Cell Physiology MCQ

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1. Chromatin fibers coil into rod-like structures known as
a. Ribosomes
b. Nucleolus
c. Chromosomes
d. Lysosomes
e. Centromere
Correct Answer – Chromosome
– Chromatin fibers: are very long molecules of DNA associated with proteins (histones and other nuclear proteins). Each chromatin fiber, at the time of cell division, organizes into Chromosomes.
– Nucleolus: is present in the nucleus when the cell is not dividing. No membrane bounds it. It assembles both units of Ribosomes.

2. The nucleolus is a small, dense body composed mainly of
a. Chromatin
b. DNA
c. RNA
d. Cytoplasm
e. Endoplasm
Correct answer – RNA
The Nucleolus
Ribosomal RNA is a structural component of ribosomes and is synthesized in the nucleolus. The nucleolus is very prominent in cells that are active in protein synthesis. Often, two or more nucleoli are present in the same nucleus.

3. Substances such as which of these diffuse readily through the cell membrane
a. Oxygen
b. Carbon dioxide
c. Alcohol
d. Only a and b
e. a b and c
f. None of the above
Correct Answer: Oxygen, Carbon dioxide, and alcohol all readily diffuse through the cell membrane.

4. Osmosis is a special case of:
a. Filtration
b. Active transport
c. Diffusion
d. Facilitated transport
e. Pinocytosis
Correct Answer: C (Diffusion)
• The unassisted diffusion of lipid soluble or very small particles is called simple diffusion. Simple diffusion of water is known as osmosis
• Osmosis is just the same as diffusion, but only for water

5. The substance that moves through the cell membrane during osmosis is:
a. Glucose
b. Oxygen
c. Water
d. Sodium
e. Any cation
Correct Answer: C (Water)
• Osmosis is the diffusion of a solvent, such as WATER, through a selectively permeable membrane
• Since water is highly polar, it cannot pass through the lipid bi-layer, but it is small enough to pass through the pores of most plasma membranes

6. The phase of the cycle in which cell contents grow and duplicate is:
a. Interphase
b. Prophase
c. Metaphase
d. Anaphase
e. Telophase
Answer: Interphase
• Cell Cycle
o Living cells go through a series of stages known as the cell cycle. Cell cycle can be thought of as the life cycle of a cell. That is, the series of growth and development steps a cell undergoes between its “birth”—formation by the division of a mother cell—and reproduction—division to make two new daughter cells.
o During Interphase, the cell grows and makes a copy of its DNA
• Interphase
o Preparation for division (interphase) happens in three steps:
 During the first stage, the cell grows physically larger, copies organelles, and makes the molecular building blocks it will need in later steps.
 In the second stage, the cell synthesizes a complete copy of the DNA in its nucleus.
 In the third and final stage, the cell grows more, makes proteins and organelles, and begins to reorganize its contents in preparation for mitosis.

7. Chromosomes first appear distinct during the mitotic stage of:
a. Prophase
b. Metaphase
c. Anaphase
d. Telophase
e. none of the above
Correct Answer: Prophase

8. Which of the following series of events of mitosis is in the correct order?
a. Telophase, prophase, anaphase, metaphase
b. Prophase, metaphase, anaphase, telophase
c. Anaphase, prophase, metaphase, telophase
d. Metaphase, prophase, anaphase, telophase
Answer: prophase, metaphase, anaphase, telophase
Mitosis and meiosis proceed through Interphase through prophase, metaphase, anaphase and telophase

9. The process through which cells develop different characteristics in structure and function is called:
a. Specialization
b. Maturation
c. Differentiation
d. Hybridization
e. Clonal expansion
Answer: Differentiation
• Differentiation and stem cells
 As an individual unit, the cell is capable of metabolizing its own nutrients, synthesizing many types of molecules, providing its own energy, and replicating itself in order to produce succeeding generations.
 In a multicellular organism, cells become specialized to perform different functions through the process of differentiation.
 Most types of animal cells differentiate at an early stage – they become specialized for a particular function and cannot change into different types of cell
 Stem cells can be made to differentiate to form different types of cell, such as nerve cells.

10. Which of the following are characteristic of cancer?
a. Hyperplasia
b. De-differentiation
c. Metastasis
d. All of the above
e. None of the above
Ans – D
• Hyperplasia is any abnormal multiplication of cells, but the cells themselves look ‘normal’. Hyperplasia refers to an abnormal increase in cellular quantity (i.e., constantly dividing cells)
• Dedifferentiation is a process by which structures that were specialized for a specific function lose their specialization and become simplified or generalized
• Metastasis is the spread of a cancer or other disease from one organ or part of the body to another without being directly connected with it. The new occurrences of disease thus generated are referred to as metastases

11. The principal intracellular cation is:
a. Na+
b. K+
c. Cl-
d. Ca2+
e. Mg2+

Correct answer – K+ (Potassium ions)
– The principal intracellular cation is potassium (K+).
– Sodium (Na+) is the principal extracellular cation.
– Chloride (Cl-) is an anion.
– Potassium is accumulated by cells because of the operation of the sodium pump.

12. Which of the following values is closest to the resting membrane potential of mammalian cells?
a. -20 mV
b. -60 mV
c. +60 mV
d. +20 mV
e. +30 mV
Correct answer: (b) -60 mV
• The resting membrane potential of mammalian cells is negative and is around -50 to -70 mV in many cells.
• Nerve and muscle cells generally have more negative membrane potentials than other cells (in the region of -70 to -90 mV).

13. The Principal extracellular cation is:
a. Sodium (Na+)
b. Potassium (K+)
c. Chloride (Cl-)
d. Calcium (Ca2+)
e. Magnesium (Mg2+)
Correct Answer: Sodium (Na+)
• Sodium is the principal extracellular cation and potassium is the principal intracellular cation
• Cl- is the principal extracellular anion

14. The resting membrane potential is mainly determined by:
a. The Cl- gradient
b. The Ca2+ gradient
c. The Na+ gradient
d. The K+ gradient
e. The Mg2+ gradient
• The resting membrane potential is determined by the K+ gradient because there are many more open K+ channels than Na+
• Consequently the resting membrane potential is close to the K+ equilibrium potential. Chloride ions distribute passively to mirror the potassium gradient.

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