Question

The proteins encoded by Cry I Ac and Cry II Ab genes control.
(A) Boll worms
(B) Pinworms
(C) Book worms
(D) Nematodes

Answer 1

Hint: The proteins produced by Bacillus Thuringiensis (Bt) bacterium are known as cry proteins. These proteins are produced during sporulation. They have insecticidal properties and they are capable of killing many crop pests. Hence, they are also known as insecticidal toxins or insecticidal proteins.

Complete answer:
Cry proteins are used worldwide to efficiently control the crop pests. They are effective against insect species belonging to orders:
> Lepidoptera (moths and butterflies)
> Diptera (mosquitoes and flies)
> Coleoptera (beetles)
> Hymenoptera (wasps, sawflies bees, and ants)
> Nematodes
Cry proteins work by damaging the digestive tract of the pest. When a pest ingests cry protein crystals, the alkaline pH of their digestive tract makes the crystals soluble. As a result, the crystals are acted upon by the pest gut which allows the crystals to release toxins. These toxins now enter the gut wall of pests. This damages the digestive tract so that the pest stops feeding. This in turn results in death of pests due to starvation. Sometimes, live Bt bacteria can also kill the pests by entering and colonizing them.
Cry proteins are a large family of toxins. They include cry toxins such as Cry I Aa, Cry I Ac, Cry II Aa, Cry II Ab, Cry III Aa, Cry III Ba, Cry IV Aa, and Cry IV Ba which are encoded by specific genes. Collectively cry toxins can kill a number of pests, but individually each toxin is target specific that can kill specific organism/s. For example - the proteins/toxins encoded by Cry I Ac and Cry II Ab genes kill the pink bollworm of cotton.

So the correct answer is Option (A) Boll worms.

Note:
Cry proteins produced by Bacillus Thuringiensis (BT) bacterium are in crystal form. Hence, they are called cry (cry for crystal) proteins. These proteins are encoded by genes called cry genes. These genes are isolated and inserted in many crops such as cotton to provide insecticidal properties to the crop. These crops are called genetically modified crops (Example Bt cotton produced by inserting cry genes in cotton crop).