Biology
Mendel crossed a homozygous pea plant having round seeds (RR) with a homozygous pea plant having wrinkled seeds (rr). He got different results. On the basis of it, answer the following questions:
(a) Which character of seed is studied in the experiment?
(b) Which of the above two traits is dominant ?
(c) Write the phenotype and genotype of F1 offspring.
(d) Mention and state the Mendel’s law shown in the above cross.
(e) Make a Punnett square for F2 generation when two plants of F1 offspring are crossed with each other.
(f) Write the phenotypic ratio of F2 progeny.
(g) What will be the genotypic ratio of F2 offsprings ?
(h) What are the two traits of seed colour ? Also mention which is dominant and recessive ?
(i) Write the scientific name of garden pea.
(j) Write two main features of pea plant due to which Mendel had selected it for his hybridisation studies.
Genetics
ICSE
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Answer
(a) Shape of seed
(b) Round seed shape is dominant.
(c) Phenotype — Round seed
Genotype — Rr
(d) Law of dominance, which states that out of a pair of contrasting characters present together, only one is able to express itself while the other remains suppressed.
(e)
| Gamete | R | r |
|---|---|---|
| R | RR | Rr |
| r | Rr | rr |
(f) Phenotypic ratio — 3:1
(g) Genotypic ratio — 1:2:1
(h) The two traits of seed colour are:
- Yellow (dominant)
- Green (recessive)
(i) Pisum sativum
(j) The two main features due to which Mendel selected pea plants are :
- Many varieties were available in alternative forms of a character.
- The life span of pea plants is short and many generations can be obtained and studied in less time.
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