Which blood vessels have valves to prevent backflow?
A. Arteries
B. Arterioles
C. Capillaries
D. Veins
Answer: Option D
Solution (By JKSSB Mock Tests)
Veins carry blood back to the heart under low pressure and have one-way valves that prevent backflow. Skeletal muscle contractions also assist venous return.
Explanation:
Neurulation involves the folding of the neural plate to form the neural tube, which becomes the brain and spinal cord. Gastrulation forms germ layers.
Explanation:
Vitamin B₆ exists in three forms: pyridoxine, pyridoxal, and pyridoxamine. Its active form, pyridoxal phosphate (PLP), is a coenzyme in amino acid metabolism and neurotransmitter synthesis. Deficiency can cause peripheral neuropathy and anemia.
Explanation:
Tetanus (lockjaw) is caused by a neurotoxin produced by Clostridium tetani, which enters through wounds and causes painful muscle spasms. Botulism is C. botulinum, gas gangrene C. perfringens, leprosy M. leprae.
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