Hi Student, Here is the Biology 5th lesson – Cell Structure and Functions in the 9th Class. We have provided you with Detailed Notes, Questions and Answers from the Textbook. You can find the Important Questions for Examinations.
Cell – Its Structure and Functions
Difference between Plant Cell and Animal Cell?
| Plant cell | Animal cell |
| 1. Plant cells are,usually large in size | 1. Animal cells are generally small in size |
| 2. Cell wall is present. | 2. Cell wall is absent. |
| 3 Plastids (chromoplasts and chloroplasts) are present. | 3. Plastids are absent except the protozoan Euglena. |
| 4. Centrioles are absent. | 4. Centrioles are present. |
| 5. Vacuoles are larger in size. | 5. Vacuoles are smaller in size. |
Difference between Prokaryotic cell and Eukaryotic Cell
| Prokaryotic cell | Eukaryotic Cell |
| 1. Nuclear membrane around the nucleus is absent. | 1. Nuclear membrane around the nucleus is present. |
| 2. Membrane-bound cell organelles are absent. | 2. Membrane-bound cell organelles are absent. |
| 3. Most prokaryotic cells are unicellular. | 3. Most eukaryotic cells are multicellular. |
| 4. It contains a single chromosome. | 4. It contains more than one chromosome |
| 5. Nucleolus is absent. | 5. Nucleolus is present. |
| 6. Cell division occurs by mitosis. | 6. Cell division occurs by both mitosis and meiosis. |
| 7. Size of the cell is generally small. | 7. Size of the cell is generally large. |
| 8. These are found in bacteria and blue green algae. | 8. These are present in fungi, plants and animal cells. |
What would happen to the cell if the nucleus is removed? Give two reasons to support your answer.
1. Nucleus controls all the functions of the cell. It is the most important organell. It carries chromosomes on which hereditary materials are coded.
2. The chromosomes bears DNA, which is the genetic material. It gives information for the manufacture of proteins in the cell.
3. If the nucleus is removed, it results in the death of the cytoplasm and cell dies.
4. No protein can be produced inside the cell, if nucleus is removed as it manufactures proteins in the cell.
Lysosomes are known as suicidal bags of the cell. Why?
1. Lysosomes contain destructive enzymes.
2. The materials that need to be destroyed are transported to the lysosomes.
3. At times the lysosomes burst and the enzymes are released to digest cell.
4. Hence lysosomes are also known as the suicidal bags of the cell.
Why do plant cell posses large-sized vacuole?
1. Plant vacuoles are a water reservoir, an osmoregulator, a waste reservoir, they control turgor and are part of cell’s structural form, especially in leaves and petals that wilt.
2. The central vacuole presses out against the cell wall keeping the cell’s shape.
3. Plants can use the internal pressure in cell elongation for controlled growth.
4. The plant’s vacuole is critical to more function than the animal’s vacuole.
5. Hence plant cells possess large sized vacuole.
“Cell is the basic unit of life”, explain the statement.
1. The cell theory states that cells are fundamental units of life, that all organisms are
composed of cells and that all cells come from pre-existing cell.
2. The cellular level of an organism is where the metabolic processess occur that keep
the organism alive.
3. That is why the cell is the basic unit of life.
Who and when was “The cell theory” proposed? When did they prepare it? What are its salient features of it?
M.J. Schleiden and Theodar Schwann was proposed “The cell theory” in 1838-39.
Statements of the modern form of cell theory:
1. All the living organisms are madeup of cells and their products.
2. All the cells are formed from pre-existing cells.
3. All the cells are made up of similar chemicals and show similar metabolic activities.
4. Functioning of an organism depends on the functions carried out and the interaction
of different cells present in the organism.
What happens if the plasma membrane ruptures or breaks?
1. If the plasma membrane of a cell is ruptured, then the cell will die.
2. The plasma membrane regulates the movement of substances in and out of the cell
by diffusion or osmosis.
3. Thus if plasma membrane is ruptured then the cell might leak out its contents.
What would happen to the life of cell if there was no golgi complex?
1. If there was no golgi apparatus in the cell, the most activities performed by golgi apparatus will not takes place.
2. Package of various substances would not takes place if golgi apparatus is absent.
3. From golgi complex proteins and other substances are either sent towards the cell membrane or to another organelle, lysosome.
4. Proteins and other substances produced in the ribosomes may not be transferred to the lysosome.
5. If that occurs, repairs of cell membranes would not take place, hence ultimately the cell dies.
6. If the toxic substances are not sent to lysosomes and they are not destroyed they get
stored in the cell and the cell dies.
When you are observing the nucleus of check cell in the laboratory, what precautions do you
A. Precautions :
1. Use a brush to transfer peel from one apparatus to another.
2. Staining of the peel should neither be too dark nor too light.
3. Extra glycerine stain should be removed using blotting paper.
4. There should be no air bubbles under the coverslip.
