Class 6 Science Chapter 4 Important Questions

Which type of plants do you observe in around yourself?

Generally, plants are classified on the basis of their height, type of stem and the mode of branching. There are many plants much smaller than you. Some plants that are about your size, whereas some plants which are much taller than you.
Tomato, carrot, cabbage, sunflower, mustard are smaller than you. Pomegranate, china rose, mehndi, lemon, are about your size. And coconut, banyan, sandalwood, mango are much taller than you.

Plants with green and tender stems are called herbs. They are usually short and may not have many branches. Herbs is usually do not grow more than 1 metre in height. They may live for only one or two seasons. Some of the examples of herbs are carrot, radish, tomato, wheat, paddy etc.
Some plants have the stem branching out near the base. The stem is hard but not very thick. Such plants are called shrubs. Shrubs are medium-sized plants with a hard and woody stem. Some of the examples of shrubs are china rose, jasmine, pomegranate, henna, lemon etc.
Some plants are very tall and have hard and thick brown stem. The stems have branches in the upper part, much above the ground. Such plants are called trees. The trees have one main stem called “trunk” which usually gives out branches and leaves. Some of the examples of trees are mango, coconut, jamun, sandalwood, palm, neem etc.

Plants with weak stems that cannot stand upright and spread on the ground are called “creepers”, while those that take support on neighbouring structures and climb up are called “climbers”. These are different from the herbs, shrubs and trees.
A climber plant has special organs for climbing called “tendrils” and it helps the plants to climb up but creepers plants have no such climbing organs. This is the main difference between them.

Pour water to fill one-third of the glass. Add a few drops of red ink to the water. Cut the base of the stem of the herb and put it in the glass. Observe it the next day. The colour reached there. You can cut the stem across and look for the red colour inside the stem.
From this activity we see that water moves up the stem. In other words, stem conducts water.

Yes, we can find out the type of root by looking at the impression of its leaf on a sheet of paper. Put paper on the leaf, hold the pencil trip sideways and rub it on the portion of paper having leaf below. We get impression of leaf with some lines on it. If the leaf has parallel venation, the fibrous roots are present in plant and if the leaf has reticulated venation, the tap roots are present in plant.

We will require a herb, two transparent polythene bags and some string. This activity should be done during day time on a sunny day. Use a healthy, well-watered plant that has been growing in the sun, for this activity.
Enclose a leafy branch of the plant in a polythene bag and tie up its mouth. Tie up the mouth of the empty polythene bag and keep it also in the sun. After a few hours, observe the inner surface of the bags. There are droplets of water in the bags. Water comes out of leaves in the form of vapour by a process called transpiration. Plants release a lot of water into the air through this process.

We would require a leaf, spirit, a beaker, test tube, burner, water, a plate and iodine solution for this activity. Put a leaf in a test tube and pour spirit to completely cover the leaf. Now, put the test tube in a beaker half filled with water. Heat the beaker till all the green colour from the leaf comes out into the spirit in the test tube. Take out the leaf carefully and wash it in water. Put it on a plate and pour some iodine solution over it. the leaf turns black showing the presence of starch in it this is starch is food which has been prepared by the leaf by photosynthesis.

The leaves are food factories. The leaves make food for the plant by the process of photosynthesis. The term “photo” means “light” and “synthesis” means “to make things”.
In photosynthesis, the green leaves of plant combine carbon dioxide and water in the presence of sunlight to make food and oxygen gas. Generally, raw materials as carbon dioxide gas need for making food is taken by the leaves from air and water is taken by roots from the soil. Sunlight provides energy for making food. Chlorophyll which is present in the leaves to helps in trap energy from sunlight. Lastly, oxygen gas is produced during photosynthesis. The food prepared by the leaves is glucose. These glucoses are converted into starch and stored as food in various parts of a plant including leaves.

The part of a plant which is present below the ground or in the soil, called root.
The main functions of the roots of a plant are as follows:
i)Roots help in holding the soil together. As roots prevent the soil from being blown away by wind or washed away by water.
ii) Roots absorb water and minerals from the soil which are needed for the making of food by plant leaves.
iii)Roots act as an anchor of the plant to the soil. As it fixes the plant firmly into the soil. This prevent the plant from the easily blown away by the wind.

