Biology · Science General

Cell Biology and Structure

3,221 Questions

Cell biology focuses on the structure and function of cellular organelles. Key topics include cellular respiration, DNA inheritance, and energy production. These fundamental biology concepts are crucial for medical entrance and state service examinations.

Cell organelles functionsCellular respiration sitesDNA and ribosomesAnimal cell structurePlant cell components

Cell Biology and Structure Questions

Multiple choice

Match the following cell organelles present in column I with their functions in column II.

 
Column I Column II
A. Mitochondria a. Synthesis of membrane lipid
B. SER b. Autophagy
C. RER c. Post translational modification of proteins
D. Lysosome d. ATP synthesis

  1. A - b; B - c; C - a; D - d

  2. A - d; B - a; C - c; D - b

  3. A - b; B - d; C - a; D - b

  4. A - a; B - b; C - c; D - d
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cell organelles are correctly matched with their functions. Mitochondria synthesise ATP by means of electron transport chain. SER is responsible for the synthesis of fatty acids whereas post translational modification of proteins occur in the lumens of RER. Lysosomes are responsible for autophagy, a process of self-digestion.

Multiple choice

A cell, which is very active in the synthesis and secretion of proteins, would be expected to have

  1. equal amount of smooth and rough ER

  2. more smooth than rough ER

  3. more rough than smooth ER

  4. more Golgi complex
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Proteins are synthesised by ribosomes associated with the cytoplasmic side of the membrane of rough endoplasmic reticulum (RER). Synthesised proteins enter into the membrane and lumen of RER by the process of co-translational translocation. Modification of proteins is also occurred in the lumen. Proteins destined to be secreted then follow the secretory pathway. On the other hand, SER is responsible for lipid biosynthesis, detoxification, etc.

Multiple choice

Mitochondria are energy-converting organelles, which are present in virtually all eukaryotic cells. These are also called semi-autonomous organelles because of the presence of mitochondrial DNA genome, special mitochondrial ribosomes, tRNAs and various enzymes required for the expression of the mitochondrial genes.

Which of the following is incorrect about mammalian mitochondrial DNA?

  1. It is double stranded.

  2. Each mitochondrion contains about 100 DNA molecules.

  3. It is circular in nature.

  4. It is inherited paternally.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mitochondrial DNA is not inherited paternally. It is inherited maternally. Mitochondria and their DNA molecules (mtDNA), are the genetic units of this method of inheritance. Mitochondrial genes, in the contrast to genes in the nucleus, have an exclusively maternal mode of inheritance in mammals.

Multiple choice

A nuclear pore is a passage between nuclear matrix and cytoplasm. The nuclear pore

  1. allows ribosomes to enter the nucleus

  2. allows DNA to enter the cytoplasm for translation

  3. allows cytoplasmic proteins to enter the nucleus

  4. structurally fortifies the nucleus
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Allows cytoplasmic proteins to enter the nucleus. In the nucleus, important activities as DNA replication, transcription, etc. take place. These are initiated and mediated by many enzymes that are produced inside the cell. Therefore, the enzymes are transported from cytoplasm to nuclear matrix through nuclear pore.

Multiple choice

Which of the following describes the F1 particle of mitochondria?

  1. It is a type of ribosome that takes part in synthesis of mitochondrial proteins.

  2. It is present in the mitochondrial inner membrane.

  3. It is a type of storage complex in the mitochondria.

  4. It is made up of enzymes that synthesises ATP.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It is made up of enzymes that synthesises ATP. The F1 particle is attached to the inner membrane of mitochondria. It has a motor like structure at the base just as bacterial flagella. The motor rotates and generates ATP.

Multiple choice

Which of the following mechanisms is NOT followed by a cell to degrade its own cytosolic proteins?

  1. Phagocytosis and secondary lysosome fusion

  2. Autophagic vacuoles

  3. 26S Proteosome degradation

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Phagocytosis and secondary lysosome fusion. Phagocytosis and lysosome fusion are engulfing of small particles by a cell, generally for its nutrition. These are generally observed in macrophages to destroy bacteria.

Multiple choice

Colchicine disrupts the microtubules in a cell. If a eukaryotic cell is given such a treatment, which of the following will happen?

  1. The cell will lose directional movement.

  2. The cell will lose its nutrient transport.

  3. The cell will lose its shape.

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

All of the above. Microtubules are infrastructure of a cell and give specific shape to it. Since colchicines disrupt microtubules, thus, shape of the cell will get upset resulting in the above mentioned losses.

