NCERT

Biology Grade 11 Chapter 5 Morphology of flowering plants

CBSE NCERT Solutions for Class 11 biology Chapter 5

Exercises

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

Solution: The plant consists of two types of the root system, namely the tap root and fibrous root system. The root
absorbs water and minerals from the soil. But some roots are modified for other functions like storage, support
and absorb oxygen from the atmosphere.
Root modification found in the Banyan tree:
In the Banyan tree, roots are called prop roots. They arise from the stem and reaches to the ground. The
primary function of these roots is to provide support to the plant as it grows.

Q.2. What type of modification of root is found in the turnip?

Solution: The plant consists of two types of the root system, namely the taproot and fibrous root system. The root
absorbs water and minerals from the soil. But some roots are modified for other functions like storage, support
and absorb oxygen from the atmosphere. In turnip, the taproot of the plant gets modifies to store food. This
type of modification is present in other plants such as carrot, radish, and adventitious root of sweet potato.

Q.3. What type of modification of root is found in the Mangrove trees?

Solution: The plant consists of two types of the root system, namely the taproot and fibrous root system. The root
absorbs water and minerals from the soil. But some roots are modified for other functions like storage, support
and absorb oxygen from the atmosphere. Mangroves trees grows in the marshy and swampy area, so roots
could not respire. The roots show negative geotropism, grows above th soil vertically to absorb oxygen from
the atmosphere; such modified roots are known as pneumatophores.

Q.4. Describe the various types of placentations found in flowering plants

Solution: Placentation is the pattern of arrangement of ovules inside the ovary.

Marginal Placentation - The placenta forms the ridge on the ventral suture of the ovary and ovules
present on the ridge dividing it into two rows. An example is peas.

Axile Placentation - The placenta is present at the axis, and ovules are present in a multilocular ovary.
Examples are china rose, tomato and lemon.

Parietal placentation - The development of the ovules takes place from the inner wall or the peripheral
part of the ovary. Examples are mustard and argemone.

Free Central placentation - The ovules are present on the central axis, and there is no margin or septa
present. Examples are dianthus and primrose.

​Basal placentation - When the placenta develops at the base of the ovary, and a single ovule is attached
to it. Examples are sunflower and mustard.

Q.5. What is a flower? Describe the parts of a typical angiosperm flower.

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Solution: The flower is the reproductive unit in the angiosperms. A typical flower has four different kinds of whorls
arranged successively on the swollen end of the stalk or pedicel, called thalamus or receptacle. These are
calyx, corolla, androecium, and gynoecium. Calyx and corolla are accessory organs, while androecium and
gynoecium are reproductive organs.

Parts of the flowers are:

Calyx - This is the outermost whorl formed of green leaf life structures called sepals. Their primary
function is the protection of flowers in the bud stage and the reproductive structures of the flower.

Corolla - This is the second whorl which is formed by leaf like structures called petals which are bright
in colour. The main function is to attract agents for pollination.

Androecium: The male reproductive part of the plant called the stamen - consists of anther and filament.
The anther is a bilobed structure containing pollen sacs. The pollen sacs carry out the production of
pollen grains and store them till dehiscence. The stamens collectively form the androecium.
Gynoecium: This is the innermost whorl and the female reproductive part. It is composed of individual
units called pistils or carpels. Each carpel consists of three main parts, which are stigma, style and ovary.

Q.6. How do the various leaf modifications help plants?

Solution: The major functions of the leaf are transpiration and photosynthesis. But under some conditions, they are
modified to perform other function like storage, climbing, attachment, protection, trapping, and digesting
insects.
Leaf modifications-

Fleshy leaves for storage: Leaves becomes fleshy a swollen and store food in the form of carbohydrates.
Examples are onion and garlic.
Spines for protection: In xerophytic plants, leaves are modified into spines to prevent water loss through
transpiration. Examples are opuntia and euphorbia.

Tendril for support: Leaves in certain plants get converted into the spirally coiled structure to support the
plant. An example is the pea plant.
Nutrient deriving leaves: Leaves of insectivorous plants get modified to obtain nitrogen from insects.
Examples are pitcher plant and Venus-fly trap.

