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1. What is food?
The substances eaten by human beings and other animals, for growth and development, and to derive energy for various activities, is called food.
2. Why should we eat cooked food?
We should eat cooked food because cooking kills harmful germs, there by making food healthy and fit for consumption. Cooked food can be easily digested and absorbed by our body. Cooking also increases the taste of food.
3. Explain the various sources of food with the help of examples.
There are mainly two sources of food:
( i ) Plants – Plants provide us fruits, vegetables, pulses, grain, cereals etc.
( ii ) Animals – Animals provide us milk, eggs, meat etc.
4. Define the term ‘Herbivores’.
The animals which eat only plants and plant products are called ‘herbivores’. These animals usually have sharp cutting – teeth in front and flat wide grinding – teeth at the back. Examples: Cow, Goat and Buffalo.
5. What are ‘Carnivores’? Explain with examples.
The animals which eat other animals are called ‘carnivores’ animals. Such as lion, tiger, eagle, and wolf. These animals have long, sharp teeth while the birds have curved, pointed beaks that aid in tearing flesh.
6. Define the term 'Omnivores'.
Human beings, bear, and crow are examples of Omnivores. They feed on both plants and animals. Omnivores do not eat all types of plants or animals. We eat only parts of certain plants. Similarly, we do not eat the flesh of all animals. Other groups of animals with special eating habits include scavengers, decomposers, and parasites.
7. What are Scavengers?
Scavengers are animals such as jackal, vulture, and even crow that mainly consume dead bodies of other animals. Scavengers eat or consume dead animals whereas decomposers break down the dead remains of plants and animals.
8. What are Decomposers?
Decomposers are organisms such as bacteria and fungi that feed on dead plants and animals or their products. Decomposers and scavengers play a very important role in keeping our surroundings clean.
9. What are Parasites?
Parasites are small organisms that depend and survive on other living organisms. For example, fleas and leeches suck blood from humans and other animals. Tapeworm and hookworm are also parasites that live inside the bodies of some animals.
10. What are deficiency diseases?
Diseases that are caused by the lack of some particular nutrient in a person’s diet are called deficiency diseases.
| Nutrient | Signs and symptoms of the deficiency disease | Name of the deficiency disease |
| Proteins | Deficiency of proteins in the diet leads to stunted growth, discoloration of hair, patchy skin, thinning of legs, or swollen stomach. It may also affect the functioning of the brain. |
Kwashiorkor |
| Proteins and carbohydrates |
Deficiency of proteins and carbohydrates leads to thinning, weight loss, and weakness. |
Marasmus |
| Vitamin A | Vitamin A deficiency leads to poor vision. | Night Blindness |
| Vitamin B | Lack of Vitamin B may result in weakening of muscles and weight loss. |
Beriberi |
| Vitamin C | Vitamin C deficiency can cause bleeding gums. | Scurvy |
| Vitamin D | Vitamin D deficiency leads to a disease in children where, the bones become soft and weak. |
Rickets |
| Calcium | Calcium deficiency leads to bone and tooth decay | |
| Iodine | Lack of iodine in the diet causes the swelling of the thyroid gland |
Goitre |
| Iron | Deficiency of iron is marked by low energy levels and paleness. They are caused due to the lack of less oxygen in the body. The lack of iron decreases haemoglobin in blood and hence decreases the oxygen carrying capacity of blood. |
Anaemia |
11. Certain signs and symptoms of disease are given below. Identify the type of deficiency disease in each case.
a. Stunted growth, weakness, mental retardation - kwashiorkor
b. Bleeding gums, wounds take time to heal - Scurvy
c. Brittle bones, bow – shaped legs in children – Rickets
d. Pale skin, laziness, weakness - Anaemia
