Life Processes

Question 1

Nutrition

Answer 1

Nutrition: The process by which an organism takes food and utilizes it, is called nutrition.

Question 2

Need for Nutrition:

Answer 2

Organisms need the energy to perform various activities supplied by nutrients.
for growth and repair.

Question 3

Nutrients

Answer 3

Materials that provide nutrition to organisms are called nutrients.
Carbohydrates, proteins, and fats are the main nutrients are macronutrients.
Minerals and vitamins are required in small amounts are micronutrients.

Question 4

Modes of Nutrition

Answer 4

1. Autotrophic Nutrition.
2. Heterotrophic Nutrition.

Question 5

Autotrophic

Answer 5

The mode of nutrition in which an organism prepares its own food is called autotrophic nutrition. Green plants and blue-green algae follow the autotrophic mode of nutrition.

Autotrophic nutrition is fulfilled by the process, by which autotrophs intake CO2 and H2O, and convert these into carbohydrates in the presence of chlorophyll, sunlight is called photosynthesis.

Question 6

Nutrition in Plants

Answer 6

Green plants prepare their own food. They make food in the presence of sunlight. Sunlight provides energy, carbon dioxide and water are the raw materials and chloroplast is the site where food is made.

Question 7

Photosynthesis

Answer 7

The process by which green plants prepare food is called photosynthesis.

Question 8

Extra photosynthesis

Answer 8

During this process, solar energy is converted into chemical energy, and carbohydrates are formed.
Green leaves are the main site of photosynthesis.
The green portion of the plant contains the pigment chloroplast, chlorophyll (green pigment).

Question 9

Raw Materials for Photosynthesis:

Answer 9

Sunlight
Chlorophyll: Sunlight absorbed by chloroplast
CO2: Enters through stomata, and oxygen (O2) is released as a byproduct through stomata on the leaf.
Water: Water + dissolved minerals like nitrogen, phosphorous etc., are taken up by the roots from the soil.

Question 10

How do raw materials for photosynthesis become available to the plant?

Answer 10

Water comes from the soil, through the xylem tissue in roots and stems.
Carbon dioxide comes in the leaves through stomata.

Question 11

Main Events of Photosynthesis:

Answer 11

Absorption of light energy by chlorophyll.
Conversion of light energy into chemical energy + splitting (breaking) of water into hydrogen and oxygen.
Reduction of CO2 to carbohydrates.
Sunlight activates chlorophyll, which leads to splitting of the water molecule.
The hydrogen, released by the splitting of a water molecule is utilized for the reduction of carbon dioxide to produce carbohydrates.
Oxygen is the by-product of photosynthesis.
Carbohydrate is subsequently converted into starch and is stored in leaves and other storage parts.
The splitting of water molecules is a part of the light reaction.

Question 12

Stomata

Answer 12

These are tiny pores present in the epidermis of leaf or stem through which gaseous exchange and transpiration occur.

Question 13

Functions of stomata

Answer 13

Exchange of gases, O2 and CO2.
Loses a large amount of water (water vapour) during transpiration.

Question 14

Significance of Photosynthesis:

Answer 14

Photosynthesis is the main way through which solar energy is made available for different living beings.
Green plants are the main producers of food in the ecosystem. All other organisms directly or indirectly depend on green plants for food.
The process of photosynthesis also helps in maintaining the balance of carbon dioxide and oxygen in the air.