Assertion (A): The blood-brain barrier protects the brain. Reason (R): It is formed by tight junctions between endothelial cells of brain capillaries. MCQ with Answer and Explanation
Assertion (A): The blood-brain barrier protects the brain.
Reason (R): It is formed by tight junctions between endothelial cells of brain capillaries.
A. Both A and R are true, and R is the correct explanation.
B. A false, R true.
C. Both A and R are true, but R is not the correct explanation.
D. A true, R false.
Answer: Option A
Solution (By JKExamLibrary)
The BBB restricts entry of pathogens and large molecules, maintaining brain homeostasis. Tight junctions between capillary endothelial cells are the structural basis. R explains A.
Explanation:
Meiosis consists of two successive divisions resulting in four genetically diverse haploid cells (gametes). Mitosis produces two identical diploid cells, amitosis is direct nuclear division, binary fission is prokaryotic asexual reproduction.
Explanation:
Alzheimer's disease is a progressive neurodegenerative disorder marked by extracellular amyloid-beta plaques and intracellular neurofibrillary tangles of tau protein, leading to memory loss and cognitive decline. Parkinson's involves dopamine neuron loss, multiple sclerosis demyelination, epilepsy seizures.
Explanation:
Fungi are heterotrophic organisms; they cannot perform photosynthesis because they lack chlorophyll and chloroplasts. They obtain nutrients through absorption after extracellular digestion (saprophytic or parasitic). The cell wall contains chitin, and most are multicellular with a filamentous body (mycelium), though yeasts are unicellular. Thus, autotrophy is not a fungal characteristic.
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