Question

Attached ear lobe in humans is
(a)Recessive trait
(b)Dominant trait
(c)Homozygous trait
(d)Heterozygous trait

Answer 1

Hint: The physical characteristics that belong to any human being are guided by genes and hence called the genetic traits. Each trait is governed by a recessive and a dominant allele. The human traits other than the sexual ones are controlled by 22 pairs of autosomes.

Complete answer:
The human genome consists of 22 pairs of autosomes and sex chromosomes. In humans, an autosomal trait is not guided by two alleles but for simplicity, you can consider the representation of two alleles. One of the two alleles is of the dominant form and the other is of the recessive form. It is seen that the presence of the dominant form in a heterozygous genotype results in the expression of the dominant trait only. Gene containing information about earlobes also has two alleles, the dominant free-hanging earlobe trait, and the recessive attached lobe trait. Being a recessive trait the presence of attached earlobes is quite rare, it happens only when the genotype consists of two recessive alleles which result in the expression of the attached earlobes.

Additional Information: -Other autosome controlled traits include Hitchhiker's thumb and widow's peak.
-Except for the autosomal traits there is also the presence of sex-linked traits.
-The X-linked trait is a type of single gene pattern inheritance and this type of inheritance is quite different from that shown by the autosomal traits.
-Y- chromosome in males also determines the characteristics of the appearance of a male.
-The most common type of earlobes that are found in humans are the free earlobes while the attached earlobes are much rarer to find.
-There is also the presence of many genetic diseases like Down’s syndrome, Turner syndrome.
-Congenital diseases are passed on from generation to generation depending on whether the alleles of the genetic traits present in the human body are dominant or recessive.
So, the correct option is, “Recessive Trait”.

Note: -You must note that it is not necessary that a child having attached earlobes should belong to a father or mother who also has attached earlobes, it depends upon the Pedigree of the family.
-Congenital diseases can also be severe, moderate, or minor depending upon the type of alleles which are present in the human body