List of top Biology Questions

(ii) The ecological pyramids may have an ‘upright’ or an ‘inverted’ shape. Justify with the help of suitable examples.
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(i) What does an ecological pyramid represent?
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(a) Tropical regions harbour more species than temperate regions. How have biologists tried to explain this in their own ways? Explain.
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Expression of different genes for different traits may show dominance, incomplete dominance, or co-dominance. Write about expression of such genes with examples for one of the above modes.
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(b) “DNA replication is continuous and discontinuous on the two strands within the replication fork.” Explain with the help of a schematic representation.
(a) Why does DNA replication occur within a replication fork and not in its entire length simultaneously?
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(b) State the role of “biolistic gun” in biotechnology experiments.
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(a) Why must a cell be made ‘competent’ in biotechnology experiments? How does calcium ion help in doing so?
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If the cells in the leaves of a maize plant contain 10 chromosomes each, write the number of chromosomes in its endosperm and zygote. Name and explain the process by which an endosperm and a zygote are formed in maize.
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(b) “The detritus food chain may be connected to the grazing food chain at some levels in an ecosystem.” Give an example in support of the statement.
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(a) How is the grazing food chain different from the detritus food chain?
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(b) Explain the arrows and the result.
Sequence:
5’ – G$\uparrow$A A T T C – 3’
3’ – C T T A A$\uparrow$G – 5’
(a) Name the restriction enzyme and type of sequence.
(b) What does ‘K’ represent?
(a) State the conditions for growth curve ‘A’ and growth curve ‘B’.
(b) Mention one advantage and disadvantage of amniocentesis.
(a) Why do farmers prefer apomictic seeds to hybrid seeds?

If adenine is 31% in DNA, calculate the percentage of cytosine. Explain briefly. 
 

(b) Why is dung preferred for the production of biogas?
(a) Identify ‘X’, ‘Y’, and ‘Z’.
Assertion (A): AIDS is a syndrome caused by HIV.
Reason (R): HIV is a virus that damages the immune system with AIDS as its genetic material.
Assertion (A): In molecular diagnosis, single-stranded DNA or RNA tagged with radioactive molecule is called a probe.
Reason (R): A probe always searches and hybridizes with its complementary DNA in a clone of cells.
Assertion (A): The sugar-phosphate backbone of two chains in DNA double helix shows anti-parallel polarity.
Reason (R): The phosphor-diester bonds in one strand go from a 3’ carbon of one nucleotide to a 5’ carbon of adjacent nucleotide, whereas those in complementary strand go vice versa.
Assertion (A): Communities that comprise of more species tend to be more stable.
Reason (R): A higher number of species results in less year-to-year variation in total biomass.

Study the pedigree chart of a family showing the inheritance pattern of a certain disorder. Select the option that correctly identifies the nature of the trait depicted in the pedigree chart: