What Is a Cell?

 

VERY SHORT QUESTION

1)    Who discovered the presence of cell?

Ans. Antoni Van Leeuwenhoek.

2)    Who coined the term “Cell”?

Ans. Robert Hooke.

3)  Which cell is irregular in shape ?

Ans. White blood cell or leucocytes

4)   Which cell is  the largest cell in the world.

Ans. Ostrich egg.

5) What is tonoplast?

Ans. Membrane covering vacuole is called tonoplast.

6) Why is Rough Endoplasmic reticulum named so?

Ans. Rough endoplasmic reticulum  (RER)contains ribosome that is why it’s surface is rough;  which helps to  synthesis protein.

7) Which of the following is not true?

a) Living cells are made up of cells.

b) The structural and functional unit of life is cell

c) The cell membrane is impermeable.

d) The cell is the functional unit of life.

Ans. c) The cell membrane is impermeable.

8) What is the function of Nucleus?

Ans. To Control all cellular activities.

9) What is the function of Centrosome?

Ans. Centrosome helps in cell division.

FILL IN THE BLANKS

1)Chlorophyll is stored in _____.

Ans. Chloroplast.

2) Amoeba form ____ to store food.

Ans. Food Vacuole.

SHORT QUESTION

1)  Why is the cell called structural and functional unit of life?

Ans. All living beings are made of cells. The cel is the living and smallest unit of life that has life and by own it can exist. That is why cell is called structural and functional unit of life.

2)  What are the functions of cell membrane?

Ans. Cell membrane is a semipermeable membrane so it allows some selective materials to enter into the cell and some selective substances to exit from the cell.

Cell membrane protects protoplasm.

3) Which organelle is differently shaped in plant cell and animal cell?

Ans. Vacuole is present in both plant cell and animal cell but it larger in size in plant cell and smaller in size in animal cell.

4)  What is the difference between plant cell and animal cell in various characters?

Characters Plant cell Animal cell
i)    Cell wall        Present         Absent
ii)   Chloroplast         Present        Absent
iii)  Centrosome        Absent        Present
iv)   Vacuole       Large in size       Smaller in size

 

5)  What is cytoplasm?

Ans. The cell is a tiny sac containing semifluid substance. This semiliquid contains various salts, minerals and proteins. This watery fluid is called cytoplasm.

6)   What is the covering of cell?

Ans. Cell is covered by a thin membrane called cell membrane or plasma membrane.

7)   Name two organelles performing energy transfer.

Ans. Chloroplast to absorb energy by photosynthesis Mitochondria to release energy by respiration.

8)  Which organelle is termed as power house of the cell?                                                                      Ans.Power house of the cell is mitochondria which helps to break the food to release the energy  is  which energy is utilised to perform various metabolic systems.

9)  Name the organelle termed as kitchen of the cell? Why is it named so?

Ans. in the cell chloroplast is termed as kitchen of the cell. It prepares food in the plant body by the help of sunlight, water and carbon-di-oxide with the help of photosynthesis.

10)  What is cell wall?

Ans. Outside the cell membrane there is another rigid membrane around plant cell called cell wall.

11)  What is cell sap?

Ans. There is a fluid present inside vacuole which contains various salts, sugars, water and other food materials termed as cell sap.

12)  What is plastid?

Ans. Organelle found only in plant cell containing pigment or food material is known as plastid.

13)  What are different types of plastid?

Ans. There are  three types of plastids

a) Chloroplast (helps in photosynthesis)

b) Chromoplast (helps in imparting colour to the flower)

c) Leucoplast (helps in storage of food).

14)  What are the characteristics of plastid?

Ans. Plastid is a double membrane organelle. It’s shape varies from round to filamentous.

15)  What is protoplasm?

Ans. Living material inside cell including cytoplasm and nucleus is called protoplasm.

 

LONG QUESTION / ANSWER

1)  What are the functions of the cell wall?

Ans. Cell wall performs following functions: –

i)Cell wall helps to maintain the  definite shape of the plant cell.

ii) As it is freely permeable so it allows all substances to enter and leave the cell which helps in absorption of water from soil.

iii) It makes the cell rigid.

iv) It protects the cell from injury.

2)  State various structures of a nucleus.

Ans. Nucleus has main four structures-

i) Nuclear membrane: Nucleus is enclosed by this membrane.

ii) Nucleoplasm: Nucleus is filled by this semifluid substance.

iii) Nucleolus: It is a small spherical body.

iv) Chromatin: It is a fine threadlike structure arranged in a network.

3) Differentiate between chloroplast, chromoplast leucoplast.

Ans.

Character Chloroplast Chromoplast Leucoplast
i)                   Colour Green Yellow or Red Colourless
ii)                 Function Helps in preparing food by Photosynthesis Impart red and yellow colour to fruit & flower Storage of food mainly under the ground.

 

4) What are the functions of vacuole?

Ans. Functions of vacuole are:

a) By it’s tonicity shape of the cell is maintained.

b) It maintains the balance of water in the cell

c) It helps in storage of various chemicals, water salts, excretory products and foods.

d) It stores waste products sometimes.

5) How do multicellular organisms grow?

Ans. By zygote the higher organism’s life is started which is a single cell. Zygote is formed by the fusion of sperm (male gamete ) and ovum (female gamete). The single cell divides into two cells, two cells into four cells and so on. By this division zygote transforms into an embryo which develops into a baby and then an adult.

6) How do unicellular organisms reproduce?

Ans.Unicellular organism contains single cell which divides and redivides to form new organism. So by this division one organism can reproduce two or more  new organisms.

7) How does skin repair itself when we have an injury.

Ans. By constant cell division new cells are formed which replace the damaged cells. This is the process by which skin can mend it’s wound constantly when we have injury.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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