The process of cell division that results in the production of identical daughter cells for growth and repair is:
A. Meiosis
B. Budding
C. Binary fission
D. Mitosis
Answer: Option D
Solution (By JKExamLibrary)
Mitosis is equational division producing two genetically identical diploid daughter cells, essential for growth, development, and tissue repair in multicellular organisms. Meiosis produces haploid gametes with variation, binary fission is asexual in prokaryotes, budding in yeast. Mitosis maintains chromosome number.
Assertion (A): Red blood cells lack a nucleus in mammals.
Reason (R): The absence of a nucleus allows more space for hemoglobin, increasing oxygen-carrying capacity.
A.A is false, but R is true.
B.Both A and R are true, but R is not the correct explanation.
C.Both A and R are true, and R is the correct explanation of A.
Explanation:
Mature mammalian RBCs are anucleate, having lost their nucleus during maturation. This provides more space for hemoglobin, enhancing oxygen transport. The reason correctly explains the assertion. Nucleated RBCs are found in other vertebrates.
Explanation:
Alexander Fleming discovered penicillin in 1928 from the mold Penicillium notatum (later renamed P. chrysogenum). Aspergillus niger is used for citric acid production, Saccharomyces is yeast, Rhizopus is a bread mold. Penicillin was the first true antibiotic and its mass production during WWII saved countless lives. It inhibits bacterial cell wall synthesis.
Explanation:
Diastole is the relaxation phase of the cardiac cycle, during which the ventricles fill with blood from the atria. Systole is the contraction phase, pumping blood out. Atrial contraction (atrial systole) contributes to ventricular filling. Ejection phase is part of ventricular systole when blood is ejected. Normal diastolic and systolic pressures are 80 and 120 mmHg respectively.
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