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प्रश्न
In the F2 generation of a cross, progeny having different traits are produced in the ratio 3 : 1. State whether it is a monohybrid cross or a dihybrid cross? Give one example of such a cross.
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उत्तर
It is a monohybrid cross. When a tall pea plant (TT) is crossed with a dwarf pea plant (tt), then in the F1generation, all tall pea plants (with genotype Tt) are obtained. If these tall plants (Tt) are self-crossed, then in the F2 generation, the tall and dwarf plants will be in the ratio 3:1.
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संबंधित प्रश्न
How did Mendel interpret his results to show that traits may be dominant or recessive? Describe briefly.
In a monohybrid cross between tall pea plants (TT) and short pea plants (tt), a scientist obtained only tall pea plants (Tt) in the F1 generation. However, on selfing the F1 generation pea plants, he obtained both tall and short plants in F2 generation. On the basis of above observations with other angiosperms also, can the scientist arrive at a law? If yes, explain the law. If not, give justification for your answer.
Name the information source for making proteins in the cells.
Outline a project which aims to find the dominant coat colour in dogs.
How did Mendel explain that it is possible that a trait is inherited but not expressed in an organism?
Using height (tallness/dwarfness) of a plant as an example, show that genes control the characteristics or traits in an organism.
What will you get in the F1 and F2 generations in the following cross?
Pure tall pea plant × Pure dwarf pea plant
What is the genotype of dwarf plants which always produced dwarf offspring?
Give the contrasting traits of the following characters in pea plant and mention which is dominant and which is recessive :
Round seed
State Mendel's second law of inheritance.
If the ratio of each phenotype of the seeds of pea plants in the F2 generation is 9 : 3 : 3 : 1, it is known as :
(a) tetrahybrid ratio
(b) monohybrid ratio
(c) dihybrid ratio
(d) trihybrid ratio
Pure-bred tall pea plants are first crossed with pure-bred dwarf pea plants. The pea plants obtained in F1generation are then cross-bred to produce F2 generation of pea plants.
(a) What do the plants of F1 generation look like?
(b) What is the ratio of tall plants to dwarf plants in F2 generation?
(c) Which type of plants were missing in F1 generation but reappeared in F2 generation?
A red-haired woman marries a brown-haired man, and all the children are brown haired. Explain this genetically.
A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits-blood group A or O - is dominant? Why or why not?
A person first crossed pure-bred pea plants having round-yellow seeds with pure-bred pea plants having wrinkled-green seeds and found that only A-B type of seeds were produced in the F1 generation. When F1generation pea plants having A-B type of seeds were cross-bred by self-pollination, then in addition to the original round-yellow and wrinkled-green seeds, two new varieties A-D and C-B type of seeds were also obtained.
(a) What are A-B type of seeds?
(b) State whether A and B are dominant traits or recessive traits.
(c) What are A-D type of seeds?
(d) What are C-B type of seeds?
(c) Out of A-B and A-D types of seeds, which one will be produced in (i) minimum numbers, and (ii) maximum numbers, in the F2 generation?
Define Heredity. Give two examples.
Write the advantages of heredity.
