Question

Genes located on the same locus but having different expressions are
A. Multiple alleles
B. Oncogenes
C. Polygenes
D. Codominants

Answer 1

Hint: The chromosomes form the basis of the genetic information. The huge genetic information is compacted in such a manner that it is held in the small nucleus. These genes on the chromosomes are the sites of the information that is passed down to the next generation. There are 23 pairs of chromosomes in humans.

Complete answer:
Gene is a sequence of nucleotides that will encode for the synthesis of a product- RNA or protein.
Locus is a fixed position on the chromosome with a genetic marker.
The expression is the outcome of the gene, to what the gene is encoded for.
Option A: Multiple alleles: When there are more than 2 alleles on the same chromosome, they are called the multiple alleles. That means when two genes at the same position are present but will express different expressions.
Option B: Oncogenes: The genes that can cause cancer are oncogenes. When there is a tumour, these genes are expressed at a high level due to mutation.
Option C: Polygenes: The gene whose effect on the phenotype individually is very small or ignorant. But when many genes are expressed together they show an observant expression.
Option D: Codominants: When two alleles of the same gene are present. One is dominant over the other but both are expressed as codominance.

So the answer is option A: Multiple alleles.

Note: The blood group follows the ABO grouping. Thus the blood group depends on the three types of the alleles. Out of the three, only two are present at a time. For a given gene, generally, there are only 2 alleles, one can be dominant and the other recessive or both can be dominant/recessive.