The VIDYANKER team has thoughtfully prepared the NCERT Solutions for Class 11 Biology Chapter 5, "Morphology of flowering plants" These solutions are designed to help you tackle the NCERT textbook questions with ease. We recommend going through the chapter's theory before diving into the solutions for a deeper understanding. Feel free to share these NCERT Solutions for Class 11 Biology with others—learning is always better when shared!
NCERT TEXTBOOK QUESTIONS SOLVED
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
Ans: Roots of some plants change their shape and structure and become modified to perform certain functions other than absorption and conduction of water and minerals. It is called modification of roots. Roots are modified for support, storage of food and respiration, etc.
(a) Root modification in 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) Root modification in turnip : The modification of root found in turnip is napiform for food storage. The upper portion of these fleshy roots is inflated or swollen which tapers towards the lower end.
(c) Root modification in 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.
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
Ans: (i) The underground portions of a plant are not always roots since the stem also becomes underground and may get modified in many different forms to fulfill the varied functions of storage, vegetative propagation, perennation, etc. Underground modifications of stems are tuber, rhizome, corm and bulb. Externally, the underground stems can be distinguished from the roots by the presence of nodes and internodes, axillary buds, scale leaves etc. and absence of root cap and root hairs.
(ii) Flower is the reproductive part of the angiospermic plant and it is defined as the modified shoot because (a) like shoot, flower develops from an axillary or rarely terminal bud. (b) flowers may get modified into fleshy buds or bulbils, (c) A transition from foliage leaves to floral leaves is found in Paeonia. (d) Nymphaea exhibits development of internodes from sepals into petals and then into stamens, (e) In Passiflora and Cleome internodes are much elongated before gynoecium and stamens.
3. How is pinnately compound leaf different from palmately compound leaf?
Ans: In pinnately compound leaf, on a common axis, some number of leaflets get attached. For example neem leaves while in palmately compound leaf number of leaflets gets attached on the common point at the leaf stalk. Example- cotton leaves.
4. Explain with suitable examples the different types of phyllotaxy?
Ans: Phyllotaxy is defined as 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, one leaf comes up from the node of the branch. This type of phyllotaxy can be seen in the sunflower, mustard, and peepal. Those plants whose two leaves rise in opposite directions are of opposite phyllotaxy. 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.
5. Define the following terms:
(a) Aestivation
(b) Placentation
(c) Actinomorphic
(d) Zygomorphic
(e) Superior ovary
(f) Perigynous flower
(g) Epipetalous Stamen
Ans: (a) Aestivation : The term aestivation refers to the mode of arrangement of accessory floral organs (sepals and petals) one over the other in floral bud. The major kind of aestivation are valvate, twisted, imbricate, and vexillary.
(b) Placentation : The arrangement of ovules within the ovary is known as placentation. The placentation are of different types namely, marginal, axile, parietal, basal, central and free central.
(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, Example: mustard and chilli.
(d) Zygomorphic : When a flower can be divided into two similar halves by a single vertical plane, it is said to be zygomorphic, e.g., pea, gulmohar, bean, Cassia.
(e) Superior ovary : Superiors ovary flowers are those in which gynoecium is positioned at the topmost location, while the rest of the floral parts lie at lower positions. A flower, which consists of this kind of placement, is called hypogynous. Example-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 : When stamens are attached to the petals, they are epipetalous as in brinjal.
6. Differentiate between
(a) Racemose and cymose inflorescence
(b) Fibrous roots and adventitious roots
(c) Apocarpous and syncarpous ovary
Ans: (a) Differences between racemose and cymose inflorescence are as follows:
| Racemose Inflorescence | Cymose Inflorescence |
|---|---|
| Younger flowers are found at the tip, while the older ones are positioned at the base of this inflorescence. This type of arrangement is known as acropetal succession. | Younger flowers can be found at the base of the inflorescence, whereas older flowers are located at the top. This arrangement is known as basipetal succession. |
| The main axis of a racemose inflorescence continues to grow and produces flowers on the sides. | The main axis in cymose inflorescence has restricted growth, eventually ending in a flower. |
(b) Differences between fibrous and adventitious roots are as follows :
| Fibrous root | Adventitious root |
|---|---|
| In monocots, the primary root that develops from the seed's radicle is short-lived and is replaced by numerous roots that emerge from the base of the stem. | These roots originate from any part of the plant except for the radicle of seeds. |
| It is found in wheat and other cereals. | It is found in banyan, Monstera, and other plants. |
(b) Differences between Apocarpous and syncarpous ovary are as follows :
| Apocarpous ovary | Syncarpous ovary |
|---|---|
| The flowers that have an apocarpous ovary contain multiple carpels. These carpels are separate from each other. | The flowers that have a syncarpous ovary contain multiple carpels. However, these carpels are fused together. |
| It is found in lotus and rose flowers. | It is found in the flowers of tomato and mustard. |
7. Draw the labelled diagram of the following:
(i) Gram seed
(ii) V.S. of maize seed
Ans: 
