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प्रश्न
A pea plant with blue colour flower denoted by BB is cross-bred with a pea plant with white flower denoted by ww.
(a) What is the expected colour of the flowers in their F1 progeny?
(b) What will be the percentage of plants bearing white flower in F2 generation, when the flowers of F1 plants were selfed?
(c) State the expected ratio of the genotype BB and Bw in the F2 progeny.
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उत्तर
(a) The expected colour of flowers in their F1 progeny is blue.
(b) 1/4 of the F2 generation have white flowers. So, we can calculate the percentage as follows:-
1/4 × 100 = 25%
Hence, the percentage of plants bearing white flowers in F2 progeny is 25.
(c) The ratio of the genotype BB and Bw in the F2 progeny is 1 (BB) : 2 (Bw).
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संबंधित प्रश्न
How did Mendel interpret his results to show that traits may be dominant or recessive? Describe briefly.
List any two contrasting characters other than height that Mendel used in his experiments in pea plants.
Give the contrasting traits of the following characters in pea plant and mention which is dominant and which is recessive:
Yellow seed
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?
Hereditary characters are transferred from parents to offspring by ______ hence they are said to be structural and functional units of heredity.
Define Heredity. Give two examples.
Write the advantages of heredity.
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?
Figures (a) to (d) given below represent the type of ear lobes present in a family consisting of 2 children - Rahul, Nisha and their parents.
|
(a) Rahul's Father |
(b) Rahul |
(c) Rahul's Mother |
(d) Rahul's sister Nisha |
|
(e) |
(f) |
||
| Types of ear lobes | |||
Excited by his observation of different types of ear lobes present in his family, Rahul conducted a survey of the type of ear lobes found {Figure (e) and (f)} in his classmates. He found two types of ear lobes in his classmates as per the frequency given below:
| Sex | Free | Attached |
| Male | 36 | 14 |
| Female | 31 | 19 |
On the basis of the above data answer the following questions.
- Which of the two characteristics - ‘free ear lobe’ or ‘attached ear lobe’ appears to be dominant in this case? Why?
- Is the inheritance of the free ear lobe linked with the sex of the individual? Give a reason for your answer.
- What type of ear lobe is present in father, mother, Rahul and his sister Nisha? Write the genetic constitution of each of these family members which explains the inheritance of this character in this family.
(Gene for the Free ear lobe is represented by F and the gene for the attached ear lobe is represented by f for writing the genetic constitution).
OR
Suresh’s parents have attached ear lobes. What type of ear lobe can be seen in Suresh and his sister Siya? Explain by giving the genetic composition of all.
Mendel crossed pea plants with two pairs of contrasting characters.
| RRYY | × |
rryy |
| Round, Yellow | Wrinkled, Green |
He observed 4 types of combinations in F2 generation. Which of the combinations were new? Write the conclusion drawn by this experiment.
