Samacheer Kalvi Class 11 Bio Zoology Solutions Chapter 2 Kingdom Animalia

Part I

I. Choose The Best Options

 

Question 1. The symmetry exhibited in cnidarians is
(a) Radial
(b) Bilateral
(c) Pentamerous radial
(d) Asymmetrical
Answer: (a) Radial
In simple words: Cnidarians, like jellyfish and sea anemones, have a body shape that is circular, meaning you can cut them into identical halves in many ways through their center. This is called radial symmetry.

🎯 Exam Tip: Remember radial symmetry allows an animal to detect food or threats from any direction, which is common in animals that are sessile or float.

 

Question 2. Sea anemone belongs to phylum
(a) Protozoa
(b) Porifera
(c) Coelenterata
(d) Echinodermata
Answer: (c) Coelenterata
In simple words: Sea anemones are simple marine animals that belong to the phylum Coelenterata, also known as Cnidaria. They have stinging cells used for catching food and defense.

🎯 Exam Tip: Coelenterata is often used interchangeably with Cnidaria; both refer to the same group of animals with a hollow body cavity and stinging cells.

 

Question 3. The excretory cells that are found in platyhelminthes are
(a) Protonephridia
(b) Flame cells
(c) Solenocytes
(d) All of these
Answer: (b) Flame cells
In simple words: Platyhelminthes, or flatworms, get rid of waste using special cells called flame cells. These cells have cilia that beat like a flickering flame to move waste out of the body.

🎯 Exam Tip: Flame cells are a distinctive feature of flatworms and are part of their protonephridia, which are primitive excretory organs.

 

Question 4. In which of the following organisms, self fertilization is seen.
(a) Fish
(c) Earthworm
(d) Liver fluke
Answer: (d) Liver fluke
In simple words: Self-fertilization means an organism can fertilize its own eggs. This is common in some parasites like the liver fluke, allowing them to reproduce even when alone inside a host.

🎯 Exam Tip: Self-fertilization is a key adaptation for many parasitic organisms, ensuring reproduction even when finding a mate is difficult.

 

Question 5. Nephridia of Earthworms are performing the same functions as
(a) Gills of prawn
(b) Flame cells of Planaria
(c) The trachea of insects
(d) Nematoblasts of Hydra
Answer: (b) Flame cells of Planaria
In simple words: Earthworms use nephridia to remove waste and control water balance. This is similar to how flame cells in Planaria (a type of flatworm) work, as both are excretory organs.

🎯 Exam Tip: Comparing excretory organs across different phyla helps understand evolutionary adaptations for waste removal and osmoregulation.

 

Question 6. Which of the following animals has a true coelom?
(a) Ascaris
(b) Pheretima
(c) Sycon
(d) Taenia solium
Answer: (b) Pheretima
In simple words: A true coelom is a body cavity completely lined by mesoderm tissue. Pheretima, which is an earthworm, belongs to Annelida, a group known for having a true coelom.

🎯 Exam Tip: Identifying true coelomates is important for classifying animals based on their body plan and developmental characteristics.

 

Question 7. Metameric segmentation is the main feature of
(a) Annelida
(c) Anropoda
(d) Coelenterata
Answer: (a) Annelida
In simple words: Metameric segmentation means an animal's body is divided into repeating segments, both internally and externally. This feature is a key characteristic of the phylum Annelida, which includes earthworms and leeches.

🎯 Exam Tip: Metamerism allows for specialized functions in different segments and more efficient movement, especially in worms.

 

Question 8. In Pheretima locomotion occurs with the help of
(a) circular muscles
(b) longitudinal muscles and setae
(c) circular, longitudinal muscles and setae
(d) parapodia
Answer: (c) circular, longitudinal muscles and setae
In simple words: Earthworms (Pheretima) move by using both their circular and longitudinal muscles. They also use small bristles called setae to grip the ground, which helps them crawl and burrow.

🎯 Exam Tip: The coordinated action of antagonistic muscles and structures like setae or parapodia is crucial for locomotion in segmented worms.

 

Question 9. Which of the following have the highest number of species in nature?
(a) Insects
(b) Birds
(c) Angiosperms
Answer: (a) Insects
In simple words: Insects are the most diverse group of animals on Earth, with more species than any other group. They live in almost every habitat and play many roles in ecosystems.

🎯 Exam Tip: Remember that insects, specifically beetles, represent the largest and most diverse order in the animal kingdom.

 

Question 10. Which of the following is a crustacean?
(a) Prawn
(b) Snail
(c) Sea anemone
Answer: (a) Prawn
In simple words: Prawns are part of a group of animals called crustaceans, which are mostly aquatic and have hard outer shells (exoskeletons) and jointed legs. Other crustaceans include crabs and lobsters.

🎯 Exam Tip: Crustaceans are arthropods, characterized by their exoskeleton, segmented bodies, and jointed appendages, typically found in aquatic environments.

 

Question 11. The respiratory pigment in cockroach is
(a) Haemoglobin
(b) Haemocyanin
(c) Heamoerythrin
(d) None of the options
Answer: (d) None of the options
In simple words: Cockroaches, like most insects, do not have respiratory pigments like haemoglobin in their blood to carry oxygen. Instead, they use a system of tubes called tracheae to deliver oxygen directly to their tissues.

🎯 Exam Tip: Insects have an open circulatory system and a tracheal system for respiration, which makes respiratory pigments in their hemolymph (blood) unnecessary.

 

Question 12. Exoskeleton of which phylum consists of chitinous cuticle?
(a) Annelida
(b) Porifera
(c) Arthropoda
(d) Echinodermata
Answer: (c) Arthropoda
In simple words: Arthropods, which include insects, spiders, and crustaceans, have an external skeleton made mainly of a tough material called chitin. This chitin forms a protective cuticle around their bodies.

🎯 Exam Tip: The chitinous exoskeleton provides support, protection, and prevents water loss, but it requires molting (shedding) for growth.

 

Question 13. Lateral line sense organs occur in
(a) Salamander
(b) Frog
(d) Fish
Answer: (d) Fish
In simple words: Fish have a special sensory system called the lateral line, which runs along their sides. This system helps them detect movement, vibrations, and pressure changes in the water, helping them navigate and find prey.

🎯 Exam Tip: The lateral line system is unique to aquatic vertebrates and is essential for their survival in water, functioning similarly to hearing and touch.

 

Question 14. The limbless amphibian is
(a) Icthyophis
(b) Hyla
(c) Rana
(d) Salamander
Answer: (a) Icthyophis
In simple words: Icthyophis, also known as caecilians, are a type of amphibian that look like large worms or snakes and do not have limbs. They live mostly underground or in water.

🎯 Exam Tip: Amphibians are diverse, and while most are known for having four limbs, caecilians are an important limbless exception.

 

Question 15. Four chambered heart is present in
(a) Lizard
(b) Snake
(c) Scorpion
(d) Crocodile
Answer: (d) Crocodile
In simple words: Most reptiles have a three-chambered heart, but crocodiles are unique among reptiles for having a fully four-chambered heart. This efficient heart structure is similar to that of birds and mammals.

🎯 Exam Tip: Knowing exceptions to general rules, like the crocodile's four-chambered heart among reptiles, is crucial for higher-level biology questions.