8. Describe modifications of stem with suitable examples.
Ans: The modifications of Stem with suitable examples are:
→ Food Storage: Stems are modified to perform different functions. Underground stems of potato, ginger, turmeric, zaminkand, Colocasia are modified to store food in them. They also act as organs of perennation to tide over conditions unfavourable for growth.
Tendrils: Stem tendrils, which are developed from axillary buds, are thread-like and spirally twisted and assist plants in climbing as in gourds, like cucumber, pumpkins, watermelon, and grapevines.
→Thorns: Axillary buds of stems may also be converted into woody, straight and pointed thorns. Thorns are encountered in many plants such as Citrus, Bougainvillea. They avoid browsers from eating plants. Few plants of arid zones alter their stems into platied structure(Opuntia), or into soft,fleshy cylindrical body structure like Euphorbia, which have chloroplast and perform photosynthesis.
→ Vegetative Reproduction: 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. In aquatic plants, such as Pistia and Eichhornia, a lateral branch with very short internodes and each node bearing a rosette of leaves and a tuft of roots is produced. In banana, pineapple and Chrysanthemum the lateral branches originate from the basal and underground portion of the main stem, grow horizontally below the soil, and come out obliquely upward producing leafy shoots.
9. Take one flower each of families Fabaceae and Solanaceae and write its semi-technical description. Also draw their floral diagrams after studying them.
Ans: → Family Fabaceae (Pea)
Fabaceae, previously called Papilionaceae, is a sub-family of the Leguminoseae family.
• Vegetative characters:
Habit: Pinnately compound, laterally arranged with leaf tendril with the pulvinus present at the base of the leaf along folaceous stipules.
Root: Tap root system, with root nodules,
• Floral characters:
Inflorescence: Racemose, usually axial than terminal
Flower: Zygomorphic, bisexual flowers
Calyx: Five sepals are present that are gamosepalous and the aestivation is imbricate.
Corolla: It has five petals (polypetalous) with vexillary aestivation.
Androecium: It has ten anthers that are diadelphous with dithecous anthers.
Gynoecium: Monocarpellary superior ovary which is unilocular with marginal placentation.
Fruit: Legume pod with non-endospermic seeds
Floral formula: % ⚥ K(5) C1+2+(2) A(9)+1 G1
Economic importance: Peas are used as vegetables for making various culinary preparations.
→ Solanum nigrum flowers
Family Solanaceae
• Vegetative characters:
Habit: Erect, herbaceous plant
Leaves: Simple, exstipulate leaves with reticulate venation
Stem: Erect stem with numerous branches.
• Floral characters:
Inflorescence: Solitary and axillary
Flowers: Actinomorphic, bisexual flowers
Calyx: Calyx is made up of five sepals that are united and persistent. Aestivation is valvate.
Corolla: Corolla is made up of five united petals with valvate aestivation.
Androecium: It consists of five epipetalous stamens.
Gynoecium: It consists of bicarpellary syncarpous superior ovary with axile placentation.
Fruits: Berry
Seeds: Many, endospermic
Floral formula: ⊕K(5)C(5)A5G(2)
Economic importance: Used for medicinal purposes.
10. Describe the various types of placentations found in flowering plants.
Ans: Placentation: The manner in which ovules occur within the ovary is termed as placentation. The placentation are of various types such as marginal, axile, parietal, basal, central, and free central.
The different kinds of placentations which exist in flowering plants are:
→ Marginal placentation: The ovary in which the placenta forms a ridge along the ventral suture of the ovary and the ovules develop on two separate rows is known to have marginal placentation. This type of placentation is found in peas.
