Chapter 1
The major nutrients in our food are named carbohydrates, proteins, fats, vitamins and minerals. In addition, food contains dietary fibres and water which are also needed by our body.
There are many types of carbohydrates. The main carbohydrates found in our food are in the form of starch and sugar.
Carbohydrates mainly provide energy to our body. Fats also give us energy. In fact, fats give much more energy as compared to the same amount of carbohydrates.
Proteins are needed for the growth and repair of our body.
Vitamins help in protecting our body against diseases. Vitamins also help in keeping our eyes, bones, teeth and gums healthy.
Vitamins are of different kinds known by different names. Some of these are Vitamin A, Vitamin C, Vitamin D, Vitamin E and K. There is also a group of vitamins called Vitamin B-complex. Our body needs all types of vitamins in small quantities. Vitamin A keeps our skin and eyes healthy. Vitamin C helps body to fight against many diseases. Vitamin D helps our body to use calcium for bones and teeth
Minerals are needed by our body in small amounts. Each one is essential for proper growth of body and to maintain good health.
Besides these nutrients, our body needs dietary fibres and water. Dietary fibres are also known as roughage. Roughage is mainly provided by plant products in our foods. Whole grains and pulses, potatoes, fresh fruits and vegetables are main sources of roughage. Roughage does not provide any nutrient to our body, but is an essential component of our food and adds to its bulk. This helps our body get rid of undigested food.
Water helps our body to absorb nutrients from food. It also helps in throwing out some wastes from body as urine and sweat.
We all know that cooking improves the taste of food and makes it easier to digest. At the same time, cooking also results in the loss of certain nutrients. Many useful proteins and considerable amounts of minerals are lost if excess water is used during cooking and is then thrown away.
A person may be getting enough food to eat, but sometimes the food may not contain a particular nutrient. If this continues over a long period of time, the person may suffer from its deficiency. Deficiency of one or more nutrients can cause diseases or disorders in our body. Diseases that occur due to lack of nutrients over a long period are called deficiency diseases.
If a person does not get enough proteins in his/her food for a long time, he/she is likely to have stunted growth, swelling of face, discolouration of hair, skin diseases and diarrhoea.
All deficiency diseases can be prevented by taking a balanced diet.
Chapter 3
draped=
Some examples of synthetic fibres are polyester, nylon and acrylic.
Jute fibre is obtained from the stem of the jute plant (Fig 3.8). It is cultivated during the rainy season. In India, jute is mainly grown in West Bengal, Bihar and Assam. The jute plant is normally harvested when it is at flowering stage. The stems of the harvested plants are immersed in water for a few days. The stems rot and fibres are separated by hand.
The process of making yarn from fibres is called spinning. In this process, fibres from a mass of cotton wool are drawn out and twisted. This brings the fibres together to form a yarn.
The early Indians wore fabrics made out of cotton that grew in the regions near the river Ganga
In ancient Egypt, cotton as well as flax were cultivated near the river Nile and were used for making fabrics.
Chapter 5
When the heavier component in a mixture settles after water is added to it, the process is called sedimentation. When the water (along with the dust) is removed, the process is called decantation
The process of conversion of water into its vapour is called evaporation. The process of evaporation takes place continuously wherever water is present.
The process of conversion of water vapour into its liquid form is called condensation
Chapter 7
Plants with green and tender stems are called herbs. They are usually short and may not have many branches [Fig.7.3 (a)].
Some plants have the stem branching out near the base. The stem is hard but not very thick. Such plants are called shrubs [Fig .7.3(b)].
Some plants are very tall and have hard and thick brown stem. The stems have branches in the upper part, much above the ground. Such plants are called trees
Plants with weak stems that cannot stand upright and spread on the ground are called creepers, while those that take support on neighbouring structures and climb up are called climbers
The water and minerals go to leaves and other plant parts attached to the stem, through narrow tubes inside the stem.
