NCERT Solutions For Class 11 | Biology | Chapter 5 | Morphology of Flowering Plants
NCERT Solutions for Class 11 Biology Chapter 5 – Morphology of Flowering Plants is a chapter under Unit 2 – Structural organization in Plants and Animals (Term – I). About 19% of the questions in the previous year papers came from this unit. Thus, it becomes necessary for students to understand the concepts and important terminologies in the chapter.
List of subtopics covered in Chapter 5 – Morphology of Flowering Plants
| Number | Subtopic |
| 5.1 | The Root |
| 5.2 | The Stem |
| 5.3 | The Leaf |
| 5.4 | The Inflorescence |
| 5.5 | The Flower |
| 5.6 | The Fruit |
| 5.7 | The Seed |
| 5.8 | Semi-technical description of a typical flowering plant |
| 5.9 | Description of some important families |
The chapter provides insights into the different parts of the flowering plant. Flowering plants exhibit a variety of shapes, size, mode of nutrition, structure, habit, habitat, and life span.
They have well-developed root and shoot systems. The root system is fibrous or taproot.
Details on stem modifications, terms associated with morphology of flowering plants are also provided in the chapter. The chapter also includes details on seeds, its various types, and their structure.
1. What is meant by modification of root? What type of modification of root is found in the:
- Banyan Tree
- Turnip
- Mangrove trees
Answer – Other than performing the functions like absorption and conduction of water and minerals, some roots are modified by changing their shape and size to perform functions like support, storage and respiration.
- Banyan tree– Prop roots, hanging for support.
- Turnip– Tap roots of turnip get swollen up to store food.
- Mangrove trees– Roots called pneumatophores to grow vertically upwards to help get oxygen for respiration.
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) In plants like ginger, the stem is underground for vegetative reproduction and storage of food.
- Also in potatoes, the stem is underground for the storage of food.
- In potato tuber, the presence of nodes and internodes and also the presence of apical bud shows that it is the stem.
- This justifies that all the underground parts of a plant are not always roots.
- (ii) The shoot apical meristem changes into floral meristem.
- The internodes do not elongate and the axis gets condensed thus, the flower appendages arise in place of the stem.
- Therefore, the flower is a modified shoot.
3. How is a pinnately compound leaf different from a palmately compound leaf?
Answer –
| PINNATELY COMPOUND LEAF | PALMATELY COMPOUND LEAF |
| leaflets are present on the same axis. | All the leaflets are attached to a common point. |
| The common axis is known as rachis, which also represents midrib. | The common point is known as the leaf stalk. |
| The axis-bearing leaflets are the continuation of the petiole. | The leaf stalk is present at the tip of a petiole. |
| Example- Neem | Example- Silk cotton |
4. Explain with suitable examples the different types of phyllotaxy.
Answer – Phyllotaxy- The arrangement patterns of the leaves on the stem or the branch.
The three common types of phyllotaxy found are-
- (a) ALTERNATE– A single leaf arises at every node alternatively. Example- Mustard.
- (b) WHORLED– More than two leaves are attached at each node and look like a whorl. Example- Alstonia
- (c) OPPOSITE– At each node, a pair of leaves arise opposite each other. Example- Calatropis.
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– Aestivation is the mode of arrangement of sepals and petals in the floral bud with respect to the other whorl members.
The main types of aestivation are as follows-
- Valvate– Without overlapping when the sepals or petals are arranged in a whorl touching at the margin. Example- Calatropis
- Twisted– When the margin of the sepals or petals overlaps each other. Example- China Rose
- Imbricate– Without any particular direction, the sepals or petals overlap with each other. Example- Cassia
- Vexillary– The largest petal called standard overlaps the two petals called wings, and the wings overlap with the two smallest petals called a keel. Example- Pea and Bean flower.
(b) placentation– The arrangement of the ovules inside the ovary is called placentation.
The main types of placentation are-
- Marginal– The ovules are borne forming two rows on the ridge made by the placenta along the ventral suture of the ovary. Example- Pea.
- Axile– The placenta is axial and the ovule is borne on it in a multiocular ovary. Example- China rose, Lemon, Tomato
- Parietal– Ovules are borne on the inner or peripheral part of the ovary. The ovary is single-chambered but becomes two-chambered due to the formation of a false septum. Example- Mustard, Argemone
- Free Central– When septa are absent and the ovules are borne centrally. Example- Dianthus and Primrose
- Basal– The placenta is at the base of the ovary and a single ovule is borne. Example- Sunflower, Marigold.
