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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The population growth curve of a species in an environment with limited resources (logistic growth) is:
सही उत्तर: ख) Sigmoid (S-shaped)
Logistic growth slows as the population approaches carrying capacity (K), giving an S-shaped curve; unlimited growth gives a J-shaped curve.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The Avena curvature test, a bioassay for auxin using oat coleoptiles, was developed by:
सही उत्तर: क) F. W. Went
Went placed auxin-containing agar blocks on one side of decapitated oat coleoptiles; the curvature was proportional to auxin concentration.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Kinetin, the first cytokinin to be discovered, was isolated by Skoog and Miller from:
सही उत्तर: ख) Autoclaved herring sperm DNA
Kinetin (6-furfurylaminopurine) was obtained from heated herring sperm DNA; zeatin was later isolated from maize.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The respiratory quotient (RQ) when fats such as tripalmitin are the respiratory substrate is about:
सही उत्तर: घ) 0.7
Fats are poor in oxygen and need much O2 for oxidation, so CO2 released / O2 used is about 0.7.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The increase in the rate of photosynthesis when far-red light (above 680 nm) is supplemented with light of shorter wavelength, which suggested the existence of two photosystems, is called the:
सही उत्तर: घ) Emerson enhancement effect
Emerson found that far-red light plus shorter-wavelength red light gives a higher rate than the sum of the two given separately, pointing to two cooperating photosystems.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The 'law of limiting factors' in photosynthesis was proposed in 1905 by:
सही उत्तर: घ) F. F. Blackman
Blackman stated that when a process depends on several factors, its rate is limited by the factor present in the least amount.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a blastocyst, the outer layer of cells that attaches to the endometrium and later helps form the placenta is the:
सही उत्तर: घ) Trophoblast
The trophoblast attaches to the uterine wall during implantation, while the inner cell mass develops into the embryo.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Myxoedema, with a puffy face, low metabolic rate and lethargy, is caused by:
सही उत्तर: घ) Hyposecretion of thyroid hormones in adults
Deficiency of thyroxine in adults causes myxoedema; in children it causes cretinism.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The photosensitive pigment present in the cone cells of the human retina is:
सही उत्तर: ख) Iodopsin
Cones contain iodopsin (photopsin) for colour and bright-light vision; rods contain rhodopsin.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The 11th and 12th pairs of human ribs are called floating ribs because they:
सही उत्तर: ग) Are not attached ventrally to the sternum or to other ribs
These two pairs are attached dorsally to thoracic vertebrae but have no ventral connection to the sternum.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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