The structure that prevents backflow of blood from the left ventricle to the left atrium is the:
A. Mitral valve
B. Pulmonary valve
C. Aortic valve
D. Tricuspid valve
Answer: Option A
Solution (By JKExamLibrary)
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.
Consider statements about microorganisms: 1. Bacteria reproduce asexually by binary fission. 2. Fungi reproduce by spore formation. 3. Viruses can reproduce independently. Which are correct?
Explanation:
Bacteria are prokaryotes that primarily reproduce asexually through binary fission, a process where a single cell divides into two identical daughter cells. Fungi reproduce both sexually and asexually, but asexual reproduction commonly occurs through the formation and dispersal of spores (like conidia or sporangiospores). Viruses are obligate intracellular parasites; they lack the metabolic machinery for independent reproduction and must hijack a host cell's machinery to replicate. Thus, statements 1 and 2 are correct.
Explanation:
Thiamine pyrophosphate (TPP) is a coenzyme for pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, and transketolase, playing a key role in carbohydrate metabolism. Riboflavin is FAD, niacin NAD, pantothenic acid CoA.
Explanation:
Renin is secreted by juxtaglomerular cells of the kidney in response to low blood pressure or sodium. It converts angiotensinogen to angiotensin I, initiating the RAAS. Liver produces angiotensinogen, adrenal aldosterone, heart ANP.
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