MULTIPLE CHOICE. Choose the one alternative that best completes the statement or

Question

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A form of diffusion in which the molecules pass through a protein instead of between the phospholipids is called . A) facilitated diffusion C) osmosis B) diffusion D) active transport 2) Which of these processes brings into the cell large macromolecules and particles by the formation of a vesicle in the outer membrane? B) endocytosis A) facilitated transport C) pinocytosis 3) Microfilaments are made of B) tubulin A) actin C) intermediate proteins 4) Cilia and flagella are both made of A) actin C) intermediate proteins B) tubulin D) phospholipids 5) Which of these is most abundant in the plasma membrane? A) proteins B) carbohydrates C) cholesterol 6) If a liver cell were to be placed in a beaker with a solution containing the same solute concentration as that found inside the cell, we would say that the beaker contained a(n) solution. B) hypertonic C) isotonic D) hypotonic 7) You have a bacterial infection. Your immune system will be able to distinguish this foreign invader from other cells by A) recognizing cell adhesion molecules (CAMs) B) finding glycolipids on the plasma membrane C) identifying glycoproteins on the plasma membrane D) determining the presence or absence of a nucleus 8) When bacteria appear in tissues, a type of large cell engulfs and destroys them. Which process are these cells using to engulf the bacteria? A) exocytosis B) active transport C) pinocytosis D) phagocytosis 9) Which of the following is a membranous organelle that chemically modifies and ships proteins to other organelles or out of the cell? A) lysosome B) chloroplast D) Golgi complex 10) Most of the energy used by the cell is converted to ATP in B) Golgi complexes C) nuclei

Explanation / Answer

1) Diffusion is spontaneous movement of particles from an area of higher concentration to an area of lower concentration.

Simple diffusion occurs when small molecules pass through the lipid bilayer of the cell membrane. Hence, it does not pass through the proteins.

Hence, option (B) is incorrect.

Diffusion refers to movement of any molecule from one place to another. But osmosis refers to the movement of solvent molecules alone and it always occur through the semipermeable membrane.

Hence, option (C) is incorrect.

When the particles move from a region of lower concentration to a region of higher concentration against the concentration gradient and requires some amount of chemical energy, it is referred to as active transport.

Hence, option (D) is incorrect.

Facilitated diffusion is the process of spontaneous passive transport of molecules across a biological membrane via specific integral proteins. Facilitated diffusion depends on carrier proteins embedded in the membrane to allow specific substances to pass through, that might not be able to pass through lipid bilayer.

Hence, the correct answer is option (A).

2) Vesicles are small fluid-filled sacs found in the cells. They may be formed during secretion or uptake of particles and helps in the transport of particles. Vesicles are formed in the outer membrane to transport macromolecules and particles into or out of the cell.

Facilitated transport is the process of spontaneous passive transport of molecules across a biological membrane via specific integral protein. It does not involve the formation of vesicles in the outer membrane.

Hence, option (A) is incorrect.

Pinocytosis is also called fluid endocytosis is a process by which small molecules suspended in extracellular fluid are brought into the cell through the formation of vesicle.

So, it does not bring in large macromolecules and particles by the formation of a vesicle.

Hence, option (C) is incorrect.

Exocytosis involves the secretion of molecules into the extracellular environment and not into the cell.

Hence, option (D) is incorrect.

Endocytosis is a form of active transport in which cells transport molecules into the cell. Hence, it involve the transport of molecules by engulfing. Receptor-mediated endocytosis is a process by which the cell absorbs macro or large molecules like proteins, hormones by inward budding of plasma membrane vesicles containing certain site-specific proteins to the molecules being absorbed.

Hence, endocytosis brings in large macromolecules and particles by the formation of a vesicle in the outer membrane.

Therefore, the correct answer is option (B).

3) Microfilaments are rod-like structures present in the cytoplasm of eukaryotic cells and they form a part of cytoskeleton. They are the thinnest filaments of the cytoskeleton. They provide support to the cell.

Tubulins make up microtubules not microfilaments.

Hence, option (B) is not correct.

Intermediate filaments are cytoskeletal components, but have a thicker diameter than microfilaments.

Hence, option (C) is incorrect.

Phospholipids are a class of lipids that form the major component of cell membranes. They do not make up microfilaments.

Hence, option (D) is not correct.

Actin is a globular protein that make up the microfilaments. Microfilaments are also referred to as actin filaments. They are primarily composed of polymers of actin.

Hence, the correct answer is option (A).

4) Cilia and flagella are projections of the cell that help in the movement of cells. They are made up of microscopic tubular structures called microtubules.

Actin makes up microfilaments not microtubules.

Hence, option (A) is not correct.

Microtubules are not made up of intermediate proteins.

Hence, option (C) is incorrect.

Phospholipids make up cell membrane and not microtubules.

Hence, option (D) is not correct.

Cilia and flagella are made up of microtubules which in turn is made of tubular polymers called tubulin.

Therefore, the correct answer is option (B).

5) Plasma membrane separates the interior of the cell from the outside environment.

Plasma membrane do have proteins in them but do not form the abundant part of the cell membrane.

Hence, option (A) is incorrect.

Carbohydrates covalently linked to glycoproteins or glycolipids are part of cell membrane.

But they are not found plentifully on the membrane.

Hence, option (B) is incorrect.

Cholesterol too form the part of cell membrane. But cell membranes are not rich in cholesterol.

Hence, option (C) is not correct.

The phospholipid bilayer forms the universal basis of cell membrane. Phospholipids are lipids containing phosphate group in its molecule. They form the major component of cell membrane.

Therefore, the correct answer is option (D).

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