The site of gas exchange in the human lungs is: MCQ with Answer and Explanation

Explanation:
Prokaryotic cells contain 70S ribosomes, which are composed of a 50S large subunit and a 30S small subunit. The 'S' stands for Svedberg units, a measure of sedimentation rate. Eukaryotic cytoplasm contains 80S ribosomes, though their mitochondria and chloroplasts contain 70S ribosomes.

Explanation:
Growth hormone (somatotropin) stimulates protein synthesis, cell division, and growth of bones and muscles, especially during childhood. Thyroxine regulates metabolism, cortisol is a stress hormone from the adrenal cortex, adrenaline is from the adrenal medulla. GH deficiency leads to dwarfism; excess causes gigantism or acromegaly.

Explanation:
The spleen filters blood, removing aged or damaged RBCs, recycles iron, and stores platelets. The liver also processes hemoglobin products, but the spleen is the primary organ for RBC removal. The kidneys filter blood but don't remove RBCs.