A tall pea plants bearing violet flowers is crossed withshort pea plants bearing white flowers .work out the f1 &f2 generations.give f2 ratio
Which traits are dominant or recessive?
To determine the outcomes of the F1 and F2 generations in this cross, you need to understand the principles of Mendelian inheritance and the laws of segregation and independent assortment.
1. Mendelian Inheritance:
Mendelian inheritance describes how traits are passed from parents to offspring. Each inherited trait is controlled by two factors, known as alleles, contributed by each parent. Alleles can be dominant or recessive.
2. The Law of Segregation:
The law of segregation states that during the formation of gametes (sperm and egg cells), the alleles separate, so each gamete receives only one allele for each gene.
3. The Law of Independent Assortment:
The law of independent assortment states that different genes for different traits segregate independently during the formation of gametes.
Now, let’s apply these principles to the given cross of tall violet (TTVV) and short white (ttvv) pea plants.
F1 Generation:
When crossing the tall violet plant (TTVV) with the short white plant (ttvv), the dominant traits will be expressed in the F1 generation. The alleles segregate during gamete formation, so the possible gametes for the tall violet plant are TV and TV, and for the short white plant, they are tv and tv.
Therefore, the F1 generation will have all heterozygous tall plants with violet flowers (TtVv).
F2 Generation:
To determine the outcomes of the F2 generation, we need to consider the possible combinations of alleles when the F1 generation plants (TtVv) are crossed.
The possible gametes for the F1 plants are: TV, Tv, tV, tv.
When the F1 plants are crossed, the resulting genotypes will appear in the following ratio due to the law of independent assortment:
- Homozygous dominant tall violet (TTVV): 1/16
- Heterozygous tall violet (TTVv): 2/16
- Heterozygous tall white (TtVV): 2/16
- Homozygous recessive tall white (TtVv): 4/16
- Heterozygous short violet (ttVv): 2/16
- Homozygous recessive short violet (ttVV): 1/16
- Heterozygous short white (tTvV): 2/16
- Homozygous recessive short white (ttvv): 1/16
Simplifying the ratios, the F2 generation will have the following phenotypic ratio:
- Tall violet plants: 9/16
- Tall white plants: 3/16
- Short violet plants: 3/16
- Short white plants: 1/16