 

Question 16. Which of the following is not correctly paired?
(a) Humans – Ureotelic
(b) Birds - Uricotelic
(c) Lizards – Uricotelic
(d) Whale - Ammonotelic
Answer: (d) Whale – Ammonotelic
In simple words: Whales are marine mammals that excrete urea, making them ureotelic. Ammonotelic animals, which excrete ammonia, are typically aquatic invertebrates and fish, as ammonia needs a lot of water to dilute.

🎯 Exam Tip: The type of nitrogenous waste (ammonia, urea, uric acid) an animal excretes is closely linked to its habitat and water availability.

 

Question 17. Which of the following is an egg laying mammal?
(a) Delphinus
(b) Macropus
(c) Ornithorhynchus
(d) Equus
Answer: (c) Ornithorhynchus
In simple words: Ornithorhynchus, commonly known as the platypus, is a unique mammal because it lays eggs instead of giving birth to live young. These mammals are called monotremes.

🎯 Exam Tip: Monotremes (platypus and echidnas) are fascinating evolutionary examples, showing a blend of mammalian and reptilian characteristics.

 

Question 18. Pneumatic bones are seen in
(a) Mammalia
(b) Aves
(c) Reptilia
(d) Sponges
Answer: (b) Aves
In simple words: Pneumatic bones are hollow bones filled with air cavities, making them very light. This adaptation is found in birds (Aves) and is crucial for flight, reducing their overall body weight.

🎯 Exam Tip: Pneumatic bones, along with feathers and powerful flight muscles, are key adaptations that enable birds to fly efficiently.

 

Question 19. Match the following columns and select the correct option.
Answer: (b) p – (iii), q – (iv), r – (ii), s – (i)

In simple words: This question matches animals with their correct common names or related terms. Pila is an apple snail, the tusk shell belongs to Scaphopoda, Chaetopleura is a chiton, and Octopus is also known as a devil fish.

🎯 Exam Tip: Familiarize yourself with both scientific and common names of animals, as well as their characteristic features or taxonomic groups.

 

Question 20. In which of the following phyla, the adult shows radial symmetry but the larva shows bilateral symmetry?
(a) Mollusca
(b) Echinodermata
(c) Arthropoda
(d) Annelida
Answer: (b) Echinodermata
In simple words: Echinoderms, like starfish, have radial symmetry as adults, meaning their bodies are arranged around a central point. However, their young forms (larvae) have bilateral symmetry, with two matching halves. This suggests an evolutionary link to bilaterally symmetrical ancestors.

🎯 Exam Tip: This unique developmental pattern in echinoderms, where larval and adult symmetries differ, is a key concept in zoology and evolutionary biology.

 

Question 21. Which of the following is correctly matched?
(a) Physalia – Portuguese man of war
(b) Pennatula – Sea fan
(c) Adamsia – Sea pen
(d) Gorgonia – Sea anemone
Answer: (a) Physalia – Portuguese man of war
In simple words: Physalia is correctly known as the Portuguese man of war. It is a colonial organism made of many individual polyps working together. Pennatula is a sea pen, Adamsia is a sea anemone, and Gorgonia is a sea fan.

🎯 Exam Tip: Accurate knowledge of common names for marine invertebrates, especially cnidarians, is often tested.

 

Question 22. Why are spongin and spicules important to a sponge?
Answer: Spongin and spicules are like the skeleton of a sponge. They provide support to the soft parts of the sponge's body. Spicules, which are tiny, sharp structures, also give sponges their stiffness and shape. These structural components are crucial for maintaining the sponge's form and filtering capabilities.
In simple words: Spongin and spicules give sponges their shape and support. They act like a internal framework, helping the soft sponge body stay firm.

🎯 Exam Tip: Remember that spongin is a protein fiber and spicules are made of calcium carbonate or silica, with their composition often used in sponge classification.

 

Question 23. What are the four characteristics common to most animals?
Answer: The four characteristics common to most animals are:
1. Cellular structure: Animals are multicellular organisms with eukaryotic cells.
2. The nature of coelom: Animals can be acoelomates (no body cavity), pseudocoelomates (false body cavity), or eucoelomates (true body cavity).
3. Notochord: Many animals, especially chordates, possess a notochord at some stage of development.
4. Segmentation or absence of segmentation: Animal bodies can be segmented (like earthworms) or unsegmented. These features define the basic body plan of different animal groups.
In simple words: Most animals have bodies made of many cells, they might have a body cavity (coelom), some have a notochord, and their bodies can be segmented or not.

🎯 Exam Tip: These four characteristics (cellularity, coelom type, notochord presence, segmentation) are fundamental for understanding animal classification and evolution.

 

Question 24. List the features that all vertebrates show at some point in their development.
Answer: All vertebrates share several key features during their development. These include possessing a notochord, which is later replaced by a vertebral column in most adults. They also have paired appendages like fins or limbs, depending on the species. Their skin is protected by a skeleton that can include scales, feathers, hairs, claws, or nails. Respiration happens aerobically, often through gills, skin, or lungs, sometimes involving a buccopharyngeal cavity. Additionally, all vertebrates have a muscular heart with two, three, or four chambers, and kidneys are present for excretion and osmoregulation.
In simple words: All vertebrates have a notochord (which becomes the backbone), paired limbs, protective skin (scales, feathers, or hair), breathing organs (gills or lungs), a chambered heart, and kidneys for waste removal.

🎯 Exam Tip: Focusing on the embryonic presence of the notochord is crucial, as it's a defining chordate feature even if it transforms in adults.

 

Question 25. Compare closed and opened circulatory system
Answer:

In simple words: In an open circulatory system, blood flows freely around organs, not in vessels, like in insects. In a closed system, blood always stays inside tubes (vessels), like in humans and earthworms, making circulation more efficient.

🎯 Exam Tip: Remember that a closed circulatory system allows for faster and more controlled delivery of oxygen and nutrients to tissues.

 

Question 26. Compare Schizocoelom with enterocoelom
Answer:

In simple words: Schizocoelom forms when the mesoderm splits to create a body cavity, seen in segmented worms and insects. Enterocoelom forms from pouches budding off the primitive gut (archenteron), seen in starfish and vertebrates.

🎯 Exam Tip: The distinction between schizocoelous and enterocoelous development is a key concept in animal embryology and phylogenetic classification.

 

Question 27. Identify the structure that the archenteron becomes in a developing animal.
Answer: The archenteron is the primitive gut that forms during the early development of an embryo. In a developing animal, the archenteron becomes the entire digestive tract. It forms the foundation for all the digestive organs, from the mouth to the anus. This development establishes the basic body plan of the animal.
In simple words: The archenteron is the very first gut that forms in an embryo. It grows into the animal's entire digestive system, including the stomach and intestines.

🎯 Exam Tip: Understanding the fate of embryonic structures like the archenteron is fundamental to grasping animal development and evolutionary relationships.

 

Question 28. Observe the animal below and answer the following questions
a. Identify the animal
b. What type of symmetry does this animal exhibit?
c. Is this animal Cephalized?
d. How many germ layers does this animal have?
e. How many openings does this animal's digestive system have?
f. Does this animal have neurons?
Answer:
a) The animal is a Sea anemone.
b) It exhibits Bilateral symmetry.
c) It is not a cephalized animal (meaning it does not have a distinct head).
d) It is a Diploblastic animal, having two germ layers.
e) It has One opening in its digestive system, which acts as both mouth and anus.
f) Yes, this animal has neurons, forming a nerve net.
In simple words: This animal is a sea anemone. It has bilateral symmetry. It doesn't have a head and has two body layers. It has one opening for eating and waste, and it does have simple nerves.

