NCERT Exemplar for Class 11 Biology Chapter-6 (Book Solutions)

Multiple Choice Questions(MCQs)

1. A transverse section of stem is stained first with safranin and then with fast green following the usual schedule of double staining for the preparation of a permanent slide. What would be the colour of the stained xylem and phloem?

(a) Red and green

(b) Green and red

(c) Orange and yellow

(d) Purple and orange

Ans: (a) Red and green

When Xylem is coloured it will change into colour red and phloem is coloured green with fast green.

2. Match the followings and choose the correct option from below:

(a) A-(i), B-(iii), C-(v), D-(ii), E-(iv)
(b) A-(iii), B-(i), C-(ii), D-(v), E-(iv)
(c) A-(ii), B-(iv), C-(v), D-(i), E-(iii)
(d) A-(v), B-(iv), C-(iii), D-(ii), E-(i)

Ans: (b) A-(iii), B-(i), C-(ii), D-(v), E-(iv)

Explanation: Cells of meristem possess the ability for division, Parenchyma forms the bulk of plant tissues and photosynthesis takes place in parenchyma. Collenchyma provides mechanical support to young parts. Sclereids are a type of sclerenchyma. Stomata is an epidermal tissue.

3. Match the following and choose the correct option from below:

(a) A-(iii), B-(iv), C-(i), D-(ii)

(b) A-(i), B-(ii), C-(iii), D-(iv)

(c) A-(iii), B-(ii), C-(iv), D-(i)

(d) A-(iii), B-(ii), C-(i), D-(iv)

Ans: (a) A-(iii), B-(iv), C-(i), D-(ii)

Explanation: Guard cells are present in stomata and epidermis is composed of a single layer of cells called bulliform cells which  are empty colourless cell and cuticle has waxy layer.

4. Identify the simple tissue from among the following:

(a) Parenchyma

(b) Xylem

(c) Epidermis

(d) Phloem

Ans: (a) Parenchyma

Explanation: Only Parenchyma is a simple tissue. Xylem and phloem are complex tissues. Epidermis is also complex as it may contain stomata; apart from normal cells.

5. Cells of this tissue are living and show angular wall thickening. They also provide mechanical support. The tissue is

(a) Xylem

(b) Sclerenchyma

(c) Collenchyma

(d) Epidermis

Ans: (c) Collenchyma

Explanation: Collenchyma is the only tissue which is living and show angular wall thickening. Cells of xylem and sclerenchyma are dead cells. Cells of epidermis do not show wall thickening.

6. Epiblema of roots is equivalent to

(a) Pericycle

(b) Endodermis

(c) Epidermis

(d) Stele

Ans: (c) Epidermis

Explanation: Epidermis is equivalent to the roots of Epiblema

7. A conjoint and open vascular bundle will be observed in the transverse section of

(a) Monocot root

(b) Monocot stem

(c) Dicot root

(d) Dicot stem

Ans: (d) Dicot stem

Explanation: Open bundles are present in those parts which are capable of secondary growth. Out of the given options, only the dicot stem is capable of secondary growth.

8. Interfascicular cambium and cork cambium are formed due to

(a) Cell division

(b) Cell differentiation

(c) Cell dedifferentiation

(d) Redifferentiation

Ans: (c) Cell dedifferentiation

Explanation: The phenomenon of regeneration of permanent tissue to become meristematic is called dedifferentiation.

9. Phellogen and Phellem respectively denote

(a) Cork and cork cambium

(b) Cork cambium and cork

(c) Secondary cortex and cork

(d) Cork and secondary cortex

Ans: Cork cambium and cork

Explanation: Cork cambium generates cork and hence is called phellogen and cork is called phellem.

10. In which of the following pairs of parts of a flowering plant is epidermis absent?

(a) Root tip and shoot tip

(b) Shoot bud and floral bud

(c) Ovule and seed

(d) Petiole and pedice

Ans: (a) Root tip and shoot tip

Explanation: Root tip and shoot tip have meristematic cells and hence epidermis is absent. Epidermis has differentiated cells which is not the case in case of meristem. 

