Ch.2: Plants: Structure and Function

Plants: Structure and Function | Class 7 | Science | Chapter 2 | Maharashtra State Board

In this informative video, we will explore the fascinating world of plants and their structures. We will start by learning about the roots of plants and their functions, including the different types of roots. We will then move on to the stem and leaf, studying each part in detail and its role in the plant's survival. The beauty of the flower will also be discussed, and we will take a close look at each part, including the calyx, corolla, androecium, and gynoecium. Finally, we will learn about different types of fruits, their shapes, colors, tastes, and the importance of their seeds in plant reproduction. Join us in this educational journey and discover the amazing world of plants!

Questions & Answers

1. Give example of 3 plants that have:

(a) Spiny fruits.

Ans. Jack fruit, Pineapple, Litchi, Datura.

(b) Spiny stem.

Ans. Cactus, Wild rose, Catclaw acacia, Silk Cotton.

(c) Red flowers.

Ans. Rose, Dahlia, Hibiscus, Tulips.

(d) Yellow flowers.

Ans. Marigold, Daffodil, Sunflower, Daisy.

(e) Leaves which close at night.

Ans. Mimosa plant, Tallwood, Prayer plant, Gulmohar.

(f) Single seeded fruits.

Ans. Mango, Lychee, Jamun.

(g) Many seeded fruits.

Ans. Custard apple, Papaya, Watermelon.

2. Observe any one flower and its various parts and describe it in your own words.

Ans. A flower has following parts:

1. Pedicel:

(a) Flower may have a long or a short stalk called pedicel.

(b) One end of the pedicel is attached to the stem.

(c) The other end of the pedicel is expanded and swollen. It is called the receptacle.

(d) Petals and other parts of the flower are supported on the receptacle.

2. Calyx:

In the bud condition, the petals are covered by leaf like parts called sepals which are green in colour. They form the calyx.

3. Corolla:

This is made up of colourful parts called petals.

4. Androecium:

(a) This is the male reproductive part of the flower.

(b) It consists of stamens.

(c) Each stamen is made up of anther and filament.

5. Gynoecium:

(a) This is the female reproductive part of the flower.

(b) This is made up of carpels.

(c) A carpel consists of stigma, style and ovary.

3. What are the similarities and differences between?

(a) Jowar and Moong.

	Jowar	Moong
1.	It has fibrous root.	It has tap root.
2.	It is monocotyledonous seed.	It is a dicotyledonous seed.
3.	It is a rabi crop.	It is a kharif crop.

(b) Onion and Coriander.

	Onion	Coriander
1.	It is biennial plant.	It is an annual plant.
2.	It is a monocotyledonous seed.	It is a dicotyledonous seed.
3.	It has fibrous root.	It has tap root but later on changes to fibrous root system.

(c) Leaves of banana and Leaves of mango.

	Leaves of banana	Leaves of mango
1.	It has parallel venation.	It has reticulate venation.
2.	It is very large in size.	It is small in size.
3.	It is a monocotyledonous plant.	It is a dicotyledonous plant.

(d) Coconut tree and Jowar stalk plant.

	Coconut tree	Jowar stalk plant
1.	It is tall and has a thick stem.	It is small and has a thin stem.
2.	It has strong root system.	It has weak root system.
3.	Each and every part of tree is useful.	Only seeds are useful.

4. Explain the following images in your own words.

Ans. Diagram ‘A’ is of maize seed. It is a monocotyledonous seed and does not divide into two equal parts. The plant has fibrous root system.

Diagram ‘B’ is of bean seed. It is a dicotyledonous seed and it divides into two equal parts. The plant has tap root system.

5. Describe the functions of various parts of a plant.

Ans. The functions of various parts of a plant are as below.

(a) Root:

1. It anchors the plant body to the soil, so helps in fixation.

2. It absorbs water and nutrients from the soil, so helps in absorption.

3. The root translocate water and mineral salts into the stem.

4. A certain amount of food is stored in the root which is utilized as it grows.

5. Preventing soil erosion: It helps to bind the soil particles and prevent them from being blown away by wind or water.

(b) Stem:

1. It supports and holds leaves, flower and fruits.

2. The stem conducts the water and minerals from roots to leaves and fruits.

3. It stores the food.

(c) Leaves:

1. It synthesizes food for the plant.

2. Stomata, the tiny openings in the leaf help in gaseous exchange and are responsible for the process of transpiration.

(d) Flower: It helps in pollination.

(e) Fruit:

1. It protects the seed.

2. It helps in seed dispersal.

(f) Seed: A new plant develops from it.

6. Certain properties are mentioned below. Find a leaf corresponding to each property and describe those plants.

(a) Leaves with smooth surface:

Ans. e.g. Banana leaf.

It is large in size. It is closely rolled up one over the other. Together they look like a trunk but they form only an apparent trunk. It has parallel venation.

(b) Leaves with rough surface:

Ans. e.g. Hibiscus leaf.

It has reticulate venation. Leaf margin is toothed.

(c) Fleshy leaf:

Ans. e.g. Jade plant, water hyacinth.

It has fleshy, glossy and smooth leaves. They are coloured jade green and having a slightly red tinge towards the edge of leaves when exposed to higher level of light.

(d) Spines on leaf:

Ans. e.g. Opuntia, kevda.

Opuntia is a desert plant. Leaf is thick, fleshy and having spines on it.

