Question

A species of Coral snake has a red, yellow, and black stripe pattern. One gene controls if the stripes are thick or thin. Thin(T) is dominant over thick(t). If two snakes heterozygous for this gene are crossed, what will be the phenotype(s) of their offspring? You may need to use a Punnett square to answer the question.

A. 75% with thick stripes, 25% with thin stripes
B. All thin stripes
C. 50 % with thin stripes, 50% with thick stripes
D. 75% with thin stripes, 25% with thick stripes

Answer 1

D.

What is heterozygous?

When an organism is heterozygous for a certain gene it means that it has 1 dominant and one recessive allele, which in this case, would be T and t (Tt).

What happens when breeding 2 heterozygous organisms?

T t

T TT Tt

t Tt tt

TT = dominant (thin)

Tt = dominant (thin)

tt = recessive (thick)

Conclusion:

Given the results above, 75% (3 out of 4) will have thin stripes (T), and 25% (1 out of 4) will have thick stripes (t).

Hope it helped,

BiologiaMagister