Biology Class 11 NCERT Solutions: Chapter 5 Morphology of Flowering Plants Part 1

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Q: 1. What is meant by modification of root? What type of modification of root is found in the

(A) Banyan tree

(B) Turnip

(C) Mangrove trees

Answer:

Primarily, there are two types of root systems found in plants, namely the tap root system and fibrous root system. The main function of the roots is to absorb water and minerals from the soil. However, roots are also modified to perform various other functions. The roots of some plants act as storage sites for food, some provide support to massive plant structures, while others absorb oxygen from the atmosphere.

Roots and its modifications in various plants:

(A) Banyan tree

The banyan tree (Ficus benghalensis) has massive pillar-like adventitious roots arising from the aerial part of the stem. These roots grow towards the ground and provide support to the tree. Such roots are called prop roots.

Image shows the banyan tree

Image Shows the Banyan Tree

Image shows the banyan tree

(B) Turnip

The roots of turnip (Brassica rape) help in the storage of food. Similar food-storing roots are found in radishes, carrots, and sweet potatoes.

Image shows the roots of turnip

Image Shows the Roots of Turnip

Image shows the roots of turnip

(C) Mangrove tree

The roots of mangrove plants grow vertically upwards from the soil for the absorption of oxygen from the atmosphere as the soil is poorly aerated. These types of roots are called pneumatophores.

The roots of mangrove tree

The Roots of Mangrove Tree

The roots of mangrove tree

Q: 2. Justify the following statements on the basis of external features

(i) Underground parts of a plant are not always roots

(ii) Flower is a modified shoot

Answer

(i) Various parts of plants are modified into underground structures to perform various functions such as stems, leaves, and even fruits.

The stems in ginger and banana are underground and swollen due to storage of food. They are called rhizomes. Similarly, corm is an underground stem in Colocasia and Zamin-khand. The tips of the underground stem in potato become swollen due to the accumulation of food and forms tuber. Tubers bear eyes, which are subtended by a leaf scar. Basal leaves in onions become fleshy because of the accumulation of food. In peanuts, the flower after fertilization gets pushed inside the soil by growing a flower stalk. The formation of fruits and seeds takes place inside the soil.

(ii) During the flowering season, the apical meristem gives rise to the floral meristem. The axis of the stem gets condensed, while the internodes lie near each other. Instead of leaves, various floral appendages arise from the node. Therefore, it can be said that the flower is a modified shoot.

Q: 3. How is pinnately compound leaf different from palmately compound leaf?

Answer:

Q_3_Table of Pinnately and Palmately Compound Leaf
Q_3_Table of Pinnately and Palmately Compound Leaf

Pinnately Compound leaf

Palmately Compound leaf

The leaflets are attached to the common axis, called rachis.

The leaflets are attached at a common point on the leaf stalk.

Examples include Neem and Cassia fistula (also called golden shower plant)

Examples include silk cotton (Bombax) and Cannabis.

Image of Pinnately Compound leaf

Image of Pinnately Compound Leaf

Image of Pinnately Compound leaf

Palmately compound

Image of the Palmately Compound Leaf

Palmately compound

Q: 4. Explain with suitable examples the different types of phyllotaxy?

Answer:

Phyllotaxy refers to the pattern or arrangement of leaves on the stem or branch of a plant. It is of three types, alternate, opposite, and whorled phyllotaxy.

The different types of phyllotaxy

The Different Types of Phyllotaxy

The different types of phyllotaxy

In alternate phyllotaxy, a single leaf arises from the node of a branch. This type of phyllotaxy is observed in the sunflower, mustard, and peepal. Plants with opposite phyllotaxy have two leaves arising from the node in opposite directions. It is found in guava and jamun plants. Plants with whorled phyllotaxy have three or more leaves arising from the node. It is found in Alstonia.

Q: 5. Define the following terms:

(A) Aestivation

(B) Placentation

(C) Actinomorphic

(D) Zygomorphic

(E) Superior Ovary

(F) Perigynous Flower

(G) Epipetalous Stamen

Answer:

(A) Aestivation:

The term 'aestivation' refers to the mode in which sepals or petals are arranged in a floral bud with respect to other floral members. There are four types of aestivation in plants i.e., valvate, twisted, imbricate, and vexillary.

(B) Placentation

The term 'placentation' refers to the arrangement of ovules within the ovary of a flower. It is primarily of five types, namely marginal, basal, parietal, axile, and free central.

(C) Actinomorphic

Actinomorphic flowers can be divided into two radial halves by any radial plane passing through its centre. Examples of these flowers include chilly and mustard.

(D) Zygomorphic

Zygomorphic flowers are those flowers, which can be divided into two similar halves by a single vertical plane. Examples of these flowers include pea and beans.

(E) Superior ovary

Superior ovary flowers are those flowers in which the gynoecium is present at the highest position, while other floral parts are arranged below it. A flower with this arrangement is described as hypogynous. Examples include brinjal and mustard.

(F) Perigynous flower

In perigynous flowers, the gynoecium is present in the centre and the rest of the floral parts are arranged at the rim of the thalamus at the same level. Examples include plum and rose.

(G) Epipetalous Stamen

Epipetalous stamens are stamens attached to the petals. They are found in brinjal.