RBSE Solutions Class 11 Biology Chapter 31 Classification of Vertebrates

RBSE Class 11 Biology Chapter 31 Multiple Choice Objective Questions

 

Question 1. Operculum is absent in -
(a) Dipnoi
(b) Chondrichthyes
(c) Osteichthyes
(d) Holocephali
Answer: (b) Chondrichthyes
In simple words: Operculum is a bony flap covering the gills of fish. This covering is not found in cartilaginous fish like sharks and rays. This helps us classify different types of fish.

🎯 Exam Tip: Remember that Chondrichthyes (cartilaginous fish) have uncovered gill slits, while Osteichthyes (bony fish) have an operculum covering their gills.

 

Question 2. Which of the following group has marsupium-
(a) Metatheria
(b) Eutheria
(c) Prototheria
(d) Aves
Answer: (a) Metatheria
In simple words: The group called Metatheria includes animals that carry their young in a special pouch called a marsupium. Kangaroos are a well-known example.

🎯 Exam Tip: The presence of a marsupium is a key distinguishing feature of marsupials (Metatheria), important for understanding mammalian evolution.

 

Question 3. Protochordata is divided into which subphylum-
(a) Hemichordata
(b) Urochordata
(c) Cephalochordata
(d) All of the options
Answer: (d) All of the options
In simple words: Protochordates are a simple group of chordates. They are divided into smaller groups like Hemichordata, Urochordata, and Cephalochordata. Each group has its own special features.

🎯 Exam Tip: Protochordates are considered evolutionary links between invertebrates and vertebrates, and knowing their subdivisions is crucial for classification.

 

Question 4. Sea horse belongs to which class-
(a) Mammalia
(b) Pisces
(c) Aves
(d) Reptelia
Answer: (b) Pisces
In simple words: Despite its name, a seahorse is a type of fish, which belongs to the class Pisces. It lives in water and breathes through gills, just like other fish.

🎯 Exam Tip: Be careful with common names; always relate an animal to its scientific class based on its biological features (e.g., gills, fins, cold-blooded).

 

Question 5. Scales are found in -
(a) Pisces
(b) Reptiles
(c) Aves
(d) All of the options
Answer: (d) All of the options
In simple words: Scales are protective coverings found on many animals. You can find them on fish (Pisces) and also on reptiles like snakes and lizards. Birds (Aves) have scales on their legs and feet.

🎯 Exam Tip: Scales serve different functions in different classes, such as protection in fish and reptiles, and reducing water loss in terrestrial animals.

 

Question 6. Rajasthan state bird is
(a) Gazella gazella
(b) Great Indian bustard
(c) Peacock
(d) All of the options
Answer: (b) Great Indian bustard
In simple words: The Great Indian Bustard is the official state bird of Rajasthan. It is a large bird known for living in dry grasslands and is a symbol of the region's wildlife.

🎯 Exam Tip: State symbols like birds and animals are often part of general knowledge sections in competitive exams. Always remember both the common and scientific names.

 

Question 2. What is the number of cranial nerves in the super class - Pisces?
Answer: In the superclass Pisces (fish), there are 10 pairs of cranial nerves. These nerves help control sensory and motor functions like smell, vision, and muscle movement. This number is common in most fish species.
In simple words: Fish have 10 pairs of special nerves in their head, called cranial nerves. These nerves help them sense things and move.

🎯 Exam Tip: Knowing the number of cranial nerves in different animal groups helps in understanding their neurological complexity and evolutionary relationships.

 

Question 3. In which group, animal have distinct head and skull ?
Answer: Animals in the group Craniata have a distinct head and a skull. The skull is a bony or cartilaginous structure that protects the brain and sense organs. This is a key feature that separates them from other chordates.
In simple words: Animals that have a clear head and a skull to protect their brain belong to the Craniata group.

🎯 Exam Tip: The presence of a skull is a defining characteristic of vertebrates, which are a major part of the Craniata group.

 

Question 4. The outermost covering of sub phylum urochordata is called as ?
Answer: The outermost covering of subphylum Urochordata is called the Tunica (or Test). This tunic is a leathery, cellulose-like covering that protects the soft body of these marine animals. It's unique because it contains cellulose, which is usually found in plants.
In simple words: Urochordata animals have a strong outer skin called the Tunica or Test. It keeps their soft body safe.

