NCERT Exemplar Class 11 Biology Solutions Chapter 6 Anatomy of Flowering Plants

Question: 1

A transverse section of the 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?

1. Red and green

2. Green and red

3. Orange and yellow

4. Purple and orange

Answer:

The answer is option (a), Red and green
Explanation: Xylem is coloured red with safranin because the walls of the xylem cells contain lignin, which picks up the red dye of safranin, and phloem is coloured green with fast green because fast green stains the dense cytoplasm and cell walls present in the phloem.

Question: 2

Match the followings and choose the correct option from below

Answer:

A. Meristem: It includes a group or cluster of cells which remain in a continuous state of division or retain their power of division.
B. Parenchyma: It performs the function of storage of reserve food materials, storage of water in succulents, Buoyancy and gaseous exchange in water plants.
C. Collenchyma: It is the main supporting tissue in young dicotyledonous stems. Tissue has the capacity to expand and gives tensile strength to the body.
D. Sclerenchyma: It consists of thick-walled dead cells. It is of two main types: Fibres and Sclereids. Sclereids are short and possess extremely thick lamellated lignified walls with long tubular simple pits.
E. Epidermal tissue: The tissue originates from the outermost layer of the apical meristem. It has an epidermis, cuticles and wax, Stomata, and Trichomes. Singular of stomata is stoma. A typical stoma is microscopic and usually consists of two kidney-shaped guard cells surrounding a pore.
So, the correct answer is 'A-(iii), B-(i), C-(ii), D-(v), E-(iv)'.

Question: 3

Match the following and choose the correct option from below

Options:
(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)

Answer:

The answer is the option (a) A-(iii), B-(iv), C-(i), D-(ii)
Explanation:
A- Cuticle provides a waxy layer to the epidermis of the leaves for protection.
B- Bulli form cells are large, empty and colourless epidermal cells.
C- Stomata is a guard cell as it helps in gas exchange.
D- The Epidermis is a single layer of cells in plant

Question: 4

Identify the simple tissue from among the following

1. Parenchyma

2. Xylem

3. Epidermis

4. Phloem

Answer:

The answer is option (a), Parenchyma
Explanation: Parenchyma is a simple tissue as it contains one kind of cells while the others are complex tissues as they contain more than one type of cells.

Question: 5

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

1. Xylem

2. Sclerenchyma

3. Collenchyma

4. Epidermis

Answer:

The answer is option (c), Collenchyma
Explanation: Cells present in Xylem and Collenchyma are dead cells, and living cells may be present in the epidermis, but the epidermis does not provide mechanical support.

Question: 6

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

1. Monocot root

2. Monocot stem

3. Dicot root

4. Dicot stem

Answer:

The answer is option (d), the Dicot stem
Explanation: Vascular bundles present in dicot stems are conjoint and open unlike in another monocot stem, root and dicot root.

Question: 7

Answer:

The answer is option (c) Cell dedifferentiation
Explanation: The Process leading to the maturation of plants is differentiation. When differentiated cells regain its capacity of cell division, the phenomenon is called dedifferentiation. The formation of interfascicular cambium and cork cambium is an example of cell dedifferentiation from fully matured/differentiated parenchyma cells.

Question: 8

Phellogen and Phellem respectively denote

1. Cork and cork cambium

2. Cork cambium and cork

3. Secondary cortex and cork

4. Cork and secondary cortex

Answer:

The answer is option (b) Cork cambium and cork
Explanation: Cork cambium or phellogen is formed in the cortex region, and phellogen differentiates into cork or phellem.

Question: 9

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

Root tip and shoot tip

1. Shoot bud and floral bud

2. Ovule and seed

3. Petiole and pedicel

Answer:

The answer is option (a) Root tip and shoot tip
Explanation: Root tips and shoot tips have meristematic cells, and epidermis is absent in them.

Question:10

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

Answer:

The answer is option (c) 5

Explanation: Five shoot apical meristems are generally present in a twig of a plant having 4 branches and 26 leaves. Four tips are present in branches and one in the tip.

