Plant Life : The Flower
Section I
A. Name the following.
1. The female reproductive part of a flower.
= Gynoecium;
2. The stalk of a flower.
= Pedicel;
3. The part of a flower that develops into fruit.
= Ovary;
4. The part of a seed that develops from zygote.
= Embryo;
5. The middle pulpy layer of fruit.
= Mesocarp;
B. Choose the correct option.
1. Which of the following is not a part of a flower?
a. Corolla. [ ]
b. Calyx. [ ]
c. Stamen. [ ]
d. Epicarp. [✓]
2. The part of the pistil that contains the egg is this.
a. Stigma. [ ]
b. Ovary. [✓]
c. Style. [ ]
d. Anther. [ ]
3. Which of the following is mostly pollinated by wind?
a. Sunflower. [ ]
b. Vallisneria. [ ]
c. Maize. [✓]
d. Hibiscus. [ ]
4. This is the part of the seed that forms the root system after germination.
a. Plumule. [ ]
b. Pericarp. [ ]
c. Radicle. [✓]
d. Endosperm. [ ]
5. Which of the following is a monocot?
a. Apple. [ ]
b. Maize. [✓]
c. Bean. [ ]
d. Rose. [ ]
C. Correct the false statement by changing the underlined word/s:
1. All the floral parts are seated on the ovary.
= All the floral parts are seated on the thalamus.
2. The outermost whorl of a flower consists of petals.
= The outermost whorl of a flower consists of sepals.
3. Wind-pollinated flowers have bright colours.
= Animals-pollinated flowers have bright colours.
4. The stigma produces pollen grains.
= The stamens produces pollen grains.
5. The ripened ovule is called fruit.
= The ripened ovary is called fruit.
D. Complete the passage below by filling in the blank spaces.
(1) Flower (Flower/Leaf) is the reproductive part of a plant. Seeds develop from (2) ovule (egg/ovule) after fertilization. The (3) plumule (radicle/plumule) forms the shoot system after seed germination. The (4) cotyledon (cotyledon/endosperm), also called seed leaves, nourish the developing embryo during germination. (5) Dicot (Monocot/Dicot) seeds have two cotyledons.
E. Choose the odd one out in each of following and give reasons for your choice.
Root, Stem, Leaf, Flower
= Root, Stem, Leaf, Flower (Flower is the odd one as it is the reproductive part and the rest three are the vegetative parts)
1. Sepal, Petal, Pedicel, Carpel
= Sepal, Petal, Pedicel, Carpel (Carpel is the odd one as it is the female reproductive part and the rest are the outer part of a flower)
2. Stigma, Ovary, Anther, Style
= Stigma, Ovary, Anther, Style (Anther is the odd one as it is the part of Androecium and the rest are the parts of Gynoecium)
3. Endocarp, Seed, Epicarp, Mesocarp
= Endocarp, Seed, Epicarp, Mesocarp (Seed is the odd one as it is the part of a fruit and the rest are the parts of Pericarp)
4. Nectar, Light weight pollens, Coloured petals, Scent
= Nectar, Light weight pollens, Coloured petals, Scent (Light weight pollens is the odd one as it is the feature of the plants which have pollination by wind and the rest are the features of the plants which have pollination by animals)
5. Seed coat, Cotyledon, Fruit, Embryo
= Seed coat, Cotyledon, Fruit, Embryo (Fruit is the odd one as it is fertilized ovule and the others are the parts of a seed)
F. State the exact location of the following from the choices given below.
1. Thalamus (At the top of pedicel/At the top of the flower)
= At the top of pedicel;
2. Pedicel (Below the thalamus/Above the thalamus)
= Below the thalamus;
3. Style (Stalk of fruit/Stalk of flower)
= Stalk of flower;
4. Pollen grains (In the anther/In the stigma)
= In the anther;
5. Endocarp (Between the epicarp and mesocarp/Between the seed and mesocarp)
= Between the seed and mesocarp;
G. Match the items in Column A with that which is most appropriate in Column B.
=
|
Column A |
Column B |
|---|---|
|
1.Pollen grains |
a. Contained in ovule. [3] |
|
2. Pollen tube |
b. Changes into fruit. [ ] |
|
3. Female gamete |
c. Forms embryo. [5] |
|
4. Ovary |
d. Contained in anther. [1] |
|
5. Zygote |
e. Changes into seed. [4] |
|
|
f. Wither away. [ ] |
|
|
g. Carry male gametes. [2] |
Section II
H. Give reasons for the following.
1. Wind pollinated flowers produce large quantities of pollen grains.
= Wind pollinated flowers produce large quantities of pollen grains because there is more chance of getting waste while floating in the air at the time of pollination.
