Sindh Mdcat Exclusive Course Biology Cell — Solved MCQs

Question 1

In cross-section each Centriole consist of nine (each in triplets) of:

Accepted Answer

C. Microtubules — Typical centrioles are made of 9 triplets of microtubules organized with radial symmetry. Microfilaments, also called actin filaments, are polymers of the protein actin that are part of a cell's cytoskeleton. Microvilli are microscopic cellular membrane protrusions that increase the surface area for diffusion and minimize any increase in volume, and are involved in a wide variety of functions. Intermediate filaments are important components of the cell's cytoskeletal system. They may stabilize organelles, like the nucleus, or they may be involved in specialized junctions. They are distinguished from "thin filaments" by their size (8-10 nm) and the fact that thin filaments are motile.

Question 2

The idea that opposed the idea of abiogenesis was proposed by?

Accepted Answer

C. Rudolph Virchow — Rudolph Virchow gave statement according to the cell theory that new cells are formed from division of pre-existing cells which opposed the concept of abiogenesis.

Question 3

Which of the following is NOT a difference that would allow one to distinguish between a prokaryotic and a eukaryotic cell? Presence of absence of the nucleus Presence or absence of the cell wall Membrane bound versus no membrane bound organelles

Accepted Answer

B. II only — Eukaryotic cells have nucleus and membrane-bound organelles, which is not the property of prokaryotes.The cell wall is not a distinguishing feature between prokaryotes or eukaryotes.

Question 4

They serve as a scaffold for formation of higher order chromatin structure:

Accepted Answer

A. Nucleosome — Nucleosomes are the basic packing unit of DNA built from histone proteins around which DNA is coiled. Nucleosomes are connected by short DNA segments (termed 'linker DNA') into nucleosomal arrays, which undergo short-range interactions with neighbouring nucleosomes to form chromatin fibres. Subsequent fibre–fibre interactions contribute to the high degree of compaction observed in the condensed chromosome. They serve as a scaffold for formation of higher order chromatin structure as well as for a layer of regulatory control of gene expressio.

Question 5

The finger like infoldings, which are formed by inner membrane of mitochondria, are called:

Accepted Answer

D. Cristae — Factual recall; 'Ribosomes' are organelles, that serve as sites of protein synthesis. 'Matrix' refers to the space confined by the inner mitochondrial membrane within the mitochondria. 'Porin' refers to a transport protein that enables the passive diffusion of certain molecules across a membrane. Cristea are finger-like infoldings, which are formed by the inner membrane of the mitochondria.

Question 6

Golgi complex is responsible for the formation of secretory granules in _ cell.

Accepted Answer

C. Pancreatic — Golgi complex takes part in the formation of secretory vesicles and helps in the transportation of material within or outside the cells. The "β cells" in the pancreatic islets are involved in the storage of insulin secretory granules and instant secretion of insulin.

Question 7

All of following are common molecules in membrane of all type of cells except:

Accepted Answer

B. Cholesterol — Globular proteins, polysaccharides and phospholipids are present in both prokaryotic and eukaryotic cell membranes while cholesterol is present only in eukaryotic cell membrane.

Question 8

Hydrophobic portion of plasma membrane is present in/at:

Accepted Answer

C. Inner core of plasma membrane — The outside of plasma membrane is surrounded by water molecules. The hydrophobic portions will be present away from water moelcules i.e., towards the inner core of plasma membrane. (Hydrophobic means water-repelling)

Question 9

Which of the following statement is incorrect regarding endoplasmic reticulum ?

Accepted Answer

E. Non

Question 10

A function that is related to smooth endoplasmic reticulum:

Accepted Answer

D. A and b — Calcium storage and steroid synthesis is the function of SER, while enzyme synthesis is the function of RER. Mechanical support is, however, related to both StR and RER.

Question 11

All of the following organelles contain DNA except:

Accepted Answer

A. Ribosomes — Nucleus contains genomic DNA. chloroplast and mitochondria have their own circular genomic DNA while ribosomes are made up of rRNA and protein.

Question 12

40S is the smaller ribosomal subunit associated with:

Accepted Answer

C. Yeast — E. coli. C. botulinum and T. pallidum are prokaryotic organisms having 30S smaller ribosomal subunit while yeast is eukaryotic organism having 40S smaller ribosomal subunit.

Question 13

Identify the correct pair from the following options:

Accepted Answer

D. Modification-Golgi apparatus — DNA replication occurs in nucleus, proteins are synthesized by RER and anaerobic respiration occurs in cytoplasm. Chemical modification of biological molecules is the function of Golgi apparatus.

Question 14

Modification of proteins and lipids into glycoproteins and glycolipids is the function of:

Accepted Answer

D. Golgi apparatus — The enzymes required for protein glycosylation are solely found in lumen of rough endoplasmic reticulum and Golgi complex. Hence, the more appropriate answer is " D". Golgi bodies are center for modifications and packaging.

Question 15

The transport of secretory proteins takes place through organelles in which of the following order?

Accepted Answer

A. RER-SER-Golgi apparatus -Secretory vesicles — Proteins are synthesized on RER, and then they are transported in with the help of SER. The modification of these proteins is done in the Golgi complex. Modified proteins are transported out of the cell in the form of secretory vesicles.

Question 16

Which of the following organelle is most abundant in those animal com cells which exhibit phagocytic activity?

Accepted Answer

C. Lysosomes — Lysosomes are most abundant in those cells which are specialized for phagocytic activities, for example WBCs

Question 17

Strictly speaking, autophagosomes are actually

Accepted Answer

B. Secondary lysosomes — Autophagosomes are secondary lysosomes which are formed by fusion of primary lysosome with autophagic vesicles. The process is known as autophagocytosis in which unwanted structures within the cell are engulfed. This process occurs during starvation or it occurs in routine to control number of specific organelles.

Question 18

It is a disease characterized by the accumulation of lipids in the brain cells leading to:

Accepted Answer

D. Tay-Sachs disease — Storage diseases are due to the absence of lysosomal enzymes. If a lysosomal enzyme responsible for lipid metabolism is absent, it leads to the accumulation of lipids in brain cells which causes mental retardation and death, such storage disease is known as Tay-Sachs disease.

Question 19

What is the specific name given to the biological membrane that surrounds the vacuoles?

Accepted Answer

D. Tonoplast — Vacuole is single membrane bounded organelle. This single membrane around vacuole is known as tonoplast.

Question 20

Which of the following proteins is present in microtubules?

Accepted Answer

A. Tubulin — Tubulin is the most abundant protein found in microtubules while myosin, actin and tropomyosin are found in microfilaments.

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