Getting to Know Plants

Q27. Name the different parts of the plant. Mention main functions of each part.

Ans. Parts of plants and their function

     1.   Stem – The main function of the stem is to support the shoot of the plant. It conducts water and minerals to the leaves and transport food prepared by the leaves to the other part of the plant.

     2.   Roots – It provide support to the plant in the soil. It absorbs water and other nutrients from the soil and transports these things to the stem.

     3.   Leaves – It prepares food for plants by the process of photosynthesis. It helps in inter­change of gases between the atmosphere and the plant and evaporation of water.

     4.   Flowers – The primary purpose of a flower is reproduction. It produces seed which produce new plants.

Q28. Explain the following terms.

     a.   Transpiration

Transpiration is a process through which excess water comes out of leaves into the atmosphere in the form of vapor.

     b.   Photosynthesis

Photosynthesis is the process through which green plants prepare their food in the presence of sunlight, water, carbon dioxide and green pigment called chlorophyll.

     c.   Petiole

Petiole is a stalk by which leaf blade is attached to the stem.

     d.   Lamina

The broad, green part of the leaf is called lamina.

     e.   Midrib

The thick central vein present in the middle of the leaf is called midrib.

     f.    Leaf Venation

The pattern made by fine lines of veins in a leaf is called the leaf venation.

     g.   Bud

Bud is a compact knob-like structure that grows on a plant which later develops into a leaf, flower, or shoot.

Q29. Define the following part of a flower.

     a.   Sepals

Sepals are green leaf like structures forming the outermost part of a flower that surround the petals.

     b.   Petals

Petals are brightly colored parts of a flower that surround the reproductive organs.

     c.   Stamens

Stamens are the small, delicate stalks which grow at the flower’s center and produce pollen. It consists of an anther and a filament.

     d.   Filament

Filament is a fine thread like structure that supports the anther of a flower.

     e.   Anther

Anther is a part of a stamen that contains the pollens and occurs at the tip of filament.

     f.    Pistil

Pistil is the part of a flower that comprises of stigma, style and ovary.

     g.   Ovary

Ovary is the lowermost and swollen part of the pistil.

     h.   Style

It is a long and slender stalk like structure that connects the stigma and the ovary.

     i.     Stigma

The stigma is the head of the pistil and is a sticky platform which receives pollen.

Q30. Explain an activity to show that plant transpires.

Ans. Take a healthy plant. Enclose a leafy branch of the plant in a polythene bag and tie up its mouth. Tie up another branch without leaf with a polythene bag. Keep the plant in the sun. After a few hours, we observe tiny droplets of water on the inner surface of polythene bag with leaves and no water in the polythene bag which encloses the empty branch. This shows that plant transpire.

Q31. Write an activity to test the presence of starch in a leaf.

Ans. Take a leaf in a test tube and pour spirit to completely cover the leaf. Now place 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. We will see that colour changes to blue black. This shows the presence of starch in a leaf.

Q32. How do we know that the leaf has prepared the starch and not received it from another part of the plant?

Ans. To test this, place a potted plant with green leaves, in a dark room for a day or two. Now, cover a portion of a leaf of the plant completely with black paper and leave the plant in the sun for a day. Remove the leaf covered in black paper and pour some iodine solution over it. Change of color to blue black shows presence of starch.