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प्रश्न
How do Mendel’s experiments show that the traits may be dominant or recessive?
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उत्तर
Mendel crossed purebred tall pea plants with purebred dwarf pea plants and found that only tall pea plants were produced in the first generation, and there were no dwarf pea plants. He concluded that the first generation showed the traits of only one of the parent plants tallness. The trait of the other parent plant dwarfness did not show up in the progeny of the first generation.
He then crossed the tall pea plants obtained in the first generation (F1 generation) and found that both tall plants and dwarf plants were obtained in the second generation (F2 generation) in the ratio of 3 : 1. Mendel noted that the dwarf trait of the parent pea plant which disappeared in the first generation progeny reappeared in the second generation. In this way, Mendel’s experiments with tall and dwarf pea plants showed that the traits may be dominant and recessive.
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संबंधित प्रश्न
In one of his experiments with pea plants, Mendel observed that when a pure tall pea plant is crossed with a pure dwarf pea plant in the first generation, F1, only tall plants appear.
(a) What happens to the traits of the dwarf plants in this case?
(b) When the F1-generation plants were self-fertilised, he observed that in the plants of the second generation, F2, both tall plants and dwarf plants were present. Why it happened? Explain 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.
List any two contrasting characters other than height that Mendel used in his experiments in pea plants.
A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as:
State whether the following statement is true or false :
The sex of an infant is not a case of inheritance of characteristics.
What type of plants were used by Mendel for conducting his experiments on inheritance?
Fill in the following blank with suitable word .
In pea plants, the gene for dwarfness is ..............whereas that for tallness is ............ .
What sizes of plants are produced if both parents have genes Tt?
When two parents are crossed, the offspring are referred to as :
recessives
test cross
F1 generation
F2 generation
The following results were obtained by a scientist who crossed the F1 generation of pure-breeding parents for round and wrinkled seeds.
| Dominant trait | Recessive trait | No. of F2 offspring |
| Round seeds | Wrinkled seeds | 7524 |
From these results, it can be concluded that the actual number of round seeds he obtained was ______
A trait in an organism is influenced by ______
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?
"It is possible that a trait is inherited but may not be expressed." Give a suitable example to justify this statement.
If we pure-bred tall (dominant) pea plant with pure-bred dwarf (recessive) pea plant we will get pea plants of F1 generation. If we now self-cross the pea plant of F1 generation, then we obtain pea plants of F2 generation.
(a) What do the plants of F2 generation look like?
(b) State the ratio of tall plants to dwarf plants in F2 generation.
(c) State the type of plants not found in F1 generation but appeared in F2 generation, mentioning the reason for the same.
Explain Mendel’s law of independent inheritance. Give one example.
Answer the following question.
Name the plant Mendel used for his experiment. What type of progeny was obtained by Mendel in F1 and F2 generations when he crossed the tall and short plants? Write the ratio he obtained in F2 generation plants.
What is genetics?
In humans, if gene B gives brown eyes and gene b gives blue eyes, what will be the colour of eyes of the persons having combinations
(i) Bb and (ii) BB?
