Living Beings || Reproduction || Asexual reproduction || Sexual reproduction || Budding || Root || Flower

1) Define the following terms: 

a) Reproduction, 

b) Asexual reproduction,

c) Sexual reproduction, 

d) Fragmentation, 

e) Budding, 

f) Fission, 

g) Sporulation.

Ans:

a) Reproduction : The process of giving birth of same kind is called reproduction. The population of a species is increased by reproduction. 

b) Asexual reproduction: Asexual reproduction is that type of reproduction in which an individual produces new offspring without fusion of sex cell. This is common in lonely lower animals and plants where the body is not very complex. 

c) Sexual reproduction: The process of reproduction due to the fusion of male and female gametes is called sexual reproduction.

d) Fragmentation: The process of Asexual reproduction in an individual breaks down into two or more pieces (filament), each such pieces develops into an individual under favorable conditions. For example: spirogyra, marchentia, Chara, etc. reproduce by fragmentation. 

e) Budding: The process of formation of offspring from an outgrowth or bud of a parent is known as budding. It is common in yeast, hydra, etc. 

f) Fission: Fission is the simple method of division in which an organism divides into two or more individuals. For example: Amoeba, euglena, paracium, bacteria, diatom, plasmodium, etc. reproduces by this method. 

g) Sporulation: The type of asexual reproduction which takes place by means of spores is called sporulation. For example: Mucor, Mushroom, Fern, etc. reproduce by sporulation method.

2) What is root? Define primary and secondary root.

Ans: The parts of plants that grow under the soil is called root. The root fixes the plant on the soil at a place. Generally roots are white or brown in colours without leaves and buds.

i) Primary Root: The main root which grows downward is called primary roots.

ii) Secondary Root: The branches which arise from primary root are called secondary root. 

3) Write the types of roots.

Ans: Plants have mainly two types of roots, they are: 

a) Tap root and 

b) Fibrous root.

 

4) Why are the roots of plants modified? Explain.

Ans: The roots of plants are modified for the following purpose:

a) For storage of food. 

b) For medical support. 

c) For vital biological function.

5) What is root cap?

Ans: It is a cap like covering over the root tip for protection. Its mucilaginous secretion helps in lubrication.

6) Which plants store food from modification of stem? Give examples.

Ans: The stem of some plants are found inside the soil. The stem below ground stores food in the form of thick , fleshy, starch. For example potato. Some of stem have nodes and internodes which are dry like thorns. For example: ginger. Similarly, the stem of onion, tulip, daffodils store the food. 

7) Explain about aerial modification of stem.

Ans: Aerial stem modification are of following types:

a) Stem tendrils: Tendrils are long, thin, wiry and spirally coiled climbing organs of the plants. They coil around nearby support and help the plant to climb. Tendrils develop as modification of the stem in certain plants. The terminal bud give rise to be tendril in Cissus quandrangularis and the auxiliary bud becomes modified into a tendril in passiflora. 

b) Stem Thorns: The thorns is a hard, straight and pointed structure. In bougainvillea and Duranta, the auxiliary bud is modified into a thorn. In Carissa the terminal bud is modified into a pair of thorns. The thorns sometimes bear leaves, flowers and fruits as seen in Duranta and Pomegranate. The thorns not only check the rate of transpiration but also protect the plants from herbivore grazing. Example: Carissa, Duranta, Citrus, etc.

c) Phylloclades: A phylloclade is a flattened stem of several internodes functioning as a leaf. In opuntia the stem is modified into a green flattened structure called phyllaclade. On the surface of the phyllocalade, clusters of spines are formed. These spines are modified leaves of the auxiliary bud. These spines not only check the rate of transpiration but also protect the plants from herbivores. 

d) Cladodes and Caldophylls: Cladodes are green, flat or cylindrical branches of limited growth. They are leaf like structures which branches of limited growth. A cladophyll is a flattened leaf like stem arising in the axils of a minute branch like true leaf. 

e) Thalamus: Thalamus of a flower is a modified stem apex. Floral parts are borne on the thalamus. It may be convex. Eg: Ranunculus, Concave (Lathyrus). 

8) Explain about the sub-aerial modification of stem of plants.

Ans: The stem of some plants are soft and weak and go being parallel to the ground. Some plants have their stem both inside and above the ground. These stem produce new plants. For example: prasses. Some stem produce buds and new plant develops from it.

9) Write any three function of stem of plants.

Ans: The following are the three functions of stems of plant;

i) It helps the plants to stand upright and supports the leaves and branches.

ii) It conducts water and minerals from root to the leaves.

iii) It distributes the food from leaves to the other parts of the plants.

10) Write any three functions of leaves of plants.

Ans: The following are the three functions of leaves of plants:

i) Leaves are green in color due to presence of chlorophyll in them, Leaves prepare food.

ii) Most of the leaves contain tiny pores called stomata. They allow exchange of gases such as oxygen and carbondioxide.

iii) Leaves help to remove excess water from plant in the form of water vapour. This process of removing water by evaporation is called transpiration.

11) Define the following terms.

Root, shoot, leaf, flower, internodes, inflorescence, photosynthesis, transpiration

Ans: 

a) Root: The part of the plant that frows under the soil constitute the root system. Root has primary root, lateral root, root cap and root hair.

b) Shoot: The part of a plant that grows above the soil is called shoot. It is the aerial part of the plant. It consists of vegetative organs (stem, branches and leaves) and reproduction organs (flower, fruits, seeds, etc.).

c) Flower: Flowers are the reproductive organs of flowering plants. The flower is attached to the stem by a slender stalk called pedicel.

d) Inflorescence: The arrangement of flower is called inflorescence.

e) Photosynthesis: The process of preparation of food by green plants in the presence of water, minerals, sunlight, chlorophyll and carbondioxide is called photosynthesis.

f) Transpiration: Leaves of plants help to remove excess water from the plant in the form of water vapor. This process of removing water by evaporation is called transpiration.