The primary reason for the depletion of the ozone layer is the emission of:
A. Sulphur oxides
B. Carbon monoxide
C. Methane
D. Chlorofluorocarbons (CFCs)
Answer: Option D
Solution (By JKSSB Mock Tests)
CFCs, used in refrigerants and aerosol propellants, release chlorine atoms when exposed to UV radiation in the stratosphere. A single chlorine atom can destroy thousands of ozone (O₃) molecules. This led to the formation of the 'ozone hole' over Antarctica. The Montreal Protocol (1987) successfully phased out CFCs, allowing the ozone layer to slowly recover.
Explanation:
Type 1 diabetes mellitus is an autoimmune disease where beta cells of the pancreas are destroyed, leading to little or no insulin production. Patients require insulin injections. Type 2 involves insulin resistance. Diabetes insipidus involves ADH deficiency, Cushing's syndrome is cortisol excess.
Consider statements about human excretion: 1. The kidneys regulate blood pressure. 2. Ammonia is the primary nitrogenous waste in humans. 3. The nephron filters blood in the glomerulus. Which are correct?
Explanation:
The kidneys regulate blood pressure via the renin-angiotensin-aldosterone system and by controlling fluid volume. The nephron's glomerulus filters blood plasma into Bowman's capsule. Humans are ureotelic, meaning the primary nitrogenous waste excreted is urea, not ammonia (which is highly toxic and excreted by aquatic animals). Thus, statements 1 and 3 are correct.
Explanation:
Hemophilia A and B are X-linked recessive disorders caused by mutations in genes for clotting factor VIII or IX on the X chromosome. It predominantly affects males, while females are usually carriers. Down syndrome is an autosomal aneuploidy, cystic fibrosis and sickle cell anemia are autosomal recessive. X-linked disorders follow a characteristic pattern of inheritance.
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