All Free Biology MCQs with Answers

4431. The most stable tertiary configuration is due to:

• A. Ionic bonds
• B. Hydrogen bonds
• C. Disulphide bonds
• D. Hydrophobic interaction

Explanation: Hydrophobic amino acids are buried inside while the hydrophilic amino acids are on the surface of the molecule until the aqueous medium remains intact.

4432. Quaternary structure is maintained by:

• A. Ionic bonds
• B. Hydrophobic interaction
• C. Hydrogen bonds
• D. Ionic bonds, Hydrogen bonds and Hydrophobic interaction

Explanation: Quaternary structure is maintained by ionic bonds, hydrogen bonds, and hydrophobic interactions. Ionic bonds are formed between oppositely charged amino acids. Hydrogen bonds are formed between hydrogen atoms that are covalently bonded to electronegative atoms, such as oxygen or nitrogen. Hydrophobic interactions are formed between nonpolar amino acids that are repelled by water. All three of these types of interactions play a role in stabilizing the quaternary structure of proteins. Ionic bonds and hydrogen bonds are relatively strong interactions, while hydrophobic interactions are weaker. However, hydrophobic interactions can be very important for stabilizing the quaternary structure of proteins that contain a large number of nonpolar amino acids.

4433. Hemoglobin, the oxygen carrying protein of red blood cells exhibits:

• A. Primary structure
• B. Secondary structure
• C. Tertiary structure
• D. Quaternary structure

Explanation: A hemoglobin molecule stands at quaternary level of proteins. It involves four chain of tertiary level i.e. two alpha chains and two beta chains.

4434. Pick up the fibrous protein:

• A. Keratin
• B. Hemoglobin
• C. Enzyme
• D. Antibodies

Explanation: Keratin is that structural protein which is used to make our hair and nails and all structural proteins including keratin are included in fibrous category of proteins.

4435. Pick up the globular protein:

• A. Keratin
• B. Fibrin
• C. Collagen
• D. Hemoglobin

Explanation: All functional proteins are globular proteins including hemoglobin.

4436. In a DNA duplex, ten base pairs cover the length of 34Ao, what will be distance in between two consecutive base pairs:

• A. 3.4 Ao
• B. 34 Ao
• C. 0.34 Ao
• D. 340 Ao

Explanation: Dividing 34 A0 (3.4 nm) by 10, we get 3.4 A0 or 0.34 nm.

4437. If kidney cells of carp fish have 3.3 picograms DNA per nucleus, the amount of DNA in sperm cell of carp fish will be:

• A. 1.3 picograms
• B. 2.3 picograms
• C. 1.6 picograms
• D. 2.4 picograms

Explanation: As kidney cells are diploid (2n) as compared to haploid (n) sperm cells.

4438. In the chromosomes of the bacterium E. coli, each of the paired strand of DNA contains about:

• A. 5 million bases
• B. 5 billion bases
• C. 0.5 million bases
• D. 50 million bases

Explanation: These are 5 million bases arranged in a particular linear order.

4439. _ is synthesized by _ in a process known as transcription.

• A. RNA, DNA
• B. RNA, RNA
• C. DNA, DNA
• D. DNA, RNA

Explanation: RNA is synthesized through the process of transcription by using DNA as a template.

4440. RNAs are synthesized in the _ and then are moved out in the _ to perform their specific functions.

• A. Cytoplasm, Nucleus
• B. Nucleus, Cytoplasm
• C. Nucleus, Nucleus
• D. Cytoplasm, Cytoplasm

Explanation: Transcription occurs in nucleus by using chromosomal DNA as template, then mRNA transcript is moved on through nuclear pores to the cytoplasm where transcribed message is translated into appropriate polypeptide proteins by using all three types of RNAs.