suprapharyngeal ganglion (often considered the "brain" of the leech), the circumpharyngeal connectives, and the subpharyngeal ganglion. The subpharyngeal ganglion lies below the pharynx and is formed by the fusion of four pairs of ganglia. This organized system allows the leech to coordinate complex movements, detect stimuli from its environment, and carry out its parasitic behaviors effectively.
In simple words: A leech has a simple brain (suprapharyngeal ganglion), a nerve ring around its feeding tube, and a nerve cord running along its belly. This helps it sense and move.

🎯 Exam Tip: When describing the nervous system of an invertebrate, focus on the presence and arrangement of ganglia and nerve cords, as these are its main components.