GENETICS AND EVOLUTION
GENETIC BASIS OF INHERITANCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The parent of unknown genotype is heterozygous
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The parent of unknown genotype is homozygous dominant
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The parent of unknown genotype is homozygous recessive
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The parent of known genotype is heterozygous
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Detailed explanation-1: -A parent organism of unknown genotype is mated in a test cross. Half of the offspring have the same phenotype as the parent. What can be concluded from this result? The parent of unknown genotype is heterozygous.
Detailed explanation-2: -IF ANY OF THE OFFSPRING FROM A TEST CROSS HAVE THE RECESSIVE TRAIT, THE GENOTYPE OF THE PARENT WITH THE DOMINANT TRAIT MUST BE HETEROZYGOUS.
Detailed explanation-3: -A testcross can be used to determine the organism’s genotype. In a testcross, the individual with the unknown genotype is crossed with a homozygous recessive individual (Figure below).
Detailed explanation-4: -The test cross If the parent with the unknown genotype is homozygous dominant, all the resulting offspring will have at least one dominant allele. If the parent with the unknown genotype is heterozygous, 50 percent of the offspring will inherit a recessive allele from both parents and will have the recessive phenotype.
Detailed explanation-5: -The test cross is another fundamental tool devised by Gregor Mendel. In its simplest form, a test cross is an experimental cross of an individual organism of dominant phenotype but unknown genotype and an organism with a homozygous recessive genotype (and phenotype).