Advertisements
Advertisements
Question
How do Mendel's experiments show that traits are inherited independently?
Advertisements
Solution
Mendel chose two contrasting characters: shape and colour of seeds. The pea plants had round-yellow seeds and wrinkled green seeds. Mendel first crossed pure-bred pea plants with round-yellow seeds with pure-bred pea plants having wrinkled-green seeds and found that only round-yellow seeds were produced in the first generation. From this, he concluded that round shape and yellow colour of the seeds were dominant traits over the wrinkled shape and green colour of the seeds. When the F1 generation pea plants with round-yellow seeds were cross-bred by self pollination, then four types of seeds with different combinations of shape and colour were obtained in the F2 generation. Mendel observed that he had started with two combinations of characteristics in seeds and two new combinations of characteristics had appeared in the F2 generation i.e. round-green and wrinkled-yellow. On the basis of this observation, Mendel concluded that though the two pairs of original characteristics combine in the F1 generation, they separate and behave independently in subsequent generations.
APPEARS IN
RELATED QUESTIONS
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.
Mendel crossed tall pea plants with dwarf pea plants in his experiment. Write his observations giving reason on the F1 and F2 generations.
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 study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?
How did Mendel explain that it is possible that a trait is inherited but not expressed in an organism?
Fill in the following blank with suitable word .
In pea plants, the gene for dwarfness is ..............whereas that for tallness is ............ .
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?
What is the genotype of dwarf plants whose parental cross always produces tall offspring?
Give the contrasting traits of the following characters in pea plant and mention which is dominant and which is recessive :
Round seed
In the human blood grouping, the four basic blood types are type A, type B, type AB, and type O. The blood proteins A and B are :
(a) simple dominant and recessive traits
(b) incomplete dominant traits
(c) codominant traits
(d) sex-linked traits
Select the statements that describe characteristics of genes :
(i) genes are specific sequences of bases in a DNA molecule.
(ii) a gene does not code for proteins.
(iii) in individuals of a given species, a specific gene is located on a particular chromosome.
(iv) each chromosome has only one gene..
Pure-bred pea plants A are crossed with pure-bred pea plants B. It is found that the plants which look like A do not appear in F1 generation but re-emerge in F2 generation. Which of the plants A and B are : (i) tall, and (ii) dwarf? Give reason for your answer.
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.
Why are the traits acquired during the life time of an individual not inherited? Explain.
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?
Which of the following statement is incorrect?
