Tag: non mendelian inheritance

Questions Related to non mendelian inheritance

In Mirabilis jalapa , the percentage of plants having pink and red flowers would be ________ when pink flower plant is test crossed.

botany classical genetics non mendelian inheritance deviation from mendelism genetics

  1. 25% pink and 25% red

  2. 50% pink and 50% red

  3. 50% pink and 0% red

  4. 0% pink and 50% red

Show answer
Correct Option: B
Explanation:
 Gamete  R r 
 r Rr- Pink flower  rr- White flower 

Mirabilis jalapa is a plant showing incomplete dominance which means that when in F$ _1$ generation intermediate phenotype appears instead of the two parent phenotypes. 

While, the test cross is defined as a cross between an F$ _1$ plant and the homozygous recessive parent.
So, for plants to be pink in Mirabilis jalapa the plant has to be Rr in genotype. (where R is dominant on r while RR gives Red color and rr gives white color flowers in a plant).
Desired cross: Rr x rr 
So, the phenotype ratio is: 1:1::Pink flower:White flower
So, the correct answer is '50% pink and 50% red'.

Different forms of a gene are called

botany classical genetics non mendelian inheritance deviation from mendelism genetics

  1. Heterozygotes

  2. Alleles

  3. Complementary genes

  4. Supplementary genes

Show answer
Correct Option: B
Explanation:

A.Heterozygotes – Organisms with a pairs of contrasting characters are called Heterozygotes.

B.Alleles - An alternative form of a character in a pair, controlled by a single gene is called Allele. It is dominant either in homozygous or heterozygous state.

C.Complementary gene – Two genes present on separate loci that interact together to produce a dominant phenotype is called Complementary gene. In the F2 generation 9:7 ratio.

D.Supplementary gene – genes which include two pairs of non-allelic genes. Both of them are involved in affecting the same character. Out of the non-allelic genes, one gene is dominant and can express by itself. Second gene is also dominant but expresses only when it is supported by the presence of the first gene. In the F2 geneartion 9:3:4 ratio.

So, the correct option is ‘Alleles’. 

A cross between yellow flowered and round fruit (both dominant) bearing plant and white flowered elongated fruit (both recessive) bearing plant yielded 20 plants in $F _1$ progeny which formed 960 plants in $F _2$ generation. The number of plants with yellow flowers and round fruits in $F _1$ and $F _2$ generations would be

botany classical genetics non mendelian inheritance deviation from mendelism genetics

  1. 20, 960

  2. 20, 540

  3. 10, 180

  4. 10, 60.

Show answer
Correct Option: B
Explanation:

class=A cross is made between pure yellow flowered  and round fruit(YYRR) with white flowered elongated fruit(yyrr). In the F1 generation 20 progeny with yellow flowered and round fruits(YyRr) are formed. When they are subjected to self pollination followed by self fertilization, in the F2 generation, 960 progeny are formed. In these 540 plants are yellow flowered round fruits, plants are yellow flowered elongated fruits, 180 fruits are white flowered round fruits and 60 plants are white flowered elongated fruits the correct option is 20, 540

Two plants of Summer Squash both having circular fruits are crossed. $F _1$ plants had discoid fruits. $F _2$ generation has 3 types of fruits, discoid, circular and long in the ratio of

botany classical genetics non mendelian inheritance deviation from mendelism genetics

  1. 9 : 3 : 4

  2. 9 : 6 : 1

  3. 12 : 3 : 1

  4. 7 : 6 : 3

Show answer
Correct Option: B

A modified dihybrid mendelian ratio of 9 : 3 : 4 indicates

botany classical genetics non mendelian inheritance deviation from mendelism genetics

  1. Supplementary genes

  2. Complementary genes

  3. Lethal genes

  4. Epistalic genes

Show answer
Correct Option: A
Explanation:

A.Supplementary genes – A pair of non allelic genes, one of which produces its effect independently in the dominant state while the dominant allele of the second gene is without any independent effect but is able to modify the effect of the former to produce to a new trait are called Supplemetary genes. Due to these genes in the F2 generation, 9:3:4 ratio of progeny are obtained. It is a modified Mendel dihybrid ratio.

B.Complementary genes – Two genes present on separate loci that interact

together to produce dominant phenotypic character; neither of them if present alone can express itself are called complementary genes. Due to these genes in the F2 generation, 9:7 ratio of progeny are obtained. It is a modified Mendel dihybrid ratio.

C.Lethal genes – A pair of genes present in the homozygous conditions, causes the death of the individual are called Lethal genes. Due to the genes, in F2 generation 2:1 ratio of progeny are obtained.

D.Epistatic genes – A gene which masks the action of another gene is termed as epistatic gene and process is called epistasis. Due to these genes in the F2 generation, either 9:3:4  or 12.3.1 ratio of progeny are obtained. It is a modified Mendel dihybrid ratio.

So, the correct option is ‘supplementary genes’.