11. How many shoot apical meristems are likely to be present in a twig of a plant possessing, $4$ branches and $26$ leaves?

(a) $26$

(b) $1$

(c) $5$

(d) $30$

(e) $4$

Ans: (c) $5$

Explanation: Four apical meristems are present at the tip of four branches and the fifth one is present at the shoot apex.

12. A piece of wood having no vessels (trachea) must be belong to

(a) Teak

(b) Mango

(c) Pine

(d) Palm

Ans: (c) Pine

Explanation: Trachea is not present in gymnosperms. Rest of the options show angiosperms.

13. A plant tissue, when stained, showed the presence of hemicellulose and pectin in cell wall of its cells. The tissue represents

(a) Collenchyma

(b) Sclerenchyma

(c) Xylem

(d) Meristem

Ans: (a) Collenchyma

Explanation: Collenchyma cells have hemicellulose and pectin.

14. In conifers, fibres are likely to be absent in

(a) Secondary phloem

(b) Secondary Xylem

(c) Primary phloem

(d) Leaves

Ans: (b) Secondary Xylem

Explanation: Elongated cells of sclerenchyma are called fibres. Sclerenchyma is absent in Secondary xylem and option ‘b’ is correct.

15. When we peel the skin of a potato tuber, we remove

(a) Periderm

(b) Epidermis

(c) Cuticle

(d) Sapwood

Ans: (a) Periderm

Explanation: In some small woody stem and many non-woody stem, epidermis is replaced by periderm. It is a kind of cork.

16. A vessel-less piece of stem possessing prominent sieve tubes would belong to

(a) Pinus

(b) Eucalyptus

(c) Grass

(d) Trochodendron

Ans: (d) Trochodendron 

Explanation: Trochodendron lacks vessel elements which is quite unusual for flowering plants. Only one living species of trochodendron is known to exist.

17. Which one of the following cell types always divides by anticlinal cell division?

(a) fusiform initial cells

(b) root cap

(c) protoderm

(d) phellogen

Ans: (c) protoderm

18. What is the fate of primary xylem in a dicot root showing extensive secondary growth?

(a) It is retained in the centre of the axis

(b) It gets crushed

(c) May or may not get crushed

(d) It gets surrounded by primary phloem

Ans: (a) It is retained in the centre of the axis

19. Product of photosynthesis is transported from the leaves to various parts of the plants and stored in some cell before being utilised. What are the cells/ tissues that
store them?

Ans: Food is stored in parenchyma in trees and plants.

20. Protoxylem is the first formed xylem. If the protoxylem lies next to phloem what kind of arrangement of xylem would you call it? 

Ans: If phloem lies next to protoxylem, this kind of arrangement of xylem is called exarch. 

21. What is the function of phloem parenchyma?

Ans: The main function of phloem parenchyma is food storage. It also helps in translocation of food.

22. What is present on the surface of the leaves which helps the plant prevent loss of water but is absent in roots? 

Ans: Cuticle is present on the surface of leaves. It helps prevent the loss of water. Cuticle is absent in the roots.

23. What is the epidermal cell modification in plants which prevents water loss? 

Ans: Bulliform cells are modified epidermal cells. These are present in grasses. They help in closing the stomata under stressful conditions and this prevents water loss.

24. What part of the plant would show the following:

(a) Radial vascular bundle

Ans: Radial vascular bundle is present in roots.

(b) Polyarch xylem

Ans: Polyarch xylem is present in monocot root.

(c) Well developed pith

Ans: A well-developed pith is present in dicot stem and monocot roots.

25. What are the cells that make the leaves curl in plants during water stress? 

Ans: Bulliform cells make the leaves curl in plants during water stress. This happens because of loss of turgor pressure in these cells.

26. What constitutes the cambial ring?

Ans: Interfascicular and intrafascicular cambia together form the cambial ring.

27. Give one basic functional difference between phellogen and phelloderm.

Ans: 

28. Arrange the following in the sequence you would find them in a plant starting from the periphery – phellem, phellogen, phelloderm.

