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.
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.
Related Questions
In a certain species of animals, black fur (B) is dominant over brown fur (b). Predict the genotype and phenotype of the offspring, when both parents are 'Bb' or have heterozygous black fur.
Make a Punnett square and find out the genotypic and phenotypic ratios of F1 and F2 generations in the progeny of a genetic cross between:
(a) A pure tall (TT) pea plant with a pure dwarf (tt) pea plant.
(b) Red flower variety of pea (RR) with white flower variety of pea (rr).
Two pairs (A and B) of rabbits were crossed as given below:
(a) Can you tell which coat colour (black or white) is dominant?
(b) Is the coat colour sex-linked?
A homozygous plant having round (R) and yellow (Y) seed is crossed with another homozygous plant having wrinkled (r) and green (y) seeds. Answer the following questions :
(a) Give the genotype of the F1 generation.
(b) Mention the phenotype of the F1 offsprings.
(c) Give the possible combinations of gametes that can be obtained from F1 hybrids.
(d) Give the dihybrid phenotypic ratio and the phenotype of the offsprings of the F2 generation when two plants of F1 generation are crossed.
(e) Name and state the law which explains the dihybrid phenotypic ratio.