🎯 Exam Tip: The tunic is a notable feature for Urochordates, highlighting their distinct morphology within the chordates.

 

Question 5. Name any bioluminiscent animal ?
Answer: Pyrosoma is an example of a bioluminescent animal. Bioluminescence is the ability of living organisms to produce and emit light, often seen in deep-sea creatures. Pyrosoma are colonial tunicates that glow in the dark.
In simple words: Pyrosoma is an animal that can make its own light. This is called bioluminescence.

🎯 Exam Tip: Bioluminescence is a fascinating adaptation for communication, camouflage, or attracting prey/mates, especially in dark environments like the deep ocean.

 

Question 6. Name the extincted animal of group agnatha.
Answer: Ostracodermi is an example of an extinct animal group belonging to Agnatha. Agnathans are jawless fish, and Ostracoderms were ancient armored jawless fish that lived millions of years ago. These fish are important for understanding early vertebrate evolution.
In simple words: Ostracodermi are old, jawless fish that are no longer alive. They were part of the Agnatha group.

🎯 Exam Tip: Extinct groups like Ostracoderms provide valuable insights into the evolutionary history of vertebrates, especially the development of jaws.

 

Question 7. Which is the largest mammal ?
Answer: The Blue Whale is the largest mammal and also the largest animal on Earth. It is a marine mammal known for its enormous size and filter-feeding habits. They can grow up to 30 meters long and weigh over 180 tonnes.
In simple words: The Blue Whale is the biggest mammal on our planet.

🎯 Exam Tip: Recognizing superlatives (largest, smallest, fastest) in biology is common, and the Blue Whale is a prime example of massive marine life.

 

Question 8. In the fishes of which class, operculum is absent?
Answer: Operculum is absent in the fishes of the class Chondrichthyes. These are cartilaginous fish like sharks and rays, which instead have multiple gill slits that open directly to the outside. This is a key difference from bony fish.
In simple words: Fish that are made of cartilage, like sharks, do not have a hard gill cover called an operculum.

🎯 Exam Tip: This question directly relates to Question 1, emphasizing the importance of understanding the characteristic features of different fish classes.

 

Question 10. Which animals have 3-Chambered heart?
Answer: Animals belonging to the Class Amphibia typically have a 3-chambered heart. This heart consists of two atria and one ventricle, allowing for some mixing of oxygenated and deoxygenated blood. This heart structure is an adaptation for their amphibious lifestyle.
In simple words: Amphibians, like frogs, have a heart with three parts: two top chambers and one bottom chamber.

🎯 Exam Tip: The number of heart chambers is a significant evolutionary characteristic for classifying vertebrates and understanding their circulatory systems.

 

Question 11. Presence of diaphragm is a feature of which class?
Answer: The presence of a diaphragm is a distinctive feature of the Class Mammalia. The diaphragm is a muscular sheet that separates the chest cavity from the abdominal cavity and plays a crucial role in breathing. This specialized respiratory muscle allows for efficient air intake.
In simple words: Only mammals have a special muscle called a diaphragm, which helps them breathe.

🎯 Exam Tip: The diaphragm is a unique evolutionary adaptation that allows mammals to have a highly efficient respiratory system, supporting their active lifestyle.

 

Question 12. Animals of which class have seven cervical vertebrae ?
Answer: Animals belonging to the Class Mammalia typically have seven cervical vertebrae (neck bones). This number is remarkably consistent across almost all mammals, from a giraffe to a mouse. This shows a common evolutionary origin for all mammals.
In simple words: Mammals usually have seven bones in their neck, called cervical vertebrae.

🎯 Exam Tip: This consistent number of cervical vertebrae is a unique anatomical marker that helps in identifying mammals across their diverse forms.

 

Question 13. Egg laying mammals belong to which group?
Answer: Egg-laying mammals, also known as monotremes, belong to the group Prototheria. These are unique mammals, like the platypus and echidna, that lay eggs instead of giving birth to live young. They also possess some reptilian characteristics.
In simple words: Mammals that lay eggs are part of the Prototheria group, like the platypus.

