"AKC SCIENCE CLASSES"
CLASS 09 TH (CBSE AND MP BOARD)
CHAPTER 05
FUNDAMENTAL UNITS OF LIFE
EXERCISE QUESTIONS AND ANSWERS
Q.01:- Make comparison to write down ways in which plant cells are different from animal cells.
Ans:-
| SL No. | Animal Cell | Plant Cell |
|---|---|---|
| 1 | The cell is enclosed by a thin membrane called the plasma membrane cell wall is absent. | Plasma membrane is covered over by a thick cell wall made up of cellulose. |
| 2 | Plastids are absent. | Chloroplasts are present. |
| 3 | Vacuoles are either absent or of very small size. | Vacuoles are large, central and prominent. |
| 4 | Centrosome present with 2 centrioles. | Centrosome absent, Polar caps present. |
| 5 | Cell division takes place by the formation of a groove. | Cell-division initiates by the formation of a cell plate. |
| 6 | Golgi complex (Golgi body) presents near the nucleus of the cell. | Golgi complex consisting of unconnected units is called the dictyosomes. |
Q.02:- How is prokaryotic cell different from a eukaryotic cell?
| SL No. | Prokaryotic Cell | Eukaryotic Cell |
|---|---|---|
| 1 | A cell wall formed of amino sugars is present. | A cell wall formed of cellulose is present in plant cells. |
| 2 | Membrane bound organelles such as endoplasmic reticulum, Golgi complex, mitochondria, lysosomes, vacuoles are absent. | Membrane bound cell organelles are present in these cells. |
| 3 | Chromosome is single and strand of DNA is present in the cytoplasm. | Chromosomes are more than one and formed of DNA. They are enclosed in the nuclear membrane. |
| 4 | Nucleoid is not enclosed in nuclear membrane. | Nuclear material enclosed in nuclear membrane. |
| 5 | Nucleoli and mitotic apparatus are absent. | Nucleoli and mitotic apparatus are present. |
| 6 | These lack 9+2 axial filament structure. | These possess 9+2 axial filament structure. |
| 7 | Generally small sized : 1-10 μm. | Generally big sized : 5-100 μm. |
| 8 | The cell divides by budding or by fission. Mitosis does not occur. | Cell divides by mitosis / meiosis cell division. |
| 9 | Ribosomes are of 70 s type in these cells. | Ribosomes are of 80 s (Swedberg) type in these cells. |
Q.04:- What would happen to the life of a cell if there was no Golgi apparatus?
Ans:- There would not be any lysosome for intracellular digestion and cleansing, no complexing of molecules, no excretion and no formation of new plasma membrane.
Q.05:- Which organelle is known as power house of the cell? Why?
Ans:- Mitochondrion is known as power house of the cell because it produces most of the molecules of ATP (adenosine triphosphate) which are required for providing energy for synthesis of new chemicals, mechanical and other cellular functions.
Ans:- Proteins are synthesised over ribosomes of RER while lipid are synthesised over SER.
Q.07:- How does Amoeba obtain food?
Ans:- Plasma membrane of Amoeba is flexible. With its help, Amoeba engulfs food particle. The engulfed food particle passes into the body of Amoeba as a phagosome. Phagosome combines with lysosome to produce digestive or food vacuole. Digestion occurs in food vacuole. The digested food passes into surrounding cytoplasm. The undigested matter is thrown out of the cell.
Q.08:- What is osmosis?
Ans:- Osmosis is diffusion of water from the region of its higher concentration (pure water or dilute solution) to the region of its lower concentration (strong solution) through a semipermeable membrane.
Q.09:- Carry out the following osmosis experiment.
Take four peeled potato halves and hollow each one out to make potato cups. One of these potato cups should be made from the boiled potato. Put each potato cup in the trough containing water. Now
(a) Keep cup A empty.
(b) Put one tea spoon sugar in cup B.
(c) Put one tea spoon of salt in cup C.
(d) Put one tea spoon sugar in boiled cup D.
Keep this set up 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.
(ⅱ) Why is potato A necessary for this experiment.
(ⅲ) Explain why water does not gather in the hollowed out portion of A and D.
Ans:- (ⅰ) Sugar and salt increases osmotic concentration which results in passage of water osmotically from the trough through the cells of potato into its cavity.
(ⅱ) Potato a functions as control experiment which indicates that the cavity of potato does not induce movement of water.