Q.7. Define the term inflorescence. Explain the basis for the different types of inflorescence in flowering plants.

Solution: The inflorescence is the arrangement or the pattern of the flowers on the floral axis or stem. Based on whether
the apex gets converted into a flower or continues to grow, two major types of inflorescences are:

Racemose inflorescence: In this inflorescence, the main axis goes continuously and the flowers are
arranged laterally in acropetal succession.
Cymose inflorescence: In the cymose type of inflorescence, the main axis terminates with a flower. The
flowers are arranged in a basipetal order.

Q.8. Write the floral formula of the actinomorphic, bisexual, hypogynous flower with five united sepals, five free petals, five
free stamens and two united carpels with the superior ovary and axile placentation.

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Solution: A floral formula is a means to represent the structure of a flower using numbers, letters and various symbols,
presenting important information about the flower in a compact form.

Actinomorphic flowers are radially symmetrical.

Bisexual have both male and female reproductive parts.
Hypogynous flower has superior ovary.
The symbol represents actinomorphic flowers -

A bisexual flower is indicated by-

The calyx contains five united sepals that are represented as K(5).
The corolla consists of five free petals and it represented as C5 .
The androecium consists of five free stamens that are represented as A 5 .
The gynoecium consists of a superior ovary with two united carpels and axile placentation that
are represented as G(2).
The description is given for the floral formulae

Q.9. Describe the arrangement of floral members in relation to their insertion on thalamus.

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NCERT Biology Grade 11 Chapter 5 Morphology of flowering plants

Solution: The position of the floral parts with respect to the ovary on the thalamus, flowers are divided into three types.
They are hypogynous flower, perigynous flower and epigynous flower. The thalamus is also called receptacle.
Hypogynous flower:
In these flowers, the gynoecium occupies the highest position, and the other parts are present below it. The
ovary in these flowers is superior. Examples are mustard, china rose and brinjal.

Perigynous flower:
In these flowers, the gynoecium is at the centre, and other parts are located on the thalamus rim almost at the
same level, it is called perigynous. The ovary in these flowers is half inferior. Examples are plum, rose, and
peach.

Epigynous flower:
In these flowers, the thalamus margin grows upward enclosing the ovary completely, and the other floral parts
arise above the ovary. The ovary in these flowers is inferior.
Example of flowers guava, cucumber, and the ray florets of sunflower.

Q.10. Justify the following statements on the basis of external features:

Underground parts of a plant are not always roots.

Solution: The underground part of the plant is not always a root. But in some plants, the roots are modified to store food
materials underground.

In certain plants such as potato, ginger turmeric, and Colocasia stems grow underground to store food and
help in vegetative propagation.

Underground stem serves as the organ of perennation and prevents the plant from unfavourable conditions.

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NCERT Biology Grade 11 Chapter 5 Morphology of flowering plants

Q.11. Justify the following statements on the basis of external features:

Flower is a modified shoot.

Solution: The flower is the reproductive part of the plant consist of stamens and carpel. The apical meristem of stem gets
modified into floral meristem and starts bearing flower then it is referred to as the modification of shoot into
the flower.
The changes happen during modification are:
- The elongation of internodes stops.
- Condensation of the axis takes place.
- The position of the leaves on apex and nodes is replaced by a floral meristem.
- The formation of floral appendages takes place on the apex and the on nodes in the lateral direction.

Q.12. How is a pinnately compound leaf different from a palmately compound leaf?

Solution: Pinnately compound leaf Palmately compound leaf

In a pinnately compound leaf, leaflets are In a palmately compound leaf, the leaflets are
Leaflet attached to the lateral vein originating from the attached at a common axis known as rachis. The
position midrib. The arrangement of leaves gives a arrangement of leaves gives the appearance of
feather-like appearance. the palm.
Example Examples of pinnately compound leaves are Examples of palmately compound leaves are
neem, moringa, tamarind, etc. silk, cotton, etc.

Q.13. Explain with suitable examples of the different types of phyllotaxy.

Solution: The arrangement of leaves on an axis or stem is called phyllotaxy. 1. Alternate Phyllotaxy
Alternate phyllotaxy is the arrangement of leaf in which single leaf arises alternately at each node .

Examples are China rose, mustard, sunflower plant, etc.

