Grade 10 Q&A: Chapter 16: Animal Classification

Concept Questions

Q1: What is animal classification?

Answer: Animal classification is the scientific process of arranging animals into groups and categories based on their shared characteristics, evolutionary relationships, and distinct features.

Q2: Who is considered the 'Father of Zoology' and made early attempts at animal classification?

Answer: Aristotle is considered the 'Father of Zoology' and made early attempts at animal classification based on criteria like body size, habits, and habitat.

Q3: What are the two main groups in the traditional method of animal classification?

Answer: The two main groups in the traditional method of animal classification are Non-chordates and Chordates.

Q4: Name the two subphyla of non-chordates that are not true coelomates.

Answer: The two subphyla of non-chordates that are not true coelomates are Platyhelminthes (acoelomates) and Aschelminthes (pseudocoelomates).

Q5: What is a 'coelom'?

Answer: A coelom is a body cavity lined by mesoderm, which separates the digestive tract from the outer body wall. It provides space for internal organs to develop and function.

Q6: What is 'bilateral symmetry'?

Answer: Bilateral symmetry is a type of body symmetry where an animal's body can be divided into two identical halves along only one plane (the sagittal plane), creating a left and a right side.

Q7: Which phylum includes animals with a porous body?

Answer: The phylum Porifera includes animals with a porous body, commonly known as sponges.

Q8: What is the distinguishing feature of animals in Phylum Coelenterata (Cnidaria)?

Answer: The distinguishing feature of animals in Phylum Coelenterata (Cnidaria) is the presence of stinging cells called cnidocytes, used for defense and capturing prey.

Q9: Which phylum is known for having jointed appendages?

Answer: The phylum Arthropoda is known for having jointed appendages, making it the largest phylum in the animal kingdom.

Q10: What is a 'notochord'?

Answer: A notochord is a flexible, rod-like structure that forms the main support of the body in the embryonic stage of all chordates and in the adult stage of some chordates. It is replaced by the vertebral column in vertebrates.

Q11: Name the three subphyla of Phylum Chordata.

Answer: The three subphyla of Phylum Chordata are Urochordata, Cephalochordata, and Vertebrata.

Q12: Which class of Vertebrata includes cold-blooded animals with scales and lay eggs on land?

Answer: The class Reptilia includes cold-blooded animals with scales that typically lay eggs on land.

Q13: What is the primary characteristic of animals in Class Mammalia?

Answer: The primary characteristic of animals in Class Mammalia is the presence of mammary glands for milk production to nourish their young.

Application-Based Questions

Q14: How does the new system of animal classification differ from the traditional method?

Answer: The new system of animal classification is more complex and detailed than the traditional method. While the traditional method broadly divides animals into Non-chordates and Chordates, the new system uses more fundamental criteria like grades of organization (cellular, tissue-organ, organ-system), body symmetry (asymmetry, radial, bilateral), germ layers (diploblastic, triploblastic), body cavity (coelomate, pseudocoelomate, acoelomate), and body segmentation to classify animals, providing a more accurate evolutionary relationship.

Q15: Explain why sponges (Phylum Porifera) are considered the simplest multicellular animals.

Answer: Sponges (Phylum Porifera) are considered the simplest multicellular animals because they exhibit a cellular grade of organization. Their cells are loosely aggregated and do not form true tissues or organs. They lack a nervous system, and their body plan is very basic, relying on water flow through pores for feeding and respiration.

Q16: A newly discovered animal has a soft body, a shell, and a muscular foot. To which phylum would it most likely belong? Justify your answer.

Answer: This animal would most likely belong to the Phylum Mollusca. The key characteristics mentioned – a soft body, often protected by a shell, and a muscular foot for locomotion – are defining features of molluscs, which include snails, clams, and octopuses.

Q17: Differentiate between radial symmetry and bilateral symmetry with examples.

Answer: * **Radial Symmetry:** The body can be divided into two identical halves by any plane passing through the central axis. Examples include jellyfish (Phylum Cnidaria) and starfish (Phylum Echinodermata). * **Bilateral Symmetry:** The body can be divided into two identical halves only along a single sagittal plane, resulting in distinct left and right sides. Most complex animals, including humans, insects, and worms, exhibit bilateral symmetry.

Q18: Why are birds (Class Aves) considered warm-blooded (homeothermic) animals?

Answer: Birds (Class Aves) are considered warm-blooded (homeothermic) animals because they have the ability to maintain a constant internal body temperature, regardless of the external environmental temperature. They achieve this through a high metabolic rate, insulation provided by feathers, and physiological mechanisms like shivering or panting.

Q19: How does the presence of a vertebral column distinguish vertebrates from other chordates?

Answer: The presence of a vertebral column (backbone) distinguishes vertebrates from other chordates (Urochordata and Cephalochordata). While all chordates possess a notochord at some stage, in vertebrates, this notochord is replaced by a segmented bony or cartilaginous vertebral column, which provides stronger support and protection for the nerve cord.

