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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(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.(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.(c) Mangrove trees - 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.
Question 2.
Answer:
Question 3.
Answer: Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. This is usually of three types – alternate, opposite and whorled. In alternate type of phyllotaxy, a single leaf arises at each node in alternate manner, as in china rose, mustard and sun flower plants. In opposite type, a pair of leaves arise at each node and lie opposite to each other as in Calotropis and guava plants. If more than two leaves arise at a node and form a whorl, it is called whorled, as in Alstonia. Examples are: Compound leaf and Simple leaf.
Question 4.
Answer: (a) Aestivation:The mode of arrangement of sepals or petals in floral bud with respect to the other members of the same whorl is known as aestivation.(b) Placentation:The arrangement of ovules within the ovary is known as placentation.(c) Actinomorphic:When a flower can be divided into two equal radial halves in any radial plane passing through the centre, it is said to be actinomorphic, e.g., mustard, datura, chilli, etc.,(d) Zygomorphic:When it can be divided into two similar halves only in one particular vertical plane, it is zygomorphic, e.g., pea, gulmohur, bean, Cassia, etc.(e) Superior ovary:A superior ovary is an ovary attached to the receptacle above the attachment of other floral parts.(f) Perigynous flower:If gynoecium is situated in the centre and other parts of the flower are located on the rim of the thalamus almost at the same level, it is called perigynous.(g) Epipetalous stamen:When stamens are attached to the petals, they are epipetalous, e.g. brinjal.
Question 5.
Answer: (a) Racemose inflorescence and Cymose inflorescence:
(b) Fibrous root and adventitious root:
(c) Apocarpous and syncarpous ovary:
Question 6.
Answer:
Question 7.
Answer: The stem may not always be typically like what they are expected to be. They are modified to perform different functions. Underground stems of potato, ginger, turmeric and zaminkand, Colocasia are modified to store food in them. They also act as organs of perenation to tide over conditions unfavourable for growth. Stem tendrils, which develop from axillary buds are slender and spirally coiled and help plants to climb such as in gourds (cucumber, pumpkins and watermelon) and grapevines.Axillary buds of stems may also get modified into woody, straight and pointed thorns. Thorns are found in many plants such as Citrus, Bougainvillea etc, are protect plants from browsing animals. Some plants of arid regions modify their stems into flattened (Opuntia) or fleshy cylindrical (Euphorbia) structures. They contain chlorophyll and carry out photosynthesis. Underground stems of some plants such as grass and strawberry etc., spread to new niches and when older parts die new plants are formed. In plants like mint and jasmine a slender lateral branch arises from the base of the main axis and after growing aerially for some time arch downwards to touch the ground. A lateral branch with short internodes and each node bearing a rosette of leaves and a tuft of roots is found in aquatic plants like Pistia and Eichhornia. In banana, pineapple and Chrysanthemum, the lateral branches originate from the basal and underground portion of the main stem, grow horizontally beneath the soil and then come out obliquely upward giving rise to leafy shoots.
Question 8.
Answer: PlacentationThe arrangement of ovules within the ovary is known as placentation. The placentation is of different types namely, marginal, axile, parietal, basal, central and free central. In marginal placentation the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows, as in pea. When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentaion is said to be axile, as in china rose, tomato and lemon. In parietal placentation, the ovules develop on the inner wall of the ovary oron peripheral part. Ovary is one-chambered but it becomes two chambereddue to the formation of the false septum, e.g., mustard and Argemone. When the ovules are borne on central axis and septa are absent, as in Dianthus and Primrose the placentation is called free central. In basal placentation, the placenta develops at the base of ovary and a single ovule is attached to it, as in sunflower, marigold.
Question 9.
Answer: The flower is the reproductive unit in the angiosperms. It is meant for sexual reproduction. A typical flower has four different kinds of whorls arranged successively on the swollen end of the stalk or pedicel is called thalamus or receptacle. These are calyx, corolla, androecium and gynoecium. Calyx and corolla are accessory organs, while androecium and gynoecium are reproductive organs. In some flowers like lily, the calyx and corolla are not distinct and are termed as perianth. When a flower has both androecium and gynoecium, it is bisexual. A flower having either only stamens or only carpels is unisexual.
Question 10.
Answer: Leaves are often modified to perform functions other than photosynthesis. They are converted into tendrils for climbing as in peas or into spines for defence as in cacti. The fleshy leaves of onion and garlic store food. In some plants such as Australian acacia, the leaves are small and short-lived. The petioles in these plants expand, become green and synthesise food. Leaves of certain insectivorous plants such as pitcher plant, venus-fly trap are also modified leaves.
