Consider statements about biotechnology: 1. Agrobacterium tumefaciens is a natural plant genetic engineer. 2. Bt toxin is active in the acidic gut of insects. 3. RNAi is used to silence specific genes. Which are correct? MCQ with Answer and Explanation
Consider statements about biotechnology: 1. Agrobacterium tumefaciens is a natural plant genetic engineer. 2. Bt toxin is active in the acidic gut of insects. 3. RNAi is used to silence specific genes. Which are correct?
A. 1 and 3 only
B. 2 and 3 only
C. 1, 2 and 3
D. 1 and 2 only
Answer: Option A
Solution (By JKExamLibrary)
Agrobacterium tumefaciens is a soil bacterium that naturally transfers a segment of its Ti plasmid into plant cells, making it a natural genetic engineer used to create transgenic plants. RNA interference (RNAi) is a cellular defense mechanism used in biotechnology to silence specific mRNA molecules, preventing gene expression. Bt toxin is inactive in the insect gut until it encounters the alkaline pH, which solubilizes and activates it. Thus, statements 1 and 3 are correct.
Explanation:
Vitamin D (calciferol) promotes the absorption of calcium and phosphorus from the small intestine by inducing synthesis of calcium-binding proteins. It is synthesized in the skin upon exposure to UV light and then activated in the liver and kidneys. Deficiency leads to rickets in children and osteomalacia in adults. Vitamin A is for vision, C for collagen, B₁ for energy metabolism.
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