Explain Science ch- 1 class 7
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Answer:
Cells
Cells are tiny units that help make up a living organism. Hence, they are also called building blocks of an organism.
A cell is constituted of three major parts :
A thin outer layer is called the cell membrane.
A spherical structure located at the center of the cell is called a nucleus.
A jelly-like substance that surrounds a nucleus is called the cytoplasm.
Single and Multi-Cellular Organisms
Organisms that are made up of just one cell are called single-celled or Unicellular organisms. E.g. Amoeba
Organisms with more than one cell in their body are called multicellular organisms.
All human beings, plants, and animals are multicellular organisms.
Nutrition
Nutrition is the mode of taking food by an organism and its utilization by the body.
Nutrition is very important as the nutrients from the food consumed enable living organisms to build their bodies and grow.
Nutrition helps to repair damaged parts and organs.
Nutrition also provides energy for carrying out various functions.