21.
$$tt$$ mates with $$Tt.$$ What will be characteristic of offspring?
A
75% recessive
B
50% recessive
C
25% recessive
D
All dominant
Answer :
50% recessive
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22.
Which one is obtained by S. Miller in his experiment on origin of life before 1953
A
Simple sugars
B
Amino acids
C
Nucleotide
D
Peptides
Answer :
Amino acids
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23.
Which one of the following phenomena supports Darwin's concept of natural selection in organic evolution
A
Production of 'Dolly' the sheep by cloning
B
Development of organs from 'stem cells' for organ transplantation
C
Development of transgenic animals
D
Prevalence of pesticide resistant insects
Answer :
Prevalence of pesticide resistant insects
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24.
The main aim of plant breeding is
A
To produce improved varieties
B
To make soil fertile
C
To controle pollution
D
To become more progressive
Answer :
To produce improved varieties
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25.
Chromosome number 2n-1 is an example of
A
Trisomy
B
Euploidy
C
Poplyploid
D
Monosomy
Answer :
Monosomy
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26.
The genotypic ratio in F2 generation in a monohybrid cross would be
A
1 : 1 : 2
B
1 : 2 : 1
C
2 : 1 : 1
D
None of the above
Answer :
1 : 2 : 1
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27.
Which of the following are not analogous organs
A
Fins of fishes and flippers of whales
B
Stings of honey bee and scorpion
C
Thorn of bougainvillea and tendril of Cucurbita
D
Wings of insect and wings of bird
Answer :
Thorn of bougainvillea and tendril of Cucurbita
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28.
An example of the quantitative trait in man is
A
Hair colour
B
Colour of eye
C
Skin colour
D
Shape of nose
Answer :
Skin colour
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29.
Haemophilia is more commonly seen in human males than in human females because:
A
a greater proportion of girls die in infancy
B
this disease is due to a $$Y$$-linked recessive mutation
C
this disease is due to an $$X$$-linked recessive mutation
D
this disease is due to an $$X$$-linked dominant mutation
Answer :
this disease is due to an $$X$$-linked recessive mutation
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30.
Red $$(RR)$$ Antirrhinum is crossed with white $$(WW)$$ one. Offspring $$RW$$ are pink. This is an example of
A
dominant -recessive
B
incomplete dominance
C
hybrid
D
supplementary genes
Answer :
incomplete dominance
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