Question

Alleles represent
A. Different forms of a gene
B. Same loci on homologous chromosome
C. Two or more forms
D. All of the above

Answer 1

Hint: An allele is two or more versions of the same gene given. An individual acquires two alleles for every gene, one from each parent.

Complete Answer:
Let us consider the example of the human blood group. In the event that the two alleles are equivalent, the individual is homozygous for that gene. If the alleles are unique, the individual is heterozygous. Despite the fact that the term allele was initially used to portray variety among genes, it presently additionally alludes to variety among non-coding DNA groupings or sequences.

Features:
- A person's genotype for that gene is the arrangement of alleles it ends up having.
- In a diploid living being, one that has two duplicates of every chromosome, two alleles make up the person's genotype.
- An example is a gene for bloom tone in numerous types of blossom — a solitary gene controls the shade of the petals, however, there might be a few unique renditions (or alleles) of the gene.
- One rendition may bring about red petals, while another might bring about white petals.
- The subsequent shade of an individual blossom will rely upon which two alleles it has for the quality and how the two interface.
- An allele is an elective type of a gene (in diploids, one individual from a couple) that is situated at a particular situation on a particular chromosome.
- There are a total of four blood groups present in humans. They are A, B, AB, and O. We should know that the ABO blood grouping is controlled by the ABO gene and has six similar alleles.
- We can also define alleles as different variations of sequences for several hundred base-pair or more regions present in the genome which is concerned with protein-encoding.

Therefore, option D is correct because all the mentioned options are applicable in the case of alleles.

Note: Alleles are of different sizes and the lowest possible size can be a single nucleotide polymorphism (SNP). At the extreme highest point, it can be several thousand base pairs long.