All Free Biology MCQs with Answers

1821. Pancreas produces secretory granules that help in digestion. These granules after passing through endoplasmic reticulum are pinched off from ________ surface of Golgi apparatus:

• A. Forming face
• B. Maturating face
• C. Any of them
• D. None of these

Explanation: The Golgi apparatus receives materials at its cis or forming face and modifies, sorts and packages them toward its trans or maturing face. Secretory granules therefore pinch off from the maturing face for transport to the cell surface. Students may choose the forming face because it is the side connected functionally with the endoplasmic reticulum, but that side mainly receives vesicles.

1822. 60S and 40S subunit combine to form ________ particle.

• A. 100 S
• B. 90 S
• C. 80 S
• D. 70 S

Explanation: In eukaryotic cells, the 60S large ribosomal subunit combines with the 40S small subunit to form an 80S ribosome. The Svedberg unit measures sedimentation behaviour, so the values are not added arithmetically as ordinary mass units, but the assembled ribosome is designated 80S. Students often choose 100S by simply adding 60S and 40S, overlooking the meaning of S units.

1823. Spherical or tubular membranes which separate the material present in endoplasmic reticulum from that of cytoplasmic material are called__________?

• A. Cytosol
• B. Cisternae
• C. Polysomes
• D. Cristae

Explanation: Cisternae are the flattened or tubular membrane-bound spaces of the endoplasmic reticulum that enclose its lumen and separate it from the cytosol. Cristae are folds of the inner mitochondrial membrane, while cytosol is the fluid portion of the cytoplasm. Students may choose cristae because both terms describe internal membranes, but cristae belong to mitochondria, not ER.

1824. Magnifying power of electron microscope as compared to eye is____________?

• A. 500 X
• B. 250000X
• C. 500000X
• D. 250X

Explanation: An electron microscope can magnify objects to about 250,000 times the unaided eye, while also providing much greater resolution. The likely mistake is choosing 500,000X, which may represent an upper magnification figure for some instruments but is not the standard comparison used in this question.

1825. In cell fractionation various components of cells including its organelles can be isolated in different layers depending upon____________?

• A. Their physical properties like size & weight.
• B. Physical properties of the medium like its density.
• C. Their electrical properties like their charges
• D. Both a and b

Explanation: Cell fractionation separates organelles according to physical properties such as size and mass, while the density of the surrounding medium also affects how quickly they sediment. Thus both a and b are involved. Students may choose a alone by overlooking the role of the medium's density.

1826. Resolution power of a compound microscope is___________?

• A. 2.0 ?m
• B. 2-4 A
• C. 24 ?m
• D. 24 A

Explanation: The usual resolving power of a compound light microscope is about 2.0 µm, meaning two points closer than this cannot be distinguished separately. Students may choose 2-4 Å, but angstrom-scale resolution belongs to much more powerful instruments such as electron microscopes.

1827. Who opposed the idea the cell is an empty space bounded by thick wall?

• A. Lorenz Oken
• B. Schwann
• C. Robert Brown
• D. Rudolph Virchow

Explanation: Robert Brown's discovery of the nucleus showed that a cell is not merely an empty space enclosed by a wall, because it contains an internal, organized structure. Students may choose Schwann because he helped formulate cell theory, but Brown's observation more directly opposed the empty-cell idea.

1828. Factory of Ribosomal systhesis is__________?

• A. Cytoplasm
• B. Nucleus
• C. Nucleolus
• D. Endoplasmic reticulum

Explanation: The nucleolus makes ribosomal RNA and combines it with proteins to form ribosomal subunits, so it is regarded as the factory for ribosome synthesis. Students may choose the nucleus because the nucleolus lies inside it, but the nucleus as a whole does not perform this specialized function.

1829. Cellular organelles related with H2O2 are___________?

• A. Glyoxisomes
• B. Lysosomes
• C. Peroxisomes
• D. Ribosomes

Explanation: Peroxisomes contain oxidase and catalase enzymes that produce and then break down hydrogen peroxide, H2O2, during oxidation reactions. A student may choose lysosomes because both are membrane-bound organelles, but lysosomes digest materials using hydrolytic enzymes and are not the main organelles for H2O2 metabolism.

1830. Centrioles are composed of ________ triplets of microtubules.

• A. 3
• B. 9
• C. 10
• D. 15

Explanation: A centriole has nine peripheral triplets of microtubules arranged in a cylinder, written as 9 + 0 because it lacks a central pair. The common mistake is choosing 3 by counting the microtubules in each triplet instead of counting the nine triplets around the centriole.