Which of the following genetically modified crops is resistant to insect pests due to the presence of a gene from Bacillus thuringiensis?

[Biotechnology-and-its-Applications] [class-xii ]

• Golden rice
• Bt cotton
• Flavr Savr tomato
• Roundup Ready soybean
Correct Option: B  [ Bt cotton ]

Remark: Bt cotton contains the cry gene from the bacterium Bacillus thuringiensis. This gene produces a protein toxic to certain insect pests (especially bollworms), providing resistance without harming the plant or humans.

The method of producing thousands of genetically identical plants through tissue culture in a very short duration is called:

[Biotechnology-and-its-Applications] [class-xii ]

• Somatic hybridisation
• Micro-propagation
• Clonal selection
• Anther culture
Correct Option: B  [ Micro-propagation ]

Remark: Micro-propagation is the method of producing thousands of plants through tissue culture in short durations. Each resulting plant is genetically identical to the original plant, hence they are called somaclones.

Which of the following components must be provided in the nutrient medium for an explant grown in vitro using tissue culture techniques?

[Biotechnology-and-its-Applications] [class-xii ]

• A carbon source like sucrose
• Inorganic salts and vitamins
• Growth regulators like auxins and cytokinins
• All of the above
Correct Option: D  [ All of the above ]

Remark: The nutrient medium must provide a carbon source such as sucrose, along with inorganic salts, vitamins, amino acids, and growth regulators like auxins and cytokinins.

Which part of a diseased plant is typically removed and grown in vitro to obtain virus-free plants?

[Biotechnology-and-its-Applications] [class-xii ]

• Root tips
• Axillary and apical meristem
• Leaf epidermis
• Vascular tissue
Correct Option: B  [ Axillary and apical meristem ]

Remark: Even if a plant is infected with a virus, the meristem (apical and axillary) is typically free of the virus. Hence, the meristem can be removed and cultured in vitro to obtain virus-free plants, a technique successfully used for banana, sugarcane, and potato.

The process where isolated naked protoplasts from two different varieties of plants are fused to generate a hybrid plant is called:

[Biotechnology-and-its-Applications] [class-xii ]

• Micro-propagation
• Genetic engineering
• Somatic hybridisation
• Clonal propagation
Correct Option: C  [ Somatic hybridisation ]

Remark: Somatic hybridisation is the process involving the fusion of naked protoplasts (cells with digested cell walls) isolated from two different plant varieties, leading to hybrid protoplasts that can grow to form somatic hybrids, such as the pomato.

What term is used for plants, bacteria, fungi, and animals whose genes have been altered by manipulation?

[Biotechnology-and-its-Applications] [class-xii ]

• Bio-piracy subjects
• Somaclonal variants
• Genetically Modified Organisms (GMO)
• Hybrid protoplasts
Correct Option: C  [ Genetically Modified Organisms (GMO) ]

Remark: Plants, bacteria, fungi, and animals whose genes have been altered by manipulation are called Genetically Modified Organisms (GMO).

One major application of genetic modification in crops is the development of tolerance to abiotic stresses. Which of the following is considered an abiotic stress that GM crops can tolerate?

[Biotechnology-and-its-Applications] [class-xii ]

• Nematode infestation
• Fungal blight
• Cold and drought
• Insect pests
Correct Option: C  [ Cold and drought ]

Remark: Genetic modification has made crops more tolerant to abiotic stresses such as cold, drought, salt, and heat.

Genetically Modified (GM) plants have improved efficiency of mineral usage. What is the consequence of this improvement?

[Biotechnology-and-its-Applications] [class-xii ]

• Increased reliance on chemical pesticides
• Prevention of early exhaustion of soil fertility
• Reduced post-harvest losses due to rot
• Enhanced protein content
Correct Option: B  [ Prevention of early exhaustion of soil fertility ]

Remark: GM plants have increased efficiency of mineral usage, which prevents the early exhaustion of the fertility of the soil.

The Bt toxin protein used to create insect-resistant plants is produced by which bacterium?

[Biotechnology-and-its-Applications] [class-xii ]

• Agrobacterium tumefaciens
• Escherichia coli
• Bacillus thuringiensis
• Meloidegyne incognitia
Correct Option: C  [ Bacillus thuringiensis ]

Remark: Bt toxin is produced by the bacterium called Bacillus thuringiensis (Bt). The gene for this toxin has been cloned and expressed in plants to provide resistance to insects.

Bt toxin proteins are known to kill certain groups of insects. Which group of insects includes flies and mosquitoes, targeted by some Bt strains?

[Biotechnology-and-its-Applications] [class-xii ]

• Coleopterans (Beetles)
• Lepidopterans (Budworm, Armyworm)
• Dipterans (Flies, Mosquitoes)
• Homopterans (Aphids, Leafhoppers)
Correct Option: C  [ Dipterans (Flies, Mosquitoes) ]

Remark: Bt strains produce proteins that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles), and dipterans (flies, mosquitoes).