12
MCQ (Single Correct Answer)
Plastid differs from mitochondria on the basis of one of the following features. Mark the right answer.
A
Presence of two layers of membrane
B
Presence of ribosome
C
Presence of thylakoids
D
Presence of DNA
13
MCQ (Single Correct Answer)
Which of the following is not a function of cytoskeleton in a cell?
A
Intracellular transport
B
Maintenance of cell shape and structure
C
Support of the organelle
D
Cell motility
14
MCQ (Single Correct Answer)
The stain used to visualise mitochondria is
A
fast green
B
safranin
C
acetocarmine
D
janus green
15
What is the significance of vacuole in a plant cell?
Explanation
The vacuole is a membrane bound space found in the cytoplasm. It contain water, sap, excretory product and other materials that are not seful for the cell. In plants osmosis vacuoles occupy $90 \%$ of the volume of the cell. They help in maintaining cell fluid balance, and shape of the cell by maintaining turger pressure against the cell well.
16
What does 'S' refer in a $70 S$ and $80 S$ ribosome?
Explanation
'S' refers to Svedbergs unit for sedimentation coefficient. Sedimentation coefficient depicts that how fast a cell organelle sediments during the ultracentrifugation.
In cells heavier the structure, higher is the sedimentation coefficient.
The value of $S$ is equal to $10^{-13}$ seconds ( $1 \mathrm{~s}=1 \times 1==^{-13}$ seconds).