2. Opposite Phyllotaxy
In opposite phyllotaxy, the leaves are arranged in pairs on either side of the same node.
Examples are Calotropis and guava

3. Whorl Phyllotaxy
Whorled phyllotaxy is another type where three or more leaves are present at one node.
Examples is Alstonia

Q.14. Define aestivation.

Solution: Aestivation: The mode of arrangement of sepals and petal in the floral bud in comparison to the other members
of the same whorl ia known as aestivation. The types are valvate, twisted, imbricate and vexillary.

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Q.15. Define the following terms:

Placentation

Solution: Placentation refers to the pattern in which ovules are arranged in the ovary. Types of placentation are as
follows

Marginal in peas.
Axile in China rose, tomato, and lemon.
Parietal in mustard and argemone.
Free central in Dianthus and Primrose.
Basal in sunflower and mustard.

Q.16. Define the term actinomorphic.

Solution: When the symmetry of a flower is radial, that is when it can be divided into two radial halves by any of the
radial planes passing through the centre, and then it referred to as the Actinomorphic flower.
Examples of Actinomorphic flower are mustard, chilli, and datura.
It is represented by the symbol ⊕ when explained in floral formula and diagram.

Q.17. Define the following terms:

Zygomorphic

Solution: When the symmetry of the flower is bilateral, when the flower is divided into two equal halves, and both the
halves are mirror images, such flowers are called zygomorphic flower.
Examples of the zygomorphic flower are pea, gulmohar, bean, and cassia. It is represented by the symbol %
when explained in floral formula and diagram.

Q.18. Define the term superior ovary.

Solution: When the carpel is at the highest position while the other floral parts are present below it, then the ovary is
called superior ovary and such flowers are known as hypogynous flowers.
Examples are mustard, China rose, and brinjal.

Q.19. Define the following terms:

Perigynous flower

Solution: Perigynous Flower:

The gynoecium is present at center, and other parts of the flower are located on the rim of the thalamus almost
at the same level, it is called perigynous flower. Examples of plum, rose, and peach.

Q.20. Define the following terms:

Epipetalous stamen

Solution: Epipetalous stamen: In certain plants where stamen (androecium) is attached to the petals, such type of
conditions are referred to as epipetalous stamen.
Example of flower having epipetalous stamen is brinjal.

Q.21. Differentiate between Racemose and cymose inflorescence

Solution: Racemose Inflorescence Cymose Inflorescence

Arrangement of flowers in Arrangement of flower in which
Type of which the main axis grows the apical meristem of the main
flower indefinitely, and the axis gets converted to floral
arrangement flowers are present in the meristem and bears a flower. It has
lateral region. definite growth.

Racemose Inflorescence Cymose Inflorescence

The flowers are present The flower is present apically
Succession
laterally in acropetal succession in basipetal succession

The inflorescence is the development and arrangement of a cluster of flowers on a floral axis.
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Q.22. Differentiate between Fibrous root and adventitious root.

Solution: Fibrous Roots Adventitious Roots

Roots in which the primary root is short- Roots originate from
Root
lived and is replaced by numerous thin and different parts of the plant
Type
moderate branching roots. but not the radicle.

Fibrous Roots Adventitious Roots

The main function of
They perform accessory functions of
fibrous roots is to
anchorage, support, food storage,
Function absorb water and
respiration, synthesis of plant growth
mineral from the
regulators etc.
ground.
Examples of plants with adventitious
Examples of plants with
roots are banyan with prop roots,
Examples fibrous roots are wheat,
sugarcane with stilt roots, and
grasses, etc.
rhizophora with pneumatophores.

Q.23. Differentiate between apocarpous and syncarpous ovary.

Solution: Apocarpous Ovary Syncarpous Ovary

In this type of ovary, carpels are In this type of ovary in which
Definition
not united and are free. the carpels are fused.
Examples Lotus and rose. Mustard and tomato.

Q.24. Draw the labelled diagram of Gram seed.

Solution:

Gram plants are the dicots, i.e. their seeds have two cotyledons. The cotyledons protect the embryo which
gives rise to radicle and plumule. In gram, the endosperm gets used up at the time of development of seed.

