Heredity and Evolution — Science STD 10 — Question
CBSE BoardEnglish MediumSTD 10ScienceHeredity and Evolution1 Mark
MCQ
Which genotype represents a true dihybrid condition :
✓
$\ce{TtRr}$
B
$\ce{ttrr}$
C
$\ce{Ttrr}$
D
$\ce{TrRR}$
✓
Answer
Correct option: A.
$\ce{TtRr}$
A dihybrid cross considers two pairs of contrasting characters.
$\ce{TtRr}$ genotype is obtained from the dihybrid cross of $\ce{TTRR}$ and ttrr which are true $-$ breeding homozygous dominant and homozygous recessive breeding lines.
TtRr genotype consists of both dominant and recessive alleles for two different traits.
Hence, it's a dihybrid genotype.
On the other hand, other genotypes given in the questions contain heterozygous alleles for either one of the two traits or none at all.
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