Question 11.
Answer: A flower is a modified shoot wherein the shoot apical meristem changes to floral meristem. Internodes do not elongate and the axis gets condensed. The apex produces different kinds of floral appendages laterally at successive nodes instead of leaves. When a shoot tip transforms into a flower, it is always solitary. The arrangement of flowers on the floral axis is termed as inflorescence. Depending on whether the apex gets converted into a flower or continues to grow, two major types of inflorescences are defined – racemose and cymose. In racemose type of inflorescences the main axis continues to grow, the flowers are borne laterally in an acropetal succession. In cymose type of inflorescence the main axis terminates in a flower, hence is limited in growth. The flowers are borne in a basipetal order.
Question 12.
Answer: Based on the position of calyx, corolla and androecium in respect of the ovary on thalamus, the flowers are described as hypogynous perigynous and epigynous. In the hypogynous flower the gynoecium occupies the highest position while the other parts are situated below it. The ovary in such flowers is said to be superior, e.g., mustard, China rose and brinjal. If gynoecium is situated in the centre and otherparts of the flower are located on the rim of the thalamus almost at the same level, it is called perigynous. The ovary here is said to be half inferior, e.g., plum, rose, peach. In epigynous flowers, the margin of thalamus grows upward enclosing the ovary completely and getting fused with it, the other parts of flower arise above the ovary. Hence, the ovary is said to be inferior as in flowers of guava and cucumber, and the ray florets of sunflower.
Morphology Of Flowering Plants
Class 11th Biology Bihar Board Solution
Ncert Questions
- What is meant by modification of root? What type of modification of root is found in…
- How is a pinnately compound leaf different from a palmately compound leaf?…
- Explain with suitable examples the different types of phyllotaxy.…
- Define the following terms:(a) Aestivation(b) Placentation(c) Actinomorphic(d)…
- Differentiate between(a) Racemose and Cymose inflorescence(b) Fibrous root and…
- Draw the labeled diagram of the following:(i) Dicotyledonous seed(ii) V.S. of…
- Describe modifications of stem with suitable examples.
- Describe the various types of placentations found in flowering plants.…
- What is a flower? Describe the parts of a typical angiosperm flower?…
- How do the various leaf modifications help plants?
- Define the term inflorescence. Explain the basis for the different types of inflorescence…
- Describe the arrangement of floral members in relation to their insertion on thalamus.…
Ncert Questions
Question 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(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.(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.(c) Mangrove trees - 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.
Question 2.
How is a pinnately compound leaf different from a palmately compound leaf?
Answer:
Question 3.
Explain with suitable examples the different types of phyllotaxy.
Answer: Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. This is usually of three types – alternate, opposite and whorled. In alternate type of phyllotaxy, a single leaf arises at each node in alternate manner, as in china rose, mustard and sun flower plants. In opposite type, a pair of leaves arise at each node and lie opposite to each other as in Calotropis and guava plants. If more than two leaves arise at a node and form a whorl, it is called whorled, as in Alstonia. Examples are: Compound leaf and Simple leaf.
Question 4.
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 mode of arrangement of sepals or petals in floral bud with respect to the other members of the same whorl is known as aestivation.(b) Placentation:The arrangement of ovules within the ovary is known as placentation.(c) Actinomorphic:When a flower can be divided into two equal radial halves in any radial plane passing through the centre, it is said to be actinomorphic, e.g., mustard, datura, chilli, etc.,(d) Zygomorphic:When it can be divided into two similar halves only in one particular vertical plane, it is zygomorphic, e.g., pea, gulmohur, bean, Cassia, etc.(e) Superior ovary:A superior ovary is an ovary attached to the receptacle above the attachment of other floral parts.(f) Perigynous flower:If gynoecium is situated in the centre and other parts of the flower are located on the rim of the thalamus almost at the same level, it is called perigynous.(g) Epipetalous stamen:When stamens are attached to the petals, they are epipetalous, e.g. brinjal.
Question 5.
Differentiate between(a) Racemose and Cymose inflorescence(b) Fibrous root and adventitious root(c) Apocarpous and Syncarpous ovary
Answer: (a) Racemose inflorescence and Cymose inflorescence:
(b) Fibrous root and adventitious root:(c) Apocarpous and syncarpous ovary:
Question 6.
Draw the labeled diagram of the following: (i) Dicotyledonous seed (ii) V.S. of Monocotyledonous seed
Answer:
Question 7.
Describe modifications of stem with suitable examples.
