Answer:
- E/e ; T/t ⇒ Square eyes and long tail (Option D)
- 3/16 will have round eyes and long tails (Option C)
- 1/4 of the progeny will be heterozygous for both traits (Option A)
Explanation:
<u>Available data</u>:
- Two diallelic unlinked genes
- Gene E controls eye shape: Dominant allele E expresses square eyes, and recessive allele e expresses round eyes.
- Gene T controls the tail size. Dominant allele T expresses long trail, and recessive allele t expresses short tail.
<u>Genotypes Phenotypes</u>
EETT, EeTT, EETt, EeTt Square eyes and Long tail
eeTT, eeTt Round eyes and Long tail
EEtt, Eett Square eyes and Short tail
eett Rounf eyes and short tail.
<em>1. An individual of this new species is heterozygous for gene E and heterozygous for gene T. What is their genotype and phenotype?</em>
The heterozygous individual is E/e ; T/t, expressing square eyes and a long tail.
<em>2. Two individuals, who are both heterozygous for eye shape and tail size, mate. Which of the following is a correct statement about the phenotype ratios expected for their offspring?</em>
Cross: between two heterozygous individuals
Parentals) EeTt x EeTt
Gametes) ET, Et, eT, et
ET, Et, eT, et
Punnett square) . ET Et eT et
ET EETT EETt EeTT EeTt
Et EETt EEtt EeTt Eett
eT EeTT EeTt eeTT eeTt
et EeTt Eett eeTt eett
F1) Genotype:
- 1/16 EETT
- 2/16 EETt
- 1/16 EEtt
- 2/16 EeTT
- 4/16 EeTt ⇒ 1/4 EeTt
- 2/16 Eett
- 1/16 eeTT
- 2/16 eeTt
- 1/16 eett
Phenotype
- 9/16 E-T-, Square eyes and Long tails
- 3/16 E-tt, Square eyes and short tails
- 3/16 eeT-, Round eyes and Long tails
- 1/16 eett, round eyes and short tail
Phenotypic ratio 9:3:3:1
<em>3. From the mating described in question ABOVE, what proportion of ALL of the offspring in will be heterozygous for both traits?</em>
4/16 = 1/4 = 25% of the progeny are expected to be heterozygous for both traits, EeTt.
