Which of the following animals belongs to the phylum Annelida? MCQ with Answer and Explanation

Explanation:
Viruses are non-living outside a host cell and must hijack a host's cellular machinery to replicate, making them obligate intracellular parasites. They contain either DNA or RNA, not both (except some rare cases). They lack cell walls and metabolic machinery. Their status as living or non-living is debated, but they are biologically active only inside a host.

Explanation:
Parasitism (+/-) is a symbiotic interaction where the parasite benefits at the expense of the host. Examples: tapeworms, Plasmodium. Mutualism is +/+, commensalism +/0, amensalism -/0. Parasites may live on (ectoparasites) or inside (endoparasites) the host.

Explanation:
The nephron is the structural and functional unit of the kidney, responsible for filtration, reabsorption, and secretion to form urine. Each kidney has about 1 million nephrons. A nephron consists of the Bowman's capsule, glomerulus, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct. Neurons are units of nervous system, alveoli of lungs, hepatocytes of liver.