Food has nutritive value that human beings and animals eat or plants absorb in order to maintain life and growth.
Uses of Food in our Body:
(a) Food Variety
We eat different varieties of food like rice, bread, vegetables, eggs, butter, sweets, cheese etc.
(b) Ingredients of Food
Materials needed to prepare any food item are called ingredients. Two or more than two ingredients are needed to prepare a dish.
(i) To prepare boiled rice, rice and water are used, so rice and water are the ingredients for boiled rice.
(ii) Atta (flour) and water are the two ingredients required to make a chapatti.
(iii) Vegetables, salt, water and spices are used in cooking vegetable curry, so vegetables, salt, water and spices are ingredients of vegetable curry.
SOURCE OF FOOD MATERIALS
Plants and animals are the main sources of food.
(1) Food from Plant Source
Rice, wheat, vegetables, fruits, etc. are obtained from plant sources. We get these ingredients from certain parts of different plants.
Some examples of edible plant parts are shown below:
Fig: Edible Plant
(a) Root: We eat root of radish, carrot, turnip, sweet potato, beet, etc.
(b) Stem: In certain plants the stem grows underground and store the food. Ginger, potato(underground stem), and onion are stems of plants in which food is stored. So, we eat stem of ginger, potato, onion, etc.
(c) Leaf: Spinach, Lettuce, Trigonella, etc. We eat leaves of these plants
(d) Fruits: Orange, grapes, kiwi, apple etc. We eat fruits of these plants.
(e) Oil Seeds: Seeds of many plants are used to extract oil.
Example: Mustard oil is extracted from seeds of mustard plant. Similarly sunflower oil, coconut oil, groundnut oil, soyabean oil, etc. are obtained from seeds of respective plants.
(f) Sugar: We get sugar from sugarcane and beetroot.
(g) Tea & Coffee: These are common beverages. Tea is obtained from leaves, while coffee is obtained from seeds.
(h) Spices: They have no nutritive value and are used for adding flavour to food. The major spices are pepper, cardamom, ginger, turmeric. Other spices are cloves, saffron, fennel, cumin, coriander, asafoetida, and fenugreek.
(2) Foods from Animal Source
We get milk, eggs, meat, honey, fish, etc. from animals. Buffaloes and cow give milk. Hen and duck give eggs. We get meat from goat, chicken, hen etc. Eggs and meat are rich in protein. Fish is the major part of food for people living in the coastal regions.
(a) Honey: Honeybee produces honey from nectar of flowers. It is rich in sugar, minerals and enzymes.
(b) Autotrophs: Plants produce their own food by the process of photosynthesis and are called as autotrophs.
(Auto: self; troph: nourishment or food)
Fig: Green plants: Autotrophs
(c) Heterotrophs: Animals; including humans; do not make their own food. They eat food prepared by plants or plant products. Heterotrophs are divided into following types on the basis of their food habit:
(i) Herbivores: Animals which eat only grass and plant products are called herbivores. Cow, Elephant, Camel, Deer, Goat, etc. are examples of herbivores.
Fig: Cow: Herbivore
(ii) Carnivores: Animals which eat flesh of other animals are called carnivores. Lion, jackal, frog, tiger, lizard, snake, etc. are examples of carnivores.
Fig: Lion: Carnivore
(iii) Omnivores: Animals which eat both plants and meat are called omnivores. Crow, monkey, bear, human, sparrow, etc. are examples of omnivores.
Fig: Bear: Omnivore
(iv) Scavengers: Some animals which eat flesh of dead animals are called scavengers.
Fig: Wolf: Scavenger