Pellagra is a disease characterized by the '4 Ds': dermatitis, diarrhea, dementia, and death. It is caused by the deficiency of: MCQ with Answer and Explanation
Pellagra is a disease characterized by the '4 Ds': dermatitis, diarrhea, dementia, and death. It is caused by the deficiency of:
A. Vitamin B12 (Cobalamin)
B. Vitamin B1 (Thiamine)
C. Vitamin B2 (Riboflavin)
D. Vitamin B3 (Niacin)
Answer: Option D
Solution (By JKExamLibrary)
Pellagra is caused by a severe deficiency of Vitamin B3 (Niacin) or its precursor, the amino acid tryptophan. The classic symptoms are the '4 Ds': dermatitis (symmetrical, pigmented rash on sun-exposed skin), diarrhea, dementia (neurological symptoms), and eventually death if untreated. It is historically associated with diets heavily reliant on untreated corn (maize), which has low bioavailable niacin and tryptophan.
Explanation:
Charles Darwin and Alfred Wallace independently proposed natural selection as the mechanism for evolution. Darwin published 'On the Origin of Species' in 1859.
Explanation:
Synapsis (pairing of homologous chromosomes) and crossing over (exchange of genetic material) occur during prophase I of meiosis, not in mitosis. Mitosis involves one division producing two genetically identical diploid daughter cells. Meiosis involves two divisions producing four haploid gametes with genetic variation. Chromosome duplication and sister chromatid separation occur in both. Spindle fibres form in both divisions. Thus, synapsis and crossing over are unique to meiosis.
Explanation:
GMOs are organisms whose genetic material has been modified through recombinant DNA technology, introducing or deleting specific genes. Selective breeding and cross-pollination are traditional methods that do not directly manipulate DNA. Cloning produces genetically identical copies without necessarily altering the genome. Examples: Bt cotton, Golden rice.
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