Download ch3 - Prashanth Ellina

Lesson 3
Parts of a Plant and their Functions
We all know that plants are an important part of the living
world. We also know that plants and animals are dependent
on each other.
There are many similarities between plants and animals,
like:
both need food, water and air to live;
both have growth;
both reproduce;
both die.
Animals have certain body systems which perform
different functions. Plants also have systems.
We have learnt about the functions of the human body.
Let us find out the different parts of a plant and
functions of each part.
Look at the picture given below carefully.
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What are the similarities among mango, sunflower, wheat
and carrot plants?
All have stems.
All have leaves.
The plants also have flowers and fruits.
These are parts of the plant. There is another part of
the plant which is usually under the ground and hence
cannot be seen. This part is called the root.
Each part of the plant has its own functions.
Let us find out what are the different functions of each
part of the plant.
THE ROOT
Roots absorb minerals and water from the soil. These
are necessary for the growth of the plant.
Roots help in holding the plant firmly on to the soil.
Thus, roots also help in preventing blowing away soil
from strong winds or flow of water.
This is how plants help in holding the soil.
Do you know that plants have two types
of roots? One kind of roots grow vertically
into the soil. These have many branches.
This type of root is called taproot. The
roots of sunflower, carrot and radish
belong to this type of roots.
The second type of roots are fibre-like
which grow at the level of the ground and
spread out in the soil. Such type of roots
are called fibrous roots. Examples of such
roots are wheat, maize, paddy, etc.
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Write the names of any three plants which have taproot
and three plants having fibrous roots.
Plants with taproot
Plants with fibrous root
1. __________________
1. __________________
2. __________________
2. __________________
3. __________________
3. __________________
Some roots store food for the plant. Plants such as
carrot and radish have this type of roots. We eat these roots
as part of our food.
Write the names of any three plants whose roots we
eat.
1. ____________
2. ____________
THE STEM
Observe carefully the plant, given in
this picture.
The part of the plant above the
soil which bears leaves, flowers and
fruits is called the stem.
You must have observe plants that
have branches on their stems.
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3. ____________
The stem bearing branches, leaves, flowers and fruits
together make the shoot system of the plant.
What is the function of the stem of a plant?
Let us learn it by doing an activity.
Let us take a plant which has a soft stem, e.g. balsam (gulmehndi)
or vinca (sadabahar). Its stem should have leaves and flowers.
Put this plant in a glass of water. Mix some red ink in the water.
Observe the plant after two or three days.
What difference do you observe in the plant?
You will find some red stripes on the leaves and stem. (You can
cut a part of the stem to confirm it.)
Why does it happen?
The stem carries water and minerals from the roots to different
parts of the plant.
The stem grows in the direction of light. We can
understand this through an activity.
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Take a potted plant. Put it in a cardboard box and close the box.
Make a hole on one side of the cardboard box in such a way that
light enters only through this hole. Take another potted plant
and keep it in the open. Keep watering the plants regularly for a
few days.
>
What do you find?
You will find that the plant kept in the open, grow straight. The
plant which was inside the box has bent towards the hole because
it was getting light through this hole.
Stems of some plants remain underground. Some of these
stems also store food for the plant. These are called
underground stems, e.g. potatoes, arbi, etc.
Write the names of four plants which have
underground stems and form part of our food.
1. _____________________________________________
2. _____________________________________________
3. _____________________________________________
4. _____________________________________________
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THE LEAVES
Leaves make food for the plant.
There is a green pigment
present in the leaves. It is called
chlorophyll. Leaves of plants
make food in the presence of
sunlight with the help of
chlorophyll. This process of
making food by plants is called
photosynthesis.
Do leaves perform some other functions besides making
food for the plant?
Let us find out through an activity.
Take two potted plants.
In the first plant, apply some vaseline on both sides of
the leaves and wrap it in a polythene bag (as shown on
page 32). Wrap the other plant in a polythene bag without
applying vaseline.
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Keep both the plants in the sunlight. Observe the plants
after four to five hours.
Do you find any difference in the two plants?
Yes!
1. No drops of water are visible in the polythene bag and
on the leaves on which vaseline was applied.
2. There are drops of water in the polythene bag and on
the leaves on which vaseline was not applied.
Why have drops of water appeared on the leaves?
