जीव विज्ञान – Biology MCQ
जीव विज्ञान – कृषि/वन प्रवेश
Biology · Agriculture, Veterinary & Forestry Entrance · ८४० प्रश्न
८४० प्रश्न उपलब्ध। मोड छान्नुहोस्:
जीव विज्ञान: प्रश्न र उत्तर
सही लागेको विकल्पमा थिच्नुहोस्। सही भए हरियो, गलत भए रातो देखिन्छ; ३ सेकेन्डपछि सही उत्तर र व्याख्या देखिन्छ।
सही: ० / ०
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That X-rays can induce mutations was first demonstrated in Drosophila by:
सही उत्तर: क) H. J. Muller
Hermann J. Muller showed in 1927 that X-rays greatly increase the mutation rate in Drosophila, earning a Nobel Prize.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The first genetic (linkage) map of a chromosome was prepared in 1913 by:
सही उत्तर: घ) Alfred Sturtevant
Sturtevant, a student of Morgan, used recombination frequencies between X-linked genes of Drosophila to construct the first map.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Crossing over normally does not occur, so linkage is complete, in:
सही उत्तर: क) Male Drosophila
In Drosophila, crossing over is absent in males, so linked genes in males are inherited together (complete linkage).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Common bread wheat (Triticum aestivum) with 42 chromosomes is a:
सही उत्तर: क) Hexaploid
Bread wheat is an allohexaploid (6n = 42, with x = 7) formed by combining three different diploid genomes.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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An individual with the chromosome number 2n − 1 is described as:
सही उत्तर: ग) Monosomic
Loss of one chromosome from a diploid set (2n − 1) is monosomy; 2n − 2 is nullisomy and 2n + 1 is trisomy.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The failure of homologous chromosomes or sister chromatids to separate properly during cell division is called:
सही उत्तर: ख) Non-disjunction
Non-disjunction produces gametes with an extra or missing chromosome, leading to aneuploidy such as trisomy.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Cystic fibrosis, which causes thick mucus in the lungs, is inherited as a/an:
सही उत्तर: क) Autosomal recessive trait
Cystic fibrosis results from mutations in the CFTR gene on chromosome 7 and appears only when both alleles are defective.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A newborn with trisomy 13 who has cleft lip and palate, extra fingers and severe heart and brain defects is suffering from:
सही उत्तर: ख) Patau's syndrome
Trisomy 13 causes Patau's syndrome; Edwards' syndrome is trisomy 18 and Down's syndrome trisomy 21.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Criss-cross inheritance, in which a trait passes from a father through his daughter to his grandson, is characteristic of:
सही उत्तर: क) X-linked recessive genes
An affected father gives his X to his daughter (a carrier), who passes it to her son; this zig-zag pattern is typical of X-linked recessive traits.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Hypertrichosis of the ear (hairy pinna), passed only from father to son, is an example of:
सही उत्तर: ख) Y-linked (holandric) inheritance
Genes on the non-homologous part of the Y chromosome are holandric: they are passed only from father to all sons.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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