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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Bolting, the sudden elongation of internodes just before flowering in rosette plants like cabbage, is induced by:
सही उत्तर: घ) Gibberellin
Gibberellins promote stem elongation and can cause bolting in rosette plants such as cabbage and beet.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Vernalisation refers to:
सही उत्तर: क) Promotion of flowering by exposure to low temperature
Vernalisation is the cold treatment needed by plants such as winter wheat to flower; it prevents early flowering before winter.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The pigment that perceives light in photoperiodism and seed germination is:
सही उत्तर: घ) Phytochrome
Phytochrome exists in red-absorbing (Pr) and far-red-absorbing (Pfr) forms and controls photoperiodic flowering and light-sensitive germination.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which mineral element is a central constituent of the chlorophyll molecule?
सही उत्तर: घ) Magnesium
A magnesium atom sits at the centre of the porphyrin ring of chlorophyll; its deficiency causes chlorosis.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Leghaemoglobin in the root nodules of legumes functions to:
सही उत्तर: ग) Protect nitrogenase from oxygen
Leghaemoglobin binds oxygen and keeps its free concentration low, because nitrogenase is inactivated by oxygen.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Translocation of sugars through the phloem is best explained by the:
सही उत्तर: ख) Pressure flow (mass flow) hypothesis
Munch's pressure flow hypothesis says sugar loading at the source raises turgor pressure that pushes sap towards the sink; cohesion-tension explains xylem sap.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Opening of stomata is mainly caused by the influx of which ion into the guard cells?
सही उत्तर: ख) K+
Uptake of potassium ions lowers the water potential of guard cells, water enters, the guard cells become turgid and the pore opens.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The water potential of pure water at standard atmospheric pressure is:
सही उत्तर: घ) Zero
Pure water is taken as the reference with a water potential of zero; adding solutes makes it negative.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Guttation, the loss of water as liquid drops from leaf margins, occurs through:
सही उत्तर: क) Hydathodes
Guttation happens through hydathodes (water pores) at leaf tips and margins, usually at night when root pressure is high, as in grasses.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a dicot root, lateral roots arise from the:
सही उत्तर: ख) Pericycle
Lateral roots originate endogenously from the pericycle cells opposite the protoxylem.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
यी अभ्यास प्रश्न हुन्, आधिकारिक प्रश्न होइनन्। पाठ्यक्रम, विज्ञापन र नतिजाका लागि सम्बन्धित निकायको आधिकारिक वेबसाइट हेर्नुहोस्। उत्तरमा गल्ती भेटे प्रश्नमुनिको "टिप्पणी / गल्ती रिपोर्ट" मा लेख्नुहोस्।
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