2. Flowers pollinated by insects are sweetly scented.
= Flowers pollinated by insects are sweetly scented because this attracts the insects.
3. Self pollination is not possible in case of unisexual flowers.
= Self pollination is not possible in case of unisexual flowers because they have either androecium or gynoecium as their reproductive parts.
4. Dry seeds cannot germinate on its own.
= Dry seeds cannot germinate on its own because water is absorbed by the seed coat, which then swells up and cracks open. This helps the radicle and plumule to emerge with ease.
I. Explain the following terms.
1. Cotyledon;
= It is also called seed leave, they surround the embryo and nourish the seedling during germination. Seeds with one cotyledon and called monocot seeds while those with two cotyledons are called dicot seeds.
2. Embryo;
= It is the part of the seed that develops from the zygote. It consists of Radicle and Plumule.
Radicle:- It is the embryonic root that gives rise to the root system when a seed germinates.
Plumule:- It tis the embryonic shoot that forms the shoot system after germination.
3. Pollination;
= The transfer of pollen grains from the anther to the stigma of a flower or between flowers of the same species is called pollination.
4. Fertilization;
= The fusion of male and female gamete is called fertilization. After fertilization a single celled structure called zygote is formed. The zygote undergoes further division and develops into an embryo.
5. Germination;
= The process by which a dormant embryo in a seed develops into a young plant or seedling is called germination.
J. Differentiate between the following.
1. Self-pollination and cross pollination.
=
|
Self Pollination |
Cross Pollination |
|---|---|
|
1. The transfer of pollen grains from the anther to the stigma of the
same flower or of a flower borne on the same plant is called
self-pollination. |
1. The transfer of pollen grains from the anther of a flower of one
plant to the stigma of a flower of another plant of the same species is
called cross-pollination. |
|
2. Example- pollination in the pea flower. |
2. Example- pollination in pumpkin. |
2. Animal-pollinated flowers and water-pollinated flowers.
=
|
Animal-Pollinated Flowers |
Water-Pollinated Flowers |
|---|---|
|
1.The agents are birds and insects such as bees and butterflies, bats
and other animals. |
1. The only agent is water. |
|
2. The flowers of these plants are brightly coloured. |
2. The flowers of these plants are not brightly coloured. |
|
3. The flowers of these plants have scent. |
3. The flowers of these plants do not have scent. |
|
4. The flowers of these plants have nectar. |
4. The flowers of these plants do not have nectar. |
3. Dry fruits and fleshy fruits.
=
|
Dry Fruits |
Fleshy Fruits |
|---|---|
|
1. In dry fruits, the entire Pericarp becomes dry at maturity. |
1. In fleshy fruits, the Pericarp develops into succulent tissues. |
|
2. It is dry. |
2. It is soft and fleshy. |
|
3. The pericarp is thin and cannot be differentiated into epicarp,
mesocarp, and endocarp. |
4. It can be differentiated into outer epicarp, middle mesocarp, and
inner endocarp. |
|
4. Example – Pea and Walnut. |
4. Example – Mango and Cherry. |
4. Monocot seeds and dicot seeds.
=
|
Monocot Seed |
Dicot Seed |
|---|---|
|
1. Seeds with one cotyledon are called monocot seeds. |
1. Seeds with two cotyledons are called dicot seeds. |
|
2. Example – Maize and Rice. |
2. Example – Pea and Beans. |
K. Short answer question.
1. What do you understand by thalamus?
= The swollen, suppressed end of the stalk on which the floral parts are seated are called the thalamus.
2. State the functions of calyx and corolla.
= The main function of calyx is to protect the flower in the bud stage. They are usually green and also prepare food by photosynthesis.
Corolla attracts insects for pollination.
3. What are the parts of stamen and carpel?
= Filament and anther are the parts of Stamen.
Stigma, Style and Ovary are the parts of carpel.