🎯 Exam Tip: Prototheria represents an ancient lineage of mammals that retains some ancestral traits, making them crucial for studying mammalian evolution.

 

Question 14. Name the National Animal of India.
Answer: The National Animal of India is the Tiger, specifically the Bengal Tiger (scientific name: Panthera tigris). It is known for its strength, grace, and stealth, symbolizing India's rich wildlife heritage. Its conservation is a national priority.
In simple words: The Tiger is India's National Animal. Its scientific name is Panthera tigris.

🎯 Exam Tip: Knowing national symbols like the national animal is important for general knowledge and understanding national identity.

 

Question 15. Write the Zoological name of lion.
Answer: The zoological name of the lion is Panthera leo. This scientific name uniquely identifies the species and is used universally by scientists. It highlights its genus Panthera, which also includes other big cats like tigers and jaguars.
In simple words: The scientific name for a lion is Panthera leo.

🎯 Exam Tip: Using correct zoological (scientific) names is essential in biology for precise identification and avoiding confusion with common names.

 

Question 2. What is the basis of division of chordates ?
Answer: Chordates are classified based on several key characteristics:
1. Skull: Presence of a skull (Craniata) or its absence (Acraniata).
2. Jaws: Absence of jaws (Agnatha) or presence of jaws (Gnathostomata).
3. Locomotion: Movement by paired fins (Pisces) or by paired legs (Tetrapoda).
4. Extra-embryonic membranes: Whether these membranes are absent (Anamniota) or present (Amniota).
These divisions reflect major evolutionary milestones in chordate development.
In simple words: Chordates are grouped by if they have a skull, if they have jaws, how they move (fins or legs), and if their embryos have special membranes.

🎯 Exam Tip: Understanding these fundamental criteria for chordate classification helps in categorizing diverse animal forms and grasping their evolutionary relationships.

 

Question 3. Give five difference between chordata and non-chordata.
Answer: Here are five key differences between Chordata and Non-Chordata:

These distinctions highlight the fundamental differences in body plans and evolutionary paths of these two large animal groups. For example, the notochord provides internal support in chordates.
In simple words: Chordates have a notochord, a nerve cord on their back, and gill slits at some point, while non-chordates do not have these features. Chordates also have a post-anal tail and primarily reproduce sexually.

🎯 Exam Tip: Focus on the four defining features of chordates (notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail) as key comparison points against non-chordates.

 

Question 4. Write four salient features of flying animals.
Answer: Four important features of flying animals, especially birds, include:

• Fore limbs are modified to form wings, which are adapted for flight.
• Hind limbs are positioned anteriorly and typically have four clawed digits, used for perching or walking.
• Absence of jaws and teeth, replaced by a lightweight beak, reduces head weight for flight.
• Presence of a beak made up of Keratin protein, which is strong but light.

These adaptations collectively allow for efficient aerial locomotion.
In simple words: Flying animals have wings instead of front legs, claws on their back legs, no teeth, and a light beak made of keratin.

🎯 Exam Tip: When describing adaptations for flight, always mention how features contribute to reducing weight, increasing lift, or improving maneuverability.

 

Question 5. What do you mean by “amniotes”? Name the classes belong to this group.
Answer: Amniotes are animals that have a fetal membrane called an amnion during their embryonic development. This amnion creates a protective, fluid-filled sac around the embryo, allowing them to develop on land without drying out. This was a crucial evolutionary step for terrestrial life. This group includes the classes: Reptilia (reptiles), Aves (birds), and Mammalia (mammals).
In simple words: Amniotes are animals whose embryos grow inside special protective membranes. Reptiles, birds, and mammals are all amniotes.

🎯 Exam Tip: The evolution of the amniotic egg was a significant adaptation that enabled vertebrates to colonize dry land away from water for reproduction.

