Cell: The Unit of Life Chapter-Wise Test 5

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which statement correctly explains the fluidity of the plasma membrane in the fluid mosaic model?

Carbohydrates move freely through the hydrophobic interior of the membrane.
The quasi-fluid nature of lipids permits the lateral movement of proteins within the bilayer.
Membrane proteins remain permanently fixed between two rigid lipid layers.
Phospholipids form a rigid layer that prevents movement of membrane components.
2

In the fluid mosaic model, the quasi-fluid nature of the lipid bilayer allows proteins to move laterally within it. This movement is measured as membrane fluidity and is important in processes such as secretion, endocytosis and cell division.

Which process describes the movement of water across the plasma membrane by diffusion?

Active transport
Endocytosis
Facilitated transport
Osmosis
4

Osmosis is the movement of water by diffusion across the plasma membrane. It is a passive process and does not require the expenditure of cellular energy.

Which statement correctly describes the formation of the secondary wall in a plant cell?

It is formed on the inner side of the primary wall as the cell matures.
It is formed outside the middle lamella in a young, actively growing cell.
It replaces the plasma membrane when the cell stops growing.
It is formed only between two neighbouring plant cells.
1

The primary wall of a young plant cell is capable of growth. As the cell matures, this capacity gradually decreases and the secondary wall is formed on the inner side, towards the plasma membrane.

Which pathway correctly represents the movement of materials through the Golgi apparatus?

Trans face → cisternae → cis face → endoplasmic reticulum
Cisternae → endoplasmic reticulum → cis face → trans face
Endoplasmic reticulum → cis face → Golgi cisternae → trans face
Endoplasmic reticulum → trans face → cis face → Golgi cisternae
3

Vesicles from the endoplasmic reticulum fuse with the cis or forming face of the Golgi apparatus. Materials move through the cisternae and are released from the trans or maturing face.

Which combination of structures is characteristic of a typical plant cell but absent from an animal cell?

Plasma membrane, mitochondria and ribosomes
Cell wall, plastids and a large central vacuole
Nucleus, endoplasmic reticulum and Golgi apparatus
Cytoplasm, chromosomes and lysosomes
2

Plant cells possess a cell wall, plastids and a large central vacuole, which are absent from animal cells. Animal cells possess centrioles, which are absent from almost all plant cells.

A bacterium has a comma-shaped cell. Which basic bacterial form does it represent?

Bacillus
Coccus
Spirillum
Vibrio
4

Vibrio is the comma-shaped bacterial form. Bacillus is rod-like, coccus is spherical and spirillum is spiral in shape.

Which pair of subunits constitutes an 80S ribosome?

60S and 40S
50S and 30S
60S and 30S
50S and 40S
1

An 80S ribosome consists of a larger 60S subunit and a smaller 40S subunit. Cytoplasmic ribosomes of eukaryotic cells are 80S.

Where are chlorophyll pigments located within a chloroplast?

In the outer chloroplast membrane
Freely dissolved in the stroma
In the thylakoid membranes
Within the chloroplast ribosomes
3

Chlorophyll pigments are present in the thylakoids. The thylakoids occur in the stroma and may be arranged into stacks called grana.

A chromosome possesses a non-staining secondary constriction at a constant location. What appearance may this produce?

A kinetochore
A satellite
A second centromere
A nucleolus
2

A non-staining secondary constriction at a constant location may give the appearance of a small chromosome fragment called a satellite.

Which statement correctly describes microbodies?

They are non-membrane-bound granules found only in prokaryotic cells.
They are double-membrane-bound organelles containing 70S ribosomes.
They are cylindrical structures that form spindle fibres in animal cells.
They are minute membrane-bound vesicles containing various enzymes in plant and animal cells.
4

Microbodies are minute membrane-bound vesicles that contain various enzymes. They occur in both plant and animal cells.

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