4. What are the two types of pollination in flowering plants?
= The two types of pollination in flowering plants are - i) Self-Pollination; and ii) Cross-Pollination;
5. Give one example each, of flowers pollinated by wind, water and insects.
= One example of flowers pollinated by wind is -Maize.
One example of flowers pollinated by water is - Vallisneria.
One example of flowers pollinated by insects is - Hibiscus.
6. Name the parts of a fleshy fruit.
= The name of the parts of a fleshy fruit are - outer epicarp, middle mesocarp, and inner endocarp.
L. Long answer questions.
1. Draw a labelled diagram of a flower. Briefly describe each part.
=
A Flower and its Parts
The stalk of a flower that holds it in place and is attached to the stem is called the pedicel. The swollen, suppressed end of the stalk on which the floral parts are seated is called the thalamus. A typical flower generally consists of four parts : calyx, corolla, androecium, and gynoecium.
Calyx: It is the outermost whorl of a flower consisting of a collection leaf-like structures called sepals. There can be five or more sepals in a flower.
The main function of sepals is to protect the flower in the bud stage. They are usually green and also prepare food by photosynthesis.
Corolla: Corolla is the second whorl of a flower. It consists of a ring of petals. Petals are generally brightly coloured and scented to attract insects for pollination.
Androecium: Androecium is the male reproductive part of the flower. It consists of a collection of stamens. Each stamen has a long slender filament with an anther at its tip. Anther produce dust-like structures, called pollen grains, which contain the male gametes or male reproductive cells.
Gynoecium: Gynoecium is the female reproductive part of the flower. It is centrally located and consists of units called carpels or pistils. Each carpel has three parts: Stigma, Style and Ovary.
Stigma- It is the sticky, swollen tip of the carpel that forms the surface for receiving the pollen grains.
Style- It is the thin elongated, tube-like structure that connects the stigma to the ovary.
Ovary- It is the swollen base and has ovules containing eggs or the female gametes. The ovule, after fertilization, forms the seed, whereas the ovary forms the fruit.
2. Explain how pollination is possible between two flowers borne on two different apple trees in a garden. Name any two agents that would be able to pollinate such flowers.
= The two apple trees in the garden are the plants of the same species. So they should have cross-pollination. The pollen grains from the anther of one apple tree will be transferred to the stigma of the flower of another apple tree.
Two any agents that would be pollinate such flower are - bees and butterflies.
3. Explain how fertilisation takes place after the pollen grains land on the stigma of the receiving flower.
= After a pollen grain lands on the stigma, it germinates in response to a sugary substance secreted by the stigma. The pollen grain then sends out a pollen tube carrying the male gamete through the style, into the ovary till it reaches the ovule and it fuses with the egg or the female female gamete.
The fusion of male and female gamete is called fertilization. After fertilization a single celled structure called zygote is formed. The zygote undergoes further division and develops into an embryo.
4. How are fruits and seeds formed?
= After fertilization, a series of changes takes place in the flower. All the parts of the flower, except the ovary, wither away. The petals, sepals, and stamens shrink and fall off. In some plants, the sepals persists in the fruit as seen in tomato and brinjal. The ovary enlarges to become the fruit. The fertilized ovule develops into seed. The seed contains the embryo, which develops into a baby plant.
5. Describe the different parts of a fleshy fruit.
= In fleshy fruits, the pericarp develops into succulent tissues. It is soft and fleshy at maturity and can be differentiated into outer epicarp, middle mesocarp, and inner endocarp.
6. With the help of a labelled diagram, explain the structure of a typical dicot seed.
=
In flowering plants, seeds are enclosed within the fruit. A seed contains an embryo, which gives rise to new plants upon germination. Despite having varied shapes, sizes, and colours, most dicot seeds consist of the following parts:
Seed Coat: It is the outer protective layer of a seed. It protects the internal parts of the seed and absorbs water to soften it so that it can break open at the time of germination.
Embryo: It is the part of the seed that develops from the zygote. It consists of:
Radicle: It is the embryonic root that gives rise to the root system when a seed germinates.
Plumule: It is the embryonic shoot that forms the shoot system after germination.
Cotyledons: The seed contains two cotyledons. They surround the embryo and nourish the seedling during germination.
Endosperm: It lies just beneath the seed coat and provides food to the embryo. The endosperm gets reduced in dicot seeds.