Question

Alleles of a gene are found on
A. Same chromosome
B. Homologous chromosomes
C. Nonhomologous chromosomes
D. Any chromosomes

Answer 1

Chromosomes are oval, rod or thread like DNA and protein complexes which function as hereditary vehicles as they store, replicate and transcribe coded hereditary information.

Complete Answer:
- A gene is defined as the unit of DNA responsible for appearance and inheritance of character.
- Alleles or allelomorph is a Greek word which means belonging to one another. It refers to one of the two members of a gene pair. It is defined as a pair of genes that control the two alternatives of the same character and are located at the same locus in the homologous chromosomes.
- Homologous chromosomes can be defined as a set of chromosomes that pair up with each other during fertilization of male and female gametes. It consists of one maternal and one paternal chromosome.
- Non homologous chromosomes on the other hand do not have the same genes at the same loci.
- A heterozygote possesses two contrasting alleles for a gene but only one of them is able to express itself while the other remains hidden. The allele that expresses itself in F1 generation is the dominant allele while the allele that is unable to express itself is called recessive allele.

Hence the correct answer is option B.

Note: Chromosomes were first observed by Hofmeister as nuclear filaments in pollen mother cells of Tradescantia.
- The term Gene was given by Johanssen. Mendel used the term factor for genes in his experiments with peas.
- The term allele was given by William Bateson.