Question:11

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

1. Teak

2. Mango

3. Pine

4. Palm

Answer:

The answer is option (c) Pine
Explanation: Vessels are present in angiosperms and absent in gymnosperms, and hence, Pine is a gymnosperm and the correct answer.

Question:12

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

1. Collenchyma

2. Sclerenchyma

3. Xylem

4. Meristem

Answer:

The answer is option (a) Collenchyma

Explanation: Collenchyma cells have depositions of cellulose, pectin, and hemicellulose.

Question:13

In conifers, fibres are likely to be absent in

1. Secondary phloem

2. Secondary Xylem

3. Primary phloem

4. Leaves

Answer:

The answer is option (b) Secondary Xylem
Explanation: Elongated cells that are present in sclerenchyma are called fibres. Sclerenchyma is absent in secondary xylem; hence, there is an absence of fibres as well.

Question:14

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

1. Periderm

2. Epidermis

3. Cuticle

4. Sapwood

Answer:

The answer is option (a) Periderm
Explanation: Periderm because the potato is a modified stem, and the outermost layer of the stem is a periderm.

Question:15

Answer:

The answer is option (d) Trochodendron
Explanation: Pinus and grass are gymnosperms and, therefore, do not contain sieve tubes, while eucalyptus contains vessels. Trochodendron contains sieve tubes but lacks vessels.

Question:16

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

1. fusiform initial cells

2. root cap

3. protoderm

4. phellogen

Answer:

The answer is option (c) protoderm
Explanation: The Protoderm cell divides by anticlinal cell division, unlike others.

Question:17

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

1. It is retained in the centre of the axis

2. It gets crushed

3. May or may not get crushed

4. It gets surrounded by primary phloem

Answer:

The answer is option (a) It is retained in the centre of the axis
Explanation: The Primary xylem is retained in the centre of the axis while the primary phloem is crushed.

Question:18

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

1. It is retained in the centre of the axis

2. It gets crushed

3. May or may not get crushed

4. It gets surrounded by primary phloem

Answer:

The answer is option (a) It is retained in the centre of the axis
Explanation: The Primary xylem is retained in the centre of the axis, while the primary phloem is crushed.

Access Answers to NCERT Exemplar Class 11 Science Chapter 6 Anatomy of Flowering Plants (Very Short Answer)

The answers to the short answer questions are given below:

Question:1

The 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?

Answer:

Food gets stored in parenchymatous cells that are present either in the stems or the roots

Question:2

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

Answer:

If the protoxylem lies next to the phloem, the arrangement is called an exarch. This arrangement can be found in roots.

Question:3

What is the function of phloem parenchyma?

Answer:

The primary function of phloem parenchyma is the storage of food and transportation of food. It also helps in storing other substances like latex and resins.

Question:4

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

Answer:

The cuticle is the waxy layer that is present on the leaves, which prevents the loss of water. The cuticles are absent in roots.

Question:5

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

Answer:

Bulli form cells are the epidermal cell modification in plants which prevents water loss.

Question:6

What part of the plant would show the following:

1. Radial vascular bundle

2. Polyarch xylem

3. Well-developed pith

Answer:

a) The radial vascular bundle is available in roots.
(b) Polyarch xylem is available in monocot roots.
(c) A well-developed pith can be found in dicot stems and monocot roots.

Question:7

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

Answer:

Bulli form cells make the leaves curl in plants during water stress because there is a loss of turgor pressure in the leaves, which makes them curl.

Question:8

What constitutes the cambial ring?

Answer:

The cambial ring is a ring of cambium that is made together by interfascicular and intrafascicular cambia.

Question:9

Give one basic functional difference between phellogen and phelloderm.

Answer:

Phellogen consists of meristematic cells, whereas phelloderm is a permanent tissue made up of permanent cells.

Question:10

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

Answer:

Phellem is the outermost layer followed by Phellogen and then Phelloderm.

