The structure that prevents the backflow of urine from the bladder to the ureters is the: MCQ with Answer and Explanation

Explanation:
The cerebrum is the largest part of the brain, responsible for higher functions like voluntary motor actions, sensory processing, and intelligence. The cerebellum coordinates muscle movements and maintains posture and balance. The medulla oblongata contains vital centers controlling involuntary functions like heartbeat, breathing, and blood pressure. All three statements are correct.

Explanation:
The corpus luteum, formed after ovulation, secretes progesterone (and some estrogen) to maintain the uterine lining for pregnancy. If no fertilization, it degenerates, causing menstruation. Estrogen is also produced by growing follicles, testosterone by Leydig cells, prolactin by anterior pituitary.

Explanation:
Bacteria are unicellular prokaryotes lacking a true nucleus and membrane-bound organelles. Fungi are heterotrophic eukaryotes that lack chlorophyll and cannot perform photosynthesis. Viruses are obligate intracellular parasites that lack metabolic machinery and absolutely require a living host cell to replicate. Therefore, only statement 1 is correct.