 

Question 6. Define and give 2-2 examples of craniata and acraniata.
Answer:
Craniata: These are members of the phylum Chordata that possess a skull to protect their brain. The skull can be made of bone or cartilage. This feature is characteristic of all vertebrates. Examples of Craniata include Agnatha (jawless fish) and Gnathostomata (jawed vertebrates).
Acraniata: These are members of the phylum Chordata that do not have a skull. They represent simpler, more primitive chordates. Their brain is not enclosed by a bony or cartilaginous structure. Examples of Acraniata include Urochordata and Cephalochordata.
In simple words: Craniata are animals with a skull, like fish with jaws or without. Acraniata are animals without a skull, like sea squirts and lancelets.

🎯 Exam Tip: Distinguishing between Craniata and Acraniata is fundamental to understanding the early evolutionary branches within the phylum Chordata.

 

Question 7. What do you mean by diphyodont ? Members of which class show this feature?
Answer: Diphyodont refers to animals that develop two sets of teeth during their lifetime. The first set is typically temporary (milk teeth or deciduous teeth), followed by a permanent set of teeth. This allows for specialized dentition as an animal grows and its diet may change. This feature is a salient characteristic of the class Mammalia.
In simple words: Diphyodont animals grow two sets of teeth: baby teeth first, then permanent teeth. This is a main feature of mammals.

🎯 Exam Tip: Understanding dental patterns like diphyodonty is important for classifying mammals and interpreting their feeding ecology.

 

Question 9. Which group of mammals has marsupium ? What is the importance of marsupium ?
Answer: Members of Infraclass Metatheria (marsupials) possess a pouch-like structure called a marsupium. The importance of the marsupium is to provide a safe and nurturing environment for the young to complete their development after being born at a very immature stage. The young attach to a nipple inside the pouch and continue to grow, protected from the outside world.
In simple words: Marsupials, like kangaroos, have a pouch called a marsupium. It helps their tiny babies finish growing safely after birth.

🎯 Exam Tip: The marsupium is a key reproductive adaptation that distinguishes marsupials from other mammals, reflecting a different evolutionary strategy for offspring care.

 

Question 10. Explain movement of fishes according to the season. Give examples.
Answer: Fishes exhibit seasonal movements, often called migration, for purposes like reproduction or feeding. There are two main types:
(a) Catadromous: These are freshwater fishes that migrate to the sea to reproduce. After spawning, the adults usually die, and the young then return to freshwater habitats. An example is the Anguilla (freshwater eel).
(b) Anadromous: These are marine fishes that migrate to freshwater environments to reproduce. The young hatch in freshwater and later migrate back to the sea to grow into adults. Examples include Salmon, Hilsa, and Trout.
These migrations are essential for the survival of the species, ensuring suitable conditions for different life stages.
In simple words: Fish move between fresh and saltwater during different seasons. Catadromous fish go from fresh to salt water to lay eggs, like eels. Anadromous fish go from salt to fresh water to lay eggs, like salmon.

🎯 Exam Tip: Remember the direction of migration (Catadromous: freshwater -> sea; Anadromous: sea -> freshwater) and associate a classic example with each type.

 

Question 11. Name the class having dicondyllic skull.
Answer: The classes of phylum Chordata that possess a dicondylic skull include Superclass-Pisces (some), Class-Amphibia, and Class-Mammalia. A dicondylic skull means there are two occipital condyles at the base of the skull, which articulate with the first vertebra of the spinal column. This allows for precise head movement and is an evolutionary advancement.
In simple words: Some fish, amphibians, and mammals have a dicondylic skull, which means their head connects to the spine with two special joints.

🎯 Exam Tip: The type of skull articulation (monocondylic vs. dicondylic) is a key feature in vertebrate anatomy, indicating evolutionary relationships and adaptations for head mobility.

 

Question 12. Write four features of infra class eutheria.
Answer: Four key features of the Infraclass Eutheria (placental mammals) are:

• It includes true mammals that give birth to well-developed live young.
• Presence of well-developed pinnae (external ears).
• Presence of a highly developed corpus callosum in the brain, a structure that connects the two cerebral hemispheres.
• Presence of developed mammary glands bearing distinct teats for nursing young.

These features highlight their advanced reproductive and sensory adaptations.
In simple words: Eutheria are true mammals with good external ears, a well-developed brain connection (corpus callosum), and clear teats on their mammary glands.

🎯 Exam Tip: Eutheria represents the most diverse and successful group of mammals, largely due to their advanced placental reproduction and neurological development.