Answer: The stem may not always be typically like what they are expected to be. They are modified to perform different functions. Underground stems of potato, ginger, turmeric and zaminkand, Colocasia are modified to store food in them. They also act as organs of perenation to tide over conditions unfavourable for growth. Stem tendrils, which develop from axillary buds are slender and spirally coiled and help plants to climb such as in gourds (cucumber, pumpkins and watermelon) and grapevines.Axillary buds of stems may also get modified into woody, straight and pointed thorns. Thorns are found in many plants such as Citrus, Bougainvillea etc, are protect plants from browsing animals. Some plants of arid regions modify their stems into flattened (Opuntia) or fleshy cylindrical (Euphorbia) structures. They contain chlorophyll and carry out photosynthesis. Underground stems of some plants such as grass and strawberry etc., spread to new niches and when older parts die new plants are formed. In plants like mint and jasmine a slender lateral branch arises from the base of the main axis and after growing aerially for some time arch downwards to touch the ground. A lateral branch with short internodes and each node bearing a rosette of leaves and a tuft of roots is found in aquatic plants like Pistia and Eichhornia. In banana, pineapple and Chrysanthemum, the lateral branches originate from the basal and underground portion of the main stem, grow horizontally beneath the soil and then come out obliquely upward giving rise to leafy shoots.
Question 8.
Describe the various types of placentations found in flowering plants.
Answer: PlacentationThe arrangement of ovules within the ovary is known as placentation. The placentation is of different types namely, marginal, axile, parietal, basal, central and free central. In marginal placentation the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows, as in pea. When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentaion is said to be axile, as in china rose, tomato and lemon. In parietal placentation, the ovules develop on the inner wall of the ovary oron peripheral part. Ovary is one-chambered but it becomes two chambereddue to the formation of the false septum, e.g., mustard and Argemone. When the ovules are borne on central axis and septa are absent, as in Dianthus and Primrose the placentation is called free central. In basal placentation, the placenta develops at the base of ovary and a single ovule is attached to it, as in sunflower, marigold.
Question 9.
What is a flower? Describe the parts of a typical angiosperm flower?
Answer: The flower is the reproductive unit in the angiosperms. It is meant for sexual reproduction. A typical flower has four different kinds of whorls arranged successively on the swollen end of the stalk or pedicel is called thalamus or receptacle. These are calyx, corolla, androecium and gynoecium. Calyx and corolla are accessory organs, while androecium and gynoecium are reproductive organs. In some flowers like lily, the calyx and corolla are not distinct and are termed as perianth. When a flower has both androecium and gynoecium, it is bisexual. A flower having either only stamens or only carpels is unisexual.
Question 10.
How do the various leaf modifications help plants?
Answer: Leaves are often modified to perform functions other than photosynthesis. They are converted into tendrils for climbing as in peas or into spines for defence as in cacti. The fleshy leaves of onion and garlic store food. In some plants such as Australian acacia, the leaves are small and short-lived. The petioles in these plants expand, become green and synthesise food. Leaves of certain insectivorous plants such as pitcher plant, venus-fly trap are also modified leaves.
Question 11.
Define the term inflorescence. Explain the basis for the different types of inflorescence in flowering plants.
Answer: A flower is a modified shoot wherein the shoot apical meristem changes to floral meristem. Internodes do not elongate and the axis gets condensed. The apex produces different kinds of floral appendages laterally at successive nodes instead of leaves. When a shoot tip transforms into a flower, it is always solitary. The arrangement of flowers on the floral axis is termed as inflorescence. Depending on whether the apex gets converted into a flower or continues to grow, two major types of inflorescences are defined – racemose and cymose. In racemose type of inflorescences the main axis continues to grow, the flowers are borne laterally in an acropetal succession. In cymose type of inflorescence the main axis terminates in a flower, hence is limited in growth. The flowers are borne in a basipetal order.
Question 12.
Describe the arrangement of floral members in relation to their insertion on thalamus.
Answer: Based on the position of calyx, corolla and androecium in respect of the ovary on thalamus, the flowers are described as hypogynous perigynous and epigynous. In the hypogynous flower the gynoecium occupies the highest position while the other parts are situated below it. The ovary in such flowers is said to be superior, e.g., mustard, China rose and brinjal. If gynoecium is situated in the centre and otherparts of the flower are located on the rim of the thalamus almost at the same level, it is called perigynous. The ovary here is said to be half inferior, e.g., plum, rose, peach. In epigynous flowers, the margin of thalamus grows upward enclosing the ovary completely and getting fused with it, the other parts of flower arise above the ovary. Hence, the ovary is said to be inferior as in flowers of guava and cucumber, and the ray florets of sunflower.