Which of these are a type of mutation?

Correct Answer: D

Rationale: The correct answer is D: recombination. Recombination is a type of mutation that involves the exchange of genetic material between two DNA molecules. This process can lead to genetic variation and evolution. Base substitution (A) is a point mutation where one base is replaced by another. Translocation (B) involves the movement of a segment of DNA to another location in the genome. Insertion sequences (C) are short segments of DNA that can move within the genome but are not considered a type of mutation. Recombination (D) is the only choice directly related to a type of mutation involving the exchange of genetic material.

Correct Answer: A

Rationale: Step-by-step rationale: 1. During an allergic reaction, allergens trigger the release of IgE antibodies. 2. The allergen binds with IgE antibodies, leading to the activation of mast cells. 3. Activated mast cells release histamine and other inflammatory mediators. 4. This cascade of events causes allergic symptoms. Therefore, option A is correct as it accurately describes the initial binding of allergen with IgE antibodies. Option B is incorrect as mast cells are activated, not deactivated. Option C is incorrect as the body is hypersensitive, not immunodeficient. Option D is incorrect as it is mast cells, not Helper T cells, that release histamine.

Correct Answer: B

Rationale: DNA ligase catalyzes the formation of phosphodiester bonds between the sugar-phosphate backbone of DNA strands. The correct answer is B because DNA ligase specifically acts on these phosphodiester bonds to seal nicks in the DNA molecule during processes like DNA replication and repair. Option A, ester bonds, are not formed by DNA ligase. Option C, phosphohydroxyl bonds, is not a recognized type of bond in DNA ligation. Option D, amide bonds, are not formed by DNA ligase either. Thus, the correct answer is B as it aligns with the known function of DNA ligase.

Correct Answer: B

Rationale: The correct answer is B: increased yield. If the amount of template in a PCR falls significantly below the optimal amount, it would be expected to result in a decreased yield rather than an increased yield. The template is essential for DNA amplification in PCR, and a lower amount would lead to fewer copies being produced. Non-specific amplification (choice A) can occur if there is too much template or incorrect primer annealing. Allelic drop-out (choice C) is likely to happen if there is insufficient template present to amplify all alleles. Longer targets amplifying poorly or failing (choice D) is also a common outcome when template concentration is low. Therefore, the least expected outcome would be an increased yield as that goes against the principle of PCR amplification.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.