🎯 Exam Tip: For diagram-based questions, carefully identify the animal and recall its characteristic features related to body plan, germ layers, and digestive system.

 

Question 29. Choose the term that does not belong in the following group and explain why it does not belong?
• The notochord, cephalization, dorsal nerve cord, and radial symmetry.
Answer: Radial symmetry is the term that does not belong to the group. Notochord, cephalization, and dorsal nerve cord are all characteristic features of chordates or animals with a more advanced body plan. The radial symmetry, however, is not a characteristic feature of chordates. Instead, it is typically found in cnidarians (like jellyfish) and adult echinoderms (like starfish). Thus, radial symmetry stands out as different from the other features listed, which are more specific to chordate development and body organization.
In simple words: Radial symmetry doesn't fit with the other terms. Notochord, cephalization, and dorsal nerve cord are features of animals with backbones or advanced body plans. Radial symmetry is found in simpler animals like jellyfish or adult starfish.

🎯 Exam Tip: Always analyze groups of biological terms for common evolutionary or developmental links to identify the odd one out. Radial symmetry is a very primitive body plan.

 

Question 30. Why flatworms are called acoelomates?
Answer: Flatworms are called acoelomates because they do not have a true body cavity (coelom). While their body cavity is formed from mesoderm, in flatworms, there is no empty body cavity. Instead, the space between the body wall and the digestive tract is completely filled with a solid tissue called parenchyma. This gives their body a solid structure, lacking the fluid-filled space found in coelomates.
In simple words: Flatworms are called acoelomates because they don't have a hollow body space. Their bodies are solid inside, filled with tissue between the outer wall and the gut.

🎯 Exam Tip: Understanding the presence or absence of a coelom is fundamental to classifying animals and understanding their internal organization.

 

Question 31. What are flame cells?
Answer: Flame cells are specialized excretory cells found in flatworms, such as Planaria. These cells are unique because they possess a tuft of cilia that flicker continuously, resembling a flame. Their main role is to remove excess water, metabolic wastes, and other harmful substances from the flatworm's body. They also play a critical role in osmoregulation, helping to maintain the internal water balance of the organism.
In simple words: Flame cells are special cells in flatworms that act like kidneys. They use tiny hairs (cilia) that beat to push out waste and control water inside the worm's body.

🎯 Exam Tip: Flame cells are part of the protonephridia system, representing a simple but effective excretory and osmoregulatory organ in lower invertebrates.

 

Question 32. Concept Mapping – Use the following terms to create a concept map that shows the major characteristic features of the phylum Nematoda: Roundworms, pseudocoelomates, digestive tract, cuticle, parasite, sexual dimorphism
Answer: The phylum Nematoda consists of Roundworms. These animals are characterized by being pseudocoelomates, meaning they have a false body cavity not fully lined by mesoderm. They possess a complete digestive tract with a mouth, pharynx, and anus. A tough outer covering called a cuticle protects their bodies. Many nematodes live as parasites, affecting plants and animals. They also show sexual dimorphism, meaning males and females have distinct physical differences, often with males having a small, pointed tail and females being larger.
In simple words: Nematodes are roundworms with a fake body cavity and a full gut. They have a tough skin and can be parasites. Males and females look different.

🎯 Exam Tip: When creating a concept map from terms, start with the main topic (Nematoda) and then link related characteristics, describing how each term applies to the phylum.

 

Question 33. In which phylum is the trochophore larva found?
Answer: The trochophore larva is a free-swimming larval form that is typically found in the Phylum Annelida (segmented worms) and also in some molluscs. This larva has a distinctive band of cilia around its middle that helps it move through water. It represents a common larval stage found in many Lophotrochozoan invertebrates.
In simple words: The trochophore larva, which swims freely, is found in the phylum Annelida, which includes animals like earthworms.

🎯 Exam Tip: Trochophore larvae are important indicators of evolutionary relationships between different invertebrate phyla, particularly Annelida and Mollusca.

 

Question 34. Which of the chordate characteristics do tunicates retain as adults?
Answer: Tunicates, which are marine filter-feeders, are chordates that undergo significant metamorphosis. As adults, they primarily retain the ventral and tubular heart, which is a key characteristic. They also perform respiration through gill slits (pharyngeal slits). While larvae possess a notochord and dorsal nerve cord, these are typically lost in the adult stage. The presence of a post-anal tail is also usually lost.
In simple words: Adult tunicates keep their ventral heart and breathe using gill slits. They lose other chordate features like the notochord and tail when they grow up.

🎯 Exam Tip: Tunicates highlight how some chordate features are transient, appearing only during larval stages, making them an important example in evolutionary studies.

 

Question 35. List the characteristic features that distinguish cartilaginous fishes from living jawless fishes.
Answer:

In simple words: Jawless fish are eel-shaped, parasitic, have many gill slits, and a round mouth without jaws. Cartilaginous fish have tough skin with special scales, jaws, fewer gill slits, and are free-living predators.

🎯 Exam Tip: Focus on fundamental differences like the presence of jaws, skeleton type (cartilage vs. bone), and scale structure when comparing fish groups.

 

Question 36. List three features that characterise bony fishes.
Answer: Three features that characterize bony fishes are:
1. These fishes have a bony endoskeleton, which is a hard internal skeleton made of bone.
2. The skin is typically covered by ganoid, cycloid, or ctenoid scales, providing protection.
3. Gills are covered by an operculum, a bony flap that protects the gills and aids in water flow. Bony fishes are also generally ammonotelic, meaning they excrete ammonia, and have mesonephric kidneys.
4. They are ammonotelic.
5. They have mesonephric kidneys.
6. External fertilization is seen.
In simple words: Bony fish have a skeleton made of bone, their skin has scales, and their gills are covered by a protective flap. They excrete ammonia and usually fertilize eggs outside the body.

🎯 Exam Tip: The operculum and bony skeleton are key distinguishing features of bony fish compared to cartilaginous fish.

 

Question 37. List the functions of air bladder in fishes.
Answer: The air bladder in fishes serves several important functions:

• The air bladder may be connected to the gut or not, depending on the fish species (physostomous vs. physoclistous).
• They help in gaseous exchange, acting as a primitive lung in some species.
• In ray-finned fishes, they primarily help in buoyancy, allowing the fish to maintain its depth in the water column without expending too much energy.

The air bladder is a versatile organ, adapting its role to the specific needs and environment of different fish.
In simple words: The air bladder helps fish float at different depths, can assist with breathing in some species, and might be connected to the gut.

🎯 Exam Tip: Remember that while buoyancy is the primary role, the air bladder's secondary functions, such as respiration and sound production, are also important.

 

Question 38. Write the characteristics that contribute to the success of reptiles on land.
Answer: The features that help reptiles succeed on land include:
- Their skin is dry and tough, with scales, which stops water loss from their body.
- They have a metanephric kidney that helps them save water.
- Reptiles are uricotelic, meaning they excrete uric acid, which is another way to prevent water loss. This makes them well-adapted to drier environments.
In simple words: Reptiles have dry skin, special kidneys, and get rid of waste in a way that helps them keep water, which are all important for living on land.

🎯 Exam Tip: When listing characteristics, ensure you explain *why* each feature is advantageous for the animal's survival in its specific environment.

 

Question 39. List the unique features of a bird's endoskeleton.
Answer: A bird's skeleton has unique features to support flight:
- Their inner skeleton is fully hardened (ossified).
- The long bones in their body are hollow and filled with air spaces, making them lighter. This reduction in weight is crucial for effective flight.
In simple words: Birds have very strong but light bones because they are hollow, which helps them fly easily.

