Tuesday, April 26, 2022

Cell: The unit of Life | Class 11 | Previous Years Questions and Answers (Web and PDF)

 CELL-THE UNIT OF LIFE

2020 MARCH


1.   Choose the correct answer. The organelle known as power house of the cell is:

a.  Ribosome                 

b.  Vacuole                     

c.  Mitochondrion                       

d.  Chloroplast


Answer: c) Mitochondrion.


2.   Peculiarities of certain cell organelles are given below:

a.    Involved in protein synthesis.

b.    Made up of many flat, disc shaped sacs or cisternae.

c.     Bear ribosomes on their surface.

d.    Rich in hydrolytic enzymes.

e.    Membrane is absent.

Copy the table given below and write the above peculiarities in appropriate column.


Lysosome

Golgi apparatus

Ribosome

 

 

 


Answer:

Lysosome

Golgi apparatus

Ribosome

Rich in hydrolytic enzymes.

Made up of many flat, disc shaped sacs or cisternae.

·   Involved in protein synthesis.

·   Membrane is absent.


3.    Cell theory was formulated by two scientists.

a.       Name the scientists.

b.       Write the two main points in cell theory.


Answer:

(a) Schleiden and Schwann.

(b) All living organisms are composed of cells and product of cells.

All cells arise from pre-existing cells.


2019 JULY IMPROVEMENT


1.  An improved model of the structure of plasma membrane was proposed by Singer and Nicholson.

a.       What is this model called?

b.       Which component forms bilayer?

c.        Identify two types of proteins present in cell membrane.


Answer:

(a) Fluid mosaic model.

(b) Lipids/Phosphoglycerides

(c) Integral proteins, Peripheral or extrinsic proteins.


2019 MARCH


1.   Choose the correct answer.

A structure seen in bacterial cell is ..................

a.       Nucleus

b.       Lysosome

c.        Plastid

d.       Mesosome


Answer: d) Mesosome


2018 JULY IMPROVEMENT


1.   Fill in the blank.

Small disc-shaped structures at the surface of the centromere are called ...........


Answer: Kinetochore.


2.    The nucleoplasm contains small spherical shaped structures.

a)      Name the structures.

b)      Name the openings seen in nuclear envelope and state their function.


Answer:

(a) Nucleolus

(b) Nuclear pores.

Function: Movement of RNA and Protein takes place in both directions between the nucleus and the cytoplasm.


2018 MARCH


1.   There are different types of leucoplasts in plant cells. Name the leucoplast that store proteins.


Answer: Aleuroplast (proteinoplast).


2.   Ribosomes are organelles without a membrane found in all cells. Name another organelle devoid of membrane, seen in animal cells. Write its function.


Answer:

Centrioles or centrosomes.

Function: Takes part in the formation of spindle apparatus during cell division.


2017 JULY (IMPROVEMENT)


1.   Position of centromere determine the shape of the chromosomes.

a)    Name the different types of chromosomes based on the position of centromere.

b)   Draw any one chromosome among them. (3)


Answer:

a) Metacentric, Submetacentric, Acrocentric & Telocentric.

b) Figure (any one):

2017 MARCH


1.   a)  Identify a cell organelle which contains hydrolytic enzymes.

b) Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER) are morphologically and functionally different. Justify this statement. (3)


Answer:

a)   Lysosome.

b) Rough endoplasmic reticulum (RER): Bear ribosomes on their surface. RER is frequently observed in the cells actively involved in protein synthesis and secretion. They extend to the outer membrane of the nucleus.

Smooth endoplasmic reticulum (SER): Ribosomes are absent. SER is the major site for synthesis of lipid. In animal cells lipid-like steroidal hormones are synthesized in SER.


2016 MARCH


1.   Observe the given diagram. Analyze this diagram and explain the structure of plasma membrane. (3)

Answer:

It consists of lipid bilayer. They are arranged within the membrane with the polar head towards the outer sides and the hydrophobic tails towards the inner part. The peripheral proteins lie on the surface of membrane while the integral proteins are buried in the membrane.


2015 SEPTEMBER (IMPROVEMENT)


1.   Several ribosomes may attach to a single mRNA and form a chain called …………..       (1)


Answer: Polysomes or Polyribosomes.


2.   Name the type of chromosome based on the position of centromere in the figure and label the parts A, B & C.   (2)

Answer:

Metacentric chromosome.

A= Centromere.       

B= Secondary constriction.

C= Satellite.


2015 MARCH


1.  a) Due to the presence of a secondary constriction, a knob-like small fragment appears in some chromosomes called

       i) Kinetochore                  ii) Histone                         iii) Satellite               iv) Chiasmata

b) Classify chromosomes based on the position of centromere. (2)


Answer:

a) iii) Satellite.

b) Metacentric, Submetacentric, Acrocentric & Telocentric. 


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