In apomixis, the formation of seeds without meiosis and fertilization occurs through which mechanisms?
Answer: B
Apomixis includes apospory (diploid egg from vegetative cells), apomeiosis (unreduced spore formation), and parthenogenesis (unfertilized egg development), all bypassing meiosis and fertilization.
Q.82Hard
A man with hemophilia (XʰY) marries a normal woman (XʰXʰ). All their daughters will be _______ and all sons will be _______.
Answer: C
Cross: XʰY × XʰXʰ produces XʰXʰ (carrier daughters) and XʰY (normal sons). Daughters carry one recessive allele but are phenotypically normal.
Q.83Hard
In Drosophila, white eye color (w) is recessive to red eye color (w⁺) and is X-linked. If a white-eyed female is crossed with a red-eyed male, what will be the eye color of the F1 females?
Answer: B
Cross: ww × w⁺Y produces w⁺w (heterozygous females with red eyes) and wY (white-eyed males). F1 females are red-eyed.
Q.84Hard
A cross between a plant with genotype AaBb and a plant with genotype aabb produces 160 offspring. Due to linkage between genes A and B (20 map units apart), the expected frequency of AaBb offspring will be approximately ______.
Answer: C
With 20 map units distance, recombination frequency is 20%. Parental types (AB/ab) = 40% each, recombinants = 10% each. AaBb from coupling = 40 out of 160.
Q.85Hard
The biodiversity of India is attributed primarily to:
Answer: B
India's exceptional biodiversity is due to its diverse climatic zones (tropical to alpine), varied topography, monsoon patterns, and complex geological history creating multiple ecological niches.
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Q.86Hard
Which of the following phenomena is an example of positive feedback in an ecosystem?
Answer: B
Climate warming → permafrost thaw → CO₂ release → more warming is a positive feedback loop that amplifies the initial change, unlike negative feedback which stabilizes systems.
Q.87Hard
Which of the following traits cannot be introduced into plants through Bt technology?
Answer: C
Bt technology specifically transfers bacterial genes for insecticidal proteins. Drought resistance requires different genes and mechanisms.
Q.88Hard
What is the concern associated with widespread cultivation of Bt crops?
Answer: B
Repeated exposure to Bt toxin can lead to the evolution of resistant insect populations, a major concern in sustainable agriculture.
Q.89Hard
Which technique is used to confirm the integration of foreign DNA into plant genome?
Answer: B
Southern blotting detects integrated DNA sequences in the plant genome, confirming stable genetic transformation.
Q.90Hard
What is the main advantage of using somatic embryogenesis over organogenesis in plant tissue culture?
Answer: B
Somatic embryogenesis produces complete plants directly from embryos, ensuring genetic fidelity better than organogenesis which may show variations.
