[General Instructions: Students need to keep a record of the subject matters and copy the provided exercise works in their notebooks.]

CHAPTER-4:

THEME:- Plants in the Surroundings and Environment

DATE- 20-05-2020 1

PARTS OF PLANT

AND THEIR USES

DATE- 20-05-2020 2

OBJECTIVES:

❖ PARTS OF A PLANT

Definition, different parts of root and shoot.

Structure, Types and Functions of Root with

diagrams:

Activity: To show that stem carries water.

❖ LEAF: Structure and functions.

❖ PHOTOSYNTHESIS IN PLANTS.

❖ SCRAPBOOK WORK

DATE- 20-05-2020 3

PARTS OF A PLANT:-

❑ Plants are one of the most essential living organisms on earth. They

are immensely beneficial to both animals and human beings. They

produce oxygen which is crucial for the survival of living organisms.

❑ Trees provide shelter to animals and are also known for their

medicinal benefits. Overall, different parts of plants exhibit

different roles.

❑ They act as a source of food and oxygen and maintain the

ecological balance.

❑ A plant has many parts. Different parts perform

different functionalities.

❑ They are:

1. The Root.

2. The Shoot:

(i) Stem

(ii)Leaf

(iii) Flower

(iv) Fruit

DATE- 20-05-2020 4

ROOT AND SHOOT SYSTEM:-

❑ Roots are the important and underground part of a plant,

which are collectively called the root system.

❑ They are the major part that anchors the plant firmly in the

soil.

❑ STRUCTURE:-

❑ The primary root, or radicle, is the first organ to appear when

a seed germinates. It grows downward into the soil, anchoring

the seedling.

❑ In gymnosperms and dicotyledons the radicle becomes

a taproot. It grows downward, and secondary roots grow

laterally from it to form a taproot system.

❑ They absorb water and minerals from the soil, synthesize

plant growth regulators, and store reserve food material.

Click on the URL for an animatic overview-

https://www.youtube.com/watch?v=nz3ClBQojU8

FUNCTION:-

DATE- 20-05-2020 5

❑ Roots grow in length only from their ends.

ROOT CAP:-The very tip of the root is covered by a thimble-

shaped root cap, which serves to protect the growing tip as it

makes its way through the soil.

APICAL MERISTEM: Just behind the root cap lies

the apical meristem, it is a tissue of actively dividing cells.

REGION OF ELONGATION:- It lies just above the

meristematic region. It is in the region of elongation that

growth in length occurs.

REGION OF MATURATION:- It lies above this elongation

zone where the primary tissues of the root mature, completing

the process of cell differentiation that actually begins in the

upper portion of the meristematic region..

STRUCTURE OF A ROOT:-

DATE- 20-05-2020 6

TYPES OF ROOTS:-

❑ Plants have three types of root systems:

1.) TAPROOT ROOTS:- the main root that grows from the base

of the stem is called a tap root.

secondary roots grow laterally from it to form a taproot system.

E.g.- Pea, sunflower, mustard and carrot have tap roots.

2.) FIBROUS ROOTS:- A bunch of thin and small roots about

the same size that grows from the base of the stem is called a

fibrous root.

E.g.- Grass, onion, rice and wheat have fibrous roots.

3.) ADVENTITIOUS ROOTS:-that arise from an organ other

than the root—usually a stem, sometimes a leaf.

E.g.- those are seen in corn (maize), screw pine, and banyan.

Click on the URL for an animatic overview-

https://www.youtube.com/watch?v=Ra021LvCiZM

DATE- 20-05-2020 7

PARTS OF SHOOT SYSTEM:- (i) STEM:

❑ The stem is the part of the plant which is found above the ground. The

bark of trees are brown in colour and younger stems are green in

colour.

❑ It forms the basis of the shoot system and bears leaves, fruits and

flowers.

❑ Stems arise from the plumule, vertically upwards to the ground. Initially,

stems are usually weak and cannot stand straight.

❑ It eventually grows to become the toughest part of the plant called the

trunk.

❑ The trunk is covered by a thick outer covering known as the bark.

Overall stem provides a definite framework and structure to a plant,

which later develops into a tree.

