Recessive characters are expressed:

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(A) Recessive alleles are those that only express their phenotype when present in a homozygous condition. In the case of $X$-linked recessive traits,m

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Only when they are present on $X$ chromosomes of male

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(A) Recessive alleles are those that only express their phenotype when present in a homozygous condition. In the case of $X$-linked recessive traits,males are hemizygous (having only one $X$ chromosome). Therefore,if a recessive allele is present on the single $X$ chromosome of a male,it will be expressed because there is no dominant allele on a second $X$ chromosome to mask its effect. Thus,the correct condition for the expression of $X$-linked recessive characters in males is their presence on the $X$ chromosome.

Column $I$	Column $II$
$(1)$ Albinism	$(q)$ Recessive gene represented by $cc$
$(2)$ Phenylketonuria	$(s)$ Recessive gene represented by $pp$
$(3)$ Sickle cell anaemia	$(p)$ Recessive gene represented by $Hb^sHb^s$
$(4)$ Alkaptonuria	$(r)$ Recessive gene represented by $aa$

Similar Questions

Haemophilia is a:

In the provided pedigree,assume that no outsider marrying into the family carries the disease. Determine the genotypes of $C$ and $D$.

Identify the genetic disorders based on the following characteristics:
$(i)$ Presence of sickle-shaped $RBC$.
$(ii)$ Blood does not clot,leading to non-stop bleeding.
$(iii)$ The heterozygous female transmits the disease to sons.
$(iv)$ Both heterozygous parents transmit the disease to offspring.

Absence of teeth,bifid tongue and mental retardness are observed in . . . . . . .

Match the columns:

Column $I$ Column $II$

$(1)$ Albinism $(q)$ Recessive gene represented by $cc$

$(2)$ Phenylketonuria $(s)$ Recessive gene represented by $pp$

$(3)$ Sickle cell anaemia $(p)$ Recessive gene represented by $Hb^sHb^s$

$(4)$ Alkaptonuria $(r)$ Recessive gene represented by $aa$

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