The food chain starts with: MCQ with Answer and Explanation

Explanation:
Ergotism is caused by the fungus Claviceps purpurea, which infects the ovaries of rye and other grasses, replacing the seeds with hard, dark sclerotia (ergots). These sclerotia contain potent alkaloids (like ergotamine) that cause severe vasoconstriction and neurological symptoms in humans and animals consuming contaminated grain. Ustilago causes smut, and Puccinia causes rust.

Explanation:
In C3 plants (e.g., wheat, rice), CO₂ is fixed by the enzyme RuBisCO, which catalyzes the reaction between CO₂ and RuBP, producing two molecules of 3-phosphoglycerate (3-PGA), a three-carbon compound. In C4 plants, the primary acceptor is PEP, leading to four-carbon OAA. C3 plants are the most common, but are less efficient in hot, dry conditions due to photorespiration.

Explanation:
Solar energy is captured by photosynthetic autotrophs and converted to chemical energy, which then flows through food chains. Except for deep-sea hydrothermal vents relying on chemosynthesis, the sun powers virtually all life on Earth.