Which of the following statements about the food chain is correct? MCQ with Answer and Explanation

Explanation:
Penicillin and other beta-lactam antibiotics (cephalosporins, carbapenems) inhibit the transpeptidase enzyme involved in cross-linking peptidoglycan, weakening the cell wall and causing bacterial lysis. Tetracycline and streptomycin inhibit protein synthesis by acting on ribosomes. Chloramphenicol also inhibits protein synthesis. Penicillin is most effective against actively dividing gram-positive bacteria.

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:
Porifera (sponges) are characterized by the presence of a complex water canal system (canal system) used for food gathering, respiratory exchange, and waste removal. Water enters through numerous small pores called ostia and exits through a large opening called the osculum. They are mostly marine and asymmetrical.