Question:11

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

Answer:

Bark consists of cork, cork cambium, secondary cortex, and secondary phloem. If one debarks a tree, these parts will be removed.

Question:12

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

1. The vascular bundles were radially arranged.

2. Four xylem strands with exarch condition of protoxylem.

To which organ should it be assigned?

Answer:

In roots, vascular bundles are radially arranged, and the four xylem strands are arranged with exarch condition.

Question:13

What do hardwood and softwood stand for?

Answer:

Dicot angiospermic wood is called hardwood, and gymnosperm wood is called softwood.

Question:14

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?

Answer:

While eating peach or pear, it is usually seen that entangled in teeth are called stone cells. Stone cells are a type of sclerenchyma cells.

Question: 15

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

Answer:

The commercial source of cork is Quercus suber. Cork is formed from phellogen or cork cambium that is formed as secondary meristem due to dedifferentiation.

Question: 16

Below is a list of plant fibres. From which part of the plant are these obtained
(a) Coir (b) Hemp (c) Cotton (d) Jute

Answer:

a) Coir is obtained from the outer coating of a coconut seed

b) Hemp is obtained from the stem of the Cannabis sativa plant

c) Cotton is obtained from cotton boll seeds

d) Jute is obtained from the stem of the jute plant

Question: 17

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

Answer:

Question: 18

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

Answer:

Some of the modifications of epidermal cells and their functions are-

1. Root hair helps in absorbing water and important minerals for the plant.

2. Stinging hair (trichomes) protects the plant from the physical environment.

Question: 19

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

Answer:

Meristematic tissue is responsible for the overgrowth of lawn grass. When grass is mowed, the apical layer is removed, which gives way to the growth of lateral branches which was obstructed by the apical buds. This makes the grass bushier.

Question: 20

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

Answer:

Ans. Water is a necessary element for the survival of a plant. But excessive watering can lead to its death because excess water replaces the air, and there is a lack of oxygen respiration, leading to the death of plant cells.

Question: 21

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?

Answer:

Growth rings are formed from meristematic tissue of the cambium in dicot trees. Cambium is very active in the spring season, leading to the formation of a large number of xylary elements having wider vessel cavities. This wood is called springwood. In winter, the cambium activity is slowed down, leading to lesser xylary element with narrow vessel cavities. The wood is called latewood or autumn wood.

The two kinds of wood appear together with concentric rings known as annual rings or growth rings. These rings give an estimated age of a tree.

Question: 22

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.

Answer:

It is a case of anatomical abnormality, which is due to abnormal secondary growth caused by the abnormal positioning of meristematic tissue cambium. Sometimes in aged trees, the abnormal secondary growth produces extravascular bundles which lead to the growth of fused trunks.

Question: 23

What is the difference between lenticels and stomata?

Answer:

Question: 24

Write the precise function of
(a) Sieve tube (b) Interfascicular cambium
(c) Collenchyma (d) Aerenchyma

Answer:

1. Transportation of synthesised food.

2. It helps in secondary growth.

3. It provides mechanical support to herbaceous stems.

4. It helps hydrophytes in facilitating buoyancy.

Question: 25

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.

Answer:

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

Question: 26

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

Answer:

Question: 27

The palm is a monocotyledonous plant, yet it increases in girth. Why and how?

Answer:

Palm tree shows secondary growth due to the repeated division of parenchymatous cells which causes an increase in the girth of the stem.

Access Answers to NCERT Exemplar Class 11 Science Chapter 6 Anatomy of Flowering Plants (Long Answer)

Question:1

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

Answer:

The placenta is soft tissue to which the ovules are attached. It is found in the inner ovary wall. The arrangement of ovules inside the ovary is called placentation. Placentation can be of different types like marginal, basal, parietal, axile and free central placentation. In marginal one, a ridge kind of structure is formed between the placenta and the ovary. The ovules are arranged on this ridge in two rows, for example, pea. In basal one, the placenta is formed at the lower region of the ovary. Only a single ovule is attached to the placenta: example- sunflower. In parietal one, the ovules are attached in the inner wall of the ovary or in the peripheral area in two chambers, example- mustard. In axile placentation, the ovules develop in the central axis in a multilocular ovary, for example, tomato. In free central placentation, the ovules develop in central axis but in a unilocular ovary, example- primrose.

