Genetic Engineering

Correct answer: A. Production of a product from the foreign gene

Expression means the gene produces a protein or useful product. For exams connect gene expression with a functional gene.

Correct answer: A. To signal the end of gene expression

Direct answer: Option A is correct. A terminator sequence normally signals that transcription or gene expression should stop at a particular point. In simple terms, genetic information is read to make an RNA molecule and, when applicable, a protein. The terminator acts like a stop instruction so the reading process ends at the proper place rather than continuing unnecessarily. The exact molecular details can differ between systems, but the general school-level role is termination of transcription or expression. Option A works because it describes this stop signal. Option B, giving light to a cell, is not the function of a DNA terminator; light production, when present in biotechnology, depends on particular genes and proteins. Option C, making RNA into fat, is not a definition of a terminator sequence and confuses genetic information with metabolism. Option D, making DNA into salt, is biologically meaningless and does not describe nucleic-acid regulation. Therefore the stated answer is sound. Memory trick: promoter means start, terminator means stop; do not confuse a terminator with a gene that produces a visible marker.

Correct answer: A. Extracting DNA from the source organism

To obtain a desired gene DNA is first extracted from the source. For exams consider gene isolation to begin with DNA extraction.

Correct answer: A. To deliver DNA into cells

Gene gun delivers DNA into cells using tiny particles. For exams remember it as a direct gene transfer method.

Correct answer: A. Into a cell using a very fine needle

In microinjection DNA is directly introduced into a cell. For exams remember it as a direct method.

Correct answer: A. Temporary small pores are formed

Electroporation creates temporary pores in the membrane using electric pulses. For exams remember it as a helper for DNA entry.

Correct answer: A. It is related to cutting and joining DNA

Recombinant DNA technology mainly involves cutting and joining DNA. For exams remember restriction enzyme and ligase as key enzymes.

Correct answer: A. Gene

Direct answer: Option A, gene, is correct. A gene is a particular stretch of DNA that contains hereditary information. That information may provide instructions for making a specific protein or may help determine a characteristic or trait through a biological process. Start from the basic idea: DNA is a long molecule made of information-bearing sequences; a gene is one meaningful information unit within that DNA. When a gene is expressed, its information can be copied into RNA and used in producing a protein, although not every gene directly codes for a protein. Option A is therefore the scientifically appropriate term. Option B, water, is a substance and not an information-carrying DNA segment. Option C, lipid, is a type of biological molecule used in membranes and other functions, not the name of a DNA information unit. Option D, mineral, is an inorganic nutrient or material and cannot mean a coded region of DNA. The wording says “for a specific protein,” so gene is the expected answer, even though genes may also code for functional RNA. Memory cue: DNA is the information library; a gene is one instruction or entry in that library.

Correct answer: A. Escherichia coli

Escherichia coli is a common host due to fast growth and easy handling. For exams remember it as a bacterial host.

Correct answer: A. Selectable marker

An antibiotic resistance gene helps select transformed cells. For exams remember it as an example of selectable marker.

Correct answer: A. Transformed cell

A cell that takes up a recombinant plasmid is called transformed. For exams remember the link between transformation and transformed cell.

Correct answer: A. To prevent unwanted effects on organisms and environment

Safety rules reduce uncontrolled effects and risks. For exams connect biosafety with responsible use.

Correct answer: A. To treat a disease linked with a faulty gene

Gene therapy tries to correct problems caused by faulty genes. For exams remember it as a medical application.

Correct answer: A. To deliver a gene into a cell

Viral vectors can deliver genetic material into cells. For exams remember them as gene delivery tools.

Correct answer: A. To know the order of bases in DNA

DNA sequencing reveals the exact order of bases. For exams connect it with gene identification and analysis.

Correct answer: A. Restriction enzyme and DNA cutting

Restriction enzymes cut DNA at specific sites. For exams carefully match enzymes with their functions.

Correct answer: D. Gel electrophoresis and protein synthesis

Gel electrophoresis is used to separate DNA fragments not for protein synthesis. For exams remember the main use of each technique.

Correct answer: A. Because it carries information for a desired trait

Direct answer: Option A is correct. In genetic engineering, a foreign gene means a gene introduced from another organism or source into the organism being modified. It is selected because its DNA sequence carries instructions for a desired product or characteristic, such as production of a useful protein, resistance to a condition, or another planned trait. The reasoning is: first identify the required trait; then find a gene associated with that trait; then introduce and express it in a suitable host, if the technique is successful. Option A states the real purpose of choosing the foreign gene. Option B is wrong because a gene is not selected because it is always colorless; colour is not the general criterion. Option C is wrong because genes do not all make water, and water production is not the aim of genetic engineering. Option D is wrong because stopping sound is unrelated to the genetic information being selected. The exact result depends on the gene, host and regulation, so “desired trait” is the correct general answer, not a claim that success is automatic. Memory cue: choose the gene for the feature you want.

Correct answer: A. Introducing it into a host cell

A recombinant plasmid is introduced into a host cell so it can replicate or express. For exams remember the order as joining gene then inserting into host.

Correct answer: A. Producing disease resistant crops

Genetic engineering can produce crops with useful traits. For exams remember both agricultural and medical applications.

Correct answer: A. Ethidium bromide

Ethidium bromide helps visualize DNA fragments. For exams connect it with DNA detection in gels.

Correct answer: B. It helps the vector replicate inside the host

Origin of replication allows copies of vector DNA to form. For exams connect it with plasmid replication.

Correct answer: C. Reverse transcriptase

Reverse transcriptase makes complementary DNA from RNA. For exams connect it with cDNA synthesis.

Correct answer: D. Entry of external DNA

Calcium chloride treatment makes bacterial cells able to take up DNA. For exams connect it with competent cell preparation.

Correct answer: A. A cell that can take up external DNA

A competent cell is able to take up external DNA. For exams remember it as a cell ready for transformation.