Genetic Engineering

Correct answer: C. Adenine pairs with thymine and guanine pairs with cytosine

Complementary base pairing helps identify target DNA. For exams remember A with T and G with C.

Correct answer: B. Identifying the desired gene

Usually the desired gene is identified first. For exams remember the order as identification then isolation then insertion into a vector.

Correct answer: A. To transfer it into a host

The desired gene gives the trait that needs to be added to an organism. For exams remember gene identification as an important first step.

Correct answer: A. Because they cut DNA at specific sites

Restriction enzymes cut DNA at recognition sites. For exams remember them as DNA cutting enzymes.

Correct answer: A. Because it can carry a foreign gene into a host cell

A plasmid is a small DNA molecule that can carry foreign genes. For exams remember plasmid as a common gene vector.

Correct answer: A. To allow DNA replication or expression

A host cell can multiply or express recombinant DNA. For exams think of the host as a gene workshop.

Correct answer: A. Specific DNA segment

PCR makes many copies of a specific DNA segment. For exams remember PCR as DNA amplification technique.

Correct answer: A. Selectable marker

A selectable marker helps identify modified cells. For exams remember antibiotic resistance gene as its example.

Correct answer: A. A cell prepared for DNA uptake

A competent cell is a host cell that has been made capable of taking up foreign DNA from its surroundings. In bacterial transformation, competence may be induced by chemical methods, such as treatment with divalent cations and heat shock, or by electroporation, which briefly increases membrane permeability. Therefore option A is correct. The word competent refers specifically to increased ability for DNA uptake; it does not mean that the cell makes water, digests protein, or contains only chlorophyll. Once DNA enters, other requirements still determine whether the vector survives, replicates, expresses a gene, or is selected successfully. Competence is thus an entry condition, not the complete outcome of transformation.

Correct answer: A. While handling DNA samples obtained from humans

Genetic-data privacy is governed by ethical handling of information that may identify a person or reveal sensitive inherited characteristics. Human DNA can contain information about identity, health-related variants, family relationships, or ancestry, even when the immediate laboratory activity is only restriction digestion. Therefore, option A is correct: access, storage, labelling, sharing, and disposal of such samples should follow consent, institutional approval, and applicable privacy rules. Buying agarose, observing enzyme colour, or boiling water does not itself involve identifiable genetic information and is not the relevant privacy issue.