You would require two pots, some soil, khurpi (for digging), blade or a pair of scissors and water. Select two weeds of the same kind from an open ground and dig them out. Take care that their roots do not break. Plant one of the weeds in the soil in pot A. Cut off the roots from the other weed and plant it in the soil in pot B.
Water them regularly. After a week, the plants which have roots, look like healthy whereas the plants which do not have roots looks like very thin and withered. If we would gently try to pull both plants, the plants which is withered, easily come out from the soil. But, the plants which looks healthy, firmly catches the soil. This activity helps to understand the importance of the root that helps to fix the plant firmly into the soil.

Yes, the stem of a plant can be compared with a street with two ways traffic because movement of substances occur in different directions in it.
i)It carries water and minerals from the roots to the leaves and other parts of plant in upward direction.
ii)It takes the food prepared by the leaves to other parts of the plant, in downward direction.

No, a leaf from a potted plant kept in dark will not turn blue-black when tested for the presence of starch. This is because all the stored starch would have been used up by the plant. No fresh starch would be synthesized by leaves due to non-availability of Sunlight (i.e. no photosynthesis can occur, thus no food is prepared.)

Flowers are the most beautiful part of a plant. Different plants have different types of flowers. Flowers are of many sizes, shapes and colours. Some of the common flowers are sunflower, lily, marigold, rose etc. The flower is that part of a plant which contains the reproductive organs. All the flowers have the same basic parts such as sepals, petals, stamen and pistil.
a)Sepals: The outermost green leafy structure in the flower are called sepals. They protect the flower at the bud stage.
b)Petals: The leaf like structures next to the sepals are known as petals. The bright colour and fragrance of the petals attract insects that help plants in reproduction.
c)Stamens: These are little stalks with swollen tops around the centre of the flower. These are the male parts of the flower. Each stamen consists of a thin green stalk called filament with a bag like top, called Anther which carries pollen grains.
d)Pistil or Carpel: A flask shaped structure in the centre of the flower is known as pistil or carpel. It is the female part of the flower. The lower broader portion of the pistil is called ovary and the narrow upper portion of the pistil is called the style. The sticky end at the top of the style is called stigma. The ovary contains ovules.
Function of flower:
i)Flower contains the male and female reproductive organs that are needed for reproduction.
ii)Different coloured flowers make the plant beautiful.

No, it is not a herb because sapling is a stage in the growth of the plant. A mango sapling would grow into a tree.

In many flowers, the numbers of petals is equal to the number of sepals in it. For examples, the buttercup flower has five green sepals and an equal number of Five petals. In some flowers, the numbers of petals is not equal to the number of sepals. In such flowers, the number of petals is much more than the numbers of sepals. For example, the rose flower has five green sepals but the number of petals is much more than 5. Thus, number of petals and sepals in a flower is not always equal.

A fruit is that part of a plant which contains the seeds, such as oranges, apples, lemons tomatoes etc. The fruits and seeds are formed from flowers by the process of pollination and fertilization. Pollination is done by insects, wind and water. The transfer of pollen grains from anther of a stamen to the stigma of a pistil is called pollination. When the pollen grains fall on stigma, they move down through the tube called style and reach the ovary. In the ovary, the male sex cells present in pollen join with the female sex cells present in ovules. The joining together of male and female sex cells is called fertilization. After fertilization, the ovules grow and become seeds. The ovary of flower grows and becomes a fruit with seeds inside it. A fruit protects the seeds. All the seeds can germinate under suitable condition to produce new plants.

In some plants, roots get modified and perform additional functions like storage of food, e.g. turnip, radish etc. or provide additional support to the plant e.g. in banyan tree, rope like roots arise from the main branches and reach the ground to live support. These roots are called “prop roots”.

(Note: Modified stem, some modified stems can store food like potato, ginger etc. Some can make food, such as cactus, prickly pear)

Money plant has a long but weak stem; it is a climber.

Functions of stem in a plant:
i)It holds the branches, leaves, flowers and fruits.
ii)The stem transports water and minerals from roots to the upper parts.
iii)It also transports the prepared food from the leaves to the other parts.

Characteristics of plants are:
i)They cannot move from one place to another.
ii)They can prepare their own food.
iii)These are the living organisms on the earth which are responsible for the formation of food for all the living forms directly or indirectly.
iv)All other organisms on the earth depend on the plants and their products on their survival.
v)Plants grow in the soil from where they take nutrients for their growth and propagation.