Ans: The correct sequence is:

Phellem $ \to $ Phellogen $ \to $ Phelloderm

29. If one debarks a tree, what parts of the plant is being removed?

Ans: If bark is removed from a tree then periderm is being removed. Periderm contains phellogen, phellem and phelloderm. Bark also contains secondary phloem.

30. The cross-section of a plant material showed the following features when viewed under the microscope.

(a) The vascular bundles were radially arranged.

(b) Four xylem strands with exarch condition of protoxylem.

To which organ should it be assigned?

Ans: From the given cross-section in the question, it should be assigned to the root.

31. What do hardwood and softwood stand for?

Ans: Wood from gymnosperm is called softwood, while wood from angiosperm is called hardwood.

32. While eating peach or pear it is usually seen that some stone-like structures get entangled in the teeth. What are these stone-like structures called?

Ans: The fruits of peach or pear contain stone cells or sclereids. These stone cells are a type of  sclerenchyma. These cells give stone-like consistency to small particles of these fruits.

33. What is the commercial source of cork? How is it formed in the plant?

Ans: The commercial source of cork is the cork tissue of Quercus suber. Cork cambium or phellogen cell are used to form cork. Then phellogen cells divide periclinaly; cutting cells towards the inside and outside. The cells which are cut off towards the outside become suberised and dead and form cork.

34. Below is a list of plant fibres. From which part of the plant these are obtained

(a) Coir

Ans: Coir is obtained from Coconut husk 

(b) Hemp 

Ans: Hemp is obtained from the stem of Cannabis sativa

(c) Cotton 

Ans: Cotton is from Epidermal growth of cotton seeds 

(d) Jute

Ans: Jute is obtained from the stem of Corchorus capsularis

35. What are the characteristic differences found in the vascular tissue of gymnosperms and angiosperms? 

Ans: The differences between vascular tissues of gymnosperms and angiosperms are following: 

36. Epidermal cells are often modified to perform specialized functions in plants. Name some of them and the functions they perform.

Ans: Some of the modifications of epidermal cells and their functions are as follow: 

1. Root hair: Root hairs increase the surface area and thus enhance absorption.

2. Trichomes: Some have stinging purpose and some glandular secretions. Trichomes also help in preventing water loss due to transpiration.

37. The lawn grass (Cyandon dactylon) needs to be mowed frequently to prevent its overgrowth. Which tissue is responsible for its rapid growth? 

Ans: The meristematic tissue in lawn grass is responsible for its rapid growth. When lawn is mowed, it destroys the apical meristem and thus prevents growth in height. But it promotes the growth of lateral branches; making the lawn more bushy.

38. Plants require water for their survival. But when watered excessively, plants die. Discuss. 

Ans: Excess water in soil removes the air trapped between soil particles. This results in oxygen deprivation for roots. Hence, plants die when watered excessively.

39. A transverse section of the trunk of a tree shows concentric rings which are known as growth rings. How are these rings formed? What is the significance of these rings? 

Ans: These rings are formed due to secondary growth in the trunk. The cambium activity is more in spring than in winter. So, the wood formed during spring has larger xylem compared to the wood formed in winter. As a result, light-coloured wood is formed during spring and dark-coloured wood is formed during winter. This gives the appearance of concentric rings. Concentric rings help in making an estimate about the age of the tree.

40. Trunks of some of the aged tree species appear to be composed of several fused trunks. Is it a physiological or anatomical abnormality? Explain in detail.

Ans: This is an anatomical abnormality. In case of abnormal secondary growth, cortical and medullary vascular bundles are formed. This gives rise to additional or accessory vascular bundles which give the appearance of additional trunks which appear to be fused.

41. What is the difference between lenticels and stomata?

Ans: 

42. Write the precise function of

(a) Sieve tube 

Ans: Translocation of food.

(b) Interfascicular cambium

Ans: It facilitates secondary growth.

(c) Collenchyma 

Ans: It provides mechanical support to young stem.

(d) Aerenchyma

Ans: It provides buoyancy to floating plants.

