All Free Biology MCQs with Answers

• A. Animals, with inferior traits
• B. Transgenic mice for testing the safety of the polio vaccine before use in humans
• C. Animals, that have the same genetic constitution
• D. None of the above

Explanation: Transgenic mice are being formed for use in testing the safety of vaccines before they are used on human beings. Transgenic mice are being used to test the safety of the polio vaccine. Many transgenic animals are developed to increase our understanding of how genes contribute to the development of disease so, that investigation of new treatments for diseases is made possible. Now transgenic models exist for many human diseases such as cancer, cystic fibrosis, rheumatoid arthritis, Alzheimer's disease, hemophilia, thalassemia, etc. Therefore, the correct answer is option B.

• A. Streptomycin
• B. Ampicillin and Tetracycline
• C. Tetracycline and doxycycline
• D. Ampicillin

Explanation: Factual recall;pBR322 is base pairs in length and has two antibiotic resistance genes - the gene 'bla', encoding the ampicillin resistance (AmpR) protein, and the gene 'tetA', encoding the tetracycline resistance (TetR) protein.

• A. Replication
• B. Recombination
• C. Gene mapping
• D. None of these options is correct

Explanation: Option A: Replication refers to the process of copying DNA during cell division and is not directly related to gene mapping.Option B: Recombination is the process by which genetic material is exchanged between chromosomes during meiosis, and can be used to map genes to particular regions of a chromosome. However, it is not the sole process involved in gene mapping.Option C: Gene mapping describes the methods used to identify the locus of a gene and the distances between genes. Gene mapping can also describe the distances between different sites within a gene. The essence of all genome mapping is to place a collection of molecular markers onto their respective positions on the genome. Option D: As explained above this option is incorrect.

• A. RNA
• B. Protein
• C. Carbohydrate
• D. DNA

Explanation: Primers are small, chemically synthesised oligonucleotides that are complementary to the sequences, present at 3' end of the template DNA. They hybridise to the target DNA region, one to each strand of the double helix. These primers are oriented with their ends facing each other allowing synthesis of the DNA towards one another. Thus, the primer is a short, single-stranded DNA sequence which hybridises with the template DNA and defines the region of the DNA that needs to be amplified.

• A. Polymerase chronic reaction
• B. Polymerase chain reaction
• C. Polymerase copy reaction
• D. Polymerase cross-reaction

Explanation: Polymerase chain reaction (abbreviated PCR) is a laboratory technique for rapidly producing (amplifying) millions to billions of copies of a specific segment of DNA, which can then be studied in greater detail.

• A. Adenosine transcriptase
• B. Adenosine transaminase
• C. Adenosine polymerase
• D. Adenosine deaminase

Explanation: Adenosine deaminase deficiency (ADA deficiency) is an inherited condition that damages the immune system and is a common cause of severe combined immunodeficiency (SCID).

• A. Restriction Exonuclease
• B. Restriction Ligase
• C. Restriction Endonuclease
• D. DNA polymerase

Explanation: Restriction enzyme, also called restriction endonuclease, a protein produced by bacteria that cleaves DNA at specific sites along the molecule. In the bacterial cell, restriction enzymes cleave foreign DNA, thus eliminating infecting organisms.Specific endonucleases, also called restriction endonucleases, are available that cleave specific sites within a DNA sequence. Exonuclease is usually non-specific and does not have defensive properties against the entry of pathogenic microbes.Ligase is an enzyme that uses ATP to form bonds, and is used in recombinant DNA cloning to join restriction endonuclease fragments that have annealed. (There is no such thing as restriction ligase)A DNA polymerase is a member of a family of enzymes that catalyze the synthesis of DNA molecules from nucleoside triphosphates, the molecular precursors of DNA.

• A. Readily incorporate cloned DNA
• B. Capable of automatic replication
• C. Capable of being isolated from genomic DNA
• D. All of these

Explanation: Scientists have taken advantage of plasmids to use them as tools to clone, transfer, and manipulate genes. Therefore, all of these are correct.

• A. Both sense and anti­sense RNA
• B. A particular hormone
• C. An antifeedant
• D. A toxic protein

Explanation: Many nematodes live in plants and animals including human beings. a nematode Meloidogyne incognita infects tobacco plants and causes a great reduction in yield. A novel strategy was adopted to prevent this infection that was based on the process of RNA interference. RNA interference is the phenomenon of inhibiting the activity of a gene by the synthesis of RNA molecules complementary to the mRNA. The normal messenger RNA of a gene is said to be 'sense' because it carries the codon that is 'read' during translation. Normally the complement to the mRNA 'sense' strand will not contain a sequence of codons that can be translated to produce a functional protein thus this complementary stand is called antisense RNA. The antisense RNA and messenger RNA molecules will anneal to form duplex RNA molecules and the duplex RNA molecules cannot be translated. Thus the presence of antisense RNA will block the translation of the Messenger RNA of the affected gene. Recent evidence indicates that these RNA duplexes are often rapidly degraded in Vivo.

• A. Producing a petrol­like fuel from rice
• B. Alleviation of vitamin A deficiency
• C. Pest resistance
• D. Herbicide tolerance.

Explanation: Golden rice is a transgenic variety of rice (Oryza sativa) which contains good quantities of B­-carotene (provitamin A-inactive state of vitamin A). B­-carotene is a principal source of vitamin A. Since the grains of this rice is yellow in colour due to B­-carotene and commonly called golden rice.