vivek mehto(roll no 43)

fundamental unit of life  

Q. How do substances like CO2 and water move in and out of the cell? Discuss.

Answer: Substances move in and out of the cell because of diffusion. Diffusion is the random movement of particles in order to attain concentration equilibrium. The movement of water through a semi-permeable membrane is called osmosis. It is important to note that plasma membrane is a semi-permeable membrane. Water always moves from high water concentration to low water concentration.

Q Why is the plasma membrane called a selectively permeable membrane?

Answer: Plasma membrane allows passage to some selected substances. Hence it is called a selectively permeable or semi-permeable membrane.

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Q.Can you name the two organelles we have studied that contain their own genetic material?

Answer: Mitochondria and Chloroplast contain their own genetic material.

Q. Make a comparison and write down ways in which plant cells are different from animal cells.

Answer:

Plant cell	Animal cell
Cell wall present	Cell wall absent
Plastids present	Plastids absent
Vacuole is usually very large and single	Vacuoles are much smaller an may be absent

 Cell is a Latin word which means ‘a little room’. The word cell was derived from a Greek word“Cellulae” which means small room. First living cell was discovered by A.V. Leeuwenhoek with the improved microscope in pond water.