🎯 Exam Tip: Remember that bone structure is directly related to an animal's locomotion and lifestyle, especially for flying creatures.

 

Question 40. Could the number of eggs or young ones produced by an oviparous and viviparous female be equal? Why?
Answer: No, the number of eggs or young ones produced by an oviparous (egg-laying) and viviparous (live-bearing) female cannot be equal.
When oviparous animals lay eggs in the environment, the chances of these eggs surviving and developing into adults are not very high due to external threats. Therefore, they lay more eggs to increase the odds of some surviving. Viviparous animals, however, nurture their young inside their bodies, providing protection and care, which leads to a higher survival rate for each offspring. This internal development means fewer offspring are needed for the species to continue.
In simple words: Egg-laying animals make more eggs because many might not survive outside the body. Animals that give birth to live young have fewer babies because they protect them inside, so more of them live.

🎯 Exam Tip: Focus on the concept of parental investment and environmental hazards as key reasons for the difference in offspring numbers between oviparous and viviparous species.

Part II

11th Bio Zoology Guide Kingdom Animalia Additional Important Questions and Answers

I. Choose The Best Options

 

Question 1. ..................................... is the first group of animals to exhibit tissue-level organization.
(a) Cnidaria
(b) Porifera
(c) Mollusca
(d) Echinodermata
Answer: (a) Cnidaria
In simple words: Cnidarians, like jellyfish and sea anemones, are important because they are the first animals to have tissues, which are groups of cells working together.

🎯 Exam Tip: Remember that the progression of organization levels is key in animal classification, starting from cellular (Porifera) to tissue (Cnidaria), then organ, and finally organ system.

 

Question 2. Name the organs formed from ectoderm.
(a) Heart
(b) Hair
(c) Muscle
(d) Intestine
Answer: (b) Hair
In simple words: The ectoderm is the outermost layer of cells in an early embryo, and it forms external parts like hair and skin.

🎯 Exam Tip: Knowing the derivatives of the three germ layers (ectoderm, mesoderm, endoderm) is fundamental for understanding animal development and anatomy.

 

Question 3. The mesoglea seen in between the ectoderm and endoderm is present in phylum
(a) Platyhelminthes
(b) Arthropoda
(c) Annelida
(d) Coelenterates
Answer: (d) Coelenterates
In simple words: Coelenterates, also known as Cnidarians, have a jelly-like layer called mesoglea between their two main cell layers. This layer provides support to their body.

🎯 Exam Tip: The presence of mesoglea is a distinguishing feature of diploblastic animals, which have only two germ layers.

 

Question 4. Inporiferans through pores water enters into the body and goes out through.
(a) Osculum Ostia
(b) Ostia Osculum
(c) Mouth Ostia
(d) Mouth Osculum
Answer: (b) Ostia Osculum
In simple words: In sponges, water enters through many small pores called ostia and then leaves through a larger opening called the osculum.

🎯 Exam Tip: Understanding the water canal system in Porifera (sponges) is key to knowing how they feed and respire.

 

Question 5. Choose the correct option.
(a) Segmentation – Annelida
(b) Archenteron – Heart Formation
(c) Ostia - Sea anemone
(d) Polyp Medusa – Phylum Ptenopora
Answer: (a) Segmentation – Annelida
In simple words: Annelids, like earthworms, have bodies divided into many segments, which is called segmentation. This feature allows for specialized functions in different body parts.

🎯 Exam Tip: Metameric segmentation is a key characteristic for classifying Annelids, so remember this association.

 

Question 6. Find out the correct and wrong statement and find out the correct sequence
I. Ctenophores have nematocysts.
II. In evolutionary history, the annelid is the first segmented animal.
III. Roundworms are diploblastic bilateral animals.
IV. Arthropods excrete through flame cells.
(a) I – False, II – False, III – True, IV – True
(b) I – True, II – False, III – False, IV – True
(c) I – True, II – True, III – False, IV – False
(d) I - False, II – True, III – True, IV – False
Answer: (c) I – True, II – True, III – False, IV – False
In simple words: We need to check if each statement is true or false. Ctenophores do have nematocysts (I-True). Annelids were indeed the first animals to show true segmentation (II-True). Roundworms are triploblastic, not diploblastic (III-False). Arthropods use Malpighian tubules or coxal glands for excretion, not flame cells (IV-False).

🎯 Exam Tip: For true/false statement questions, evaluate each statement individually before choosing the option that represents the correct sequence of true/false values.

 

Question 7. The organism that shows the regeneration character
(a) Planaria
(b) Liver fluke
(c) Tapeworm
(d) Leech
Answer: (a) Planaria
In simple words: Planaria are known for their amazing ability to regrow lost body parts, even a whole new body from a small piece.

🎯 Exam Tip: Regeneration is a fascinating biological process; Planaria is a classic example of an animal with high regenerative capacity.

 

Question 8. What is the excretory organ of roundworm?
(a) Flame cells
(b) Rennet glands
(c) Green glands
(d) Malpighian tubules
Answer: (b) Rennet glands
In simple words: Roundworms use special organs called rennet glands to remove waste from their bodies.

🎯 Exam Tip: Each animal group has specialized structures for excretion; knowing these helps in understanding their adaptation.

 

Question 9. The coelom of phylum Arthropoda is
(a) Pseudo coelom
(b) Eucoelom
(c) Schizo coelom
(d) Enter coelom
Answer: (c) Schizo coelom
In simple words: Arthropods have a schizocoelom, which is a body cavity that forms when the mesoderm, a middle cell layer, splits apart.

🎯 Exam Tip: Understanding how the coelom forms (schizocoelous vs. enterocoelous) is a key difference in classifying animal phyla.

 

Question 10. Name the respiratory organ of Mollusca.
(a) Ctenidia
(b) Gills
(c) Book lungs
(d) Trachea
Answer: (a) Ctenidia
In simple words: Molluscs breathe using ctenidia, which are special gill-like structures found inside their mantle cavity. These feather-like gills help them take oxygen from water.

🎯 Exam Tip: Ctenidia are characteristic respiratory organs for many aquatic molluscs, demonstrating adaptation to their environment.

 

Question 11. Name the excretory organ of Cephalo Chordata.
(a) Mesonephridia
(b) Metanephridia
(c) Protonephridia
(d) Flame cells
Answer: (d) Flame cells
In simple words: Cephalo Chordates use flame cells to filter waste, similar to how simple worms excrete substances.

🎯 Exam Tip: Protonephridia, which include flame cells, are primitive excretory structures found in simpler invertebrates and some chordates.

 

Question 12. Name the organism which has both features of chordate and non-chordates?
(a) Balanoglossus
(b) Ascidia
(c) Amphioxces
(d) Salpa
Answer: (a) Balanoglossus
In simple words: Balanoglossus is an interesting animal because it shares some features with chordates and some with non-chordates, acting like a connecting link between the two groups.

🎯 Exam Tip: Identifying "connecting links" between major animal groups is important for understanding evolutionary relationships.

 

Question 13. .............................. are called as tunicates
(a) Urochordates
(b) Cephalo chordates
(c) Vertebrata
(d) Hemi Chordata
Answer: (a) Urochordates
In simple words: Urochordates are known as tunicates because their body is covered by a tough, leathery outer layer called a tunic.