Q.25. Draw the labelled diagram of V.S. of maize seed.

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Solution:

Maize is a monocot plant. It's cotyledons have endosperm. The seed coat protects the developing embryo.
When the seeds germinate, the radicle gives rise to root system and the plumule gives rise to the shoot system.

Q.26. Describe modifications of the stem with suitable examples

Solution: The stem helps in providing structure and support to the plant. When stem changes its original form and shapes
to perform certain functions such as storage, protection, vegetative propagation, it is referred to as the stem
modification.
Modification in stem and function performed by them are as follows:

Food storage stems-In certain plants stems stores the food. These stems also serve as the organ of
perennation to prevent the plant from the unfavourable condition. Examples of food storage stems are
potato, ginger, turmeric, zaminkand, colocasia, etc.

Stem Tendrils for support- Tendrils are slender and spirally coiled. They help the plant to climb along
with the support. Examples of the plants having stem tendrils are gourds such as cucumber, pumpkins,
watermelon, and grapevines.

Thorns for protection - Some the axillary bud gets modified into a woody, a straight prickly, and pointed
structure. Their function is to prevent the plant from getting consumed by animals. Examples of plants
having thorns are citrus and bougainvillaea.

Water storage stems- In certain plants that grow in the arid region stem get flattened or turns fleshy
cylindrical to store water. Examples are euphorbia and opuntia.

Stems for vegetative propagation - In certain plants stems get buried and spread underground, when the
old part of the plant dies it leads to the formation of the new plant. Examples are grass and strawberry.

In certain plants, the soft and slender lateral branches arise from the main branch. After growing for a
certain time, it gets buried underground and starts bearing roots for absorbing water later the lateral
branch serves as the main plant. Examples are mint and jasmine.

In aquatic plants, the node and internode bear the tuft of roots. Examples are Pistia and Eichhornia.
​Lateral stems of plants originate from the main axis grows beneath the soil, comes vertically upwards
and further bears leaves. Examples are pineapple, banana, and chrysanthemum.

Q.27. Take one flower each of the families Fabaceae and Solanaceae and write its semi-technical description. Also, draw their
floral diagram after studying them.
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NCERT Biology Grade 11 Chapter 5 Morphology of flowering plants

Solution: The representation of flower structure using numbers, letters and symbols, a compact form of a species is
called floral characters. For the writing of floral formula, one starts analysing the bract and bracteole then
symmetry and sex of flower, calyx (K), corolla (C), androecium (A) and gynoecium (G). Fabaceae family was
earlier known as Papilionoideae.
Floral characters of the family Fabaceae:
Inflorescence- Arrangement of the flower is racemose that is plant bear flowers on the lateral region.
Flower type- Flower is bisexual and bilaterally symmetrical known as zygomorphic.
Calyx- Sepals are five and are fused, which means gamosepalous. Aestivation of sepals is either valvate or
imbricate.

Corolla- Petals are five, that is polypetalous, consisting of a posterior standard, two lateral wings, two anterior
ones are forming a keel (enclosing stamens and pistil), Aestivation is vexillary.
Androecium- Stamens are ten, and are diadelphous (9 fused & 1 free). Anther has two layers and is known as
dithecous.

Androecium- Stamens are ten, and are diadelphous ( 9 fused and 1 free). Anther has two layers and is known
as dithecous.
Gynoecium- Ovary is superior. It has a single carpel, monocarpellary, unilocular with many ovules, and style is
single.
Fruit- It is mainly legume; seeds in fruit can be one too many. The endosperm is absent hence non-
endospermic. % K(5) C1+2+(2) A(9)+1 G1

Family Solanaceae is large and is known as 'potato family'.

Floral Characters of family Solanaceae are:
Inflorescence- Arrangement of the flower is cymose.
Flower- The flower is bisexual, and symmetry is a radial type known as actinomorphic.

Calyx- Sepals are five, and are united. Aestivation of sepals is valvate.
Corolla- Petals are five, and they are united. Aestivation of petals is valvate.
Androecium- Stamens are five and are epipetalous.

Gynoecium- The gynoecium is bicarpellary, and carpels are fused known as syncarpous; The ovary is superior
and bilocular.
The placenta is swollen with many ovules.

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