(c) actinomorphic-When the flower is divided into two equal halves radially with the radial plane passing through the centre. Example- Mustard, Datura, Chilli.
(d) zygomorphic– When the flower is divided into two equal halves with the vertical plane. Example- Pea, Gulmohar, Bean, Cassia.
(e) superior ovary– The ovary is present in the Hypogynous flower where the gynoecium is present in the highest position with respect to other parts. Example- Mustard, Brinjal, china rose.
(f) perigynous flower– The flower where the gynoecium is situated in the centre and other whorl members are located on the rim of the thalamus and at the same level. Example- Plum, Rose, Peach.
(g) epipetalous stamen– the stamen where they are attached to the petals. Example- Brinjal.
6. Differentiate between
- (a) Racemose and cymose inflorescence
- (b) Fibrous root and adventitious root
- (c) Apocarpous and syncarpous ovary
Answer –
(a) Racemose and cymose inflorescence-
| RACEMOSE INFLORESCENCE | CYMOSE INFLORESCENCE |
| Main axis continues to grow. | The main axis terminates into a flower. |
| Growth is not limited | Growth is limited |
| Flowers grow laterally in an acropetal manner, where young flowers are present at the tip and old flowers are at the base of the stem. | Flowers grow in a basipetal manner, where old flowers are at the tip and young flowers are present at the base of the stem. |
(b) Fibrous root and adventitious root–
| FIBROUS ROOTS | ADVENTITIOUS ROOTS |
| The primary root is short-lived and a large number of roots arise from the base of the stem replacing it in monocotyledonous plants. | When roots arise from parts other than the radicle. |
| Example- Wheat | Example- Banyan tree, Monstera |
(c) Apocarpous and syncarpous ovary–
| APOCARPOUS OVARY | SYNCARPOUS OVARY |
| When more than one carpal is present in an ovary, in a free condition. | When more than one carpel is present in an ovary, in a fused condition |
| Example- Lotus and Rose | Example- Mustard and Tomato |
7. Draw the labelled diagram of the following:
- (i) gram seed
- (ii) V.S. of maize seed
Answer –
(i) gram seed
(ii) V.S. of maize seed
8. Describe modifications of a stem with suitable examples.
Answer – Modifications of the stem are as follows –
- Underground stems like potato, ginger, zaminkand, turmeric, and Colocasia are modified to store food but also work as an organ of perennation to surpass the non-ideal and unfavourable conditions for growth.
- Stem tendrils like in gourds and grapevines help the plant to climb. The tendrils arise from axillary buds and are slender and spirally coiled. Example- cucumber, pumpkins, and watermelon.
- Stem thorns modified from axillary buds help plants protect themselves. They are woody, straight and pointed. Example- Citrus, Bougainvillea.
- In arid regions, stems of some plants are flattened or become fleshy cylindrical. They also contain chlorophyll to carry out photosynthesis. Example- Opuntia, Euphorbia.
- In some plants like grasses and strawberries, underground stems spread in the area and when older parts die, the new ones are formed.
- A thin lateral branch comes out of the basal part of the main axis which grows aerially for some time and then arches downwards to touch the ground. Example- mint and jasmine.
- In aquatic plants like Pistia and Eichhornia, the lateral branch contains short internodes and each node contains a tuft of roots and rosette of leaves.
- The lateral branch that comes out of the underground part of the main stem grows horizontally below the ground and then comes out upward with leafy shoots. Example- banana, pineapple and Chrysanthemum.
9. Take one flower of each of the families Fabaceae and Solanaceae and write its semi-technical description. Also, draw their floral diagram after studying them.
Answer –
Characters of Fabaceae family –
- They include trees, shrubs and herbs. The roots contain nodules.
- Stem is either erect or climber.
- Reticulate venation is found in leaves. The phyllotaxy is alternate and pinnately compound or simple. Leaf base is pulvinus and it is stipulate.
- Inflorescence: racemose
- Flower: bisexual, zygomorphic
- Calyx: sepals five, gamosepalous; valvate/imbricate aestivation
- Corolla: petals five, polypetalous, papilionaceous, vexillary aestivation
- Androecium: stamens ten in number, diadelphous, anther dithecous
- Gynoecium: ovary superior, monocarpellary, unilocular with many ovules, style single
- Fruit: legume; seed: one to many, non-endospermic
- Economic importance: Plants from these families are pulses, fodder, dye, fibres, ornamentals and medicine
- Ex: Peas, Trifolium.