❑ The important functions of a stem includes:

Support: Primary function of the stem is to hold up buds, flowers,

leaves, and fruits to the plant.

Transportation:It is the part which transports water and minerals from

the root and prepared food from leaves to other parts of the plant.

Storage: A few underground stems such as potato and ginger are

modified to store food.

FUNCTIONS:-

Click on the URL for an animatic overview-

https://www.youtube.com/watch?v=cYkvsD_jWSM

DATE- 20-05-2020 8

❑ Leaves are the most important part of a plant. They contain

chlorophyll that helps the plants to prepare their food using

sunlight, carbon dioxide and water. A leaf consists of three

main parts- petiole, leaf base and lamina.

PARTS OF SHOOT SYSTEM:- (ii) LEAF:

LEAF:

1. Petiole❑ It is the stalk that connects a leaf to the stem of the plant, it is made of

complex conducting tissues called vascular tissues.

➢ Functions:

Providing support to the leaf and keeps it erect

Transporting water and nutrients absorbed by the roots to the leaves

Transporting photosynthetic products from the leaves to the rest of the

plant.

2. Leaf Base❑ It is the lowermost part of a leaf, which is closest to the petiole.

➢ Functions:

Helping in the attachment of the leaf to the stem

It protects the young axillary bud

Click on the URL for an animatic overview-

https://www.youtube.com/watch?v=AOxCnlkQiyQ

DATE- 20-05-2020 9

3. Leaf-blade or Lamina:❑ It is the thin, flat part of the leaf that is typically green in color.

❑ It is further divided into three parts:

i) leaf apex – the tip of the leaf blade,

ii) leaf margin – the edge of the leaf and,

iii) leaf veins – the small channels or capillaries, which are further

subdivided into venules.

Functions: Helping plants to prepare their food using raw materials like water,

carbon dioxide, and minerals through photosynthesis.

Performing evaporation from the aerial parts of a plant by a process

known as transpiration.

Veins help in transporting water and nutrients throughout the leaf.

PARTS OF SHOOT SYSTEM:- (ii) LEAF:

DATE- 20-05-2020 10

❑ Primarily, leaves have three main functions:

Photosynthesis: Green leaves prepare food for plants by using

water and carbon dioxide in the presence of sunlight. This process

is called photosynthesis.

Transpiration: Other than photosynthesis, leaves play a crucial

role in the removal of excess of water from plants through tiny

pores called stomata. This is the process of transpiration.

Reproduction: Leaves of some plants helps in reproduction also.

For e.g. leaves of Bryophyllum give rise to a

new Bryophyllum plant.

Storage: They store food in some plants. We eat these leaves as

food. Examples: are spinach, coriander, cabbage and mint.

FUNCTIONS OF THE LEAVES:

DATE- 20-05-202011

PHOTOSYNTHESIS IN PLANTS:

Click on the URL for an animatic overview-

https://www.youtube.com/watch?v=GSfvl_XQIwE

DATE- 20-05-2020 12

ACTIVITY:

❖ Learn the below given activity from

your textbook pg. no. 33.

DATE- 20-05-2020 13

EXERCISE FOR REVISION: (pg. 33-34)

A.Tick(√) the correct answers :-

1. The two main parts of a plant are-

Ans: (c) root and shoot.

2. In which of the following plants is a tap root not found?

Ans: (d) grass.

3. In which of the following plants is a fibrous root not found?

Ans:- (a) carrot.

4. Which of the following is not a function of roots?

Ans:- (c) they keep the plant upright.

5. A shoot has

Ans:- (d) all of these.

6. Which of the following is the function of the stem?

Ans: (d) All of these.

B. Fill in the blanks :-

1. The part of the plant that grows under the ground is called the root.

2. The part of a plant that grows above the ground is called the stem.

3. The stem carries water and minerals from the roots to the leaves.

4. The stem carries food prepared by leaves to different parts of the plant.

DATE- 20-05-2020 14

SCRAPBOOK WORK:❖ Draw colorful well labeled diagrams of the following with necessary descriptions in

your scrapbook:

1. Human Digestive system.

2. Human Excretory system.

3. The Parts of a Leaf.

TITHI BISWAS

RAKHI R. ROY