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NEET-XI-Biology

05: Morphology of Flowering Plants

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    5 - Morphology of Flowering Plants
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    Section : I
    Page No 82:
  • Qstn #1
    What is meant by modification of root? What type of modification of root is found in the
    Ans : 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:
  • #1-a
    Banyan tree
    Ans : 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.
  • #1-b
    Turnip
    Ans : 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.
  • #1-c
    Mangrove trees
    Ans : 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.
  • Qstn #2
    Justify the following statements on the basis of external features
  • Qstn #2-i
    Underground parts of a plant are not always roots
    Ans : 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.
  • Qstn #2-ii
    Flower is a modified shoot
    Ans : 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.
  • Qstn #3
    How is pinnately compound leaf different from palmately compound leaf?
    Ans :
    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.
  • Qstn #4
    Explain with suitable examples the different types of phyllotaxy?
    Ans : 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.

    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.

    SECTION I SECTION I Page No 83:
  • #5-a
    Aestivation
    Ans : 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.
  • #5-b
    Placentation
    Ans : 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.
  • #5-c
    Actinomorphic
    Ans : 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.
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