| # | Statement (Answer in bold) |
|---|---|
| 1 | The posterior sucker is formed by the fusion of the last 7 segments. |
| 2 | The existence of two sets of teeth in the life of an animal is called diphyodont dentition. |
| 3 | The anterior end of leech has a lobe-like structure called anterior sucker. |
| 4 | The blood sucking habit of leech is known as sanguivorous. |
| 5 | Kidneys separate nitrogenous waste, mainly urea, from the blood in rabbit. |
| 6 | 37 pairs of spinal nerves are present in rabbit. |
| # | Statement | Answer | Correction (if False) |
|---|---|---|---|
| 1 | An anticoagulant present in saliva of leech is called heparin. | False | Anticoagulant present in saliva of leech is called hirudin. |
| 2 | The vas deferens serves to transport the ovum. | False | The vas deferens serves to transport the sperm. |
| 3 | The rabbit has a third eyelid called tympanic membrane which is movable. | False | The rabbit has a third eyelid called nictitating membrane which is movable. |
| 4 | Diastema is a gap between premolar and molar teeth in rabbit. | False | Diastema is a gap between incisors and premolar teeth in rabbit. |
| 5 | The cerebral hemispheres of rabbit are connected by band of nerve tissue called corpora quadrigemina. | False | The cerebral hemispheres of rabbit are connected by a band of nerve tissue called corpus callosum. |
Refer to textbook for match answers.
Leeches respire through their body surface, which is their skin. They possess a cutaneous respiratory system. The skin of the leech is thin and permeable, allowing for the diffusion of dissolved oxygen from the surrounding water into the leech's body and the diffusion of carbon dioxide out of the body. This process is efficient in aquatic environments where oxygen is readily available in the water.
I 2/1, C 0/0, PM 3/2, M 3/3
Total number of teeth = 28.
Diastema in rabbits refers to the significant gap present between the incisor teeth at the front of the mouth and the cheek teeth (premolars and molars) located further back. This anatomical feature is a result of the complete absence of canine teeth in rabbits. The presence of this diastema plays a crucial role in the rabbit's feeding mechanism, facilitating the efficient grinding and chewing of tough plant material, which forms the bulk of their diet.
The teeth of a rabbit are described as heterodont because they exhibit variation in form and function, meaning different types of teeth are present. Specifically, rabbits possess incisors for gnawing, and premolars and molars for grinding. Notably, canine teeth are entirely absent in rabbits, which is a characteristic feature distinguishing them from many other mammals.
When a leech attaches to a host, it uses its anterior sucker to anchor itself. It then employs three sharp jaws, arranged in a Y-shaped pattern, to make a painless incision in the skin. Simultaneously, its salivary glands release hirudin, a potent anticoagulant that prevents the host's blood from clotting. This ensures a continuous flow of blood, which is then efficiently sucked into the leech's crop by the action of its muscular pharynx for storage and later digestion.
The trachea, commonly known as the windpipe, in rabbits is reinforced with C-shaped rings of cartilage. These cartilaginous rings are crucial because they provide structural support to the tracheal walls, preventing them from collapsing inwards. This support ensures that the air passage remains open at all times, allowing for the unimpeded and free movement of air into and out of the lungs during respiration.
Leeches exhibit several remarkable adaptations for their parasitic lifestyle of blood-feeding on vertebrates. Their muscular pharynx acts as a powerful suction pump to ingest blood. Both the anterior and posterior suckers are highly developed, enabling the leech to firmly attach to the host's body. For feeding, they possess three sharp jaws that create a Y-shaped, painless wound, minimizing detection. The salivary glands secrete hirudin, an anticoagulant that prevents blood coagulation, thus ensuring a steady supply of blood. Unlike many other annelids, leeches lack parapodia and setae, which are external appendages used for locomotion or anchoring in other species. Finally, their specialized crop allows for the storage of large quantities of blood, which can sustain the leech for extended periods, sometimes for several months, between feedings.
In leeches, the circulatory system is primarily a haemocoelic system, meaning it is integrated with the coelomic cavity, and there isn't a distinct, highly developed heart as seen in many other animals. Circulation is managed by four longitudinal channels that are filled with a blood-like coelomic fluid containing haemoglobin. One of these channels is located dorsally, another ventrally, and two are situated laterally. The two lateral channels are particularly important as they are contractile and possess valves, functioning analogously to hearts. These contractile lateral channels rhythmically pump the coelomic fluid throughout the body, effectively circulating nutrients and oxygen, and compensating for the absence of a centralized, complex cardiac structure.
Locomotion in leeches occurs through two primary methods: looping or crawling, and swimming. During looping or crawling, the leech utilizes its muscles to contract and relax in a coordinated manner, moving in a wave-like fashion. This movement involves the alternate attachment and release of its anterior and posterior suckers to the substratum, creating a characteristic inching motion. When in water, leeches are also capable of active swimming. This is achieved by undulating their entire body, propelling themselves through the water with rhythmic, sinuous movements.
The doctor would have explained that leeches possess a remarkable ability to make their bite painless initially. This is due to the secretion of an anaesthetic substance along with saliva when they attach to the skin, which numbs the area and prevents the host from feeling the bite immediately. Furthermore, the leech secretes hirudin, a powerful anticoagulant, which inhibits the clotting of blood. This ensures that the blood remains in a liquid state, allowing the leech to feed continuously and efficiently without interruption.
His grandfather would have explained that rabbits have a unique dental arrangement characterized by a noticeable gap between their front teeth, the incisors, and their back teeth, the premolars and molars. This gap is known as a diastema. The absence of canine teeth, which are typically found between incisors and premolars in many mammals, is the reason for this space. Since rabbits are herbivores and primarily consume plant matter, this specialized dental structure, particularly the diastema, is advantageous as it aids in the efficient manipulation, grinding, and chewing of fibrous plant material, making their diet easier to process.
The digestive system of a rabbit is highly adapted for its herbivorous diet, which primarily consists of fibrous plant material. Key adaptations include specialized dentition and a significantly enlarged caecum. Rabbits possess heterodont dentition, meaning they have different types of teeth suited for their diet, although they lack canine teeth. Their incisors are prominent for gnawing, followed by a gap called the diastema, which facilitates chewing and manipulation of food. The large, well-developed caecum is a crucial component where microbial fermentation occurs. This fermentation process, carried out by bacteria and other microorganisms, breaks down cellulose, a complex carbohydrate found in plant cell walls that rabbits cannot digest on their own. The caecum's structure and the presence of these symbiotic microbes allow rabbits to extract maximum nutrients from their fibrous food. Following caecal fermentation, rabbits practice coprophagy, re-ingesting soft fecal pellets (caecotrophes) to absorb the nutrients produced during fermentation, further enhancing nutrient assimilation.
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