Cell - The Unit of Life Test 14

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Cell - The Unit of Life Test 14

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Question 1
1 / -0

What is true about genetic material of a prokaryotic cell?

A
Lacks histones

B
Not enveloped by nuclear membrane

C
Composed of a single circular DNA molecule

D
All of these

Solution

In prokaryotes, the genetic material consists of single circular DNA molecule lying entangled in nucleoid. It is not bounded by a definite nuclear membrance. Histones are water-soluble proteins rich in arginine and lysine that help in DNA packaging in chromosomes. Prokaryotic cells lack pistone proteins.
Question 2
1 / -0

Arrange the following steps in a correct sequeence as per Gram's staining technique:
Treatment with 0.5% iodine solution (1). washing was water (2). treatment with absolute alcohol/acetore (3). staining with weak alkaline solution of crystal violet (4).

A
4 → 1 → 2 → 3

B
3 → 2 → 1 → 4

C
3 → 1 → 2 → 4

D
4 → 2 → 3 → 1

Solution

The grouping of bacteria is based upon reaction of bacteria to Grams's stain (Christian Gram, 1884). Bacteria are first stained with weakly alkaline solution of crystal violet and then treated with 0.5% iodine solution. This is followed by washing with water and then with alcohol or acetone. Bacteria which retain blue of purple colour are known as (Gram(+) bacteria (e.g., Bacillus subtilis). Bacteria which do not retain any stain and become colourless are called Gram(-) bacteria (e.g., Escherichia colt). Washing of the stain in Gram(-ve) bacteria is due to high lipid content of their cell wall which gets dissolved in organic solvents like acetone.
Question 3
1 / -0

Prokaryotic cells are generally _____ and multiply _____ than the eukaryotic cells.

A
smaller, slower

B
larger, slower

C
smaller, faster

D
larger, faster

Solution

Prokaryotic cell is usually small (0.1-5.1μm) in size whereas eukaryotic cell size is comparatively larger (5-100μm). Prokaryotic cells multiply very rapidly by asecial means like binary fission, sporulation etc.
Question 4
1 / -0

Mesosomes are the infoldings of cell membrane, which
(i) are present in both prokaryotic and eukaryotic cells.
(ii) help in cell wall formation, DNA replication and respitation.
(iii) increase the surface area of plasma membrane.

A
(i) and (ii)

B
(ii) and (iii)

C
(i) and (iii)

D
(i), (ii) and (iii)

Solution

Mesosomes are present only in prokaryotes.
Question 5
1 / -0

Glycocalyx (mucilage sheath) of a bacterial cell may occur in the form of a loose sheath called ____ or it may be thick and tough called _____ .

A
capsule, slime layer

B
slime layer, capsule

C
mesosome, capsule

D
mesosome, slime layer

Solution

Glycocalyx (mucilage sheath) is the outermost layer of the bacterial cell envelope which consists of non-cellulosic polysacharides with or without proteins. It may occur in the form of loose sheath, called slime layer. If it is a thick coering, it is called capsule. Glycocalyx gives sticky character to the cell and is not absolutely essential for survival of bacteria. It prevents desiccation, protects from phagocytes, toxic chemicals and viruses and serves in attachment. It may give selective advantage though in certain situations.
Question 6
1 / -0

Correct sequence of layers of bacterial cell envelope from outward to inward is

A
Cell wall → Glycocalyx → Cell membrane

B
Cell membrane → Glycocalyx → Cell wall

C
Glycocalyx → Cell wall → Cell membrane

D
Glycocalyx → Cell membrane → Cell wall

Solution

Glycocalyx is the outermost layer of the cell envelope. Cell wall lies between plasma membrane andd glycocalyx.
Question 7
1 / -0

_____ are self replicating, extra chromosomal segments of double stranded circular and naked DNA, present in a bacterial cell.

A
Plasmids

B
Nucleoid

C
Mesosomes

D
Bacteriophages

Solution

Plasmid is a structure in bacterial cell consisting of DNA that can exist and replicate independently of the chromosome. Plasmids provide genetic instructions for certain cell activities (e.g., antibiotic, resistance). They can be transferred from cell to cell in a bacterial colony.
Question 8
1 / -0

Read the given statements and select the correct option.
Statement 1: In prokaryotes mitochondira are absent.
Statement 2: In prokaryotes mesosomes are present which help in respiration.

A
Both statements 1 and 2 are correct and statement 2 is the correct explanation of statement 1.

B
Both statements 1 and 2 are correct but statement 2 is not the correct explanation of statement 1.

C
Statement 1 is correct and statement 2 is incorrect.

D
Both statements 1 and 2 are incorrect.

Solution

Mitochondria are absent in prokaryotes. Mesosomes are characteristic circular to villiform specialisation of cell membrance of bacteria that develop as an ingrowth from the plasma membrane. It helps in nucleoid replication and cell division. Lateral mesosome is not connected with nucleoid. It contains resspiratory enzymes and is, therefore, often called chondrioid. It is believed to be equal to mitochondrion of eukaryotes. However, respiratory enzymes are also present over the plasma membrane.
Question 9
1 / -0

The type of ribosomes found in prokaryotes is

A
80S type

B
70S type

C
30S type

D
50S type

Solution

The cytoplasmic ribosomes of prokaryotes (blue green algae, bacteria and PPLOs) are 70S. They have two subunits 50S and 30S.
Question 10
1 / -0

If you remove the fimbriae from the bacterial cell, which of the following would you expect to happen?

A
The bacteria could no longer swim

B
The bacteria would not adhere to the host tissue

C
Transportation of molecules across the membrane would stop

D
The shape of bacteria would change

Solution

Fimbriae are hair like structures present in large number in bacteria. They help in attaching bacteria to solid surface or host tissues.

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Cell - The Unit of Life Test 14

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Cell - The Unit of Life Test 14

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SHARING IS CARING

Question 1

Lacks histones

Not enveloped by nuclear membrane

Composed of a single circular DNA molecule

All of these

Solution

Question 2

4 → 1 → 2 → 3

3 → 2 → 1 → 4

3 → 1 → 2 → 4

4 → 2 → 3 → 1

Solution

Question 3

smaller, slower

larger, slower

smaller, faster

larger, faster

Solution

Question 4

(i) and (ii)

(ii) and (iii)

(i) and (iii)

(i), (ii) and (iii)

Solution

Question 5

capsule, slime layer

slime layer, capsule

mesosome, capsule

mesosome, slime layer

Solution

Question 6

Cell wall → Glycocalyx → Cell membrane

Cell membrane → Glycocalyx → Cell wall

Glycocalyx → Cell wall → Cell membrane

Glycocalyx → Cell membrane → Cell wall

Solution

Question 7

Plasmids

Nucleoid

Mesosomes

Bacteriophages

Solution

Question 8

Both statements 1 and 2 are correct and statement 2 is the correct explanation of statement 1.

Both statements 1 and 2 are correct but statement 2 is not the correct explanation of statement 1.

Statement 1 is correct and statement 2 is incorrect.

Both statements 1 and 2 are incorrect.

Solution

Question 9

80S type

70S type

30S type

50S type

Solution

Question 10

The bacteria could no longer swim

The bacteria would not adhere to the host tissue

Transportation of molecules across the membrane would stop

The shape of bacteria would change

Solution

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