 

Question 1. Write main features of class mammalia. Explain its sub classes with examples.
Answer: Mammals (Class Mammalia) exhibit a wide range of characteristics that distinguish them from other vertebrates. They are highly adaptable and found in diverse habitats globally. Here are their main features and subclasses with examples:

**Characters:**

• They are cosmopolitan, meaning they are found in all types of habitats across the globe.
• The skin is thick, water-resistant, and well-developed, featuring various glands (like sweat and sebaceous) and sense organs.
• Presence of a corpus callosum in the brain, connecting the cerebral hemispheres.
• Presence of external, middle, and internal ears. The external ear has a distinct pinna, and the middle ear contains three ear ossicles (malleus, incus, stapes) for sound transmission.
• Presence of scrolled and porous turbinal bones in the nasal cavities, aiding in olfaction and regulating air temperature.
• Presence of seven cervical vertebrae (neck bones) in almost all mammals, regardless of neck length.
• Presence of mammary glands, normally functional in females, which produce milk to nourish young. These glands have teats or nipples.
• The teeth are thecodont (set in sockets), diphyodont (two sets of teeth), and heterodont (different types of teeth like incisors, canines, premolars, molars).
• Presence of a diaphragm between the thoracic (chest) and abdominal cavities, crucial for respiration.
• The thoracic cavity houses the heart (within the pericardial cavity) and lungs (within the pleural cavity).
• The heart is perfectly four-chambered (two atria, two ventricles), ensuring complete separation of oxygenated and deoxygenated blood.
• RBCs (red blood cells) are enucleated (lacking a nucleus) and biconcave in shape, increasing oxygen-carrying capacity. Sinus venosus is absent in the heart.
• Absence of a right systemic arch and a renal portal system (though a hepatic portal system is present).
• Presence of a dicondylic skull, articulating with the vertebral column via two occipital condyles.
• They are homiothermic (warm-blooded), maintaining a constant body temperature.
• They are ureotelic, meaning they excrete urea as their primary nitrogenous waste. Kidneys are metanephric, and a well-developed urinary bladder is present.
• Presence of 12 pairs of cranial nerves.
• Presence of four optic lobes (corpora quadrigemina) in the brain, involved in visual and auditory reflexes.
• Presence of Graffian follicles in the ovary, indicating advanced reproductive structures.
• Testes are exabdominal (located outside the abdominal cavity) in most, but abdominal testes are found in aquatic mammals (e.g., Whale, Dolphin, Seal) and elephants.
• They can be oviparous (egg-laying), ovo-viviparous (eggs hatch internally), or viviparous (live birth).
• Presence of a single copulatory organ and internal fertilization.
• Eggs are alecithal or microlecithal (little or no yolk) or polylecithal in some.
• Formation of a placenta in most mammals, which facilitates nutrient and gas exchange between mother and embryo.
• They are amniotes (possess embryonic membranes).
• Absence of a cloaca in most mammals.

**Subclasses and Examples:**
(A) **Subclass 1 = Prototheria (Monotremes)**
1. They are reptile-like mammals, retaining ancestral characteristics.
2. Mammary glands are present but without teats, functional in both males and females.
3. Absence of ear pinnae (external ear flaps).
4. Absence of a corpus callosum in the brain.
5. Presence of a cloaca (a single opening for excretion and reproduction).
6. Testes are abdominal.
7. Oviparous (egg-laying) and ova are polylecithal (large amount of yolk).
*Examples:* Tachyglossus (Echidna or spiny anteater, found in Australia & Tasmania); Ornithorhyncus (Duck-billed platypus).

(B) **Subclass 2 = Theria**
This subclass is further divided into two Infraclasses:

(a) **Infraclass 1 = Metatheria (Marsupials)**
1. Presence of ear pinnae.
2. Presence of corpus callosum in the brain, but it is less developed compared to eutherians.
3. In mammary glands, only teats are distinct.
4. The hind legs are much longer and stouter, adapted for leaping (e.g., kangaroos).
5. Presence of a long and massive tail that helps maintain body balance during leaping.
6. Presence of a marsupial pouch or marsupium, bearing teats in females, for carrying underdeveloped young.
7. They are ovoviviparous, giving birth to undeveloped young that complete development in the marsupium.
8. Eggs are microlecithal.
9. Absence of a cloaca.
10. Testes are exabdominal.
11. Presence of a yolk sac placenta.
*Examples:* Macropus (Kangaroo), Didelphys (Opossum, found in South America), Bandicoot.

