Question

Carbohydrates are essential for life in both plants and animals. Name the carbohydrates that are used as storage molecules in plants and animals, also name the carbohydrates which are present in wood or the fibre of cotton cloth.

Answer 1

Hint: Every living being needs energy in order to work. Energy can neither be created nor be destroyed. So it has to be stored in some form in order to be utilized as and when required by the body. Different types of carbohydrates are stored in plants and animals.

Complete step by step solution:
-Energy is defined as the ability to do work. It exists in different forms and is found in all the living things as well as many non-living things. Different forms of energy for non-living substances are solar energy, wind energy, electrical energy, mechanical energy, chemical energy, etc.
-Energy can be transformed from one phase to another with a little loss of it to the surrounding. Total energy thus remains the same during any transformation. In living beings, energy occurs in many forms as carbohydrates, fats, sugar, ADP,ATP, etc.
-Energy is needed by everything and everybody to do work. While doing that, energy is transferred from potential energy to kinetic energy and vice versa. So a non-living thing can store these forms of energy and utilize it to do work.
-Living organisms cannot store energy in different forms. They get energy from food, sleep, breathing, etc. There is no concept of kinetic and potential energy in living organisms. Our cells need constant energy supply. All of it is not fulfilled by breathing and so we need energy sources.
-Free energy present in the cell can destroy the cell completely and so it is not available to the cells else it may lead to an increase in the body temperature. The cells of the plants store carbohydrates in the form of starch.
-Carbohydrates are subdivided into simple carbohydrates and complex carbohydrates which are forms of sugar. Simple carbohydrates can be monosaccharides or disaccharides which have one and two sugar molecules respectively.
-Complex carbohydrates are polysaccharides which have many sugar molecules in them. They are basically starch, fibre and glycogen while the simple carbohydrates include glucose, fructose, sucrose, maltose, etc.
-Starch is the main form of carbohydrates stored in plants and animals and is used by them to provide energy. It is a source for the humans also. Cereals contain the maximum starch content.
-The type of carbohydrates present in wood or the fibre of cotton cloth is different from starch as it does not need energy for the desired purpose. Cellulose is the type of carbohydrate present in them. It is the main composition of the cell walls of the plants which is absent in animals. This outer layer is extracted from the plants to make cloth.
-Thus, cellulose is extracted from the cell walls of the plants and is used to build furniture in the form of wood and also used to make clothes in the form of cotton fibre.
Therefore the type of carbohydrate present in plants and animals is starch while that present in wood and cotton is cellulose.

Note: Cellulose is not present in animals as the cells of the animals do not contain the cell wall. Their outer layer is the cell membrane. Cellulose does not provide any energy and plants prepare their own food by photosynthesis and convert it into starch.