🎯 Exam Tip: The presence of a tunic is a distinctive feature that sets Urochordates apart within the subphylum Chordata.

 

Question 14. The eggs of birds are ..............................
(a) Megalecithal
(b) Mesolecithal
(c) Telolocithal
(d) Alecithal
Answer: (a) Megalecithal
In simple words: Bird eggs are called megalecithal because they contain a very large amount of yolk, which provides all the food needed for the developing embryo.

🎯 Exam Tip: The amount of yolk in an egg is classified based on its size, and megalecithal eggs are characteristic of animals with prolonged embryonic development outside the mother's body.

 

Question 15. Find the correct answer by matching.
A. Sponges – I. Mesoglea
B. Open circulation – II. Asymmetrical
C. Diploblastic animal – III. Echinodermata
D. Snails – IV. Coanocytes
Answer: C. Diploblastic animal – III. Echinodermata
In simple words: This answer states that diploblastic animals are Echinodermata. This is a direct statement presented as the correct matching pair from the choices.

🎯 Exam Tip: Always carefully read the question to understand if it asks for a single correct pair or a full match of columns. In some cases, questions directly state one option as the answer.

 

Question 16. Find out the correct pair.
(a) Planula – Planeria
(b) Regeneration – Annelida
(c) Trochopore larva – Cnidaria
(d) Veliger larva – Mollusca
Answer: (d) Veliger larva – Mollusca
In simple words: The veliger larva is a distinct larval stage found in many molluscs, which shows that this pairing is correct.

🎯 Exam Tip: Knowing the characteristic larval stages of different phyla is important for understanding their life cycles and evolutionary relationships.

 

Question 17. Which one of the following is not correctly paired?
(a) Ctenophora – Veliger
(b) Annelida – Trochophore
(c) Cnidaria – Planula
(d) Porifera – Parenchymula
Answer: (a) Ctenophora – Veliger
In simple words: Ctenophores do not have a veliger larva; the veliger larva is found in molluscs. Therefore, this pairing is incorrect.

🎯 Exam Tip: Pay close attention to negative questions like "not correctly paired" to avoid common mistakes.

 

Question 18. Find out the wrong statement.
(a) In most animals the coelom lies between the body wall and the alimentary canal
(b) In acoelomate organisms the free movement of the internal organ is restricted.
(c) The cavity formed from the mesoderm is pseudo coelom.
(d) If in a body cavity scattered pouches are seen then the coelom is pseudo coelom.
Answer: (c) The cavity formed from the mesoderm is pseudo coelom.
In simple words: A pseudocoelom is actually a body cavity that is not fully lined by the mesoderm, whereas if the cavity is completely formed *within* the mesoderm, it is a true coelom (eucoelom), not a pseudocoelom.

🎯 Exam Tip: Accurately understanding the definitions of different types of coeloms (acoelom, pseudocoelom, eucoelom) and their formation is crucial for animal classification.

II. Very Short Questions

 

Question 1. What are pinacocytes?
Answer: Pinacocytes are plate-like cells that make up the outer surface of sponges. They help to maintain the size and shape of the sponge. These cells play a crucial role in forming the external protective layer of the sponge body.
In simple words: Pinacocytes are flat cells that cover the outside of a sponge and help it keep its shape.

🎯 Exam Tip: Remember that pinacocytes form the pinacoderm, the outermost layer, and are distinct from choanocytes which line the internal chambers.

 

Question 2. What are choanocytes?
Answer: Choanocytes are special flagellated collar cells that form the inner lining of sponges. They create water currents within the sponge, which helps in feeding, respiration, and waste removal. These cells are very important for the sponge's survival as they filter food particles from the water.
In simple words: Choanocytes are cells with flagella inside sponges that create water flow to help them eat, breathe, and get rid of waste.

🎯 Exam Tip: Choanocytes are unique to Porifera and are essential for their filter-feeding mechanism, a key characteristic of sponges.

 

Question 3. Define tissue.
Answer: A tissue is a group of similar cells that work together to perform a specific function. For example, muscle tissue helps in movement, and nervous tissue sends signals. Tissues are an important level of organization above individual cells.
In simple words: Tissues are groups of the same kind of cells that do a special job together.

🎯 Exam Tip: Understand that the formation of tissues is a major evolutionary step, distinguishing more complex animals from simpler ones like sponges.

 

Question 4. Define organ? Which was the first animal to have organ system?
Answer: An organ is formed when different types of tissues come together to perform a specific, complex function, such as the heart pumping blood or the stomach digesting food. The phylum Platyhelminthes (flatworms) was the first group of animals to show an organ level of organization. This means their body parts were specialized to perform different tasks more efficiently.
In simple words: An organ is different tissues working together for one job. Flatworms were the first animals to have organs.

🎯 Exam Tip: Recognizing the hierarchy of biological organization (cells -> tissues -> organs -> organ systems) is fundamental to zoology.

 

Question 5. Differentiate between a complete digestive system from an incomplete digestive system.
Answer:

In simple words: An incomplete system has one opening for both eating and waste. A complete system has two separate openings, a mouth for eating and an anus for waste.

🎯 Exam Tip: The type of digestive system is a key characteristic for classifying animal phyla and indicates their complexity and efficiency in nutrient processing.

 

Question 6. What are diploblastic animals?
Answer: Diploblastic animals are those whose cells are organized into two primary embryonic layers: the ectoderm (outer layer) and the endoderm (inner layer). They do not have a middle layer called mesoderm. The ectoderm gives rise to the epidermis (outer skin), while the endoderm forms the tissue lining the gut. This simple body plan is characteristic of animals like jellyfish and sea anemones. Often, a non-living, jelly-like layer called mesoglea is found between these two layers.
In simple words: Diploblastic animals have bodies made of only two main cell layers, an outer layer and an inner layer, with no middle layer.

🎯 Exam Tip: Distinguishing between diploblastic and triploblastic animals is crucial for understanding fundamental differences in animal body plans and evolution.

 

Question 7. What is radial symmetry?
Answer: Radial symmetry is a type of body arrangement where any plane passing through the central axis of the body divides the organism into two identical halves. This means the body parts are arranged around a central point, like spokes on a wheel. A good example is a sea anemone or a starfish. This type of symmetry is often found in sessile or slow-moving animals.
In simple words: Radial symmetry means an animal's body can be cut into two matching halves from many directions through its middle, like a pie.

🎯 Exam Tip: Contrast radial symmetry with bilateral symmetry, where an animal can only be divided into two mirror-image halves along a single plane.

 

Question 8. What is protostomia?
Answer: Protostomia refers to a group of Eumetazoans (animals with true tissues) where the embryonic blastopore, an opening that forms during early development, develops into the mouth. In these animals, the anus forms later at a different location. This developmental pattern is characteristic of many invertebrate phyla, including molluscs, annelids, and arthropods.
In simple words: Protostomia are animals where the first opening in their embryo becomes the mouth.

🎯 Exam Tip: Understanding the fate of the blastopore (whether it becomes the mouth or the anus) is a key concept in developmental biology and animal classification.

 

Question 9. What are deuterostomes?
Answer: Deuterostomes are Eumetazoans in which the embryonic blastopore develops into the anus, or an anus forms near it. The mouth then forms from a new opening somewhere else on the embryo. This group includes important phyla like Echinodermata and Chordata (which includes vertebrates). This developmental pathway represents a distinct evolutionary lineage in the animal kingdom.
In simple words: Deuterostomes are animals where the first opening in their embryo becomes the anus, and the mouth forms later.

