In which plant was the lethal gene first observed?

If a starfish possesses six arms instead of five,what is this an example of?

$A$ person may have one gene for normal haemoglobin and one gene for sickle cell haemoglobin. This heterozygous condition is called:

Among the four couples given,who could be the biological parents of a child with $O^+$ blood group?

Select the group of $CORRECT$ statements.
$I$. If phenotype of offsprings shows only the dominant trait then the parent plants are heterozygous.
$II$. $A$ true breeding line shows stable trait inheritance and expression for several generations.
$III$. In mendelian experiment material,contrasting characters can be easily recognized.
$IV$. When a single gene controls two (or more) different traits,it is called polygene.
$V$. When interactions occurs between the alleles of different genes present on the same or different chromosome it is called intragenic interaction.

The number of chromosomes present in a gorilla is: