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KENDRIYA VIDYALAYA, NAD, VISAKHAPATNAM–9

ASSIGNMENT ON CHAPTER THE FUNDAMENTAL UNIT OF LIFE (CELL)

Std.:–IX Subject: Science (Biology) GENERAL INSTRUCTIONS:

(i) All questions are compulsory. (ii) Write the answer numbers as given in the question paper. (iii) Wherever necessary, the diagrams drawn should be neat and properly labelled.

1) Which structure do the cork cells resemble as observed by Robert Hooke? 1 Ans. Honey comb structure. 1 2) State the function of chromosome in a cell. 1 Ans. Chromosome is the carrier of genetic information. 1 3) What is the importance of osmosis in?

(a) Unicellular organisms (b) plants? 2 Ans. Unicellular–gain water by osmosis Plants–roots absorb water by osmosis 1+1 4) (a) Why is plasma membrane called selectively permeable membrane?

(b) How is flexible nature of plasma membrane useful for Amoeba? Name this process. 3

Ans. (a) It allows the entry and exit of some materials in and out of the cell,

and prevents movement of some other materials. (½+½) (b) It enables cells to engulf food and other materials from its external

environment. Amoeba acquires food through this process. (½+½) The process is called endocytosis. 1 5) Name the processes by which CO2 and H2O move into and out of the cell? 1 Ans. By diffusion and osmosis. ½, ½ 6) What will happen if: (a) ribosomes are removed from the cell, (b) golgi apparatus is

removed from the cell, (c) plasma membrane ruptures? 3 Ans.

(a) Protein will not be synthesized (b) Packaging of materials, synthesis of complex sugar and formation of lysosome will be adversely affected (any one of these) (c) The inside materials will come out. 1+1+1

7) Describe the role played by the Lysosomes. Why these are termed as suicidal bags? How do they perform their function? 3

Ans. Role-digestion of foreign material, digestion of worn–out organelles; because these burst themselves and digest the own cell; lysosomes are filled with digestive enzymes. Capable of breaking down all organic material. 1+1+1 8) Explain your observation in the following with reason involved in the process. 3

(a) Salt is applied to raw mango pieces (b) Dried raisins are kept in water for a few hours.

Ans. a) Mango pieces will shrink due to exosmosis in which more water molecules will

go out

SECTION–A (HOTS) & PREVIOUS YEARS QUESTION ANSWERS

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b) Raisin will swell up because medium surrounding it has higher concentration of water than the cell. Raisin gains water due to osmosis. 1½+1½

9) (a) What is DNA? Mention its function? Where is it found? (b) Name the functional segment of DNA. 2

Ans. (a) DNA or Deoxyribose Nucleic Acid molecule. ½

Contains information necessary for constructing and organising cells and inheritance of features from parents to next generation. ½ They are found in chromosomes. ½

(b) Genes. ½ 10) (a) Name the two types of endoplasmic reticulum

(b) What crucial role does it play in the liver cells of vertebrates? (c) Mention it’s any other function. 2

Ans. (a) Rough endoplasmic reticulum and smooth endoplasmic reticulum.1 (b) Detoxifying many poisons and drugs. ½ (c) Functions of ER: ½

ER forms a network in cytoplasm, giving mechanical support to the cell. It functions as an intracellular transport system for substances like

nucleoproteins. Protein Synthesis occurs on the surface of rough ER by ribosomes. Synthesis of lipids occurs on the surface of smooth ER.

(Any one) 11) How would (i) a plant cell (ii) an animal cell behave when placed in a hypotonic

solution of sodium chloride? Explain giving reasons. (Present your answer in a tabular form) 3

Ans. Plant cell swells, does not burst, because of the cell wall.

Animal cell swells, bursts because of the absence of a cell wall. 1½+1½ 12) (a) What would happen to the life of a cell if there was no Golgi

apparatus? (Any two) (b) Which two cell organelles of a cell contain their own genetic material? (c) What happen if the organisation of a cell is destroyed due to some physical or

chemical influence? (1+1+1) =3 Ans.

