Class 9 Science : Chapter 5 The Fundamental Unit of Life ( Extra question Answer )

 Chapter 5 The Fundamental Unit of Life ( Extra question Answer )

Question 1: What are plastids? Name the different types of plastids found in a plant cell.

Answer: Plastids are organelles found only in plants. They are:

(a) Chloroplast-Containing chlorophyll.
(b) Chromoplast-Containing carotenoids and xanthophyll (coloured plastids).
(c) Leucoplast-White or colourless plastids.

Question 2: Do you agree that ‘A cell is a building unit of on organism’. If yes, explain why?

Answer: Yes, cells are called as building unit of an organism.Cells are basic functional unit of life and living organisms. Cells gather together to form tissues, tissues form organs, organs form organ system, and finally organ system lead to the formation of living organisms.Thus, in all such organisational complexity, cell remains the basic building unit of the organism.

Question 3: Why does the skin of your finger shrink when you wash clothes for a long time?

Answer: Soap solution is a hypertonic solution i.e., it is more concentrated than the cells of our skin. As we know when a cell is immersed in a hypertonic solution, water leaves the cell by the process of exosmosis resulting in shrinkage of the cell. In the same way, while washing clothes for a long time, exosmosis occurs in the skin cells resulting in the shrinkage of skin cells of our fingers.

Question 4: Why is endcytosis found in animals only?

Answer: Endocytosis is found only in animals because the cell wall is absent in animals. Due to this, the movement of substances inside the cell is easier in animals than in plants.

Question 5: A person takes concentrated solution of salt, after sometime, he starts vomiting. What is the phenomenon responsible for such situation? Explain.

Answer: Concentrated salt solution is a hypertonic solution which causes dehydration in the alimentary canal due to exosmosis. This causes stretching and hence vomiting.

Question 6: Name any cell organelle which is non-membranous.

Answer: The ribosome is the only non-membranous cell organelle.

Question 7: We eat food composed of all the nutrients like carbohydrates, proteins, fats, vitamins, minerals, and water. After digestion, these are absorbed in the form of glucose, amino acids, fatty acids, glycerol, etc. What mechanisms are involved in the absorption of digested food and water?

Answer: Absorption and digestion involve diffusion and osmosis respectively.

Question 8: If you are provided with some vegetables to cook. You generally add salt into the vegetables during cooking process. After adding salt, vegetables release water. What mechanism is responsible for this?

Answer: The addition of salt makes the external environment hypertonic. This means that the concentration of water outside is lowered as compared to the concentration of water inside the cell. This results in the elimination of water from the vegetables due to exosmosis.

Question 9: Bacteria do not have chloroplast, but some bacteria are photoautotrophic in nature and perform photosynthesis. Which part of bacterial cell performs this?

Answer: Bacterial cell do not have chloroplast but yet some photoautotrophic bacteria perform photosynthesis because Small vesicles associated with the plasma membrane are present in bacteria. These vesicles have photosynthetic  pigment which can trap sunlight to carry photosynthesis.

Question 10: Write the name of different plant parts in which chromoplast, chloroplast, and leucoplast are present.

Answer: 1. Chromoplast : Flower (petals) and fruits.

              2. Chloroplast : Green leaves and green stem.

              3. Leucoplast : Root and underground stem.

Question 11: Name the organelles which show the analogy written as under

(a) Transporting channels of the cell
(b) Power house of the cell
(c) Packaging and dispatching unit of the cell
(d) Digestive bag of the cell
(e) Storages sacs of the cell
(f) Kitchen of the cell
(g) Control room of the cell

Answer: (a) Endoplasmic reticulum

(b) Mitochondria

(c) Golgi apparatus / body

(d) Lysosome

(e) Vacuole

(f) Chloroplasts

(g) Nucleus.

Question 12:  What is hypotonic solution?

Answer:  A solution having solute concentration lower than that of the cell sap is called hypotonic solution.

Question 13: What is hypertonic solution?

Answer: A solution having solute concentration higher than that of the cell sap is called hypertonic solution.

Question 14: What is isotonic solution?

Answer: A solution having solute concentration same as that of the cell sap is called isotonic solution.

Question 15: Define plasmolysis.

Answer: It is the shrinkage of cytoplasm away from cell membrane when kept in a hypertonic medium.

Question 16: Differntiate between diffusion and osmosis.

Answer:

DIFFUSION	OSMOSIS
It occurs in any medium.	It occurs in liquid medium only.
Diffusing molecules may be solid, liquid or gaseous solutes.	It involves movement of solvent molecules only.
Semipermeable membrane is not required.	Semipermeable membrane is required.

 

Question 17:  In what form do mitochondria release energy? Write its full form.

Answer: The energy is released by mitochondria in form of ATP. Full form of ATP is adenosine triphosphate.

Question 18: Which cell organelle controls most of the activities of the cell?

Answer: The nucleus controls most of the activities of the cell.

Question 19: Why do plant cells possess large-sized vacuole?

Answer: Plant cells possess large sized vacuole because it performs following functions in plant cells:

(i) Vacuole helps in osmoregulation in a cell.

(ii) It stores toxic metabolic by-products or end products of the plant cell.

(iii) It helps in maintaining turgidity of the cell.

(iv) Plant don't possess the ability to move freely like that of animals. Thus, they possess large vacuoles as a reservoir in unfavorable conditions.

Question 20: Differentiate between rough and smooth endoplasmic reticulum. 

Answer:

Rough Endoplasmic Reticulum (RER)	Smooth Endoplasmic Reticulum (SER)
It possesses ribosomes attached to its membrane.	It does not have ribosomes on its membrane.
Formed of cisternae and a few tubules.	Formed of vesicles and tubules.
It participates in the synthesis of enzymes and proteins.	Synthesises glycogen, lipids and steroids.
May develop from the nucleus.	May develop from the rough endoplasmic reticulum.

Question 21:  What happens when  dry apricots are left for some time in pure water and later transferred to sugar solution?

Answer: When dry apricot is placed in pure water, it gains water and swells due to endosmosis. After that if the swollen apricot is placed in the concentrated sugar solution, it loses water and consequently shrinks again due to exosmosis.

Question 22:  What happens a Red Blood Cell is kept in concentrated saline solution?

Answer: When red blood cell is kept in concentrated saline solution. The cell loses water immediately and shrinks. 

Question 23: What happens when Rhoeo leaves are boiled in water first and then a drop of sugar syrup is put on it?

Answer:  When Rhoeo leaves are boiled, all the cells of leaves become dead. When sugar solution is added on to the boiled Rhoeo leaves, nothing will happen because liquid cannot pass through dead cell.

Question 24: State  important functions of the nucleus of a cell.

Answer:

1. Genetic Information: Nucleus contains genetic information not only for the cell but also for the whole organism.
2. Control Centre: Nucleus functions as control centre for cell metabolism and cell activities.

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