Test Cross & back cross & also their differences.

1. TEST CROSS AND BACK CROSS
Md.Robiul Islam
Roll: 181305

2. TEST CROSS
A test cross is used to find out the genotype of any plant with
dominant expression when it is not known whether it is
homozygous (pure) or heterozygous for that trait. For example, a
pea plant having purple flowers (F1 hybrid with unknown
genotype) is crossed with a pea plant with white flowers
(recessive).

3. BACK CROSS
The breeding of F1 hybrid with one of the two parents is referred
to as a backcross.
When F1 is bred with the homozygous dominant, the offspring
produces a 100% dominant phenotype. This cross produces an
offspring which is genetically closer to the parents of the F1.
Hence, backcross is often used in horticulture and animal
breeding in order to achieve genetically identical offspring
carrying elite genotypes.

4. DIFFERENCE BETWEEN TEST CROSS AND BACK
CROSS
 The test cross is the cross that
occurs between a dominant
phenotype and a recessive
phenotype.
 Test cross is the breeding of
dominant phenotype with its
recessive phenotype.
 All text crosses are back
crosses
 The backcross is the cross that
occurs between generation F1
hybrid and one of the two
parents.
 Backcross is the breeding of
F1 hybrid with one of the
parents.
 Backcross of the F1 hybrid with
recessive phenotype can be
considered as the test cross
Test Cross Back Cross

5.  Test cross indentifies the
zygosity of the dominant
phenotype.
 A test cross is important to
determine the genotype (TT
or Tt) of the dominant
phenotype.
 Backcross recovers the elite
genotype.
 Backcross is useful in
recovering important
characteristics of the parent.