Advertisements
Advertisements
प्रश्न
Describe the cross between a homozygous tall, round-seeded pea plant and a dwarf, wrinkled-seeded pea plant. What will be the types of progeny in the F2 generation of this cross and in what proportion will it be?
Name and state the law which is explained by this example.
उत्तर
Let the gene for the tall habit of the pea plant be represented by ‘T’ and the dwarf habit be represented by ‘t’.
Let the gene for round seed be represented by ‘R’ and that of wrinkled seed be represented by gene ‘r’.
Then, the genotypes of the parents would be:
- Homozygous tall, round seeded − TTRR
- Homozygous dwarf, wrinkled seeded – ttrr
F2 progeny obtained → Tall Round; Tall Wrinkled; Dwarf Round; Dwarf Wrinkled
Phenotypic ratio → 9 : 3 : 3 : 1
Genotypic ratio→
| 1 : | 2 : | 2 : | 4 : | 1 : | 2 : | 1 : | 2 : | 1 |
| TTRR | TTRr | TtRR | TtRr | ttRR | ttRr | TTrr | Ttrr | ttrr |
The above example of a dihybrid cross between a homozygous tall, round-seeded pea plant and dwarf, wrinkled-seeded pea plant explains the ‘Law of Independent Assortment’.
The law of independent assortment states that “when two parents differing from each other in two or more pairs of contrasting characters are crossed, then the inheritance of one pair of characters is independent of the other pair of characters.”
APPEARS IN
संबंधित प्रश्न
Mendel published his work on inheritance of characters in 1865, but it remained unrecognised till 1900. Give three reasons for the delay in accepting his work.
In Mendel’s experiments, tall pea plants (T) are dominant over dwarf pea plants (t).
What is the phenotype and genotype of the F1 generation if a homozygous tall plant is crossed with a homozygous dwarf plant?
Suppose you are given two pairs of contrasting characters: Seed colour → yellow and green , seed coat → round and wrinkled.
Fill in the following table to show that F2 generation according to the principle of independant assortment as given by Mendel.
| Selfing among hybrids of F1 | RY | Ry | rY | ry |
| RY | ||||
| Ry | ||||
| rY | ||||
| Ry | ||||
| F2 generation |
Predict the genotype and phenotype of the following cross in pea.
TTrr x ttRR
(Capital letters show dominance)
Choose the correct answer:
Mendel used ______ pairs of a characters for his experiments.
The 9 : 3 : 3 : 1 dihybrid ratio is due to ______.
Which one from those given below is the period for Mendel's hybridization experiments?
Which of the following are reasons for Mendel’s success?
- Usage of pure lines or pure breeding varieties
- Consideration of one character at a time
- Maintenance of statistical records of experiments
- Knowledge of linkage and incomplete dominance
Read the following and answer from given below:
Prashant wanted to find the genotype of a pea plant bearing purple coloured flowers in his kitchen garden. For this, he crossed purple-flowered plants with white-flowered plants. As a result, all plants which were produced had purple flowers only. Upon selfing these plants, 75 purple flower plants and 25 white flowers plants were produced. Now, he can determine the genotype of a purple-flowered plant by crossing it with a white-flowered plant.
In white-flowered plants, the allele is expressed in ______
Give the pair of contrasting traits of the following characters in the pea plant and mention which is dominant and recessive
- yellow seed
- round seed
