Both plants and animals are interdependent on each other for their survival. Plants cannot survive for long without animals, as they need CO₂ for photosynthesis, which is exhaled by animals. Similarly, in absence of plants, there will be no oxygen for animals to breathe in Hence we can say that both need each other and the balance of oxygen and carbon dioxide in the atmosphere is maintained by their presence.

Hardness is the property of materials that can be found out by pressing the materials. A material may be soft or hard.
Soft materials : The materials which can be compressed easily are known as soft materials.e.g.,-cotton, sponge, etc.
Hard materials: The materials that are difficult to compress are known as hard materials. e.g., - iron, wood, etc.

(1) It helps in gaining systematic knowledge of things.
(2) It gives a general idea about all the members of a group and the differences between the members of different groups.
(3) It is convenient to work with all members of a group after knowing their properties

(i) To reduce the wastes in that area.
(ii) Smoke and dust particles.
(iii) Composting is a method used to reduce wastes like leaves, as it is eco-friendly process
(iv) Recycling of waste papers.

In Beri-Beri, nervous system is affected which causes weak muscles and little energy to work. It is caused due to deficiency of vitamin B, found in seafood, milk, meat, peas, cereals and green vegetables.

Fish breathes through gills which take up dissolved oxygen present in water. When it is kept out of the water, it is unable to respire due to difference in pressure of gas. Hence, it dies.

If an organism fails to adapt to its environment, the possible consequences could be:
(i) The organism will die.
(ii) The species will become extinct

No, it will not turn blue-black because the stored starch would have been used up by the plant when kept in a dark room for a few days. Starch would not be synthesized due to absence of sunlight.

Sprouted seeds are the seeds with seedlings. Seeds are first soaked in water for one day. The water is drained and the seeds are kept wrapped in a wet cloth and left for one more day. After sprouting, they can be eaten raw. They can also be boiled. They can also be made into a tasty snack by adding spices to them.

(i) Length of the scale, that you are using to measure, must be greater than the length of the object.
(ii) The eye must be placed just above the point, that you are reading, otherwise there will be an error due to parallax.
(iii) If the zero mark of the scale is damaged or the edge of the scale is not smooth, then start the measurement from another mark

There are following properties by which we can prove that these materials are different:

Cotton:
Source: Fruits of cotton plants
Uses: It is used in making clothes, bed sheets, curtains, towels and quilts.
Jute:
Source: Bast or skin of jute plant stem
Uses: It is used in making curtains, chair coverings, carpets and rugs.
Silk:
Source: Cocoons of silkworms
Uses: It is used in making clothes, velvet etc.
Wool:
Source: Fleeces of sheep or other hairy animals such as yak, camel, goat etc.
Uses: It is used in making clothes, sweaters, carpets etc.

Cockroaches walk and climb as well as fly in the air. They have three pairs of legs which help them in walking. The body is covered with a hard outer skeleton. This outer skeleton is made of different units joined together which permit movement. There are two pairs of wings attached to the thorax. The cockroaches have distinct muscles-those near the legs move the legs for walking. The thoracic muscles move the wings when the cockroach flies.

The presence of proteins in food items is tested by using following steps :
Step I: Take a small quantity of food item in a test-tube.
Step II: Add 10 drops of water into it and shake the test-tube
Step III: With the help of dropper, add two drops of copper sulphate solution.
Step IV: Add 10 drops of caustic soda solution to the test-tube and shake the test tube and leave it for a few minutes.
The appearance of violet colour indicates the presence of proteins in the food item.

There are following adaptive features of a lion that help it in hunting:
(i) Light brown colour of skin, which helps it to hide in dry grasslands when it hunts for prey.
(ii) Eyes in front of face, which help it to know the correct location of its prey.
(iii) Powerful paws and long claws, which help it . to catch and kill the prey

A leaf is a thin expanded outgrowth arising from the node of a stem. The part of a leaf by which it is attached to the stem is called a petiole. The broad green part of the leaf is called lamina. The lines on the leaf are called veins. The thick vein in the middle of the leaf is called the midrib. The design made by the veins on the leaf is called venation. H the design is net-like, it is termed as reticulate venation whereas if the veins are parallel to each other, it is termed as parallel venation.

The method to separate each component from the mixture is given below:
(i) Hand picking: It is used to separate iron nails from the mixture.
(ii) Decantation: The mixture is allowed to stand for some time. The clear liquid is poured to another container to separate oil from the mixture.
(iii) Evaporation: The remaining liquid is allowed to evaporate till residue is obtained. This residue is salt.

Draw a curved line CD. Take a thread and make a knot at one of its ends. Keep the knot made in the thread on point C of the line. Place a small portion of the thread along the line, keeping it tight using your fingers and thumb. Keep on stretching the thread on the curved line till you take the thread to the point D of the line. Make a mark on the thread where it touches the other end of the line at point D. Now, stretch the thread along a metre scale and the length between the knot in the beginning and mark on the thread is measured through scale. This measured length on scale will give you the length of the curved line CD.

The materials through which objects are partially visible, are known as translucent materials, e.g., butter paper

Cotton is also used in hospitals as absorbent and for preparing bandages.

Muscles always work in pairs. When one of them contracts, the bone is pulled in that direction. The other muscle of the pair relaxes. To move the bone in the opposite direction, the relaxed muscle contracts to pull the bone to its original position. A muscle can only pull. It cannot push.

Physical change:
(a) Drawing a line from light pencil on a paper.
(b) Arranging building blocks.
(c)Ironing clothes.
(d) Taking bath.
Chemical change :
(a) Preparation of ghee.
(b) Preparation of Dosa.
(c) Rusting of iron
(d) Making coffee

(a) The components of food that provide nutrients are given below:
(i) Carbohydrates
(ii) Fats
(iii) Proteins
(iv) Vitamins
(v) Minerals
(b) The two components of food that do not provide nutrients are:
(i)Water
(ii)Roughage.

Life is not possible without plants. We should save plants. Plants give us oxygen which is essential for life. They provide us raw materials for various purposes. They are the house of many birds and animals.

Biotic components include living things such as plants and animals. Abiotic components include-living things such as air, water, soil, rocks, heat and light, etc.

Herbs are comparatively smaller plants, have green stem whereas shrubs have distinct and harder stem with branching from near the ground.

This can be done by dissolving both of them in water. Sugar gets dissolved in water while or chalk is insoluble in water.

Bees collect nectar from flowers and convert it into honey. The honey is stored in the beehives so as to be used throughout the year.