CBSE Revision Notes

Transportation in Animals and Plants Class 7 Science Notes – Chapter 11

The blood circulating in the body also distributes oxygen and food to different part/ cells of the body. Also, the waste products from various parts of the body are carried to the process of excretion. The human circulatory system comprises of blood vessels (arteries and veins) and heart (pumping organ).

• Arteries – They transport blood from the heart to all the parts of the body
• Veins – The blood from all the part of the body is got back to the heart by veins. Please refer Transportation in Animals and Plants Class 7 Notes for more revision notes.

Respiration in Organisms Class 7 Science Notes – Chapter 10

All living organisms breathe to survive. Respiration is necessary for survival. When we inhale oxygen, it breaks down glucose into water and carbon dioxide. This occurs in the cells of organisms. Therefore Energy is released from the food in the process. The breakdown occurs in two forms viz aerobic respiration or anaerobic respiration.

• Anaerobic respiration – Breakdown occurs in the absence of oxygen. Example, If the supply to the muscles is not sufficient during heavy exercise, the breakdown of food occurs through this type of respiration.
• Aerobic respiration – Breakdown occurs in the presence of oxygen. Please refer Respiration in Organisms Class 7 Notes for more revision notes.

Soil Class 7 Science Notes – Chapter 9

Soil plays an important role in the existence of life on earth. Soil profile can be defined as a section through various layers of soil. These various layers are known as horizons. The percolation rate of water differs from soil to soil. Different crops are cultivated in different types of soil. The different types of soils are –

• Clayey Soil – The percolation rate of water is least in clayey soil. This soil is used to make statues and pots. Crops that can be grown in such type of soil are gram, paddy, etc.
• Sandy Soil – They are free draining, with a fine as well as hard particles and gritty feel. It does not bind very well. The nutrient value is low. Also, the percolation rate of water is highest in sandy soil. Example, cotton can be grown in sandy loam soil.
• Loamy Soil – It is a mixture of clay, sand, and silt. Silt is found in river beds. The size of these particles is between those of clay and sand. The percolation rate of water is moderate. Crops that can be grown in such type of soil are wheat, paddy, etc. Please refer Soil Class 7 Notes for more revision notes.

Winds, Storms and Cyclones Class 7 Science Notes – Chapter 8

Air is defined as an invisible substance which surrounds the earth in the gaseous form. It is mainly a mixture of nitrogen and oxygen. Wind is defined as the moving air. Air exerts pressure. On heating, air expands and occupies more space. Whereas on cooling it contracts. The land near the equator warms faster during summer and therefore the temperature of the land is high when compared to the ocean water. The air over the land area heats and rises. The warm air is lighter than the cold air and causes the wind to flow from oceans to lands. These are called monsoon winds. These winds carry water and hence it rains. Please refer Winds, Storms and Cyclones Class 7 Notes for more revision notes.

Weather, Climate and Adaptations of Animals to Climate Class 7 Science Notes – Chapter 7

Weather of a place is defined as the daily condition of the atmosphere of a particular place concerning humidity, wind-speed,  temperature, rainfall, etc. It is different every day and week. The temperature is said to be at the maximum during the afternoon and minimum during early mornings. Also, the sunrise and sunset timings change. The sun plays a major role in these changes. The climate of the place is defined as the average weather pattern taken over 25 years of time. Please refer Weather, Climate and Adaptations of Animals to Climate Class 7 Notes for more revision notes.

Physical and Chemical Changes Class 7 Science Notes – Chapter 6

Changes can be classified into two types viz physical change and chemical change.

• Physical change is a change in which the molecular arrangements are rearranged and the chemical composition remains as it is. It is usually a reversible process. During a physical change, there is no formation of the new product. Physical properties such as size, color, shape, of the substances changes. Example, freezing of water.
• A chemical change is a change in which the chemical composition of a substance is changed to transform into a new substance. It is usually an irreversible process. Whenever a chemical change occurs it forms a new product. Example, the setting of curd. Please refer Physical and Chemical Changes Class 7 Notes for more revision notes.

Acids, Bases and Salts Class 7 Science Notes – Chapter 5

Substances that taste sour in water solutions are called acids. For example, mineral acids, phosphoric acids, etc. Some properties of acids are as follows –

• They change the color of a few indicators. The blue litmus paper turns red
• They liberate hydrogen on reacting with some metals such as iron
• They form salts on reacting with bases
• Acid catalysis – they encourage definite chemical reactions. Please refer Acids, Bases and Salts Class 7 Notes for more revision notes.

Heat Class 7 Science Notes – Chapter 4

Have you ever experienced feeling cold inside the house and warm in sun during winter? Also, feeling hot inside as well as outside the house in the summer season? To protect ourselves from the chilling cold we wear clothes made of wool. These woolen clothes are obtained from wool yielding animals such as sheep, goat, yack, etc. Wearing light colored clothes during summer will give us a feeling of coolness. To know if the object is hot or cold, and the degree of its hotness, we will be studying this chapter. The measure of the intensity of heat present in a substance is called temperature. It is measured with the use of a device called thermometer. Please refer Heat Class 7 Notes for more revision notes.

Fibre to Fabric Class 7 Science Notes – Chapter 3

Some fibres are obtained from plants and some from animals. Fibres obtained from animals are silk and wool. Let us understand what type of fibres are got from which animals along with the process of extraction.

• Silk – These fibres are got from cocoons of a silk moth. How? It is obtained from a process called sericulture. When a female silkworm lays eggs and then, it hatches to form silkworms or caterpillars.
• Wool is obtained from wool yielding animals such as yak, goat, sheep, etc. The steps involved are sheering, scouring, sorting and rolling. Please refer Fibre to Fabric Class 7 Notes for more revision notes.

Nutrition in Animals Class 7 Science Notes – Chapter 2

Animal nutrition can be defined as the nutrient requirement, the mode of food intake and how it is utilized in the body. The important digestive glands that secrete digestive juice viz liver, pancreas and salivary glands. The digestive system in human consists of secretory glands and alimentary canal. The alimentary canal consists of a buccal cavity, oesophagus, stomach, small intestine, large intestine, and anus. The intake of food is carried out by the mouth. This process is called ingestion. We chew the food to make it into small pieces. The food mixes with saliva and we swallow it. The swallowed food is pushed downward to pass through food pipe and chest. Please refer Nutrition in Animals Class 7 Notes for more revision notes.