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1. Cellular Organization of Plants and Animals eLearn.Punjab
4. Nucleus
The most important part of a cell is its nucleus. It controls all the activities of the cell. Therefore, a
nucleus is the control centre of the cell. A thin membrane, called nuclear
membrane, surrounds the nucleus. Many thread like structures called
chromosomes are present in the nucleus. Chromosomes pass on the
characteristics of the cell to new cells. The number of chromosomes is
fixed in every cell. A human cell has 46 chromosomes.
Point to think! Fig. 1.4: Nucleus of a cell
What would happen to a cell if we removed its nucleus?
Activity 1.2
You will need
• A light microscope
• Prepared slide of human cheek cells
• Prepared slide of onion cells
Procedure
1. Observe the slide of onion cells under the microscope.
Draw a diagram of one onion cell. Identify and label its
parts.
2. Observe the slide of human cheek cells under the
microscope. Draw the diagram of one cell and label its
parts.
3. Compare the two cells. What difference do you find?
Differences Between Animal And Plant Cell
Cell membrane, nucleus, mitochondria and endoplasmic reticulum, etc. are present in both plant
and animal cells. But there are some differences too.
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