The number of autosomes in a normal human sperm cell is:
A. 22
B. 46
C. 23
D. 44
Answer: Option A
Solution (By JKSSB Mock Tests)
Human somatic cells have 46 chromosomes: 44 autosomes and 2 sex chromosomes (XX or XY). Sperm cells are haploid (n=23), containing 22 autosomes and one sex chromosome (either X or Y). The ovum also has 22 autosomes and one X. Fertilization restores 44 autosomes plus XX or XY. So sperm has 22 autosomes.
Explanation:
Meiosis involves two divisions, producing four haploid, genetically diverse cells. Crossing over between homologous chromosomes occurs during prophase I, leading to recombination. Thus, C is correct.
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.
Explanation:
Chief cells (peptic cells) in the gastric mucosa secrete pepsinogen, which is converted to active pepsin by HCl. Pepsin digests proteins into peptides. Parietal cells secrete HCl and intrinsic factor. Mucous cells produce mucus that protects the stomach lining. G cells secrete gastrin hormone. Pepsin functions optimally at pH 1.8-2.0. The stomach thus initiates protein digestion.
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