The Fundamental Unit of Life Test

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The Fundamental Unit of Life Test - 39

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Question 1
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Statement I : All prokaryotes have a cell wall, eukaryotes do not.
Statement II : Prokaryotes have a true nucleus, eukaryotes have a primitive nucleus.

A
Both statement I and statement II are true and statement II is the correct explanation of statement I.

B
Both statement I and statement II are true but statement II is not the correct explanation of statement I.

C
Statement I is true but statement II is false.

D
Both statement I and statement II are false.

Solution

Prokaryotes generally have a tough layer which helps to maintain the strength and rigidity of the cells known as the cell wall. All the prokaryotes do not possess cell walls such as Mycoplasma. Eukaryotes like animals lack cell walls it starts with plasma membrane while plants have a cell wall.
Prokaryotes have a primitive nucleus that lacks membrane while eukaryotes have a true nucleus that has a double membrane nucleus. Thus, the correct answer is option D.
Question 2
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Study the given picture and identify them.

A
Onion peel cells

B
Cheek cell

C
Bacterial cell

D
Cork cells

Solution

An onion is a multicellular (consisting of many cells) plant organism. As in all plant cells, the cell of an onion peel consists of a cell wall, cell membrane, cytoplasm, nucleus and a large vacuole. The nucleus is present at the periphery of the cytoplasm. The vacuole is prominent and present at the centre of the cell. It is surrounded by cytoplasm. The presence of a cell wall and a large vacuole are indicators that help identify plant cells, such as seen in the onion peel.
Question 3
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Movement of ions or molecules against electrochemical gradient is called

A
Pinocytosis

B
Diffusion

C
Active transport

D
Brownican movement
Question 4
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Water molecules move from their ______ concentration to their ______ concentration during osmosis.

A
Higher, lower

B
Lower, higher

C
Isotonic, higher

D
Higher, isotonic

Solution

Osmosis is defined as a process in which the water molecules move from their higher concentration to their lower concentration through a semi-permeable membrane.
Question 5
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Why does the skin of fingers shrink when washing clothes for a long time?

A
Soap solution has high concentration of solutes (hypertonic)

B
Water moves out of finger due to exosmosis

C
Both A and B

D
None of the above

Solution

Soap contains large amount of solutes. Soap is a hypertonic solution with high amounts of salts. Hence, when washing clothes solute concentration is more in soap water than in cells of hand. Due to this, exosmosis occurs in which the water molecules present in cells of hand move out in soap solution. This is an osmotic process in which the water molecules move from lower solute concentration to higher solute concentration, i.e., from dilute solutions to concentrated solution through a semi-permeable membrane.
Question 6
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Name the process which is useful for the movement of substances like CO$$_2$$ and O$$_2$$ across the cell membrane.

A
Diffusion

B
Osmosis

C
Active diffusion

D
Reverse osmosis

Solution

Diffusion is a process in which the gaseous molecules spread, due to their kinetic energy, and the movement of molecules is from higher concentration to lower concentration. CO$$_2$$ and O$$_2$$ are gases. They move in and out of the cell by diffusion.
So, the correct answer is 'Diffusion'
Question 7
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Membrane biogenesis is associated with which of the following cell organelles?

A

B

C

D
Both A and B

Solution

Membrane biogenesis is the process of formation of plasma membrane and plasma membrane, is composed of lipids and proteins. Endoplasmic reticulum has ribosomes which release proteins. Therefore, it plays an important role. Membrane biogenesis is the process, when some proteins and lipids (produced in smooth endoplasmic reticulum) help in building the cell membrane, inside a cell.The organelle E.R.'s (Endoplasmic Reticulum) membrane of the E.R. is involved in membrane biogenesis. As the R.E.R (Rough Endoplasmic Reticulum) is involved in protein synthesis and the S.E.R (Smooth Endoplasmic Reticulum) is involved in lipid formation. Lipids and proteins are used to make the plasma membrane of the cell.
Question 8
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In a plant cell, cytokinesis occurs by

A
Separation of the cytoplasm from the periphery to central region

B
Separation of the cytoplasm from cell centre to its periphery

C
Separation of the cytoplasm throughout the equatorial plane simultaneously

D
Furrowing of cytoplasm from two sides at right angles to the plane of spindle pole
Solution
- In plant cells, a new cell wall must form between the daughter cells.
- During telophase, Golgi vesicles are transported on microtubules to form a phragmoplast (a vesicular structure) at the metaphase plate.
- There, the vesicles fuses to form cell plate from the center toward the periphery.
- Thus, separation of cytoplasm i.e. cytokinesis starts from center in a plant cell.
So, the correct answer is option B.
Question 9
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The fact that nucleus possessed the ability to control phenotype was first determined by

A
Experiments with radiolabelled phages

B
Experiments with bacteria that identified DNA polymerase

C
Transformation experiments with Streptococcus pneumoniae

D
Identification of restriction endonucleases

E
Grafting experiments with Acetabularia

Solution

Acetabularia consists of a rootlike holdfast, a long, cylindrical stalk; and a cuplike cap. The nucleus is present in the holdfast. Acetabularia exhibits regeneration of the cap after any injury. A. mediterranea has a smooth cap and A. crenulata, has a cap with fingerlike projections. Danish biologist J. Hämmerling and Belgian biologist J. Brachet performed grafting experiment on above mentioned species and showed that type of caps that regenerated were determined by the type of the donor species of the holdfasts, not by those donating the stalks. It was concluded, that nucleus in the holdfast of Acetabularia controls the shape of the caps. The correct answer is E.
Question 10
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A eukaryotic organelle that can best be seen with the light microscope is the:

A
Endoplasmic reticulum

B
Nucleus

C
Polyribosome

D
Microtubule

Solution

The nucleus is a membrane-bound organelle that is seen under a light microscope because of its large size. These are spherical in shape and encompass nuclear membrane, chromosomes, nucleoplasm, and nucleolus. It contains the cell's genetic material.
Hence, the correct answer is 'Nucleus'.