Question: 2

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.

Answer:

Shedding of leaves in plants is known as abscission of leaves. Apart from physiological changes, anatomical changes are also involved in the shedding of leaves.

Some anatomical changes are –

1. Formation of an abscission zone, also known as a separation zone, at the base of the petiole in deciduous trees. This zone is made up of a weak top layer and a bottom layer. In the autumn, the bottom layer expands, breaking the cells of the top layer, which allows the leaf to shed.

2. Excess loss of chlorophyll can also be attributed to the falling of the leaves.

3. Hormonal change can also occur in deciduous trees due to excess secretion of abscisic acid, which stimulates the process of abscission.

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 the shedding of leaves.

Question:3

Is Pinus an evergreen tree? Comment.

Answer:

Pinus is not a deciduous tree because it does not shed its leaves in any particular season. It is an evergreen tree because it has leaves throughout the year and the leaves shed throughout the year and grow back. This is because Pinus trees have thicker cuticles and sunken stomata that reduce the loss of water, helping it to grow leaves throughout the year.

Question: 4

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.

Answer:

It can be cut vertically, horizontally and diagonally. If a plant cell is cut in two equal halves, it can be cut in bilateral symmetry. If a plant is cut in different planes, it will result in radial symmetry. Therefore, it can be cut either in a single plane or a different plane.

Question: 5

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

1. Plasmadesmoses/ Plasmodesmata

2. Middle lamella

3. Secondary wall

Answer:

(a) Plasmodesmata are channels that directly connect the cytoplasm of one plant cell to another. It helps in establishing communication and transportation of food and other important minerals from one plant cell to another.

(b) Middle lamella consists of pectin which acts as a glueing agent helping in holding cell walls of two adjacent cells together.


(c) Secondary walls are composed of cellulose, lignin and hemicellulose, which provide strength to the plant and protect it from any mechanical stress.

Question: 6

Distinguish between the following:
(a) Exarch and endarch condition of protoxylem
(b) Stele and vascular bundle
(c) Protoxylem and metaxylem
(d) Interfasicular cambium and intrafasicular cambium
(e) Open and closed vascular bundles
(f) Stem hair and root hair

Answer:

(a) Endarch is a protoxylem condition that occurs in the stem of a plant when the protoxylem is arranged in the centre and the metaxylem is arranged at the periphery of the stem. Exarch is a protoxylem condition that occurs in the roots of a plant. In this, the protoxylem lies at the periphery, and the metaxylem is arranged in the centre. This arrangement is called the exarch.

(b) The stele comprises the major part of the root and stem. Stele consists of the vascular bundles, pericycle and the pith. The vascular bundle is a part of the stele consisting of xylem and phloem types of complex tissues.

(c) There are two kinds of primary xylem- protoxylem and metaxylem. The primary xylem, which formed earlier and is smaller in size, is the protoxylem, and the one which is formed later and is larger in size is called the metaxylem.

(d) In dicot stems, the cambium cells that are present between the primary xylem and primary phloem are called the intrafascicular cambium, whereas the interfascicular cambium is formed by the adjoining medullary cells with the intrafascicular cambium. This meristematic form is the interfascicular cambium.

(e) A closed vascular bundle is the one which lacks cambium and, therefore, cannot perform secondary growth, whereas an opened vascular bundle is the one which has cambium and can very well perform secondary growth.

(f) Stem hairs are trichomes that grow on stems. Trichomes are multicellular epidermal cells, and these can be branched or unbranched and soft or rigid. These protect plants form physical dangers and also help in preventing much loss of water. Root hairs are unicellular epidermal cells present in the roots of plants. Root hairs help in absorbing water and important minerals from the soil for the growth of the plant.