The Fundamental Unit of Life

Question (1) Make a comparison and write down ways in which plant cells are different from animal cells.

Answer:

Comparison between Plant Cells and Animal Cells

(a) Cell Wall: The cell wall is present in plant cells while the cell wall is absent in animal cells.

(b) Plastids: Plastids are present in plant cells while plastids are absent in animal cells.

(c) Photosynthesis: Photosynthesis takes place in the cell of green plant cells because of the presence of chlorophylls which are a type of plastids in them. While photosynthesis does not take place in animal cells as chlorophylls are absent.

(d) Vacuoles: Vacuoles are larger in plant cells, sometimes vacuoles take up to 50% of the size of a plant cell. While vacuoles are smaller in the animal cells and in some of the animal cells vacuoles are absent.

Question (2) How is a prokaryotic cell different from a eukaryotic cell?

Answer

Question (3) What would happen if the plasma membrane ruptures or breaks down?

Answer

The Plasma membrane is a type of shield that keeps a cell isolated from its external environment and in this way it keeps a cell and its content safe.

If the plasma membrane ruptures or breaks down, then cytoplasm and other contents of a cell would be exposed to the external environment, and because of the mixing of the chemicals and other materials present in the external environment, the cell will die. If this were to happen to all of the cells of an organism, the organism will die finally, because the cell is the basic fundamental and functional unit of a living organism.

Question (4) What would happen to the life of a cell if there was no Golgi apparatus?

Answer

The Golgi apparatus modifies and packs proteins and fats into vesicles before transporting them to the target destination. Along with this, the Golgi apparatus makes complex sugars from simple sugars in some cases, and it also involves in the formation of lysosomes.

The modification and packaging of proteins and fats and the formation of lysosomes are very much important for life.

In the case of the absence of the Golgi apparatus, the proteins and fats would not be modified and not be transported to the required destination, and even the formation of lysosomes would also be affected. In such a case the life of a cell would be affected adversely and finally, the cell will die.

If this were to happen, the entire organism would have died.

Question (5) Which organelle is known as the powerhouse of the cell? Why?

Answer

Mitochondria are known as the powerhouse of the cell because nutrition taken is converted into energy by the process of respiration in cells in the mitochondria which is necessary for the different life processes. Without energy, a living organism can do nothing and will not even survive also.

Question (6) Where do the lipids and proteins constituting the cell membrane get synthesised?

Answer

Lipids and proteins are synthesised by the Rough Endoplasmic Reticulum (RER). The Endoplasmic Reticulum (ER) is the cell membrane organelles found at the circumference of the nucleus of the cell.

Question (7) How does an Amoeba obtain its food?

Answer

Amoeba is a unicellular organism. Amoeba has finger-like projections called pseudopodia. While taking food, the food content is first surrounded by the modification of the finger-like projection present in amoeba, and a food vacuole is made. After that food content is digested by the secretion of digestive enzymes.

Question (8) What is osmosis?

Answer

The passes of liquid molecules from the region of low concentration to the region of high concentration through the semi-permeable membrane is called Osmosis.

The water and other liquids pass in and out to the cell because of osmosis.

Question (9) Carry out the following osmosis experiment:

Take four peeled potato halves and scoos each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,

(a) Keep cup A empty

(b) Put one teaspoon sugar in cup B

(c) Put one teaspoon salt in cup C

(d) Put one teaspoon of sugar in the boiled potato cup D.

Keep these for two hours. Then observe the four potato cups and answer the following:

(i) Explain why water gathers in the hollowed portion of B and C.

Answer

In the hollowed portion of B and C, there is a high concentration of salt, i.e. sugar and salt which has been kept before in a trough containing water. Because of having a high concentration in the middle, water molecules pass through the cells of potatoes by the process of osmosis and get gathered in the middle.

This happens because water molecules pass in and out of the cells through the process of osmosis.

(ii) Why is potato A necessary for this experiment?

Answer

Potato A is necessary to observe the comparison in this experiment.

(iii) Explain why water does not gather in the hollowed-out portions of A and D.

Answer

In A nothing was put in the hollowed portion of the potato, that's why osmosis does not take place and water molecules do not pass or reach the hollow space.

In B, the boiled potato was kept in the trough. After boiling the cells of the potato died. Since osmosis does not take place through the dead cells, that's why water does not gather in the hollow space.

Question (10) Which type of cell division is required for the growth and repair of the body and which type is involved in the formation of gametes?

Answer

There are two types of cell division that take place, one is mitosis and the other is meiosis.

Mitosis takes place to repair the damaged cell and for the growth of the tissues. While meiosis takes place in the reproductive organs, such as in the testes and uterus, and forms gametes to give birth to offspring.

Thus, mitosis is required for the growth and repair of the body, and meiosis is involved in the formation of gametes.