The protein that gives red blood cells their flexibility and shape is:
A. Spectrin
B. Myosin
C. Keratin
D. Hemoglobin
Answer: Option A
Solution (By JKExamLibrary)
Spectrin is a cytoskeletal protein that lines the inner surface of the RBC membrane, maintaining its biconcave shape and providing elasticity to squeeze through capillaries. Hemoglobin carries oxygen, myosin is a motor protein, keratin is structural in skin/hair. Defects in spectrin cause spherocytosis.
Explanation:
The choroid plexus, a network of ependymal cells and capillaries in the ventricles of the brain, continuously produces CSF by filtration and secretion. CSF circulates through ventricles and the subarachnoid space and is reabsorbed by arachnoid villi into the venous system. Dura mater is the outer protective membrane.
Explanation:
The spinal cord is a long tubular bundle of nervous tissue extending from the medulla oblongata to the level of the first/second lumbar vertebra (L1-L2), where it tapers into the conus medullaris. Below this, nerves form the cauda equina. It transmits impulses between the brain and body and coordinates reflexes.
Explanation:
Frederick Griffith in 1928 demonstrated the transformation of non-virulent pneumococci to virulent by heat-killed virulent strain, suggesting a transforming principle. Avery et al. later identified it as DNA. Hershey-Chase confirmed DNA is genetic material.
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