Previous year questions: Structural Organisation in Animals

Previous year questions: structural organisation in animals

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 7, Multiple Choice Questions, Q1. Which type of epithelium forms the inner wall of a blood vessel?

Answer: The inner wall of a blood vessel is lined by squamous epithelium, which is flat and thin and lets exchange happen easily. Cuboidal epithelium lines kidney tubules and glands, columnar epithelium lines the intestine, and stratified epithelium makes the skin. The flat form is chosen for a surface that only needs a thin lining, so the answer follows the single link between shape and function. The other option names describe lining of a different shape and belong to a different surface.

Q2 (NCERT Exemplar, 1 mark)

NCERT Exemplar Class 11 Biology, Chapter 7, Multiple Choice Questions, Q2. Adipose tissue belongs to which category of tissue?

Answer: Adipose tissue is a connective tissue. In a match-the-column item the same fact is tested through the matrix, so the matrix word is worth writing down even when the option seems obvious. Its large cells store fat in a matrix, and it insulates the body and pads organs. Epithelial, muscular and neural tissues do not store fat in this way. The cells-in-a-matrix pattern is the test, and adipose passes it. A one-line example makes the answer complete: the fat in adipose pads the kidney and the eye.

Q3 (NCERT Exemplar, 1 mark)

NCERT Exemplar Class 11 Biology, Chapter 7, Multiple Choice Questions, Q3. Which of these is not a connective tissue?

Answer: Muscle is not a connective tissue, so it is the odd one in a list of bone, cartilage, blood and muscle. Bone, cartilage and blood all have cells set in a matrix, which is the connective pattern, while muscle is built for contraction. The odd item is therefore the one that contracts. The other three are all connective in their own way: bone is a hard matrix, cartilage a firm one, and blood a fluid one.

Q4 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 7, Very Short Answer Type Questions, Q4. In which sex of the frog are sound-producing vocal sacs present?

Answer: Vocal sacs belong to the male. He also has a copulatory pad on the forelimb first digit. Neither feature appears in the female, which makes the two a quick field test in the breeding season. A complete answer names both and states the sex they belong to.

Q5 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 7, Very Short Answer Type Questions, Q5. Name the process by which a tadpole develops into an adult frog.

Answer: The process is metamorphosis. The tadpole, which is the larval stage, changes its body form and organs and becomes the adult frog. The change is necessary because the larva lives in water while the adult can live on land as well. The word metamorphosis is the whole answer, and the explanation earns the second mark. The tadpole's change of form is also a change of habitat, from water to land and water both.

Q6 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 7, Very Short Answer Type Questions, Q9. Give two identifying features of an adult male frog.

Answer: The adult male frog has a pair of sound-producing vocal sacs and a copulatory pad on the forelimb first digit. Both are visible or usable identifying features, and neither is found on the female, which makes the pair a reliable test of sex. In the breeding season the vocal sacs are the more obvious of the two.

Q7 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 7, Very Short Answer Type Questions, Q11. Arrange the parts of the frog digestive system in order from the mouth: mouth, oesophagus, buccal cavity, stomach, intestine, cloaca, rectum, cloacal aperture.

Answer: The order is mouth, buccal cavity, oesophagus, stomach, intestine, rectum, cloaca, cloacal aperture. The mouth opens into the buccal cavity, and the food travels down the oesophagus to the stomach, then through the intestine and rectum to the cloaca and out through the cloacal aperture. The sequence question is a memory check, so the order must be exact. Write the parts in one line and mark the two glands separately, because the bile duct and the pancreatic duct are not part of the canal itself.

Q8 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 7, Very Short Answer Type Questions, Q12. What is the difference between cutaneous and pulmonary respiration?

Answer: Cutaneous respiration takes place through the moist skin, and oxygen dissolved in water moves in by diffusion. Pulmonary respiration takes place through the lungs, with air entering through the nostrils and the buccal cavity. A frog uses the skin in water and the lungs on land, and during dormancy it depends on the skin alone.

Q9 (NCERT Exemplar, 3 marks)

NCERT Exemplar Class 11 Biology, Chapter 7, Short Answer Type Questions, Q2. Frogs are beneficial for mankind. Justify the statement.

Answer: Frogs eat insects, and many of those insects are crop pests, so a frog population protects farm produce. They form a link in food chains and food webs, so they help keep the ecosystem in balance. In some countries their muscular legs are also eaten. The first two points are the ones that matter for the environment, and the third is the point of direct use. A full answer names the insects, the crop and the food chain. Two clear points are enough for three marks, and a third point about food use is a bonus rather than a requirement. The ecological point is the stronger one: a frog is both a predator of insects and prey for snakes and birds, so it holds two links of the web at once, and removing it disturbs both.

Q10 (NCERT Exemplar, 5 marks)

NCERT Exemplar Class 11 Biology, Chapter 7, Long Answer Type Questions, Q1. Classify and describe epithelial tissue on the basis of structural modifications of cells.

Answer: Epithelial tissue is classified by the number of cell layers and by cell shape. A simple epithelium has one layer. Its squamous form has flat cells and lines the mouth and alveoli, its cuboidal form has cube-shaped cells and lines kidney tubules and glands, and its columnar form has tall cells and lines the intestine; a ciliated columnar form bears cilia that move materials along. A compound epithelium has more than one layer and protects surfaces that face wear, as in the skin. Glandular epithelium is a further modification in which cells specialise for secretion. The cells of an epithelium are joined by tight, adhering and gap junctions, the sheet rests on a basement membrane, and it has no blood supply of its own, so it is fed by diffusion. The structure of each type follows its task: thin squamous sheets for exchange, cuboidal cells for secretion and absorption, columnar cells for absorption over a larger surface, and many layers for protection. A labelled line drawing of each type completes the five-mark answer. The drawing should show the free surface facing out and the basement membrane at the base, since those two features define an epithelium in any organ. Label the junctions too: a tight junction at the top, an adhering junction below it and a gap junction between the cells, because the question asks for structural modifications and the junctions are part of that list. A short table of the four simple and one compound type, with one site each, then finishes the answer inside the five marks. Marks come from shape, site and junction, so cover all three before stopping.