2. Describe three important functions of roots.
3. With the help of examples explain any three types of root modification
4 Discuss any three important functions of a stem
5. Explain with examples how stems are modified for food storage and multiplication of plano
6. Describe the structure of a leaf with the help of a diagram
7. What is venation: Describe the two different types of venations found in leaves
8. Explain the parts of a flower with the help of a labelled diagram
9. Describe the process of pollination and what happens to a flower after pollination
10. Describe the structure of a seed.
Answers
Explanation:
2)answer......
Following are the important functions of roots:
(1) Absorption of water and nutrients from the soil.
(2) Help to anchor the plant firmly into the plant.
(3) Prevent soil erosion by binding the soil particles together.
(4) Modified to perform various other functions like reproduction, nutrition, etc.
3)answer.....
Roots are modified for support, storage of food, respiration.
For support: Prop roots in banyan tree, stilt roots in maize and sugarcane.
For respiration: Pneumatophores in Rhizophora (mangrove).
For storage of food: Fusiform (radish), Napiform (turnip), Conical (carrot).
MODIFICATIONS OF ROOTS - DEFINITION
Roots are the part of the plant which is mainly used for support and anchorage of plants.
Some of the roots like carrot and radish are modified to perform a special function like storage of food. The food stored in the roots is utilized during unfavorable conditions.
Roots like Rhizophora, are modified for gaseous exchange. They have minute pores which help to exchange gases.
Stilt roots provide mechanical support to the plant e.g., sugarcane.
Climbing roots provide aerial support to the plant e.g., vanilla.
Clinging roots provide mechanical support to the plants e.g., orchids.
Sucking roots helps to withdraw nutrition from other parts of the plant e.g., cuscuta.
Floating roots help the aquatic plants to store air e.g., water lily.
Assimilatory roots perform photosynthesis e.g., trapa.
4) answer
The primary functions of the stem are to support the leaves; to conduct water and minerals to the leaves, where they can be converted into usable products by photosynthesis; and to transport these products from the leaves to other parts of the plant, including the roots.
5)answer
Modifications of Stem for food storage:
Rhizome: The rhizome is an underground modified stem. It grows horizontally and stores food. Nodes, internodes and scaly leaves are present on it. Buds are present; which give rise to aerial shoot. Examples: ginger, turmeric etc
Corm: Corm is an underground modified stem. It grows vertically. It bears nodes and internodes. Example: Colocasia
Tuber: Tubers arise from narrow underground branches. Tuber bears nodes and internodes. Bud arisng from the nodes are called eyes. Vegetative propagation takes place from these 'eyes'. Example: potato.
Bulb: The stem is underground and appears like a bulb. Internode becomes shortened to allow leaves to become thick and fleshy to store food material. Example: onion.
Modifications of stem for climbing:
Tendril: In some plants, the axillary bud becomes elongated and coiled to form tendrils. Tendril coils around a support and thus helps the plant in climbing. Example: grapevine, pumpkin.
Modification of Stem for Protection:
Thorn: Stem as modified thorn is present in the leaf axil or on apex of stem. Thorns prevent grazing animals from damaging the plant. Example: Bougainvillea
6)answer
A leaf has two main parts: (1) Petiole- the stalk that supports a leaf in a plant and attaches the leaf blade to the stem. (2) Lamina- the green flat part of a leaf that is specialized for photosynthesis. ... (ii) Midrib- The central, thick, linear vein that runs along the length of a leaf is called midrib
7)answer
Venation is the phenomenon of arrangement of veins in the lamina of the leaf surface. It is of three types, reticulate, parallel and furcate venation. In reticulate venation, veins form the network like structure.
8)answer
A typical flower consists of an outer whorl of green sepals (calyx) which protects the parts within. 2) The second whorl has petals (corolla) which are usually brightly coloured. ... 4) The third whorl of the flower consists of stamens (Androecium) which are the male reproductive organs(diagram of 8th answer is attached above)
9) answer
Only after pollination, when pollen has landed on the stigma of a suitable flower of the same species, can a chain of events happen that ends in the making of seeds. A pollen grain on the stigma grows a tiny tube, all the way down the style to the ovary. ... The ovary develops into a fruit to protect the seed.
10)answer
The outer covering of a seed is called the seed coat. Seed coats can be thin and soft as in beans or thick and hard as in locust or coconut seeds. ... Endosperm, a temporary food supply, is packed around the embryo in the form of special leaves called cotyledons or seed leaves.