(b) **Infraclass-2 = Eutheria (Placental Mammals)**
1. It includes true mammals that give birth to well-developed young.
2. Presence of well-developed pinnae.
3. Presence of a well-developed corpus callosum in the brain.
4. Presence of developed mammary glands bearing distinct teats.

**Examples of Eutherian Orders:**

• **Order- Insectivora:** *Example:* Hedgehog, Shrew/mole.
• **Order- Dermoptera:** *Example:* Flying squirrel.
• **Order- Chiroptera:** Includes flying mammals. Fore limbs are modified into wings. *Examples:* Pteropus (Fruit bat), Rhinopoma (Insectivorous bat), Desmodus (Vampire bat).
• **Order- Rodentia:** *Examples:* Rat, Squirrel, Porcupine (hair modified to form long spines), Guinea pig.
• **Order- Edentata:** *Examples:* Bradypus, Colaepus, Trichecus Armadilo, Giant ant eater.
• **Order- Pholidota:** *Example:* Manis (Pangolin or scaly ant eater).
• **Order- Lagomorpha:** *Examples:* Rabbit, Hare, Pika.
• **Order- Carnivora:** *Examples:* Panthera leo (lion), Panthera tigris (Tiger, National animal), Panthera pardus (leopard), Felis domesticus (cat), Canisfamiliaris (dog), Canis lupus (Wolf), Canis aureus (Jackal), Ursus (Bear), Callorhinus (Sea lion), Pinnipedia (Seal), Odobenus (walrus).
• **Order - Cetacea:** *Examples:* Porpoise (smallest whale), Balaenoptera (Largest whale and largest living mammal), Platanista gangetica gangetica (Ganga Dolphin, National aquatic animal).
• **Order - Sirenia:** *Examples:* Manatees (Sea cow), Dugong.
• **Order - Tubulidentata:** *Example:* Aardwark.
• **Order - Proboscidea:** *Examples:* Elephas (Indian elephant), Loxodonta (African elephant) - largest living terrestrial animal.
• **Order - Hyracoidea:** *Example:* Hyrax.
• **Order - Artiodactyla (Even-toed animals):** *Examples:* Cow, Buffalo, camel, Gazella gazella (Chinkara, Rajasthan state animal), Goat, Sheep, Deer, Blue cow, Giraffe, Pig, Hippopotamus.
• **Order - Perissodactyla (Odd-toed animals):** *Examples:* Horse, Donkey, Zebra, Rhinoceros.

Mammals are also highly useful to human beings directly or indirectly.
**(A) Useful Mammals:**
Mammals play a vital role in ecosystems and for humans:
(i) **In Agriculture:** Many mammals like camels and oxen are used for plowing fields. Their excreta (dung and urine) is a good source of nitrogen and other nutrients, used as fertilizer. Cow dung is also used in biogas plants to produce biogas, an alternative energy source for cooking, with the leftover slurry used as fertilizer.
(ii) **In Transportation:** Mammals like camels, elephants, horses, and oxen have been used for transportation for centuries. Camels are vital in deserts, while tundra dogs and reindeer are used in polar regions, and yaks in Tibet.
(iii) **Hunting and Recreation:** Historically, humans hunted mammals for sport, food, and other products. This practice, involving mammals like lagomorphs (rabbit, hare) and ungulates (hoofed animals), has evolved into a significant industry.
(v) **Oil:** Oil extracted from many mammals, such as whales, is used in various products like soap, paint, candles, ointments, shoe polish, and lubricants.
(vi) **Products like Musk and Ivory:** Musk, from musk deer, is a powerful aphrodisiac and used in perfumes, also having anti-inflammatory and antihistaminic properties. Ivory, from elephant tusks, is a costly hard white material used for making items like cutlery handles, musical instruments (piano keys), and bangles.
(vii) **Business point of view:** The skin of many mammals is used to make leather for purses, shoes, sandals, and suitcases. Hooves and horns are used for toys, combs, frames, and knife handles. Camel hair and pig bristles are used for brushes.
(viii) **Skeleton:** Bones of dead mammals are used to make bone charcoal for the sugar industry. Whale bones yield gum and gelatin, used in photographic films. Phosphate from bones is used as fertilizer.
(ix) **For amusement and tourism:** Many mammals like monkeys, bears, rabbits, foxes, lions, tigers, deer, blue cows, and peacocks are kept in amusement parks and zoos to entertain the public and tourists.
(x) **Laboratory use:** Many mammals such as rats, rabbits, guinea pigs, and squirrels are used in laboratories for student education and research purposes.
(xi) **Scavengers:** Many mammals like dogs, pigs, and jackals feed on decaying organic matter and dead animals, helping to clean the environment.

