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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Crossing over between homologous chromosomes occurs during:
सही उत्तर: क) Pachytene of prophase I
Crossing over occurs at pachytene, when bivalents are fully synapsed. Synapsis begins earlier in zygotene, and chiasmata become visible in diplotene.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which structure is typically absent in the cells of higher plants?
सही उत्तर: ग) Centriole
Higher plant cells form spindles without centrioles. Cell walls, plastids and large vacuoles are characteristic of plant cells.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which organelle is called the 'suicide bag' of the cell?
सही उत्तर: ख) Lysosome
Lysosomes contain hydrolytic enzymes, and their rupture can digest the cell itself (autolysis). Peroxisomes contain enzymes like catalase that break down hydrogen peroxide.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The fluid mosaic model of the plasma membrane was proposed by:
सही उत्तर: ख) Singer and Nicolson
Singer and Nicolson (1972) described the membrane as a fluid lipid bilayer with proteins floating in it. Danielli and Davson proposed the earlier sandwich model.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The cell wall of most fungi is made mainly of:
सही उत्तर: ख) Chitin
Fungal cell walls are made of chitin, a nitrogen-containing polysaccharide also found in insect exoskeletons. Peptidoglycan forms bacterial cell walls.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Proteins are synthesised in the cell on:
सही उत्तर: क) Ribosomes
Ribosomes translate mRNA into polypeptides. Golgi bodies modify and package proteins but do not synthesise them.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The synthesis of mRNA from a DNA template is called:
सही उत्तर: ग) Transcription
Transcription is carried out by RNA polymerase and produces RNA from DNA. Translation is the next step where mRNA is used to make protein on ribosomes.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Golden rice was genetically engineered to be rich in:
सही उत्तर: क) Beta-carotene
Golden rice produces beta-carotene (provitamin A) in its grains to fight vitamin A deficiency. Its golden colour comes from this pigment.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The insecticidal gene in Bt cotton is obtained from:
सही उत्तर: ख) Bacillus thuringiensis
Bt cotton carries cry genes from Bacillus thuringiensis, which encode toxins lethal to bollworms. Agrobacterium tumefaciens is used as a vector for transferring genes into plants.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Restriction endonucleases are known as 'molecular scissors' because they:
सही उत्तर: ख) Cut DNA at specific sequences
Restriction enzymes recognise specific palindromic sequences and cut DNA there. Joining fragments is the work of DNA ligase, the 'molecular glue'.
💬 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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