# Life Processes

## Class 10 NCERT Science

### NCERT

1   Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?

##### Solution :

Multicellular organisms such as humans possess complex body designs. They have specialised cells and tissues for performing various necessary functions of the body such as intake of food and oxygen. Unlike unicellular organisms, all cells in a multicellular organism are not in direct contact with the outside environment. Therefore, diffusion cannot meet their oxygen requirements.

2   What criteria do we use to decide whether something is alive?

##### Solution :

Presence of life processes and the presence of a cellular structure is used to determine whether something is alive or not. The important life processes in living organisms are: Nutrition, respiration, transportation, excretion, control and co-ordination, growth and reproduction

3   What are outside raw materials used for by an organism?

##### Solution :

An organism uses outside raw materials mostly in the form of food, water and oxygen. The raw materials are used by the organism for performing important functions in the body and vary according to the complexity of the organism and its environment.$\\$ 1. Food is used for providing energy and nutrients for the cells in the body$\\$ 2. Water is the most important medium in which cellular reactions take place. Water is also required for digestion and is the major constituent of blood and protoplasm$\\$ 3. Oxygen is used for aerobic respiration so as to release energy stored in the food.

4   What processes would you consider essential for maintaining life?

##### Solution :

Life processes essential for maintaining life are nutrition, respiration, transportation, excretion and control and co-ordination

5   What are the differences between autotrophic nutrition and heterotrophic nutrition?

##### Solution :

$\textbf{Autotrophic nutrition}$$\\ (i) Food is synthesized from simple inorganic raw materials such as CO_2 and water.\\ (ii) Presence of green pigment (chlorophyll) is necessary.\\ (iii) Food is generally prepared in presence of sunlight (photosynthesis)\\ (iv) All green plants and some bacteria have this type of nutrition.\\ \textbf{ Heterotrophic nutrition}$$\\$ (i) Food is obtained from complex organic sources such as plants or animals. This food is broken down with the help of enzymes.$\\$ (ii) No pigment is required in this type of nutrition.$\\$ (iii) Food can be obtained at all times.$\\$ (iv) All animals and fungi have this type of nutrition.