43. The stomatal pore is guarded by two kidney shaped guard cells. Name the epidermal cells surrounding the guard cells. How does a guard cell differ from an epidermal cell? Use a diagram to illustrate your answer.

Ans: The epidermal cells surrounding the guard cells are called subsidiary cells. Following are the differences between guard cells and epidermal cells:

44. Point out the differences in the anatomy of, leaf of peepal (Ficus religiosa) and maize (Zea mays). Draw the diagrams and label the differences.

Ans: 

Ficus leaf	Maize leaf
(i) This is a dorsiventral leaf.	(i) This is an isobilateral leaf.
(ii) Stomata are more on lower surface.	(ii) Stomata are equal in number on both the surfaces.
(iii) Mesophyll is made up of two types of tissues, viz. spongy parenchyma and palisade parenchyma.	(iii) Mesophyll is made up of only spongy parenchyma.
(iv) Parenchymatous cells or some collenchymatous cells are found just above and below the vascular bundle.	(iv) Sclerenchymatous cells are found just above and below the vascular bundle.
(v) Bulliform cells are absent.	(v) Bulliform cells are present.

45. Palm is a monocotyledonous plant, yet it increases in girth. Why and how? 

Ans: In spite of being a monocotyledonous plant, palm shows secondary growth. This happens because of division and enlargement of parenchymatous cells in the ground tissue. This type of secondary growth is called diffused secondary growth.

46. The arrangement of ovules within the ovary is known as placentation. What does the  term placenta refer to? Draw various types of placentations in the flower as seen in T.S.  and V.S. 

Ans: Placenta is a flattened, cushion-like tissue. One or more ovules are attached on it. Its  function is to supply nutrients to the developing embryo.

47. Deciduous plants shed their leaves during hot summer or in autumn. This process of shedding of leaves is called abscission. Apart from physiological changes what anatomical mechanism is involved in the abscission of leaves.

Ans: Shedding of leaves in plants is known as abscission of leaves.Several physiological as well as anatomical changes are causes of shedding of leaves. The abscission zone is also called the separation zone. It is formed at the base of the petiole. It is composed of a top layer and a bottom layer. The cells in the top layer have weak cell walls. The bottom layer expands in winter and breaks the cell walls of the top layer. This results in shedding of leaves.

48. Is Pinus an evergreen tree? Comment.

Ans: We know that trees which shed their leaves in a particular season are called deciduous trees. On the other hand, trees which shed their leaves throughout the year are evergreen trees; because they always appear to be covered with leaves. Pinus does not shed its leaves during any particular season rather keeps on doing so throughout the year. Hence, pinus is considered as an evergreen tree.

49. Assume that a pencil box held in your hand, represents a plant cell. In how many possible planes can it be cut? Indicate these cuts with the help of line drawings.

Ans: It can be cut vertically, horizontally and diagonally. Thus, it can be cut into three planes, through three axes, i.e. x, y, and z.

50. Each of the following terms has some anatomical significance. What do these terms mean? Explain with the help of line diagrams.

(a) Plasmadesmoses/ Plasmodesmata

The microscopic channels between two cells through the cell wall are called plasmodesmata. Plasmodesmata allows transport of materials between two cells.

(b) Middle lamella

Ans: It is a layer in the cell wall and is made of calcium pectate. It facilities cementing between two cells.

(c) Secondary wall

Ans: This is a non-extensible layer. It is made of hemicellulose. It provides rigidity to the cell.

51. Distinguish between the following:

(a) Exarch and endarch condition of protoxylem

Ans: 

(b) Stele and vascular bundle

Ans: 

(c) Protoxylem and metaxylem 

Ans: 

(d) Interfascicular cambium and interfascicular cambium

Ans: 

(e) Open and closed vascular bundles

Ans: 

(f) Stem hair and root hair

Ans:  

Anatomy of Flowering Plants

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The Contents Included in Introduction to Anatomy of Flowering Plants

• Chapter 1 – Structure of Flowering Plants; 

• Chapter 2 – Vegetative and Reproductive System; 

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• Chapter 4 – Flower Structure; 

• Chapter 5 – Flower Color; 

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