→ Basal placentation: A placentation in which a placenta develops from the base of an ovary and a single ovule is found attached to the base is called basal placentation. It occurs in marigold and sunflower.
→ Free central placentation: Free central placentation occurs where the ovules grow along the central axis but without septa. It is seen in Dianthus and in primrose.
11. What is a flower? Describe the parts of a typical angiosperm flower?
Ans: The flower is the reproductive unit in the angiosperms. It is meant for sexual reproduction. A flower has four different parts that are calyx, corolla, androecium, and gynoecium. Androecium and gynoecium stand for the male and female reproductive organs of a flower respectively. Parts of the flower are:
→ The calyx: Calyx is the outermost whorl of the flower and the members are termed as sepals. Sepals in general are green, leaf-like and protect the flower during its bud stage. If the sepals of a flower are free, they are called polysepalous. When the sepals of a flower are fused together they are termed as gamosepalous.
→ Corolla: Corolla consists of petals. Petals are typically brightly colored to attract insects for pollination. When the petals are free, they are called polypetalous, while fused petals are called gamopetalous. Corolla may be tubular, bell-shaped, funnel-shaped or wheel-shaped.
→ The androecium or the stamen is the male reproductive part of a flower. It consists of two parts, the filament and the bilobed anther. The bilobed anther is the site for meiosis and the generation of pollen grains.
→ Gynoecium: It is the female part of a flower. This represents the reproductive part. This consists of an ovary, which is connected with the stigma by a long tube (style). The ovary bears numerous ovules attached to the placenta.
12. How do the various leaf modifications help plants?
Ans: Often, leaves are modified for functions other than photosynthesis. These are:
→ Tendrils: The leaves of a pea plant are modified into tendrils that help the plant in climbing.
→ Spines: Cactus leaves have modified itself into sharp spines for defense as an organ.
→Phyllode: The leaves of some Australian acacia are ephemeral and are replaced soon by flattened, green structures known as phyllodes arising from the petiole of the leaves. In these plants, the food is synthesized in the petioles.
→ Pitcher: The leaves of the pitcher plant are modified into pitcher-like structures containing digestive juices and aid in trapping and digestion of insects.
13. Define the term inflorescence. Explain the basis for the different types of inflorescence in flowering plants.
Ans: The Inflorescence refers to the manner in which the flowers occur on the flowering axis. In the flowering season, the vegetative apex of the stem gets transformed into the floral meristem. Depending on the continuation of the floral axis either further or terminated with flower; in general, the inflorescence is classified as Racemose and Cymose. In racemose inflorescence, the floral axis will go on growing and produces flower laterally. On the other hand, in cymose inflorescence, the primary axis terminates into a flower. Thus, it is limited in growth.
14. Write the floral formula of an actinomorphic bisexual, hypogynous flower with five united sepals, five free petals, five free stamens and two united carpals with superior ovary and axile placentation.
Ans:
- Actinomorphic flower: Radial symmetry → ⚪
- Bisexual flower: Both male and female reproductive organs present → ⚥
- Hypogynous flower: Ovary is superior, other floral parts arise below the ovary →
- Calyx (Sepals): 5 united sepals → K(5)
- Corolla (Petals): 5 free petals → C5
- Androecium (Stamens): 5 free stamens → A5
- Gynoecium (Carpels): 2 united carpels, superior ovary with axile placentation → G(2)
Floral Formula:
This formula represents an actinomorphic, bisexual, hypogynous flower with the given characteristics.
15. Describe the arrangement of floral members in relation to their insertion on thalamus?
Ans: Based on the position of the calyx, corolla, and androecium (with respect to the ovary on the thalamus), flowers are classified as hypognous, perigynous, and epigynous.
In hypogynous flowers, the thalamus bears ovary at its top while the other floral parts remain lower. In such flowers, ovary is superior, for example, China rose, mustard etc.
In perigynous flowers, the ovary is placed centrally and other floral parts are positioned on the thalamus rim. The ovary here is described to be half inferior e.g., plum, rose, peach
In epigynous flowers, the thalamus grows around the ovary fusing with its wall. The other floral parts are present above the ovary. Hence, the ovary is said to be inferior e.g., flowers of guava and cucumber.