**(B) Harmful Mammals:**
(i) **Crop damage:** Blue cows (Boselaphus tragocamelus) graze on and damage various crops, especially during morning and evening.
(ii) **Vectors for pathogens:** Some mammals act as vectors for human pathogens. For example, consuming undercooked pork or beef can lead to infections by Taenia solium and Taenia saginata. Rabid dogs, foxes, and monkeys transmit rabies. Rats transmit plague via fleas.
(iii) **Predators:** Many carnivorous wild mammals, such as lions, tigers, and wolves, hunt useful domestic animals like goats, sheep, pigs, hens, and cows. Occasionally, they also attack humans.
In simple words: Mammals have hair, mammary glands, a diaphragm, and are warm-blooded. They are divided into egg-laying (monotremes), pouched (marsupials), and placental mammals. They are useful for food, transport, and research, but some can harm crops or spread diseases.

🎯 Exam Tip: When asked to describe a broad class like Mammalia, organize your answer into distinct sections (characteristics, subclasses, uses, harms) and provide specific examples for each point to score full marks.

 

Question 2. Give an account of reptilian characters and examples ?
Answer: Reptiles (Class Reptilia) are a diverse group of cold-blooded vertebrates, primarily adapted for terrestrial life. Here are their key characteristics and classification with examples:

**Characters:**

• Most reptiles are terrestrial, but some are aquatic, many crawl, and some burrow.
• The body is typically divided into a distinct head, neck, trunk, and tail.
• Their skin is rough, dry, and lacks glands, covered by epidermal scales or scutes, which prevent water loss.
• The endoskeleton is bony, and the skull can be mono- or dicondylic.
• The heart is incompletely four-chambered, with two auricles and a partially divided ventricle (except crocodiles, which have a fully four-chambered heart).
• RBCs (red blood cells) are oval, nucleated, and biconvex.
• Presence of 12 pairs of cranial nerves.
• A renal portal system is present.
• They are uricotelic, excreting uric acid as their primary nitrogenous waste. They have a pair of metanephric kidneys.
• The urinary bladder is highly reduced or absent.
• Sinus venosus is absent in the heart.
• Presence of three pairs of aortic arches.
• Respiration occurs through a pair of lungs.
• They are Poikilothermic (cold-blooded), meaning their body temperature varies with the environment.
• Presence of middle and internal ears; the middle ear has a columella auris (single ear bone).
• They are unisexual, fertilization is internal, and development is direct (no larval stage).

**Classification:**
Reptiles are classified based on the number and arrangement of temporal vacuities (openings) in their skull. It is divided into 4 subclasses:

1. **Subclass - Anapsida:**

• Absence of temporal vacuities in the skull.
• Further divided into two orders:

(i) **Order 1 - Cotylosauria:**
*Example:* Semouria – considered a connecting link between amphibians and reptiles.
(ii) **Order 2 - Chelonia:**
*Examples:* Trionyx (Freshwater terrapin); Chelone (Marine turtle); Testudo (Terrestrial tortoise).

2. **Subclass - Parapsida:**

• Possesses one pair of temporal vacuities in the skull.
• All members are extinct.

*Example:* Dinosaurs.