🎯 Exam Tip: Remember that deuterostomes include all vertebrates, making this classification highly relevant to human biology.

 

Question 10. List the excretory organs of phylum Arthropoda?
Answer: Arthropods have various specialized excretory organs, depending on the specific group:
- Malpighian tubules are found in insects and myriapods, helping them manage water and waste.
- Green glands (or antennal glands) are present in crustaceans like prawns.
- Coxal glands are found in arachnids (spiders, scorpions), located near the legs. These different organs are adapted to the diverse environments arthropods inhabit.
In simple words: Arthropods get rid of waste using different organs like Malpighian tubules in insects, green glands in crabs, and coxal glands in spiders.

🎯 Exam Tip: The diversity of excretory organs in Arthropoda highlights their wide range of adaptations to different habitats, from terrestrial to aquatic.

 

Question 11. Differentiate the respiratory pigment haemoglobin from haemocyanin.
Answer:

In simple words: Haemoglobin uses iron to carry oxygen and makes blood red, found in many animals like us. Haemocyanin uses copper to carry oxygen and makes blood blue, found in animals like snails and crabs.

🎯 Exam Tip: Remember that the metal ion (iron vs. copper) in a respiratory pigment determines its color and efficiency in oxygen transport.

 

Question 12. What are the advantages of bilaterally symmetrical animals?
Answer: Bilateral symmetry offers several advantages that contribute to an animal's success:
- It allows for more efficient movement, enabling animals to actively seek food and mates.
- They can also escape from predators more effectively.
- Bilaterally symmetrical animals typically have distinct dorsal (back) and ventral (belly) sides, along with anterior (head) and posterior (tail) ends, as well as clear right and left sides. This arrangement often leads to cephalization, meaning the development of a head region with sense organs and a brain concentrated at the anterior end. This concentration of senses helps them quickly perceive and respond to their environment.
In simple words: Animals with bilateral symmetry can move faster, find food and mates easily, and escape danger. They have a front (head) with senses, which helps them explore their world better.

🎯 Exam Tip: Cephalization, the development of a head, is a direct evolutionary advantage associated with bilateral symmetry, aiding directed movement and sensory perception.

 

Question 13. What is cleidoic egg?
Answer: A cleidoic egg is a type of shelled egg laid by female organisms, especially those living on land (like reptiles and birds). This egg has a protective shell and internal membranes (amnion, chorion, allantois) that prevent it from drying out in a terrestrial environment. It also contains enough yolk to nourish the developing embryo, allowing development to occur entirely outside of water. This adaptation was crucial for the successful colonization of land by vertebrates.
In simple words: A cleidoic egg is an egg with a hard shell that protects the baby inside and stops it from drying out, allowing animals to lay eggs on land.

🎯 Exam Tip: The cleidoic egg is a major evolutionary innovation that facilitated the transition of vertebrates from aquatic to fully terrestrial life.

 

Question 14. What are the extraembryonic membranes present in reptiles?
Answer: Reptiles, like other amniotes, possess four essential extraembryonic membranes that protect and support the developing embryo within the egg:
1. Amnion: This membrane encloses the embryo in a fluid-filled sac, cushioning it and protecting it from physical shocks.
2. Allantois: This membrane stores embryonic waste products and also facilitates gas exchange.
3. Chorion: The outermost membrane, it encloses all other membranes and the embryo, allowing for gas exchange with the outside environment.
4. Yolk sac: This membrane encloses the yolk, providing nutrients to the developing embryo.
In simple words: Reptile embryos have special layers called amnion, allantois, chorion, and yolk sac that protect them and give them food and air inside the egg.

🎯 Exam Tip: These extraembryonic membranes are critical adaptations for terrestrial life, providing a self-contained aquatic environment for the embryo and allowing for gas exchange and waste disposal.

 

Question 15. Name the muscles that help pigeons to fly. Write the kingdom, phylum, and class for pigeon.
Answer: The primary muscles that help pigeons fly are:
a. Pectoralis major
b. Pectoralis minor
For the pigeon, the classification is:
(i) Kingdom – Animalia
(ii) Phylum – Chordata
(iii) Class – Aves (birds).
These strong chest muscles are highly developed to power the wings for flight.
In simple words: Pigeons fly using strong chest muscles called pectoralis major and minor. Pigeons belong to the Animal Kingdom, Chordata Phylum, and Aves Class.

🎯 Exam Tip: For anatomical questions, always specify the correct technical terms for muscles and for classification, ensure all levels (kingdom, phylum, class) are accurate.

III. Short Questions

 

Question 1. What are the structures formed from ectoderm endoderm and mesoderm?
Answer: The three embryonic germ layers give rise to all the different tissues and organs in an animal's body:
1. Ectoderm: This outermost layer forms the skin, hair, nerves, nails, and teeth. It is responsible for external covering and the nervous system.
2. Mesoderm: This middle layer forms muscles, bones, and the heart. It also develops into connective tissues and the circulatory system.
3. Endoderm: This innermost layer forms the intestine, lungs, and liver. It primarily gives rise to the lining of the digestive and respiratory systems.
In simple words: The ectoderm makes skin and nerves, the mesoderm makes muscles and bones, and the endoderm makes organs like the gut and lungs.

🎯 Exam Tip: Understanding the derivatives of each germ layer is fundamental to understanding animal embryology and organogenesis.

 

Question 2. Name the parts A, B, and C in the diagram?
Answer: Based on a typical animal body cross-section and the provided labels:
A) Ectoderm (the outermost germ layer)
B) Pseudo coelom (the body cavity, not fully lined by mesoderm)
C) Mesoderm (the middle germ layer).
This layered structure helps organize the body plan of many animals.
In simple words: A is the outer skin (Ectoderm), B is the body space (Pseudo coelom), and C is the middle layer (Mesoderm).

🎯 Exam Tip: When interpreting diagrams of body layers, remember the general position of ectoderm (outer), mesoderm (middle), and endoderm (inner), and where the coelomic spaces would typically form.

 

Question 3. Differentiate parazoa from eumetazoa?
Answer:

In simple words: Parazoa are simple animals like sponges that don't have true tissues. Eumetazoa are more complex animals that do have true tissues and often organs.

🎯 Exam Tip: The presence or absence of true tissues is a fundamental distinction that divides the animal kingdom into these two major subkingdoms.

 

Question 4. Match
1. Cycon (Sycon)
2. Chalina
3. Euplectella
4. Hyalonema
Answer: (a) 1 - b (Sycon), 2 - d (Chalina), 3 - a (Euplectella), 4 - c (Hyalonema)
In simple words: This question asks to match the numbered sponge names with their corresponding images or common names. The correct match pairs each sponge's name with its correct label.

🎯 Exam Tip: When matching, ensure you identify the unique characteristics or common associations for each item to pair them correctly.

 

Question 5. Distinguish between hibernation and aestivation.
Answer: Hibernation and aestivation are both states of dormancy that animals enter, but they occur in different environmental conditions:
- Hibernation: This is a period of inactivity and reduced metabolic rate that some animals undergo during winter. It is also known as "winter sleep." Animals hibernate to conserve energy when food is scarce and temperatures are low. Examples include bears and groundhogs.
- Aestivation: This is a similar state of dormancy, but it occurs during hot and dry periods, typically in summer. It is known as "summer sleep." Animals aestivate to survive drought and heat, often by burrowing underground. Examples include some fish, amphibians, and snails. Both processes help animals survive harsh environmental conditions by lowering their body functions.
In simple words: Hibernation is like a long "winter sleep" to escape cold and lack of food. Aestivation is a "summer sleep" to escape heat and drought.

