All Free Biology MCQs with Answers

• A. A polypeptide of 24 amino acids will be formed.
• B. Two polypeptides of 24 and 25 amino acids will be formed.
• C. A polypeptide of 49 amino acids will be formed.
• D. A polypeptide of 25 amino acids will be formed.

Explanation: UGA, UAG and UAA are three non sense (or termination) codons which do not code for any amino acid. If, in a gene encoding a polypeptide of 50 amino acids, the 25th codon is mutated to UAA or any of the termination codons, then the chain will be terminated at that place because it will become difficult for tRNA to bring an amino acid from the amino acid pool. So in that case a polypeptide of 24 amino acids will be formed.

• A. Ligase
• B. Primase
• C. DNA polymerase
• D. Endonuclease

Explanation: DNA ligase is a type of enzyme that catalyses the formation of a phosphodiester bond between two DNA molecules. This is the same type of bond that links the nucleotides in DNA. DNA ligase is used in a variety of cellular processes, including DNA replication, DNA repair, and recombinant DNA technology.Primase, DNA polymerase, and endonuclease are all involved in DNA replication, but they are not involved in joining bits of DNA.Primase is an enzyme that synthesises short RNA primers, which are needed to initiate DNA replication.DNA polymerase is an enzyme that synthesises DNA molecules from a DNA template.An endonuclease is an enzyme that cuts DNA molecules at specific sites.

• A. repetitive DNA
• B. RNA
• C. single copy DNA
• D. none of these

Explanation: Single copy DNA - because most protein-coding genes are present in the unique (single-copy) regions of the genome, while repetitive DNA mainly serves structural or regulatory functions.

• A. F. Sanger
• B. Beadle
• C. Tatum
• D. Ingram

Explanation: Ingram because Vernon Ingram discovered that sickle cell anaemia results from a single amino acid substitution (glutamic acid → valine) in the β-chain of hemoglobin, revealing the molecular basis of this genetic disease.

• A. GGGAUCUC
• B. GGGATCTC
• C. GGAAUCUC
• D. GGGGTCTC

Explanation: C pairs with G, A pairs with T in DNA, while A pairs with U in RNA. The question asks for the corresponding mRNA sequence after transcription of the DNA sequence. The C bases will correspond to G bases on the mRNA, T will correspond to A, G will correspond to C, whereas A will correspond to U and not T because the transcript is made up of RNA and not DNA, hence U takes the place of T.Option A describes the correct transcript:C C C T A G A GG G G A U C U C

• A. DNA polymerase
• B. DNA ligase
• C. Reverse transcriptase
• D. All of these

Explanation: Reverse Transcriptase is an enzyme that uses single-stranded RNA as a template to synthesize complementary double-stranded DNA (cDNA).This process is known as reverse transcription, and it occurs in retroviruses like HIV.Reverse transcriptase allows these viruses to insert their genetic material into the host's DNA.

• A. Chromatic body
• B. Nuclear region
• C. Nuclear Body
• D. All of above

Explanation: Nucleotides are present in chromosomes that are located in the nucleus. All these options are true because all of these contain genetic information.

• A. Haploid
• B. Diploid
• C. Single nucleus
• D. None of these

Explanation: Diploid organisms have cells with two sets of chromosomes (2n), one set inherited from each parent. Most multicellular organisms, including plants, animals, and fungi, are diploid for the majority of their life cycle. Diploid cells are present in the somatic cells of the organism and undergo mitosis for growth, development, and tissue repair.

• A. RNA Polymerase
• B. tRNA synthetase
• C. Aminocyle-tRNA synthetase
• D. tRNA ligase

Explanation: So, when it comes to linking a specific amino acid with its corresponding tRNA molecule during protein synthesis, there's a special enzyme called aminoacyl-tRNA synthetase that does the job. It acts like a matchmaker, making sure that the right amino acid is paired with the right tRNA molecule. This process is crucial for building proteins correctly.

• A. It should be able to express itself in the form of 'Mendelian characters
• B. It should be able to generate its replica
• C. It should be unstable structurally and chemically
• D. It should provide the scope for slow changes that are required for evolution

Explanation: Genetic material should be structurally and chemically stable; otherwise, its expression will change. This will lead to a loss of several metabolic functions, etc. The genetic material in any living organism consists of the fundamental information required to carry out various life processes related to development, growth, metabolism, reproduction, etc. DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are known to constitute the genetic material in all organisms. The genetic material is stabilised using various interactions like van der Waals forces, hydrophobic interactions, and hydrogen bonds. The structural and chemical instability of the genetic material will result in impairment of cell function, mutations, and transformation to cancerous cells or diseases.