All Free Biology MCQs with Answers

4371. These are easily soluble in water:

• A. Carbohydrates
• B. Monosaccharides
• C. Oligosaccharides
• D. Polysaccharides

Explanation: Monosaccharides such as glucose and fructose are crystalline solids at room temperature, but they are quite soluble in eater, each molecule having several OH groups that readily engage in hydrogen bonding.

4372. All carbon atoms in a monosaccharide _ have hydroxyl group.

• A. Except one
• B. Except two
• C. Without exception
• D. Except last

Explanation: That is why they are called polyhydroxy aldehydes or polyhydroxy ketones.

4373. Aldo-triose differs from keto-triose with respect to:

• A. Number of carbon atoms
• B. Position of carbon atoms
• C. Position of hydrogen atoms
• D. Position of hydrogen and oxygen atoms

Explanation: If two hydrogen atoms from carbon number two of aldotriose are shifted to carbon number one it becomes Keto triose and vice versa.

4374. Pick up the keto-triose:

• A. DAP
• B. RuBP
• C. G.6.P
• D. G.3.P

Explanation: Dihydroxyacetone phosphate is a ketotriose.

4375. Pick up the triose:

• A. Glyceraldehyde
• B. Ribose
• C. Fructose
• D. Glucose

Explanation: It is an aldotriose i.e. a monosaccharide of three carbon atoms.

4376. _ and _ are most common monosaccharides.

• A. Trioses, tetroses
• B. Tetroses, pentoses
• C. Pentoses, hexoses
• D. Hexoses, heptoses

Explanation: Pentoses being part of nucleic acids and hexoses (glucose) being substrate for aerobic respiration are most common carbohydrates of nature.

4377. It is an aldo-hexose:

• A. Fructose
• B. Glucose
• C. Ribulose
• D. Ribose

Explanation: Having aldehyde group and six carbon atoms glucose is an aldohexose.

4378. Most of the monosaccharides form a _ when in solution.

• A. Straight chain
• B. Branched chain
• C. Ring structure
• D. Folded structure

Explanation: In solution form non cyclic monosaccharides acquire cyclic form and two types of ring structures are formed i.e. furan (5 cornered) and pyranose (6 cornered).

4379. Glucose forms a six cornered ring called:

• A. Glucopyranose
• B. Fructofuranose
• C. Ribofuranose
• D. Deoxyribofuranose

Explanation: Six cornered ring of glucose is also called glucopyranose.

4380. _ corners of ribofuranose are occupied by carbon.

• A. Three
• B. Two
• C. Four
• D. Five

Explanation: Out of five corners one is occupied by oxygen and rest of the four corners are occupied by carbon atoms whereas, and fifth carbon remains outside the ring.