Practicing Success

Target Exam

CUET

Subject

Biology

Chapter

Biotechnology and its Applications

Question:

Read the passage and answer the following questions :

Genetic modification (GM) has been utilized to create custom-designed plants that serve as alternative resources for industries, producing starches, fuels, and pharmaceuticals. Biotechnology in agriculture has numerous applications, one of which involves developing pest-resistant plants to reduce the reliance on chemical pesticides. This is achieved by introducing the Bt toxin gene from the bacterium Bacillus thuringiensis (Bt) into plants, creating what is known as a bio-pesticide. Notable examples include Bt cotton, Bt corn, rice, tomato, potato, and soybean.Bt toxin is a naturally occurring insecticidal protein produced by certain strains of Bacillus thuringiensis. During a specific phase of their growth, these bacteria form protein crystals containing toxic substances. These crystals harbor inactive protoxins, which, when activated, become lethal to targeted insects. Different Bt toxin genes, such as cryIAc and cryIIAb, have been isolated and introduced into various crop plants, depending on the crop and the specific pests targeted, as Bt toxins are often insect-group specific. By incorporating these genes, plants gain inherent resistance to insects without the need for synthetic insecticides. This advancement in biotechnology has significant implications for sustainable and eco-friendly agricultural practices.

What is the significance of Bt toxin genes being insect-group-specific?

Options:

They can only be used in certain climates.

They target specific pests without affecting other insects.

They enhance plant growth only in certain soil types.

They increase crop yield irrespective of pest presence.

Correct Answer:

They target specific pests without affecting other insects.

Explanation:

The correct answer is Option (2)-They target specific pests without affecting other insects.

The significance of Bt toxin genes being insect-group specific is that they can target specific pests without affecting other insects. Bacillus thuringiensis (Bt) is a bacterium that produces proteins called Bt toxins, which are toxic to certain insects. These toxins have been utilized in biotechnology to create pest-resistant plants, reducing the need for chemical insecticides. One such example is Bt cotton, where the Bt toxin gene is cloned from the bacterium and expressed in the plant.

Specific Bt toxin genes were isolated from Bacillus thuringiensis and incorporated into the several crop plants such as cotton .The choice of genes depends upon the crop and the targeted pest, as most Bt toxins are insect-group specific. The toxin is coded by a gene cryIAc named cry. There are a number of them, for example, the proteins encoded by the genes cryIAc and cryIIAb control the cotton bollworms, that of cryIAb controls corn borer.

Reduced Impact on Non-Target Insects:

Because Bt toxins are specific to certain insect groups, they do not harm beneficial insects and other non-target organisms. This is important for maintaining biodiversity and the ecological balance in agricultural environments. Beneficial insects, such as pollinators (bees) and natural predators of pests (ladybugs), are not affected by Bt toxins, which allows them to continue their beneficial roles in the ecosystem.