Assertion (A): Red blood cells lack a nucleus in mammals. Reason (R): The absence of a nucleus allows more space for hemoglobin, increasing oxygen-carrying capacity. MCQ with Answer and Explanation

Explanation:
DNA contains the pentose sugar 2'-deoxyribose, which lacks an oxygen atom on the 2' carbon compared to ribose in RNA. This structural difference makes DNA more chemically stable and suitable for long-term genetic storage. Nucleotides consist of a nitrogenous base, a pentose sugar, and a phosphate group. Ribose is present in RNA.

Explanation:
Lysosomes contain hydrolytic enzymes that can digest cellular components and even the whole cell if they burst, a process called autolysis. Hence, they are called suicide bags. They also perform autophagy and phagocytosis. Peroxisomes detoxify peroxides, Golgi modifies proteins, ribosomes synthesize proteins. Lysosomes are formed from the Golgi apparatus.

Explanation:
Streptomycin is an antibiotic produced by the bacterium Streptomyces griseus. Penicillin and cephalosporins are from fungi (Penicillium and Cephalosporium). Griseofulvin is a fungal antibiotic. Streptomycin is a broad-spectrum aminoglycoside, effective against gram-negative bacteria and Mycobacterium tuberculosis. It inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit.