Fungal cell walls contain chitin, a polymer of N-acetylglucosamine, which also forms the exoskeleton of arthropods. Plant cell walls are primarily cellulose, bacterial cell walls contain peptidoglycan (except Mycoplasma). Hemicellulose is a component of plant cell walls along with cellulose. Chitin provides structural strength and rigidity to fungi.
Explanation:
Selman Waksman and colleagues isolated streptomycin from Streptomyces griseus in 1943, the first effective treatment for tuberculosis. Fleming discovered penicillin, Pasteur developed vaccines, Koch identified TB bacterium.
Explanation:
Beta-carotene is a precursor of vitamin A (provitamin A) and imparts an orange color to carrots, pumpkins, and sweet potatoes. Lycopene gives red color to tomatoes, chlorophyll is green, xanthophyll is yellow. Beta-carotene is an antioxidant and is important for vision and immune function.
Explanation:
Active transport uses energy (usually ATP) to pump molecules or ions across a membrane against their electrochemical gradient, e.g., Na⁺/K⁺ pump. Diffusion, osmosis, and facilitated diffusion are passive processes that move substances down their gradient without energy expenditure.
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