Advertisements
Advertisements
Question
List two differences in tabular form between dominant trait and recessive traits. What percentage/proportion of the plants in the F2 generation/progeny were round, in Mendel's cross between round and wrinkled pea plants?
Advertisements
Solution
Difference between dominant trait and recessive gene/trait
| Dominant Trait | Recessive Trait |
| It is a trait or characteristic, which is able to express itself over another contrasting trait. | It is a trait which is unable to express its effect in the presence of the dominant trait. |
| It can express in both heterozygous and homozygous conditions. | It can express only in homozygous condition. |
Cross between round (RR) and wrinkled (rr) pea plants
Parents RR ⨉ rr
Gametes R r
F1 progeny Rr (round seed)
Selfing in F2 generation
| R | r | |
| R | RR | Rr |
| r | Rr | rr |
Result: In F2 generation, the progeny will be
75% round (RR, Rr)
25% wrinkled (rr)
APPEARS IN
RELATED QUESTIONS
Mendel said that the characteristics or traits of organisms are carried from one generation to the next by internal factors which occur in pairs. What is the modern name for these factors?
Using height (tallness/dwarfness) of a plant as an example, show that genes control the characteristics or traits in an organism.
State Mendel's second law of inheritance.
How do Mendel's experiments show that traits are inherited independently?
A cross between two individuals results in a ratio of 9 : 3 : 3 : 1 for four possible phenotypes of progeny. This is an example of a ______.
For his experiments on heredity, Mendel used :
papaya plants
potato plants
pea plants
pear plants
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..
A person first crossed pure-bred pea plants having round-yellow seeds with pure-bred pea plants having wrinkled-green seeds and found that only A-B type of seeds were produced in the F1 generation. When F1generation pea plants having A-B type of seeds were cross-bred by self-pollination, then in addition to the original round-yellow and wrinkled-green seeds, two new varieties A-D and C-B type of seeds were also obtained.
(a) What are A-B type of seeds?
(b) State whether A and B are dominant traits or recessive traits.
(c) What are A-D type of seeds?
(d) What are C-B type of seeds?
(c) Out of A-B and A-D types of seeds, which one will be produced in (i) minimum numbers, and (ii) maximum numbers, in the F2 generation?
Define Heredity. Give two examples.
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?
