▶️ Answer/Explanation
The production of human insulin via genetic engineering follows a logical sequence of molecular biology techniques. First, the bacterial plasmid (the vector) must be opened using restriction enzymes ($1$) so the human insulin gene can be spliced in. Once the recombinant plasmid is formed, it is inserted into host bacteria ($3$) through a process called transformation. These transgenic bacteria are then cultured to allow them to multiply ($4$), creating a large population. Finally, the machinery of the grown bacteria is used for the protein expression ($2$), where the human gene is transcribed and translated into actual insulin protein.
✅ Answer: (A)
▶️ Answer/Explanation
Energy enters most food chains as light energy from the Sun, which plants (producers) capture during photosynthesis to create glucose. This light energy is converted and stored as chemical energy within the organic molecules of the plant. When a consumer eats the plant, or another animal, this stored chemical energy is what gets transferred along the chain. While energy is lost as heat to the environment at each level, the actual transfer of useful energy between organisms occurs in chemical form.
✅ Answer: (C)
▶️ Answer/Explanation
The primary source of energy for almost all life on Earth is the Sun. In this food chain, lettuce acts as a producer. Producers use a process called photosynthesis to capture light energy and convert it into chemical energy stored in glucose. While plants like lettuce absorb nutrients from the soil and water for growth, these are not the source of the energy itself. The snails, ducks, and humans then obtain this energy by consuming the level below them. Therefore, the original energy entering this specific biological system started with solar radiation.
✅ Answer: (C)