The structure that prevents backflow of blood from the left ventricle to the left atrium is the:
A. Aortic valve
B. Pulmonary valve
C. Mitral valve
D. Tricuspid valve
Answer: Option C
Solution (By JKSSB Mock Tests)
The bicuspid (mitral) valve has two cusps and closes during ventricular systole to prevent regurgitation into the left atrium. The tricuspid valve is on the right.
Explanation:
The first heart sound 'lub' is caused by the closure of the atrioventricular valves (mitral and tricuspid) at the beginning of ventricular systole. The second sound 'dub' is due to closure of semilunar valves (aortic and pulmonary) at the end of systole. Abnormal sounds (murmurs) indicate valve defects. This is due to turbulence, but the sound specifically is produced by valve closure.
Explanation:
The placenta exchanges nutrients, gases, and wastes between mother and fetus. Sperm are produced in testes, fertilization is in the fallopian tube, testosterone by Leydig cells.
Explanation:
Transformation is the direct uptake and incorporation of naked DNA from the surroundings by a bacterium. Conjugation is DNA transfer via pilus, transduction via phage, lysogeny is phage DNA integration.
No comments yet. Be the first to start the discussion!