Advertisements
Advertisements
प्रश्न
In a plant tallness is dominant over dwarfness and red flower is dominant over white. Starting with the parents work out a dihybrid cross. What is standard dihybrid ratio? Do you think the values would deviate if the two genes in question are interacting with each other?
Advertisements
उत्तर
The following Punnett Square shows a cross between a tall plant with red flowers (TTRR)and a dwarf plant with white flowers (ttrr). All the plants in F1 generation will be tall and will produce red flowers.
When plants of F1 generation are allowed to self-pollinated, phenotype of plants in F2 generation can be shown by following Punnett Square.
In this case, the standard dihybrid ratio 9 : 3 : 3 : 1 which can be shown as follows:
Tall plant red flower = 9
Tall plant white flower = 3
Dwarf plant red flower = 3
Dwarf plant white flower = 1
The standard dihybrid ratio works only when the genes for contrasting characters are on different chromosomes. If characters are on the same chromosome, they may interact with each other. In that situation, the dihybrid ratio would show variation from the standard hybrid ratio.
APPEARS IN
संबंधित प्रश्न
Differentiate between the following:
Homozygous and Heterozygous
Differentiate between the following:
Monohybrid and Dihybrid
Given below are the F2 – phenotypic ratios of two independently carried monohybrid crosses :
(i) 1 : 2 : 1
(ii) 3 : 1
Mention what does each ratio suggest.
Mention whether the cross is a monohybrid or dihybrid.
A certain couple got four daughters in a sequence and no son. Does it mean that the husband does not produce Y-chromosome bearing sperms? Explain. What is the chance of this couple having a daughter?
Differentiate Between Monohybrid and Dihybrid cross.
Name the conditions when both the alleles are identical?
A garden pea plant produces axial white flowers. Another of the same species produced terminal violet flowers. Identify the dominant trait?
A pure tall plant (TT) is crossed with the pure dwarf plant (tt), what would be the F1 and F2 generations? Explain.
Pure-bred tall pea plants are first crossed with pure-bred dwarf pea plants. The pea plants obtained in the F1 generation are then selfed to produce F2 generation of pea plants.
What is the ratio of tall plants to dwarf plants in the F2 generation?
Pure-bred tall pea plants are first crossed with pure-bred dwarf pea plants. The pea plants obtained in the F1 generation are then selfed to produce F2 generation of pea plants.
Which type of plants was missing in the F1 generation but reappeared in the F2 generation?
Differentiate between inherited and acquired characters. Give one example for each type.
Genotypic ratio of a monohybrid cross is ______.
When a tall plant with rounded seeds (TTRR) is grossed with a Dwarf plant with wrinkled seeds (ttrr) the F1 generation consists of tall plants with rounded seeds. How many types of gametes the F1 plant would produce?
A Monohybrid cross is ______
Punnett square is used to know
In a monohybrid cross of plants with red and white flowered plants, Mendel got only red-flowered plants. On self-pollinating these F1 plants got both red and white flowered plants in 3:1 ratio. Explain the basis of using RR and rr symbols to represent the genotype of plants of parental generation.
Assertion (A): In humans, if gene (B) is responsible for black eyes and gene (b) responsible for brown eyes, then the colour of eyes of the progeny having gene combination Bb, bb or BB will be black only.
Reason (R): The black colour of the eyes is a dominant trait.