The Surface of the leaves have small
pores called stomata . Water vapour
has come out from the stomata and
collected on the leaves without
vaseline. Water drops are also found
on the inner side of the polythene
covering this plant.
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stomata
In the other plant, the stomata are blocked due to the
application of vaseline on the surface. Therefore, water
vapours could not come out of the leaves through the
stomata.
Plants give out the excess water through these stomata.
Stomata also help the plants by giving out oxygen and
taking in carbon dioxide from the
environment for making food.
THE FLOWER
AND THE
FRUIT
Flowers help plants in the process of
reproduction. Fruit is formed from the
flower after the process of reproduction.
We eat fruits of many plants.
Write the names of the other parts of a plant that we
eat, besides the fruit.
__________________________________________________
__________________________________________________
We eat a variety of fruits. Most of these fruits
have seeds inside them. Some fruits have only
one seed, like mango, jamun,
etc. Some fruits have many
small seeds, like Pomegranate,
guava, orange, etc.
Seed is a very important part of the plant. A new plant
grows from the seed. The seed has a cover around it. This
is called the seed coat.
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After germination of the seed, the root and the stem of
the plant come out.
To understand the structure of a seed, break open a
soaked gram and look carefully. You will find two soft
structures joined together inside the seed coat. These are
called cotyledons.
The function of the cotyledon is to provide food to the
young plant.
Are cotyledons of all seeds alike?
There are some plants which have one cotyledon in
seeds while others have two.
Let us find out through an activity.
Get some seeds of gram, peas and maize.
Soak them in water for a few days. Remove their seed coats
and observe.
What do you find?
There are two cotyledons in
grams and peas seeds.
The maize and wheat seeds
have only one cotyledon.
THERE
ARE DIFFERENT TYPES OF PLANTS
There are certain plants which
have a life span of one season.
These plants are called annual
plants, e.g., wheat, gram,
mustard, paddy, etc.
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Plants whose life cycle
requires two seasons for
complete growth are called
biennial plants, e.g., carrot,
sugarcane, etc.
Some plants which have a life span of many years are
called perennial plants. Mango, neem, lemon, etc., are
some of the perennial plants.
You must have seen that there are some
plants which are small and soft. They are
called herbs, e.g., wheat, spinach,
fenugreek plants, etc.
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Some plants have very weak
stems. Hence they need support.
Such plants grow along the
ground. These are called
creepers, e.g., pumpkin, gourd,
grapes, etc.
Some plants have very hard
stems.
In such plants,
branches may arise from the
lower part of the stem, e.g.
Karonda, henna, etc. These
plants are called shrubs.
Some plants have tall, strong
and woody stems. These are called
trees, e.g., mango, peepal, pine,
deodar, etc.
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In this lesson We Have Learnt
The root absorbs water and minerals for the plant from the
soil.
The stem carries water and minerals to all parts of the plant.
It supports the plant.
The leaves of the plant make food. Leaves take in carbon
dioxide from the air and give out oxygen. Leaves also give
out water vapour.
Flower is the reproductive part of a plant.
What Have We Learnt ?
I.
ORAL WORK
1. Tell four similarities between plants and animals.
2. Which part of a plant do you find most beautiful and why?
3. Name three fruits which have only one seed.
4. What are the differences between the functions of a root and a stem?
5. Name some plants in your neighbourhood whose flowers you find
beautiful.
II.
WRITTEN
1.
What is the difference between trees and creepers?
2.
Write one function of each part of a plant.
3.
What is the difference between taproot and fibrous root?
4.
What is the difference between annual, biennial and perennial
plants? Give one example of each of these plants.
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5.
Write the difference between shrubs and herbs.
6.
Fill in the blanks:
(a) The seed lies in the _______________ of a plant.
(b) The shoot system is the _______________ part of the plant.
(c) The stem of a tree is ______________ than that of a shrub.
(d) The stem of a shrub is ____________ than that of a herb.
III.
THINGS TO DO
•
Visit a nearby garden and observe different kinds of
plants there. List the names of three plants each of
shrubs, trees and herbs.
•
Draw a picture on a chart paper of different parts of
a plant and display it at home.
•
Find the names of any five plants which have thorns.
•
Find out which parts of plants are eaten by animals.
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