3. **Subclass - Diapsida:**

• Possesses two pairs of temporal vacuities in the skull.
• Further divided into three orders:

(i) **Order 1 - Rhyncocephalia:**
*Example:* Sphenodon (Tuatara; a living fossil).
(ii) **Order 2 - Squamata:**
*Examples:*
(A) Lizards: Hemidactylus (House lizard), Dracco (Flying lizard), Heloderma (Gila monster, venomous lizard), Calotes (Garden lizard), Ophiosaurus (Limbless lizard or glass snake), Chameleon (Garden lizard).
(B) Snakes: Naja (Cobra), Hydrophis (Sea snake), Typhlops (Blind snake), Viper.
(iii) **Order 3 - Crocodilia:**
*Examples:* Crocodile, Gavialis (Gharial), Alligator.

4. **Subclass - Synapsida:**

• Possesses two pairs of temporal vacuities in the skull, but the two vacuities of one side fuse to become one.
• Completely extinct.

*Example:* Dimetrodon.
In simple words: Reptiles have dry, scaly skin and are cold-blooded. Their hearts usually have three chambers. They reproduce by laying eggs on land. They are classified by skull openings into groups like Anapsida (turtles), Diapsida (lizards, snakes, crocodiles), and extinct groups like Parapsida and Synapsida.

🎯 Exam Tip: Focus on understanding the adaptations that allowed reptiles to thrive on land (e.g., dry skin, amniotic egg) and how skull fenestration is used in their classification.

 

Question 3. Write the main features of class amphibia.
Answer: Amphibians can live both in water and on land. They live alone, move freely, and are cold-blooded, meaning their body temperature changes with their surroundings. Their body has a head, trunk, and a tail, though some might not have a tail. They have a three-chambered heart with two upper parts and one lower part. Amphibians hibernate and aestivate, which means they go into a deep sleep during extreme cold or heat. They possess middle and inner ears, with a small bone called the columella auris. Their kidneys are mesonephric, and they get rid of waste as urea. They have a sinus venosus in their heart and three pairs of main blood vessels called aortic arches. Fertilization happens outside the body, and their development is indirect, meaning they have a larval stage. They lay eggs, and these eggs contain a medium amount of yolk. The tadpole is a common larval form for amphibians, and some larvae, like axolotls, keep their gills even as adults.
In simple words: Amphibians live on land and in water, have a three-chambered heart, and are cold-blooded. They often have a tadpole stage before becoming adults.

🎯 Exam Tip: When describing animal characteristics, always include their habitat, body temperature regulation, heart structure, and reproductive methods.

 

Question 4. Write the features and examples of super class pisces.
Answer: Pisces are aquatic animals that live in both fresh and saltwater. They can be free-swimming, live alone, or be parasites. Their bodies are streamlined, like a boat, and are divided into a head, trunk, and tail. They have paired fins (like pectoral and pelvic fins) and unpaired fins (like caudal, dorsal, and ventral fins) that help them move. These fins are supported by bone or cartilage rays. Their skin is covered with different types of scales, such as placoid, ctenoid, cycloid, or rhomboid scales. Fish are cold-blooded, meaning their body temperature depends on their environment. They breathe using 5 to 7 pairs of gill slits, and some also have an operculum, or gill cover. They have a closed blood system, and their red blood cells have a nucleus and are shaped like a disc. Fish also have a renal portal system, which is a special blood circulation path involving the kidneys. Their heart has only two chambers (one upper and one lower part) and is called a "venous heart" because it carries only deoxygenated blood. They also have a sinus venosus in their heart and six pairs of aortic arches. Most fish get rid of waste as ammonia, but some excrete urea and TMAO. They have mesonephric kidneys and no urinary bladder. Fish are anamniotes, meaning they do not have a fetal membrane. Some fish migrate seasonally; for example, catadromous fish like Anguilla move from freshwater to the sea to breed, while anadromous fish like Salmon, Hilsa, and Trout move from marine water to freshwater to reproduce. Their skull has two points where it connects to the spine.
In simple words: Fish live in water, have streamlined bodies with fins, breathe through gills, and are cold-blooded. Many fish migrate between fresh and salt water for breeding.

🎯 Exam Tip: Remember to mention the type of heart (venous), presence of gills, and scale types when describing Pisces. Including specific examples for migration types helps score extra marks.