Floral formula –
Characters of Solanaceae Family –
- They include shrubs, herbs and very few small trees.
- The stem is herbaceous, erect, solid or hollow, hairy or glabrous, underground stem as in potato.
- Leaves are in alternate phyllotaxy, simple and exstipulate. The venation found is reticulate.
- Inflorescence: Solitary, axillary or cymose as in Solanum
- Flower: bisexual, actinomorphic
- Calyx: sepals five, united, persistent, valvate aestivation
- Corolla: petals five, united; valvate aestivation
- Androecium: stamens five, epipetalous
- Gynoecium: bi-carpellary obligately placed, syncarpous; ovary superior, bilocular, the placenta is swollen with many ovules, axile
- Fruits: berry or capsule
- Seeds: many, endosperms
- Economic Importance- The plants are a source of foods, spice, medicine, fumigatory and ornamentals.
- Ex: Potato, Tomato, Chilli, Petunia.
Floral formula –
10. Describe the various types of placentations found in flowering plants.
Answer – The various types of placentations found are –
- Marginal– The ovules are borne forming two rows on the ridge made by the placenta along the ventral suture of the ovary. Example- Pea.
- Axile– The placenta is axial and the ovule is borne on it in a multiocular ovary. Example- China rose, Lemon, Tomato
- Parietal– Ovules are borne on the inner or peripheral part of the ovary. The ovary is single-chambered but becomes two-chambered due to the formation of a false septum. Example- Mustard, Argemone
- Free Central– When septa are absent and the ovules are borne centrally. Example- Dianthus and Primrose
- Basal– The placenta is at the base of the ovary and a single ovule is borne. Example- Sunflower, Marigold.
11. What is a flower? Describe the parts of a typical angiosperm flower.
Answer – It is the reproductive unit of the angiosperm plant. The flower is the modified shoot wherein the shoot apical meristem changes into floral meristem.
The four different types of whorls are arranged on the thalamus, which is the swollen end of the stalk or pedicel. The four kinds of whorls are divided into accessory organs (calyx, corolla) and reproductive organs (androecium and gynoecium).
Parts of flowers in angiosperms:
- Calyx– The outermost whorl and consists of sepals. They are green and protect the flower in the bud stage.
- Corolla– They are brightly coloured and consist of petals that attract insects for pollination.
- Androecium– They include the male reproductive part of the plant, i.e. stamen. Each stamen is made of filament and anther. The anther is bilobed and contains a pair of chambers called pollen-sacs.
- Gynoecium– this is the female reproductive part of the plant and includes carpels. Carpels consist of the ovary, style and stigma. The ovary is an enlarged basal part on which style, the elongated tip is attached. The style connects to stigma, which is a receptive organ for pollen grains.
12. How do the various leaf modifications help plants?
Answer – Various modifications for leaves are –
- In peas, tendrils help them for climbing.
- In cacti, spines help them protect themselves from grazing animals.
- In certain plants like onion and garlic, leaves are fleshy and store food.
- In some plants the leaves are short-lived and the petiole expands becoming green and photosynthesising. Example- Australian acacia.
- In insectivorous plants like pitcher plants and venus-fly traps, the leaves modify to catch the prey to suffice their nitrogen needs.
13. Define the term inflorescence. Explain the basis for the different types of inflorescence in flowering plants.
Answer – The arrangement of flowers on the floral axis is known as inflorescence.
The main types of the inflorescence are as follows –
- Racemose– The main axis continues to grow while growth is not limited. Flowers grow laterally in an acropetal manner, where young flowers are present at the tip and old flowers are at the base of the stem.
- Cymose– The main axis terminates into a flower while growth is limited. Flowers grow in a basipetal manner, where old flowers are at the tip and young flowers are present at the base of the stem.
14. Write the floral formula of an actinomorphic, bisexual, hypogynous flower with five united sepals, five free petals, five free stamens and two united carpels with superior ovary and axile placentation.
Answer –
15. Describe the arrangement of floral members in relation to their insertion on the thalamus.
Answer – Based on the position of floral members in relation to their insertion on the thalamus are
- Hypogynous– When the gynoecium is in the highest position and others are below it. Ovary found in such flowers is said to be superior. Example- Mustard, Brinjal.
- Perigynous– When the gynoecium is present in the centre and at the same level as other members. The ovary is said to be half-inferior. Example- Plum, Peach, Rose.
- Epigynous– When the gynoecium is below and the thalamus encloses it with its margin. Other members are above the ovary. The ovary is said to be inferior. Example- Guava, cucumber.
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