Previous year questions: Anatomy of Flowering Plants

Previous year questions: anatomy of flowering plants

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. The chapter has a small set of usable items, so the ten below cover the tissue systems, the two section types and the leaf, and the same content can be asked with the labels swapped.

Q1 (NCERT Exemplar, 1 mark)

NCERT Exemplar Class 11 Biology, Chapter 6, Multiple Choice Questions, Q2. Match the tissue with its work: meristem, parenchyma, collenchyma, sclerenchyma and epidermal tissue against actively dividing cells, photosynthesis and storage, mechanical support, sclereids and stomata.

Answer: The correct option is b. Meristem matches actively dividing cells, parenchyma matches photosynthesis and storage, collenchyma matches mechanical support, sclerenchyma matches sclereids, and epidermal tissue matches stomata. The pairs follow the main job of each tissue. A meristem divides, a parenchyma stores and photosynthesises, a collenchyma supports a growing part, a sclerenchyma hardens it with sclereids, and the epidermis carries the stomata.

Q2 (NCERT Exemplar, 1 mark)

NCERT Exemplar Class 11 Biology, Chapter 6, Multiple Choice Questions, Q4. Which of these is a simple tissue system?

Answer: Parenchyma is the simple tissue, so option (a) is correct. Xylem and phloem are complex tissues because each is built from more than one cell type, and the epidermis is part of the epidermal tissue system rather than a simple tissue in this list. Parenchyma, collenchyma and sclerenchyma are the three simple tissues. The question is a straight matching item, so write the five pairs as a column rather than in prose.

Q3 (NCERT Exemplar, 1 mark)

NCERT Exemplar Class 11 Biology, Chapter 6, Multiple Choice Questions, Q5. A tissue with living cells, angular wall thickening and a mechanical support role is which tissue?

Answer: The tissue is collenchyma, option (c). Its cells are living, the thickening is at the corners of the wall, and that arrangement supports young growing parts. Sclerenchyma also supports, but its cells are dead and its walls are thick all round. The living state and the corner thickening are the two marks that settle the choice. A sclerenchyma cell is dead, and its wall is uniformly thick, so it never shows the soft corner thickening of collenchyma.

Q4 (NCERT Exemplar, 1 mark)

NCERT Exemplar Class 11 Biology, Chapter 6, Multiple Choice Questions, Q7. A conjoint and open vascular bundle is observed in the transverse section of which organ?

Answer: A conjoint and open bundle occurs in the dicot stem, so option (d) is correct. A monocot stem has conjoint closed bundles, a dicot root has radial bundles, and a monocot root also has radial bundles. The cambium in the bundle is the key to the open type. In a monocot stem the absence of cambium is what makes the bundle closed.

Q5 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 6, Very Short Answer Type Questions, Q2. Protoxylem is the first-formed xylem. If protoxylem lies next to the phloem, what kind of xylem arrangement is that?

Answer: That arrangement is endarch. In an endarch bundle the first-formed xylem sits towards the centre of the axis and the later-formed metaxylem lies towards the outside, and this is the pattern of a dicot stem. In an exarch arrangement the protoxylem lies towards the periphery, as in roots. The position of the first-formed xylem therefore tells whether a section is a root or a stem. In a dicot stem the protoxylem sits at the inner edge of each bundle, next to the pith, which is the endarch condition.

Q6 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 6, Very Short Answer Type Questions, Q4. What is present on the leaf surface that prevents water loss but is absent in roots?

Answer: The waxy cuticle is present on the leaf surface and absent in roots. It is a layer over the outer wall of the epidermis, and it limits the loss of water by transpiration. Roots lack a cuticle because they must absorb water from the soil rather than conserve it. A waxy layer on a root would block the very absorption the organ exists for. That is why the cuticle is a leaf character and not a root character.

Q7 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 6, Very Short Answer Type Questions, Q6. Which parts of a plant would show a radial vascular bundle, polyarch xylem and a well-developed pith?

Answer: A radial vascular bundle is shown by roots, where xylem and phloem lie on separate radii. Polyarch xylem, with more than six xylem bundles, is shown by a monocot root. A well-developed pith is also a feature of a monocot root. All three answers therefore point to the root, and the polyarch condition and large pith together point to the monocot root. A dicot root would have shown two to four xylem patches and a small pith.

Q8 (NCERT Exemplar, 2 marks)

NCERT Exemplar Class 11 Biology, Chapter 6, Very Short Answer Type Questions, Q7. Which cells make the leaves curl during water stress?

Answer: The bulliform cells make grass leaves curl. These large, empty, colourless cells sit in the upper epidermis along the veins. When they are turgid they hold the leaf surface open, and when water stress makes them flaccid they shrink and the leaf rolls inward, reducing water loss. The cells are empty and colourless and carry no chloroplasts. Their movement is a simple water balance, not a muscular action. A dry spell makes the cells lose water and deflate, and the leaf folds along the veins, which is the whole mechanism in one line.

Q9 (NCERT Exemplar, 3 marks)

NCERT Exemplar Class 11 Biology, Chapter 6, Short Answer Type Questions, Q5. Epidermal cells are often modified for special functions. Name some of these modifications and their functions.

Answer: Epidermal cells form several special structures. Root hairs are single-cell extensions that absorb water and minerals from the soil. Trichomes are epidermal hairs of the shoot, often many-celled, and they reduce water loss by transpiration and can be secretory. Guard cells of the stomatal apparatus open and close the stomatal pore and so control gas exchange and water loss. In grasses, bulliform cells in the upper epidermis roll the leaf during water stress. Subsidiary cells around the guard cells are another epidermal modification, and they support the stomatal apparatus.

Q10 (NCERT Exemplar, 5 marks)

NCERT Exemplar Class 11 Biology, Chapter 6, Long Answer Type Questions, Q6. Distinguish between exarch and endarch, stele and vascular bundle, protoxylem and metaxylem, open and closed vascular bundles, and stem hair and root hair.

Answer: Exarch has the first-formed xylem towards the periphery, as in roots, while endarch has it towards the centre, as in stems. The stele is the whole central column inside the endodermis, made of pericycle, vascular bundles and pith, while a vascular bundle is a single strand of xylem and phloem. Protoxylem forms first and has narrow vessels and tracheids, while metaxylem forms later and has wider conducting elements. An open vascular bundle contains cambium and can form secondary tissue, while a closed bundle has no cambium. Interfascicular cambium forms in the medullary ray region between two vascular bundles, while intrafascicular cambium lies inside a bundle between its xylem and phloem. Stem hairs are trichomes, often multicellular and branched, that reduce transpiration, while root hairs are single epidermal cells that absorb water and minerals. Both are epidermal outgrowths, but their jobs and their structures are opposite in every useful sense, and that contrast is the pair most often asked from this chapter. Finish the answer by naming the section where each hair is seen: stem hairs on the epidermis of a shoot, and root hairs on the epiblema of a root. A stem hair is many-celled and often branched, while a root hair is one cell that sticks out from the epidermis and does the absorbing.