Multiple choice

Cell membrane is an indispensable part of cell that maintains vital functions of a cell besides giving proper shape and rigidity to the cell. The intracellular organelles such as vacuoles, lysosomes and golgi bodies are also made up of a similar membrane.

Which of the following substances does not move across the cell membrane of cells by passive diffusion?

  1. Palmitic acid

  2. Aldosterone

  3. Na+

  4. Testosterone
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

 Na+, a charged molecule, crosses membranes through channelby active transport as it is hydrophilic.

Multiple choice

Cell membrane is an indispensable part of cell that maintains vital functions of a cell besides giving proper shape and rigidity to the cell. The intracellular organelles such as vacuoles, lysosomes and golgi bodies are also made up of a similar membrane.

When a cell has oxygen limitations, its lysosomes tend to burst and release their contents into the cell. (Consider this statement as true.) As a result of this, what is expected to happen?

  1. The cell undergoes self-digestion and dies.

  2. The cell recycles damaged organelles.

  3. Additional ER is produced in the cell.

  4. Replacement lysosomes are produced by the cell.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The cell undergoes self-digestion and dies. Lysosomes contain different types of lytic enzymes. When a lysosome bursts inside a cell, lytic enzymes are released inside the cell resulting into its self-digestion and finally death. This is a usual phenomenon observed by a cell for apoptosis.

Multiple choice

Below are certain cell organelles found in prokaryotic as well as eukaryotic cells (Column I) and their associated organelles (Column II). Match them.

 
Column I Column II
A. Intrinsic proteins 1. Cytoplasm
B. Mesosomes 2. Endoplasmic reticulum
C. Bound Ribosomes 3. Invaginated cell membrane
D. Golgi complex 4. Cell membrane

  1. A - 1, B - 2, C - 3, D - 4

  2. A - 1, B - 3, C - 2, D - 4

  3. A - 4, B - 3, C - 2, D - 1

  4. A - 2, B - 1, C - 4, D - 3
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A - 4, B - 3, C - 2, D - 1: Intrinsic proteins are certain proteins embedded in lipid bilayer of cell membranes. Mesosomes are invaginations in cell membrane of certain gram positive bacteria that are responsible for their respiration. Bound ribosomes are found attached to endoplasmic reticulum in eukaryotic cells. Golgi complexes are dispersed in cytoplasm of eukaryotic cells.

Multiple choice

Which one of these membrane constituents are found in the inner leaflet of animal cell membrane?

  1. Phosphatidylcholine

  2. Phophatidylserine

  3. Sphingomyeline

  4. Cholesterol
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Among the phospholipids of plasma membrane, phosphatidylcholine, sphingomyelin, phospatidylserine and phosphoethanolamine are distributed asymmetrically along the plasma membrane. Phosphatidylcholine and sphingomyeline are found in the outer leaflet of plasma membrane whereas phosphatidylserine and phosphoethanolamine are found in inner leaflet. Cholesterol is distributed in both leaflets.

Multiple choice

Which one of the following pairs of hormones are the examples of those that can easily pass through the cell membrane of the target cell and bind to a receptor inside it?

  1. Insulin and glucagon

  2. Thyroxin and insulin

  3. Somatostatin and oxytocin

  4. Cortisol and testosterone
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Steroid hormones such as cortisol, testosterone, estradiol and progesterone mostly regulate gene expression and chromosome function by the interaction of hormone receptor complex with the genome. So, these can easily pass through the cell membrane of the target cell and bind to a receptor inside it.

Multiple choice

Choose the incorrect pair.

  1. Cadherin-Desmosome

  2. Selectin-Carbohydrate

  3. Integrin-Extracellular matrix protein

  4. Ig-stable cell junction
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Cadherin, selectin, integrin and Igs are considered as cell adhesion molecules. Cadherins have stable cell junction to form desmosome whereas integrin forms hemidesmosome and it binds to an extracellular matrix protein ligand. Ig binds to integrin as ligand but the cell junction is unstable.

Multiple choice

In Juxtacrine signalling, ______.

  1. signal molecules do not require physical contact of cells

  2. diffuse from that cell producing it

  3. classical cadherin signalling is involved

  4. do not interact with receptor protein of adjacent cells
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Classical cadherine is one of the examples of juxtacrine signalling. This type of signalling requires physical contacts of adjacent cells through interaction with receptor protein.