🎯 Exam Tip: Remember that both hibernation and aestivation are adaptive strategies to cope with environmental extremes, mainly temperature and resource availability.

 

Question 6. In the given diagram Balanoglossus mark A, B, and C.
Answer:
A) Proboscis
B) Collarette
C) Genital wings
In simple words: The diagram shows Balanoglossus, a marine animal. The 'A' part is its head, called the proboscis, which helps it burrow. 'B' is the collar, which is like a ring around its body. 'C' points to the genital wings, where reproductive organs are located.

🎯 Exam Tip: When identifying parts of a diagram, clearly label each part as requested and ensure your labels match the correct anatomical structures.

 

Question 7. Give any five characteristic features of Urochordata?
Answer:
1. Urochordates live only in the sea.
2. Most of them stay in one place, like sessile animals, but some can swim freely.
3. Their body is covered by a special outer layer called a tunic.
4. They do not have a coelom, which is a body cavity.
5. The notochord, a rod-like structure, is only found in the tail region of their larval stage. The presence of a notochord is a key characteristic of chordates at some point in their life cycle.
In simple words: Urochordates live in the ocean, are usually fixed in one spot, and have a tunic covering their body. They lack a body cavity, and their notochord is only present in the larva's tail.

🎯 Exam Tip: When listing features, choose distinct characteristics and use clear, concise language. Highlighting unique aspects helps in scoring better.

 

Question 8. Look at the picture given below and answer questions.
a) What is the name of this fish?
b) What is the name of the larva of this fish?
c) What is the shape of the mouth?
Answer:
a) Lamprey (iprey is a typo)
b) Ammocete
c) Circular
In simple words: The fish shown is a lamprey. Its young form is called an ammocete larva, and it has a round mouth. Lampreys are unique as they lack jaws, which makes their circular mouth distinctive.

🎯 Exam Tip: For identification questions, ensure you know both the adult and larval names, as well as distinct physical characteristics like mouth shape.

 

Question 9. What are the characteristic features of amphibia?
Answer:
1. Amphibians can live both in water and on land.
2. They are cold-blooded animals, meaning their body temperature changes with the environment.
3. They have two pairs of limbs, like arms and legs.
4. They might have a tail or not, depending on the species.
5. Their skin can be smooth or rough.
6. Their heart has three chambers.
7. They excrete urea as a waste product.
8. Their kidneys are mesonephric.
9. They lay eggs, and their development process involves stages (indirect development). The skin of amphibians is permeable, allowing for gas exchange, making it a crucial respiratory surface for them.
In simple words: Amphibians live on land and in water, are cold-blooded, and have four limbs. They have three-chambered hearts and lay eggs.

🎯 Exam Tip: When describing animal characteristics, always include their habitat, body temperature regulation, number of heart chambers, and reproductive method.

 

Question 1. Explain various patterns of organisation in animals.
Answer: Animals show different ways their bodies are organized:
**The cellular level of organisation:**
• In this type, cells are grouped loosely and do not form tissues.
• Different cells have specific jobs, like in sponges.
**Tissue level of organisation:**
• Here, cells that do similar work are grouped together to form tissues.
• These tissues then perform a common function, as seen in animals like cnidarians. For example, nerve cells form nerve tissue.
**Organ level of organisation:**
• Various kinds of tissues come together to form organs, each doing a specific task.
• This level is found in animals like flatworms and other more complex groups.
**Organ system level of organisation:**
• In this highest level, tissues are organized into organs, and organs are grouped into organ systems.
• All the organ systems work together in a coordinated way to keep the animal alive. This complex organization allows for specialized functions and efficient bodily processes.
In simple words: Animals can be organized in different ways: from just loose cells, to cells forming tissues, then tissues forming organs, and finally organs working together in systems.

🎯 Exam Tip: Remember the hierarchy: cells to tissues, tissues to organs, organs to organ systems. Provide a simple example for each level of organization.

 

Question 2. What is coelom? Describe its types?
Answer: A coelom is a body cavity lined by mesoderm. It is the space between the body wall and the digestive system.
**1. Pseudocoelom:**
The body cavity is not fully lined by the mesodermal epithelium. Instead, the mesoderm forms scattered pouches between the outer and inner layers of the body. For example, in roundworms.
**2. Eucoelom (True Coelom):**
This is a fluid-filled body cavity that develops within the mesoderm and is completely lined by mesodermal epithelium, called the peritoneum. This lining provides structural support and allows for organ movement. The true coelom is further divided into two types:
**3. Schizocoelomates:**
In these animals, the body cavity is formed when the mesoderm splits apart. For example, annelids.
**4. Enterocoelomate:**
In these animals, the body cavity is formed from pouches that pinch off from the archenteron (the primitive gut) during development. For example, echinoderms.
In simple words: A coelom is an internal body space. Some animals have a "false" coelom (pseudocoelom) that isn't fully lined by a special tissue. Animals with a "true" coelom (eucoelom) have a cavity fully lined by tissue, which can form by splitting (schizocoelom) or by budding (enterocoelom).

🎯 Exam Tip: Define coelom clearly and then list its types with simple explanations and examples. Knowing the developmental origin (splitting vs. budding) helps differentiate the true coelom types.

 

Question 3. Compare Platyhelminthes with Aschelminthes?
Answer:

In simple words: Platyhelminthes are flatworms with no body cavity, while Aschelminthes are roundworms with a false body cavity. They differ in shape, how they excrete waste, and if their sexes are separate.

🎯 Exam Tip: When comparing, always highlight key differences in body plan, presence/absence of coelom, excretory organs, and reproductive strategies, supported by examples.

 

Question 4. Classify animals based on coelom.
Answer: The coelom is the cavity found between the body wall and the gut wall. Animals are classified into three groups based on the presence or absence of this coelom:
1. **Acoelomates:** These animals do not have a coelom. Their body is solid, meaning there's no fluid-filled cavity between the body wall and the digestive tract. Flatworms are an example of acoelomates.
2. **Pseudocoelomates:** In these animals, the body cavity is not fully lined by mesodermal epithelium. The mesoderm appears as scattered pouches between the ectoderm and endoderm, creating a "false" coelom. Roundworms are a common example of pseudocoelomates.
3. **Eucoelomates (True Coelomates):** These animals have a true coelom, which is a body cavity completely lined by mesodermal epithelium. This type of coelom can form in two ways:
* **Schizocoelomates:** The coelom develops from the splitting of the mesoderm. Examples include annelids, arthropods, and mollusks.
* **Enterocoelomates:** The coelom forms from mesodermal pouches that bud off from the archenteron (primitive gut). Examples include echinoderms, hemichordates, and chordates. The coelom provides space for organs and protects them from external shocks.
In simple words: Animals are grouped by their body cavity. Some have no cavity (acoelomates), some have a false cavity (pseudocoelomates), and some have a true cavity (eucoelomates). True cavities form either by splitting or budding.

🎯 Exam Tip: Define each coelom type and provide clear examples. Mentioning the presence/absence of a mesodermal lining is crucial for distinguishing between them.

