PLANTS

IMPORTANT TERMS

Photosynthesis – Photosynthesis is the process by which green plants use sunlight to synthesize nutrients from carbon di oxide and water and generates oxygen as a by -product.

Germination – Germination is the process by which a seed produces a new plant.

Transpiration - Transpiration is process where plants absorb water through the roots and give off water vapour through stomata which are present in leaves.

Vegetative propagation - Vegetative propagation is the ability of plants to reproduce new plants from the existing vegetative parts like stems, leaves or roots.

Ploughing - Ploughing is the process of loosening and turning up the soil.

Harvesting - Harvesting is the process of collecting mature crops from the field.

Irrigation - Irrigation is the artificial application of water to the land or soil.

Seed dispersal - Seed dispersal is the movement or transport of seeds away from the parent plant.

 

METHODS OF REPRODUCTION

SEEDS

1. Flowering Plants - Most of the flowering plants would reproduce with the help of seeds dispersed from the parent plant e.g Mango.
2. Non-Flowering Plants - Non flowering plants also produce through seeds but their seeds are not contained in flowers but are contained in the cones e.g Coniferous

SPORES

There are some non flowering plants that do not produce seeds. Instead they use spores to reproduce e.g. Fungi, Fern, mosses. Spores are tiny reproductive unit that contain only a single cell.

 

AGENTS OF DISPERSAL

1. Air

Seeds are dispersed after being carried by air.

1. Seeds having wing like structure or wings on them e.g Drumstick, Jacaranda.
2. Seeds having long and fine hair around them e.g Cotton, Dandelion.

 

1. Water

Seeds are dispersed by the help of water e.g Coconut, Lotus.

 

1. Animals

Seeds are dispersed by the action of humans and animals

1. Dispersal by attaching to the body of animals with the help of spines or hooks on them e.g Xanthium, Cocklebur.
2. Dispersal by being thrown by animals and humans e.g Berries, Mango.
3. Dispersal by excretion of waste e.g Guava, Orange. This is called Endozoochory.      

 

1. Bursting/ explosion

            Seeds are dispersed by the sudden bursting action of the ripened fruits e.g Poppy, Balsam.

 

KIND OF CROPS

1. Rabi Crops – Crops that are grown in winter are called rabi crops like wheat, gram.
2. Kharif Crops – Crops that are grown in summer season are called kharif crops like rice, jowar, bajra, jute, hemp, peanut, millet, maize and pulses.
3. Fibre Crops – Crops which give us fibre are called fibre crops like cotton, jute.
4. Food crops – Crops which give us food are called food crops like wheat, rice, potato, sugarcane.
5. Oil producing crops - Crops which give us oil are called oil-producing crops e.g. sunflower and mustard.

METHODS OF VEGETATIVE PROPAGATION

1. By Leaves – Buds on the leaves of some plants can grow into new plants – e,g Bryophyllum.
2. By Stem – Stem of some plants can be sown to grow into new plant e.g Rose, Sugarcane.
3. By Roots – Roots of plants can grow into a new plant e.g Carrot, Sweet potato.

SEEDS & GERMINATION

MAIN PARTS OF SEED

1. Embryo – Embryo is the baby plant in the form of a multi-cellular structure present within the seed which eventually matures into a plant.
2. Seed Coat – Seed coat is outer covering of the seed which protects the baby plant. There are tiny pores on the surface of the seed coat that are called Micropyle, which are used by seeds to take in the water.
3. Cotyledons – Cotyledons or the seed leaf is that part of the seed that has the food stored in it and provides nourishment to the germinating seed.

KIND OF SEEDS

1. Monocots – Monocots are plants whose seeds contain only one seed leaf or cotyledon e.g. rice, wheat etc.
2. Dicot Seed - Seeds of some plants such as grams have two seed leaves inside the seed coat. They are called dicots.

GERMINATION

Main parts of the seedling during germination are:-

1. Plumule – Plumule is the baby shoot which grows upwards and gives rise to stems, leaves and flowers.
2. Radicle – Radicle is the baby root which grows downwards into the soil to form the roots of the plant.

 

Once the embryo in the seed obtains adequate warmth, water and oxygen then it starts to germinate. The embryonic plant begins to grow and the seed coat starts to swell and break open under the pressure of the growing seedling within the shell. Until the germination, the embryo uses up the food stored in the Cotyledon (seed leaf), and then it starts taking nutrients from the soil through the Radicle while making its own food through the Plumule.

 

PROTECTION OF CROPS

1. Fertilisers are chemical manmade additives to the soil to increase the crop productivity e.g Ammonium Nitrate, Ammonium Sulphate, Urea.
2. Manures are natural substances made of animal dung and farm compost that is used to enhance crop productivity.
3. Pesticides are chemicals that are sprayed on the crops to protect them from insects and pests.
4. Scarecrow is an object, usually in the shape of a human being, made of sticks and old clothes. Farmers use scarecrow to scare birds away from fields where crops are grown.
5. Crops after harvesting must be protected from Moisture too since the presence of moisture can rotten the harvest.

 

 

INTERESTING FACTS

 

Plants also need oxygen to respire just like animals and humans. The energy from the stored food is released during respiration by plants and they exhale carbon di oxide. However, during Photosynthesis (making of the food), plants use sunlight and Carbon di oxide and release oxygen as the by product.

 

Not all underground crops are roots. Sweet potato is a root but common potato is the swollen tip (Tuber) of an underground stem.

 

Tea requires moist weather but at the same time do not need standing water, therefore they grow well in hilly areas like Darjeeling.