Principles of Inheritance and Variation

The ratio in a dihybrid test cross between two individuals is given by

• 2 : 1

• 1 : 2 : 1

• 3 : 1

• 1 : 1 : 1 :1

When paternal and maternal chromosomes change their materials with each other in cell division this event is called

• synapsis

• crossing over

• bivalent forming

• dyad- forming

Frameshift mutation occurs when

• base is subsituted

• base is deleted or added

• anticodons are absent

• none of these

Sex determination in humans takes place by

• sex chromosomes of father

• measurement of sperm

• measurement of ovum

• sex chromosomes of mother

Turner's syndrome chromosome pattern is:

• XO

• XXX

• XYY

• XXY

Pure line breed refers to

• heterozygosity only

• heterozygosity and linkage

• homozygosity only

• homozygosity and self assortment

2n - 1 condition is called

• trisomy

• monosomy

• nullisomy

• tetrasomy

If a homozygous red flowered plant is crossed with a homozygous white flowered plant, the offspring would be

• half red-flowered

• all red-flowered

• half white-flowered

• half pink-flowered.

The main cause of Edward syndrome, Patau syndrome and Down syndrome is :

• mutation of gene

• change in both autosomes and heterosomes

• change in autosomes

• change in heterosomes

One of the genes present exclusively on the X-chromosome in humans is concerned with

• baldness

• red-green colour blindness

• facial hair/moustaches in males

• night blindness