 

Question 5. What are the characteristic features of Hemichordata?
Answer: Hemichordates have features of both invertebrates and chordates. Here are their main characteristics:
• They are soft, worm-like marine animals.
• They are triploblastic, meaning they have three germ layers, and are coelomate, possessing a true body cavity.
• They have bilateral symmetry, meaning their body can be divided into two similar halves.
• Their circulatory system is simple and open, meaning blood flows in open spaces, not just vessels. This helps transport nutrients throughout their body efficiently.
• They feed using cilia, which are tiny hair-like structures.
• They breathe through paired gill slits that open into the pharynx.
• Excretion is carried out by a specialized structure called the glomerulus.
• Their nervous system is primitive, and sexes are separate.
• Their development involves a free-swimming larva stage.
In simple words: Hemichordates are soft, worm-like ocean animals with features of both simple and advanced groups. They have three body layers, a body cavity, and bilateral symmetry. They breathe with gill slits and have a simple open blood system.

🎯 Exam Tip: When describing a phylum, always include body symmetry, number of germ layers, presence/absence of coelom, habitat, feeding method, and key anatomical features.

 

Question 6. What are the general characters of the phylum Vertebrata?
Answer: Vertebrates are a group of animals that share several common characteristics:
1. They have a notochord present during their embryonic stage.
2. This notochord is later replaced by a cartilaginous or bony vertebral column in adult animals. This vertebral column protects the spinal cord.
3. They possess paired appendages, which can be fins or limbs, used for movement.
4. Their skin is covered by a protective skeleton that includes scales, feathers, hairs, claws, or nails.
5. Respiration occurs through gills (in aquatic forms), skin, buccopharyngeal cavity, or lungs (in terrestrial forms).
6. The heart has two, three, or four chambers, designed for efficient blood circulation.
7. Kidneys are present for excretion and osmoregulation (balancing water and salt).
In simple words: Vertebrates have a backbone, which replaces a notochord seen when they are embryos. They have limbs or fins, skin coverings like scales or hair, and they breathe using gills or lungs. They also have a heart with chambers and kidneys.

🎯 Exam Tip: Focus on the defining characteristics of vertebrates: vertebral column, paired appendages, specialized skin, and advanced organ systems like the circulatory and excretory systems.

 

Question 7. Write the general characters of the phylum cnidaria.
Answer: Cnidarians are a diverse group of aquatic animals with these general characteristics:
• Cnidarians live in water, mainly the ocean. They show radial symmetry and are diploblastic, meaning they have two main germ layers.
• They have tentacles equipped with stinging cells called cnidocytes, cnidoblasts, or nematocysts. These cells are used for capturing prey and defense.
• They show a tissue level of organization, meaning their cells are grouped into tissues but not organs.
• They have a central gastrovascular cavity, also known as a coelenteron, where digestion takes place.
• Digestion occurs both outside (extracellular) and inside (intracellular) their cells.
• Many cnidarians show alternation of generation, switching between two forms: the polyp (sessile) and the medusa (free-swimming). This allows them to adapt to different environments.
• Their development is indirect and involves a planula larva stage, as seen in animals like Physalia.
In simple words: Cnidarians are water animals with radial symmetry and two body layers. They have stinging tentacles for catching food and a central stomach. Many can exist in two forms, polyp or medusa, and grow from a larva.

🎯 Exam Tip: Key features to remember for Cnidaria include radial symmetry, diploblastic nature, presence of cnidocytes, gastrovascular cavity, and alternation of generation.

 

Question 8. What are the general characters of mammals?
Answer: Mammals are a class of vertebrates known for several unique characteristics:
• Their body is covered by hair, which helps in insulation and protection.
• They live in various habitats, from land to water to air.
• The presence of mammary glands, which produce milk to nourish their young, is the most distinctive feature of mammals. This provides excellent care for offspring.
• They typically have two pairs of limbs, adapted for different movements like walking, running, swimming, or flying.
• Their skin contains sweat glands for cooling and sebaceous glands for oil production.
• Their exoskeleton includes various structures like horns, spines, scales, or claws, depending on the species.
• Mammalian teeth are thecodont (set in sockets), heterodont (different types of teeth), and diphyodont (two sets of teeth in a lifetime).
• The heart is four-chambered, ensuring efficient separation of oxygenated and deoxygenated blood, and they possess a left systemic arch.
• Mammals have a large, well-developed brain compared to other animals, supporting complex behaviors.
• Their kidneys are metanephric and they are ureotelic, excreting urea as their primary nitrogenous waste.
In simple words: Mammals have hair, mammary glands to feed their young, and a four-chambered heart. They also have different kinds of teeth, a big brain, and kidneys that remove urea from the body.

🎯 Exam Tip: For mammals, always mention hair, mammary glands, a four-chambered heart, and heterodont dentition as key identifying features.

 

Question 9. Give three distinct features of all chordates that are seen at some stage of their life cycle? What is the fate of two characters out of three in the matured adults?
Answer: All chordates share three distinct features at some point in their life cycle:
1. **Notochord:** A flexible, rod-like structure found below the nerve cord and above the alimentary canal.
2. **Dorsal hollow nerve cord:** A nerve cord located on the back side of the body, above the notochord.
3. **Pharyngeal gill slits:** Openings in the pharynx, present in all chordates at some stage.
**Fate of these features in matured adult animals:**

The pharyngeal gill slits may persist in aquatic chordates or disappear/be modified in terrestrial chordates. These features highlight the evolutionary link and shared ancestry among diverse chordate species.
In simple words: All chordates have three main features at some point: a notochord, a hollow nerve cord, and gill slits. In adults, the notochord becomes a backbone, and the nerve cord becomes the brain and spinal cord.

🎯 Exam Tip: Clearly state the three defining chordate features. For their fate, explain how the notochord transforms into the vertebral column and the nerve cord develops into the central nervous system.

 

Question 10. Compare the chordates with non-chordates?
Answer:

In simple words: Chordates have a notochord, a single hollow nerve cord on their back, gill slits, and a heart on their front side. Non-chordates lack a notochord, have a double solid nerve cord on their belly, no gill slits, and their heart is on the back or side, or they have no heart.

🎯 Exam Tip: Focus on the five key distinguishing features: notochord, nerve cord position, gill slits, heart position, and post-anal tail. These are fundamental to classifying animals as chordates or non-chordates.

 

Question 11. What are the parts of ABCD in the model diagram of Chordata?
Answer:
A) Dorsal Nerve Cord
B) Notochord
C) Mouth
D) Pharyngeal gill clefts
E) Muscle segment
In simple words: In the Chordata diagram, A is the nerve cord on the back, B is the notochord (a supporting rod), C is the mouth, D are the gill openings in the throat, and E are the muscle blocks.

🎯 Exam Tip: Familiarize yourself with the basic diagram of a chordate to correctly identify the dorsal hollow nerve cord, notochord, pharyngeal gill slits, and post-anal tail. These are the four distinguishing features.

 

Question 12. Look into the given diagram and answer the question.
a) What is the name of the organism.
b) What is the respiratory organ of this animal.
c) What type of metamorphosis is seen?
d) Whether this organism contain nerve card?
e) What is the outer covering of it's body?
Answer:
a) Ascidian
b) Gill clefts
c) Retrogressive metamorphosis
d) Yes, the larva consists of a nerve cord, which is a key chordate feature.
e) Tunic
In simple words: The organism is an Ascidian. It breathes using gill clefts and undergoes a change called retrogressive metamorphosis. Its larva has a nerve cord, and its body is covered by a tunic.

🎯 Exam Tip: For specific animal examples, know their classification, key anatomical features (like respiratory organs and body covering), and any unique developmental processes like metamorphosis.