Marriages between close relatives and cousins is not advisable because

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4.Principles of Inheritance and Variation

medium

Marriages between close relatives and cousins is not advisable because

More mutations can occur

More recessive defects are likely to appear

More chances are there for $Rh$ blood group anomalies

More chances are there for multiple births

Solution

(b) Marriages between close relatives and cousins is not advisable because recessive lethals are carried in heterozygous conditions and express themselves only when mating takes place between two carrier individuals or close relatives.

Standard 12

Biology

Match the Column – $I$ with $II$

Column – $I$ Column – $II$

$(a)$ Pleiotropic gene $(i)$ Both allele express equally

$(b)$ Co-dominance $(ii)$ Change in nucleotide

$(c)$ Epistasis $(iii)$ One gene shows multiple phenotypic expression

$(d)$ Mutation $(iv)$ Rust disease

hard

(AIIMS-2019)

A man can inherit his $X-$chromosome from his

medium

How many sentence are correct ?

$(i)$ Every gene contains the information to express a particular trait.

$(ii)$ Gene responsible for $\beta$ – thalassemia is present on $21^{st}$ pair of autosomal chromosome.

$(iii)$ Mendel's approach of using mathematics to explain biological phenomena was totally new and unacceptable to many of the biologists of his time.

hard

Pick out the correct statements.

$(1)$ Haemophilia is a sexlinked recessive disease.

$(2)$ Down’s syndrome is due to aneuploidy.

$(3)$ Phenylketonuria is an autosomal recessive gene disorder.

$(4)$ Sickle cell anaemia is an $X$-linked recessive gene disorder.

medium

(NEET-2016)

Match the terms in column $I$ with their description in column $II$ and choose the correct option.

Column $-I$ Column $-II$

$(A)$ Dominance $(i)$ Many genesgovern a single character

$(B)$ Codominance $(ii)$ In a heterozygousorganism only one allele expresses itself

$(C)$ Pleiotropy $(iii)$ In a heterozygousorganism both alleles express themselves fully

$(D)$ Polygenic $(iv)$ A single gene inheritanceinfluences many characters

medium

(NEET-2016)

Column – $I$	Column – $II$
$(a)$ Pleiotropic gene	$(i)$ Both allele express equally
$(b)$ Co-dominance	$(ii)$ Change in nucleotide
$(c)$ Epistasis	$(iii)$ One gene shows multiple phenotypic expression
$(d)$ Mutation	$(iv)$ Rust disease

Column $-I$	Column $-II$
$(A)$ Dominance	$(i)$ Many genesgovern a single character
$(B)$ Codominance	$(ii)$ In a heterozygousorganism only one allele expresses itself
$(C)$ Pleiotropy	$(iii)$ In a heterozygousorganism both alleles express themselves fully
$(D)$ Polygenic	$(iv)$ A single gene inheritanceinfluences many characters

Marriages between close relatives and cousins is not advisable because

Solution

Similar Questions

Match the Column – $I$ with $II$ Column – $I$ Column – $II$ $(a)$ Pleiotropic gene $(i)$ Both allele express equally $(b)$ Co-dominance $(ii)$ Change in nucleotide $(c)$ Epistasis $(iii)$ One gene shows multiple phenotypic expression $(d)$ Mutation $(iv)$ Rust disease

A man can inherit his $X-$chromosome from his

Pick out the correct statements. $(1)$ Haemophilia is a sex­linked recessive disease. $(2)$ Down’s syndrome is due to aneuploidy. $(3)$ Phenylketonuria is an autosomal recessive gene disorder. $(4)$ Sickle cell anaemia is an $X$-­linked recessive gene disorder.

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Match the Column – $I$ with $II$

Column – $I$ Column – $II$

$(a)$ Pleiotropic gene $(i)$ Both allele express equally

$(b)$ Co-dominance $(ii)$ Change in nucleotide

$(c)$ Epistasis $(iii)$ One gene shows multiple phenotypic expression

$(d)$ Mutation $(iv)$ Rust disease

Pick out the correct statements.

$(1)$ Haemophilia is a sexlinked recessive disease.

$(2)$ Down’s syndrome is due to aneuploidy.

$(3)$ Phenylketonuria is an autosomal recessive gene disorder.

$(4)$ Sickle cell anaemia is an $X$-linked recessive gene disorder.