Question

Match the following:
$\begin{array}{cccc}& \text{Column I}& & \text{Column II}\\ \text{A}& \text{Dihybrid test cross ratio}& \text{I}& \text{1 : 2 : 1 : 2 : 4 : 2 : 1 : 2 : 1}\\ \text{B}& \text{Monohybrid test cross ratio}& \text{II}& \text{1 : 1 : 1 : 1}\\ \text{C}& \text{Dihybrid phenotypic ratio}& \text{III}& \text{9 : 3 : 3 : 1}\\ \text{D}& \text{Dihybrid genotypic ratio}& \text{IV}& \text{1 : 1}\end{array}$

• A. A-I, B-II.C-III, D-IV
• B. A-II, B-IV, C-III, D-I
• C. A-II, B-III, C-IV, D-I
• D. A-IV, B-III, C-II, D-I

Answer 1

The correct option is B A-II, B-IV, C-III, D-I

Genotype is the genetic makeup of an organism. For example, the genotype of hybrid tall plant is Tt, pure tall TT and dwarf tt.
Phenotype is the external appearance of an organism for a particular trait. For example, the phenotype of TT and Tt is tall.

Monohybrid cross is a cross between two true breed organisms of a species differing in one of the characters. This helps to study the inheritance of one pair of alleles/ a particular gene. For example, TT X tt

Monohybrid test cross: It is a crossing of the hybrid with dominant phenotype (Tt), whose genotype has to be found out, with a homozygous recessive parent (tt).
It can be shown as Tt x tt.
$\begin{array}{cc}\text{Gametes}& \text{t}\\ \text{T}& \text{Tt(tall)}\\ \text{t}& \text{tt(dwarf)}\end{array}$
Genotypic ratio of F1 test cross:- Tt : tt = 1 : 1
Phenotypic ratio of F1 test cross:- Tall : Dwarf = 1 : 1

Dihybrid cross is a cross between two pure organisms of a species differing in two pairs of contrasting traits, in order to study the inheritance of two genes. For example, RRYY X rryy (Mendel’s dihybrid cross).

Dihybrid test cross: It is the crossing of the dihybrid with dominant phenotypes for both the characters, whose genotype has to be found out, with a homozygous recessive parent (yyrr).
Dihybrid test cross involves crossing of F1 dihybrid to parent recessive for both the genes.
$\begin{array}{ccccc}\text{Gametes}& YR& \text{Yr}& \text{yR}& \text{yr}\\ \text{yr}& \text{YyRr}& \text{Yyrr}& \text{yyRr}& \text{yyrr}\\ & \text{(Yellow, round seeds)}& \text{(Yellow, wrinkled seeds)}& \text{(Green, round seeds)}& \text{(Green, wrinkled seeds)}\end{array}$
The dihybrid test cross ratio is:-
YyRr : Yyrr : yyRr : yyrr = 1 : 1 : 1 : 1.