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The Fundamental Unit of Life
Intext Exercise 1
Question 1:
Who discovered cells and how?
Solution 1:
Cells were discovered in 1665 by an English Botanist, Robert Hooke. He used a primitive microscope to observe cells in a cork slice.
Question 2:
Why is the cell called the structural and functional unit of life?
Solution 2:
Cells constitute various components of plants and animals. A cell is the smallest unit of life and is capable of all living functions. Cells are the building blocks of life. This is the reason why cells are referred to as the basic structural and functional units of life. All cells vary in their shape, size, and activity they perform. In fact, the shape and size of the cell is related to the specific functions they perform.
Intext Exercise 2
Question 1:
How do substances like CO2 and water move in and out of the cell? Discuss.
Solution 1:
The cell membrane is selectively permeable and regulates the movement of substances in and out of the cell.
Movement of CO2:
CO2 is produced during cellular respiration. Therefore, it is present in high concentrations inside the cell. This CO2 must be excreted out of the cell. In the cell's external environment, the concentration of CO2 is low as compared to that inside the cell. Therefore, according to the principle of diffusion, CO2 moves from a region of higher concentration (inside the cell) towards a region of lower concentration (outside the cell). Similarly, O2 enters the cell by the process of diffusion when the concentration of O2 inside the cell is low as compared to its surroundings.
Movement of water:
Water moves from a region of high concentration to a region of low concentration through the plasma membrane. The plasma membrane acts as a semi-permeable membrane, and this movement of water is known as osmosis. However, the movement of water across the plasma membrane of the cell is affected by the amount of substance dissolved in water.
