Biology 9700 · AS & A Level · Principles of genetic technology

Principles of genetic technology — practice question

The pink bollworm moth, $\textit{Pectinophora gossypiella}$, is a pest of cotton crops. Its population can be lowered by releasing very large numbers of sterile male moths into cotton fields. The sterile male moths mate with wild females from the cotton fields, but no offspring are produced. Over a three-year period, 20 million genetically modified (GM) sterile male moths were released in the USA. Each insect contained a gene coding for a red fluorescent protein (DsRed) taken from a species of reef coral. The inserted DNA also included a promoter.
(a(i))[2]

Explain why, in gene technology, genes for fluorescent proteins such as DsRed are now used more often as markers than genes for antibiotic resistance.

(a(ii))[3]

Explain why a promoter has to be included when a gene is transferred from a coral into an insect.

(a)

Explain the reason that, in gene technology:

(b)

DsRed is visible at every stage of the moth life cycle, but whether the gene is present in a particular individual can be confirmed by genetic fingerprinting using electrophoresis.

(b(i))[4]

Outline the principles of gel electrophoresis.

(b(ii))[2]

Explain how the presence of the gene for DsRed in a moth can be confirmed after electrophoresis has been carried out.

(c)[2]

DsRed allows sterile male moths to be distinguished from wild moths when they are caught in an insect trap in a field of cotton plants. Suggest why it is important to know whether a moth caught in such a trap is a released sterile male or a wild insect.

(d)[2]

The United States Department of Agriculture has ruled that releasing sterile insects to control insect pest numbers is environmentally preferable to all other alternatives. Suggest what information would be needed to decide whether the release of the sterile male moths, carrying the gene for DsRed, has a harmful effect on the environment.

Worked solution & mark scheme

This 15-mark question has a full step-by-step worked solution and mark scheme. One marking point: Simpler to identify / screen

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI