Previous year questions: Animal Kingdom

Previous year questions: animal kingdom

All ten items are from the official NCERT Exemplar Problems in Biology for Class 11. The exemplar does not print marks against individual questions, so the marks shown here follow the section the question is printed in: one mark for a multiple choice item, two marks for a very short answer, three marks for a short answer and five marks for a long answer. Each heading names the exemplar chapter and the question number inside its section. Work each answer before reading the model answer, because the exemplar repeats its vocabulary across items.

Q1 (NCERT Exemplar, 1 mark)

NCERT Exemplar Class 11 Biology, Chapter 4, Multiple Choice Questions, Q12. Name the animals whose body cavity lacks a mesodermal lining.

Answer: The correct term is pseudocoelomates. The cavity exists, but the mesoderm is not a continuous lining around it; instead the mesoderm sits as scattered pouches between ectoderm and endoderm. Aschelminthes are the example, as in the roundworm. Acoelomates have no cavity at all, and coelomates have a cavity fully lined by mesoderm. The item tests the middle category, and the answer should name it first before adding the Aschelminthes example.

Q2 (NCERT Exemplar, 1 mark)

NCERT Exemplar Class 11 Biology, Chapter 4, Multiple Choice Questions, Q3. Which set of animals shares a four-chambered heart?

Answer: The correct set is crocodiles, birds and mammals. Birds and mammals always have a four-chambered heart, and the crocodile is the reptile that also has four chambers. Other reptiles, such as lizards and turtles, have a heart with three chambers, so any set that includes them is wrong.

Q3 (NCERT Exemplar, 1 mark)

NCERT Exemplar Class 11 Biology, Chapter 4, Multiple Choice Questions, Q9. Which of these animals is oviparous?

Answer: The platypus, Ornithorhynchus, is oviparous. It is a mammal that lays eggs instead of giving birth to live young. The flying fox, the elephant and the whale are all mammals that are viviparous, so the platypus is the exception in the list. The item is a test of that single exception, and the way to answer it is to name the animal and add the words oviparous mammal. A short reason is enough: the platypus lays eggs, and its young are fed on milk after they hatch.

Q4 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 4, Very Short Answer Type Questions, Q1. Name the phylum whose adults show radial symmetry and whose larva shows bilateral symmetry.

Answer: The phylum is Echinodermata. The adult echinoderm is radially symmetrical, which suits a slow-moving or fixed life on the sea floor, while the free-swimming larva is bilaterally symmetrical. That change in symmetry between the two stages is one of the distinctive features of the phylum. It also explains why an echinoderm looks unlike any other animal group in the chapter: the star, the sea urchin and the sea cucumber all show a radial adult body from a bilateral larva.

Q5 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 4, Very Short Answer Type Questions, Q2. What is the importance of pneumatic bones and air sacs in Aves?

Answer: Pneumatic bones are hollow bones with air cavities, so they keep the skeleton light without losing strength. The air sacs connected to the lungs store air and keep a steady flow through the lungs, which supports the high oxygen demand of flight. Light bones and a steady air supply together make sustained flight possible for birds. The same answer should mention the wings made from forelimbs and the four-chambered heart, because the marks are for the complete set of flight adaptations. A crop and a gizzard also belong in the answer, since the extra digestive chambers let a bird process food quickly enough for flight.

Q6 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 4, Very Short Answer Type Questions, Q5. Which group of chordates has a sucking and circular mouth without jaws?

Answer: The group is the cyclostomes, the class Cyclostomata. They have a sucking, circular mouth without jaws, an elongated body with 6 to 15 pairs of gill slits, no scales and no paired fins. Petromyzon and Myxine are the examples, and all of them are ectoparasites on fishes. Their skeleton is cartilaginous, the body carries no scales and no paired fins, and they migrate from the sea to fresh water to spawn. The round mouth without jaws is the feature that names the group, so it belongs in the first line of the answer.

Q7 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 4, Very Short Answer Type Questions, Q3. What is metagenesis? Give one example.

Answer: Metagenesis is the alternation of generations seen in some cnidarians, where the polyp and the medusa forms follow each other. The polyp reproduces asexually and gives medusae, and the medusae reproduce sexually and give polyps. Obelia is the example, and the process is also called alternation of generations in that phylum. The polyp is fixed and feeds like a small flower, while the medusa swims free and carries the sexual stage to new places.

Q8 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 4, Very Short Answer Type Questions, Q12. Differentiate between a diploblastic and a triploblastic animal.

Answer: A diploblastic animal has two germ layers, the outer ectoderm and the inner endoderm, with mesoglea in between, and coelenterates are the example. A triploblastic animal has a third germ layer, the mesoderm, between ectoderm and endoderm, and Platyhelminthes up to chordates show it. The extra layer is what makes a true coelom and a more complex organ system possible. Keep the two groups apart in an answer: diploblastic means coelenterates, and triploblastic means Platyhelminthes and everything above them in this chapter. The mesoderm in the triploblastic embryo is also the layer that later gives muscle and the lining of the coelom, so the distinction carries through the whole body plan.

Q9 (NCERT Exemplar, 3 marks)

NCERT Exemplar Class 11 Biology, Chapter 4, Short Answer Type Questions, Q2. Sort coelenterates, ctenophores, annelids, arthropods and echinoderms by their symmetry.

Answer: Coelenterates, ctenophores and echinoderms are radially symmetrical. In these animals any plane through the central axis gives matching halves, and the echinoderm larva is the exception because it is bilateral. Annelids and arthropods are bilaterally symmetrical, with only one plane dividing the body into matching left and right halves. Bilateral symmetry suits movement in one direction and the collection of sense organs at the front. The echinoderm pair is worth a line on its own: the adult is radial while the larva is bilateral, so the sorting depends on which stage the question means. Write the three radial groups first and the two bilateral phyla second, because the order makes the answer easy to check.

Q10 (NCERT Exemplar, 5 marks)

NCERT Exemplar Class 11 Biology, Chapter 4, Long Answer Type Questions, Q1. Give three major differences between chordates and non-chordates, and draw a schematic sketch of a chordate showing the characters.

Answer: The first difference is the notochord: chordates have one, non-chordates never form it. The second is the central nervous system: it is dorsal, hollow and single in chordates, while it is ventral, solid and double in non-chordates. The third is the throat: the chordate pharynx is perforated by gill slits, while non-chordates have no gill slits. Two more differences are worth adding. The chordate heart is ventral and non-chordate heart, where present, is dorsal. Chordates have a post-anal tail, and non-chordates do not. The sketch should show a long animal with a dorsal tubular nerve cord, a notochord below it, a pharynx with gill slits, a ventral heart and a tail running past the anus. Ascidia is a chordate only in its larval stage, so a question that asks for a sketch of a chordate expects the generalised plan, not the adult tunicate. Label every character in the sketch, because an unlabelled drawing gets few marks even when the shapes are right. The usual five labels are the notochord, the dorsal hollow nerve cord, the pharyngeal gill slits, the ventral heart and the post-anal tail, and each one should sit on the correct side of the body. A quick sketch with five clean labels earns more than a detailed drawing with none.