Rheumatoid arthritis is an example of which type of disorder?
A. Immunodeficiency
B. Autoimmune disease
C. Allergy
D. Infectious disease
Answer: Option B
Solution (By JKSSB Mock Tests)
Rheumatoid arthritis is a chronic inflammatory autoimmune disease where the immune system mistakenly attacks the body's own healthy tissues, specifically the synovial membranes of joints. This leads to painful swelling, bone erosion, and joint deformity. Other examples of autoimmune diseases include Type 1 diabetes, multiple sclerosis, and systemic lupus erythematosus.
Explanation:
Mycoplasma is a genus of bacteria that naturally lack a cell wall; they are the smallest known free-living organisms. Their membrane contains sterols providing some rigidity. Other bacteria typically have peptidoglycan cell walls. Fungi have chitinous walls, plant cells have cellulose walls. The absence of cell wall makes Mycoplasma pleomorphic and resistant to antibiotics targeting cell wall synthesis like penicillin.
Explanation:
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.
Consider the following statements regarding mitochondria:
1. They are double-membrane organelles.
2. They have their own 80S ribosomes.
3. They are the site of aerobic respiration.
Which of the statements is/are correct?
Explanation:
Mitochondria have two membranes (outer and inner) and are the site of Krebs cycle and oxidative phosphorylation. They possess 70S ribosomes, not 80S. Hence, statements 1 and 3 are correct.
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