Higher-Order Thinking Questions

Q20: Explain the evolutionary significance of the development of a true coelom in animals.

Answer: The development of a true coelom (a body cavity lined by mesoderm) is a significant evolutionary advancement. It provides several advantages: 1. **Space for Organ Development:** Allows internal organs to grow and move independently of the body wall. 2. **Hydrostatic Skeleton:** In some animals (e.g., annelids), the fluid-filled coelom acts as a hydrostatic skeleton, providing support and facilitating movement. 3. **Increased Body Size:** Enables the development of larger and more complex body plans. 4. **Protection:** Cushions internal organs from external shocks. 5. **Efficient Circulation:** Allows for more efficient transport of nutrients and waste. This innovation was crucial for the diversification and increased complexity observed in higher animal phyla like Annelida, Arthropoda, and Chordata.

Q21: Discuss the importance of 'germ layers' in animal classification.

Answer: Germ layers are fundamental embryonic tissue layers from which all organs and tissues of an animal develop. Their number and arrangement are crucial for classification: * **Diploblastic animals** (e.g., Cnidarians) have two germ layers: ectoderm and endoderm. They lack a true mesoderm and thus true organs. * **Triploblastic animals** (most other animals) have three germ layers: ectoderm, mesoderm, and endoderm. The presence of mesoderm allows for the development of complex organs and organ systems, including muscles, bones, and circulatory systems. Understanding germ layers helps in tracing evolutionary relationships and understanding the basic body plan complexity of different animal groups.

Q22: How does the concept of 'segmentation' contribute to the advanced body plan of some animal phyla? Provide examples.

Answer: Segmentation, or metamerism, is the division of the body into a series of repeated segments. This contributes to an advanced body plan by: 1. **Specialization:** Allows for the specialization of different segments for specific functions (e.g., head, thorax, abdomen in insects). 2. **Increased Mobility:** Provides greater flexibility and efficiency in movement (e.g., earthworms using segment contractions). 3. **Redundancy:** If one segment is damaged, others can still function, increasing survival chances. Examples include Phylum Annelida (e.g., earthworms), Phylum Arthropoda (e.g., insects, crustaceans), and even the segmented vertebral column in Chordates.

Q23: Compare the respiratory organs found in different classes of Vertebrata, highlighting their adaptation to habitat.

Answer: * **Pisces (Fish):** Possess **gills** for aquatic respiration, efficiently extracting dissolved oxygen from water. * **Amphibia (Amphibians):** Larvae (tadpoles) have gills; adults develop **lungs** for terrestrial respiration but also breathe through their **moist skin** and **buccal cavity**, adapting to both aquatic and semi-aquatic environments. * **Reptilia (Reptiles):** Primarily use **lungs** for respiration, well-adapted for fully terrestrial life, with more developed lungs than amphibians. * **Aves (Birds):** Have highly efficient **lungs** with air sacs, enabling high oxygen intake necessary for flight and high metabolic rates. * **Mammalia (Mammals):** Possess well-developed **lungs** with a large surface area for gas exchange, adapted for a wide range of terrestrial and aquatic environments, supporting their high metabolic demands and endothermy.

Q24: Discuss the unique characteristics that allow animals in Phylum Echinodermata to be classified separately despite their radial symmetry as adults.

Answer: Despite exhibiting radial symmetry as adults, animals in Phylum Echinodermata (like starfish, sea urchins) are classified separately from other radially symmetrical animals (like cnidarians) due to several unique characteristics: 1. **Pentaradial Symmetry:** Specifically, their radial symmetry is typically five-fold. 2. **Water Vascular System:** They possess a unique water vascular system with tube feet, used for locomotion, feeding, and gas exchange. 3. **Endoskeleton:** They have a calcareous endoskeleton made of ossicles, which is distinct from the hydrostatic skeletons or exoskeletons of other phyla. 4. **Larval Symmetry:** Their larval stages exhibit bilateral symmetry, suggesting an evolutionary link to bilaterally symmetrical ancestors. These features highlight their distinct evolutionary path and justify their separate phylum classification.

Q25: How does the concept of 'connecting links' support the theory of evolution in animal classification? Provide an example.

Answer: 'Connecting links' are organisms that possess characteristics of two different groups of animals, indicating an evolutionary transition between them. They provide strong evidence for the theory of evolution by showing how one group might have evolved from another. For example, *Peripatus* is considered a connecting link between Annelida and Arthropoda. It exhibits annelid-like characteristics such as a segmented body, thin cuticle, and parapodia-like legs, while also showing arthropod-like features like tracheal respiration and open circulatory system. Such organisms illustrate intermediate stages in evolutionary development, supporting the idea of gradual change and common ancestry among different animal phyla.

References

1. MSBSHSE Class 10 Science and Technology Textbook Part 2 (2021-22 English) - Chapter 6: Animal Classification
2. Maharashtra State Board 10th Standard Science Syllabus 2025-26
3. Balbharati Science and Technology Part 2 Textbook
4. Shaalaa.com Balbharati solutions for Science and Technology 2