Question

A tabby, short haired male (TtbLl) is crossed with a blotched tabby, short haired (tbtbLl) female. Determine ratios of the offspring.

Answer 1

The offspring of a TtbLl male cat and a tbtbLl female cat will exhibit a 9:3:3:1 ratio with respect to their coat patterns (tabby or blotched tabby) and hair length (short or long).

Step-by-step explanation:

In this scenario, we are investigating the inheritance patterns of two traits in felines: coat pattern (tabby or blotched tabby) and hair length. The male's genotype is TtbLl, where 'Tt' denotes the tabby pattern (which is incompletely dominant over blotched tabby) and 'bL' denotes short hair (with 'L' being the dominant gene for short hair). The female's genotype is tbtbLl, meaning she has the blotched tabby pattern and is heterozygous for hair length.

Lets determine the cross between TtbLl and tbtbLl.

1. We must first set up two punnet squares for each trait. The first square for tabby pattern: 1 Tt x 1 tb, and the second one for hair length: 1 Ll x 1 Ll.
2. From the first punnet square, the possible offspring patterns for coat are: 1 Tbtb (tabby), 1 Tttb (tabby), 1 tb1 (blotched tabby), and 1 tb2 (blotched tabby).
3. From the second punnet square, the hair length alleles combine to give: 1 Ll (short), 2 LL (short), and 1 ll (long).
4. Now we can combine the results from both trait crosses to determine ratios for the combined traits. The genotypes will be in the ratios of: 9 tabby, short-haired; 3 blotched tabby, short-haired; 3 tabby, long-haired; and 1 blotched tabby, long-haired.

This conclusion is based on the principle of independent assortment and predictions from a dihybrid cross between two double heterozygotes, which typically display a phenotypic ratio of 9:3:3:1.

Answer 2

Genotypic ratios:

TtbLL: TtbLl: Ttbll: tbtbLL: tbtbLl: tbtbll

1:2:1:1:2:1

Phenotypic ratios:

3 Tabby long hair

1 tabby short hair

3 blotched tabby short hair

1 blotched tabby short hair

Step-by-step explanation:

• The genotype Ttb represents tabby fur coat.
• tbtb genotype represents blotched tabby fur coat.
• Long hair (ll) is a recessive genotype.
• Short hair (Ll or LL) is the dominant genotype.
• The following Punnet square represents the dihybrid square.

Punnet Square:

TL Tl tbl tbl

tbl TtbLL TtbU tbtbLL tbtbll

tbl TtbU Ttbll tbtbll tbtbll

tbl TtbLL TtbU tbtbLL tbtbll

tbl TtbU Ttbll tbtbLI tbtbll