PATHOLOGY

PATHOLOGY MCQ

GENETICS AND DISEASE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
In certain bacteria, a round shape (R) is dominant over being oval (r) and thick cell walls (T) are dominant over thin (t). Cross a bacteria that is homozygous dominant for both traits with a bacteria that is heterozygous for both traits. What is the phenotypic ratio?
A
1 Oval shape, thick cell wall:1 Oval shape, thin cell wall
B
1 Oval shape, thick cell wall:1 Round shape, thick cell wall
C
1 Round shape, thick cell wall:1 Round shape, thin cell wall
D
1 Round shape, thick cell wall
Explanation: 

Detailed explanation-1: -In certain bacteria, an oval shape is dominant over round and thick cell walls are dominant over thin. Cross a heterozygous oval, heterozygous thick cell walled bacteria with a round, thin cell walled bacteria.

Detailed explanation-2: -Individuals carrying two identical alleles (RR or rr) are known as homozygous. While individual organisms bearing different alleles (Rr) are known as heterozygous.

Detailed explanation-3: -If the test cross results in any recessive offspring, then the parent organism is heterozygous for the allele in question. If the test cross results in only phenotypically dominant offspring, then the parent organism is homozygous dominant for the allele in question.

Detailed explanation-4: -A homozygous plant contains either of the following alleles for seed shape: (RR) or (rr). The (RR) genotype is homozygous dominant and the (rr) genotype is homozygous recessive for seed shape.

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