Consider statements about the nucleus: 1. It is bounded by a single membrane. 2. It contains the nucleolus. 3. Nuclear pores allow RNA export. Which are correct? MCQ with Answer and Explanation

Explanation:
Stanley Miller and Harold Urey (1953) simulated primitive Earth conditions by mixing methane, ammonia, hydrogen, and water vapor and providing electric discharge (simulating lightning). They obtained amino acids (glycine, alanine, etc.), supporting the chemical origin of life hypothesis. It didn't produce proteins, DNA, or lipids directly. This experiment was crucial for abiogenesis theories.

Explanation:
Oxytocin is a peptide hormone produced by the paraventricular nucleus of the hypothalamus and released by the posterior pituitary. In females, it has two major roles: 1) During childbirth, it stimulates powerful contractions of the uterine smooth muscle, facilitating labor and delivery (this is a positive feedback loop). 2) During lactation, it stimulates the contraction of myoepithelial cells surrounding the alveoli in the mammary glands, causing the ejection (let-down) of milk into the ducts in response to suckling. It does not produce milk; prolactin does that.

Explanation:
Antonie van Leeuwenhoek (1670s) constructed high-quality single-lens microscopes and was the first to observe bacteria, protozoa, sperm cells, and red blood cells, describing them as 'animalcules'. Hooke observed cells in cork. Pasteur disproved spontaneous generation, Lister introduced antiseptic surgery. Leeuwenhoek's pioneering work laid the foundation for microbiology.