(a) There will be effect on the packaging and dispatching of different types of Proteins.

The products of the cell cannot be stored. The products of the cell cannot be modified further. (Any two) (½+½) (b) Mitochondria and Plastids. (½+½) (c) Each living cell has the capacity to perform certain basic functions

due to its cell organelles which are responsible for its organisation. If this organisation of a cell is destroyed, the cell will not be able to perform

certain basic functions and ultimately it will die soon. (½+½) 13) (a) In the diagram given below identify the part marked B and C.

(d) What are the substances that organelle A stores? (Any two) (e) Mention one function of organelle B and C. 3

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Ans.

(a) A–Vacuole, B–Golgi apparatus, C–Plastid/Chloroplast. (½+½) (b) Amino acids, proteins, sugars and organic acids. (Any two) (½+½) (c) Organelle B–Golgi apparatus–storage and packaging of products,

formation of lysosomes. (Any one) Organelle C–helps in photosynthesis. (½+½)

14) Name the cell organelle which is known as ‘Suicidal bags’? Give the reason. 1 Ans.

Lysosomes are called digestive bags. They contain digestive enzymes which break down the organic material present in the cell. 15) There is a change of colour from green to reddish during the ripening

of Tomato and Chilly. Explain in context with Cell Biology? 1 Ans. Due to change of chloroplast to chromoplast. 16) Enlist any four differences between cell wall and cell membrane. 3 Ans.

CELL WALL CELL MEMBRANE

(i) It is non–living. (i) It is living.

(ii) Present in plant cell exclusively. (ii) Present both in plant cell and animal cell; predominantly in animal cell.

(iii) It is made up of cellulose. (iii) It is made up of phospholipids and proteins.

(iv) Thick & tough in nature/is very rigid.

(iv) Extremely thin & elastic in nature/flexible.

(v) Thickening of various kinds present.

(v) No thickenings.

(vi) It gives rigidity and turgidity to plant cells.

(vi) The plasma membrane allows or permits the entry and exit of some materials in and out of the cell. It also prevents movement of some other materials.

(vii) It is not selectively permeable membrane.

(vii) It is selectively permeable membrane.

(Any Three)

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17) If you are provided with some vegetables to cook, we generally add salt to the

vegetables during cooking process. After adding salt, vegetables release water. What mechanism is responsible for this? Explain. 2

Ans. After adding salt, the concentration of solvent decreases, hence water form vegetable moves out from higher concentration to lower concentration.

18) If cell of onion peel and RBC are separately placed in hypotonic solution, what among the following will take place? Explain the reason. 2 (a) Both the cells will swell (b) RBC will burst early while cells of onion peel will resist bursting to some

extent (c) Both a and b are correct (d) RBC and onion peel cells will behave similarly

Ans. (b) RBC will burst early whereas onion peel cell well resist bursting to some extent. This is due to the presence of cell wall.

19) Mention any three similarities and three differences between mitochondria and plastids/chloroplast. 3

Ans. SIMILARITIES BETWEEN MITOCHONDRIA & CHLOROPLAST

Mitochondria & chloroplasts are semi-autonomous organelle & they possess their own DNA, RNA as well as ribosomes.

They both develop & originate in the same way, formed by division of pre–existing organelle

Both of them contain circular DNA. DIFFERENCES BETWEEN MITOCHONDRIA & CHLOROPLAST

Mitochondria occurs in all eukaryotic cells (both in plant and animal cells) while chloroplast are present only in plant cells.

Pigments are absent in mitochondria but always present in chloroplast. The inner membrane of mitochondria is folded into cristae whereas grana

(Sing. Granum) are present in chloroplast

20) Draw neat and labelled (large) diagrams of all the cell organelles found in plant cell

and animal cell. 21) Draw a full page neat and labelled diagram of a plant cell. 22) Draw a full page neat and labelled diagram of an animal cell. 23) Draw a full page neat and labelled diagram of a prokaryotic cell (e.g. bacteria).

Do Well and Excel

Wish You All the Best

SECTION–B ACQUIRING EXTRA KNOWLEDGE