The part of a leaf by which it is attached to the stem is called petiole. The broad, green part of the leaf is called lamina
This vein is called the midrib. The design made by veins in a leaf is called the leaf venation. If this design is net-like on both sides of midrib, the venation is reticulate [Fig. 7.10 (a)]. In the leaves of grass you might have seen that the veins are parallel to one another. This is parallel venation [(Fig. 7.10 (b)].
Water comes out of leaves in the form of vapour by a process called transpiration. Plants release a lot of water into the air through this process.
However, leaves prepared their food in the presence of sunlight and a green coloured substance present in them. For this, they use water and carbon dioxide from air. This process is called photosynthesis. Oxygen is given out in this process. The food prepared by leaves ultimately gets stored in different parts of plant as starch.
the main root is called tap root and the smaller roots are called lateral roots. Plants with roots as shown in Fig. 7.17 (b) do not have any main root. All roots seem similar and these are called fibrous roots.
The leaves prepare food. This food travels through the stem and is stored in different parts of a plant. We eat some of these as roots— like carrot, radish, sweet potato, turnip and tapioca. We also eat many other parts of a plant where the food is stored.
Do you agree that stem is like a two way street?
Look at the prominent parts of the open flower. These are the petals of the flower. Different flowers have petals of different colours.
small leaf-like structures? They are called sepals. Take a flower and observe its petals and sepals.
Roots are mainly of two types: tap root and fibrous roots.
Plants having leaves with reticulate venation have tap roots while plants having leaves with parallel venation have fibrous roots.
Chapter 8
Walk, run, fly, jump, creep, crawl, slither and swim – these are only a few of the ways in which animals move from one place to another.
Hinge joints
Open and close a door a few times. Observe the hinges of the door carefully. They allow the door to move back and forth.
some additional parts of the skeleton that are not as hard as the bones and which can be bent. These are called cartilage.
A muscle can only pull. It cannot push. Thus, two muscles have to work together to move a bone
The head and tail of the fish are smaller than the middle portion of the body – the body tapers at both ends. This body shape is called streamlined.
Chapter 9
they are normally found. The presence of specific features or certain habits, which enable a plant or an animal to live in its surroundings, is called adaptation.
The surroundings where organisms live is called a habitat.
The plants and animals that live on land are said to live in terrestrial habitats.
if we live in the plains and suddenly go to high mountain regions, we may experience difficulty in breathing and doing physical exercise for some days. We need to breathe faster when we are on high mountains. After some days, our body adjusts to the changed conditions on the high mountain. Such small changes that take place in the body of a single organism over short periods, to overcome small problems due to changes in the surroundings, are called acclimatisation. These changes are different from the adaptations that take place over thousands of years.
The living things such as plants and animals, in a habitat, are its biotic components. Various non-living things such as rocks, soil, air and water in the habitat constitute its abiotic components. Sunlight and heat also form abiotic components of the habitat
Desert plants lose very little water through transpiration. The leaves in desert plants are either absent, very small, or they are present in the shape of spines. This helps in reducing loss of water from the leaves through transpiration. Photosynthesis in these plants is usually carried out by the stems.
The stem is also covered with a thick waxy layer, which helps to retain water. Most desert plants have roots that go very deep into the soil for absorbing water.
Mountain regions
These habitats are normally very cold and windy. In some areas, snowfall may take place in winters.
When we breathe out, the air moves from inside our body to outside. Breathing is part of a process called respiration. In respiration, some of the oxygen of the air we breathe in, is used by the living body. We breathe out the carbon dioxide produced in this process.
In some plants like mimosa, commonly known as ‘touch-me-not’, leaves close or fold when someone touches them. These are some examples of responses of plants towards changes in their surroundings.
Living things produce more of their own kind through reproduction.
- Motion in a straight line is called rectilinear motion.
Chapter 11
Objects like the sun that give out or emit light of their own are called luminous objects.
Magnet attracts materials like iron, nickel, cobalt. These are called magnetic materials.
Boojho has been reading about transpiration. He asked himself - how much water is lost through transpiration by wheat plants that give us one kilogram of wheat? He found out that this is nearly 500 litres
Water vapour gets added to air by evaporation and transpiration
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