7. Find the plant parts.

Ans. Root, Root Cap, Root Hair, Bud, Petals, Stem, Radicle, Flower, Leaf, Vein, Calyx, Node, Ovum.

---

E X T R A

1. Fill in the blanks.

1. The part that grows from inside the seed towards the soil is called the radicle.

2. The part that grows above the soil from the seed is called the plumule.

3. The part of the plant growing below the soil from radicle for support is called root.

4. The root cap protects the root-tip from injuries.

5. Roots bearing hair like processes near the root tips are called root hairs .

6. Thread-like or fibre like roots arising from the stem are called fibrous roots.

7. The stem grows above the soil from the plumule of the sprouting seed.

8. Leaves come out at the nodes .

9. The part of the stem between two nodes is called inter node .

10. The tip or the apical end of the stem is called a bud .

11. The broad, spread out part of the leaf is called the leaf blade or lamina.

12. The tip of the leaf is called the leaf apex.

13. Leaves of some plants have a stalk called a petiole.

14. The portion of the leaf attached to the stem is called the leaf base.

15. Small leaf like structures near the leaf base is called stipules.

16. Flowers may have a long or a short stalk called pedicel.

17. One end of the pedicel is attached to the stem.

18. Androecium is a male reproductive organ of the flower.

19. Gynoecium is a female reproductive organ of the flower.

20. Androecium consists of stamens.

21. Gynoecium consists of carpels.

22. Seeds which get divided into two equal parts are called dicotyledonous seeds.

23. Seeds which do not divide into two equal parts are monocotyledonous called seeds.

24. Petals and other parts of the flower are supported on the receptacle.

25. Sepals are green in colour.

2. Say whether True or False Correct and rewrite the false statements.

(a) Stem grows from radicle.

Ans. False. Stem grows from the Plumule.

(b) Leaf margins may be entire, dentate or lobed.

Ans. True.

(c) The leaf blade of leaves in some plants is divided into many small parts called leaflets.

Ans. True.

(d) Maize plant has reticulate venation.

Ans. False. Maize plant has parallel venation.

(e) A carpel consists of stigma, style and ovary.

Ans. True.

(f) A stamen is made up of nodes and internodes.

Ans. False. A stamen is made up of anther filament.

(g) The ovary develops into a fruit.

Ans. True.

(h) Fertilized ovules form the seeds.

Ans. True.

(i) A mango fruit contains many seeds.

Ans. False. A mango fruit contains only one seed.

(j) A fruit like cashew have seed outside the fruit.

Ans. True.

(k) Leaves of some plants do not have a petiole.

Ans. True.

(l) The peepal leaf has parallel venation.

Ans. False. It has reticulate venation.

3. Find the odd one out.

(a) Pea, Moong, maize, groundnut.

Ans. Maize – Its seed is monocotyledonous, while others have dicotyledonous seeds.

(b) Cashew, apple, mango, chikoo.

Ans. Cashew – Its seed is outside the fruit, others have internal seeds..

(c) Stigma, anther, style, ovary.

Ans. Anther – It is a part of androecium, while others are a part of gynoecium.

(d) Petiole, vein, calyx, apex.

Ans. Calyx – It is a part of flower, whereas others are parts of leaf.

(e) Aerial, stilt, runner, lobed.

Ans. Lobed – It is a type of leaf margin, while others are types of modified roots.

4. Answer the following in one or two sentences.

(a) Which types of roots do the fenugreek, spinach and onion plants have?

Ans. Fenugreek and spinach have tap roots with a few secondary roots whereas onion has fibrous root. Fenugreek roots also have some nodules which contain nitrogen fixing bacteria.

(b) What are called prop roots?

Ans. Roots emerging from the trunk and branches of a banyan tree grow towards the soil. These roots are called prop roots.

(c) What is called reticulate venation?

Ans. A leaf is divided into two equal parts by a single mid-vein which lies along the midline of the leaf blade. Secondary veins arise from the mid-vein. They are branched and form a network or reticulum. Such a type of venation is called reticulate venation.

(d) What is called parallel venation?

Ans. In a leaf all the veins are parallel, running from the leaf base to the leaf apex. Such a venation is called parallel venation.

(e) What is pollination?

Ans. After maturity, anthers burst and the pollen grains which are released fall on the stigma. This process is called pollination.

(f) Why are the underground parts of plants like radish, carrot, beet and sweet potato thick, fleshy and swollen? Which parts of the plant are they?

Ans. The underground parts of plants like radish, carrot, beet and sweet potato are thick, fleshy and swollen because they store food in the form of starch. These are the root part of the plant.

5. Distinguish between.

(a) Tap roots and fibrous roots.

	Tap roots	Fibrous roots
1.	Roots of some plants produce secondary roots that grow obliquely and spread far and wide in the soil. This type of root is called a tap root.	Thread like or fibre roots arising from the stem are called fibrous roots.
2.	It is found in dicotyledonous plant.	It is found in monocotyledonous plant.

(b) Dicotyledonous seeds and monocotyledonous seeds.

	Dicotyledonous seeds	Monocotyledonous seeds
1.	Seeds which get divided into two equal parts are called dicotyledonous seeds.	Seeds which do not divide into two equal parts are called monocotyledonous seeds.
2.	Dicotyledonous seeded plants have tap root system.	Monocotyledonous seeded plants have fibrous root system.

Note: If you have any additional questions or feedback, please leave them in the comment section below. We will try to answer them and update this blog accordingly as soon as possible.