Cell: The Unit of Life' For NEET
Test 4

Correct answer Carries: 4.

Wrong Answer Carries: -1.

How are phospholipids arranged in the plasma membrane?

The hydrophobic tails face the aqueous environment on both sides of the membrane.
The polar heads face the outer sides, while the hydrophobic tails remain towards the inner part of the bilayer.
The polar heads and hydrophobic tails are arranged randomly throughout the membrane.
The polar heads remain buried within the membrane, while the tails face the outer sides.
2

Phospholipids form a bilayer in which the polar heads face the outer aqueous sides and the hydrophobic tails remain towards the inner part. This protects the non-polar tails from the aqueous environment.

Which statement correctly distinguishes peripheral membrane proteins from integral membrane proteins?

Peripheral proteins are made only of lipids, whereas integral proteins are made only of carbohydrates.
Peripheral proteins occur only in prokaryotic cells, whereas integral proteins occur only in eukaryotic cells.
Peripheral proteins are buried in the bilayer, whereas integral proteins lie only on its surface.
Peripheral proteins lie on the membrane surface, whereas integral proteins are partially or totally buried in the membrane.
4

Membrane proteins are classified according to their ease of extraction. Peripheral proteins lie on the membrane surface, while integral proteins are partially or completely buried within the membrane.

A neutral solute moves across the plasma membrane from a region of higher concentration to a region of lower concentration without using energy. Which process is involved?

Simple diffusion
Active transport
Osmosis
Endocytosis
1

Neutral solutes may cross the plasma membrane by simple diffusion along their concentration gradient, from higher to lower concentration. This is a form of passive transport and does not require energy.

Which prokaryotic organism is an exception to the general presence of a cell wall outside the plasma membrane?

Cyanobacterium
Spirillum
Mycoplasma
Bacillus
3

Prokaryotes generally possess a cell wall surrounding the plasma membrane, but Mycoplasma is an exception and lacks a cell wall.

Which sequence lists the three parts of a bacterial flagellum?

Axoneme, radial spoke and basal body
Filament, hook and basal body
Filament, pilus and fimbria
Hook, capsule and cell wall
2

A bacterial flagellum consists of a filament, hook and basal body. The filament is its longest portion and extends from the cell surface to the outside.

Which pair of subunits forms a 70S ribosome?

60S and 40S
50S and 40S
60S and 30S
50S and 30S
4

A 70S ribosome consists of a larger 50S subunit and a smaller 30S subunit. Prokaryotic ribosomes and the ribosomes within mitochondria and chloroplasts are 70S.

Which combination correctly describes lysosomes?

Non-membrane-bound structures containing enzymes active at alkaline pH
Double-membrane-bound structures containing enzymes for ATP synthesis
Membrane-bound vesicles containing hydrolytic enzymes optimally active at acidic pH
Flattened sacs containing chlorophyll pigments and circular DNA
3

Lysosomes are membrane-bound vesicular structures rich in hydrolytic enzymes. These enzymes are optimally active at acidic pH and can digest carbohydrates, proteins, lipids and nucleic acids.

A cell is actively synthesising lipids and lipid-like steroidal hormones. Which organelle is expected to be particularly well developed?

Smooth endoplasmic reticulum
Rough endoplasmic reticulum
Nucleolus
Lysosome
1

The smooth endoplasmic reticulum is the major site of lipid synthesis. In animal cells, lipid-like steroidal hormones are also synthesised in the SER.

What is the principal role of the contractile vacuole in Amoeba?

Synthesis of proteins and lipids
Osmoregulation and excretion
Formation of spindle fibres
Packaging of glycoproteins and glycolipids
2

The contractile vacuole of Amoeba is important for osmoregulation and excretion. Food vacuoles, in contrast, are formed by engulfing food particles.

Which option correctly describes the cytoskeleton?

A membrane-bound system composed of cisternae, tubules and vesicles
A rigid cellulose layer that protects the plasma membrane
A network of microtubules, microfilaments and intermediate filaments involved in support, motility and maintenance of cell shape
A collection of hydrolytic enzymes enclosed within acidic vesicles
3

The cytoskeleton is an elaborate network of microtubules, microfilaments and intermediate filaments in the cytoplasm. It provides mechanical support and contributes to motility and maintenance of cell shape.

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