Question

Which is the correct cross to produce all straight, long tailed mice when straight tail (T) is dominant over bent tail (t) in mice, and long-tailed mice (L) are dominant over short-tailed mice (l)?

• A. $TtLl\times TtLl$
• B. $Ttll\times TTLl$
• C. $TtLL\times ttLL$
• D. $TtLl\times TTLL$
• E. None of the above

Answer 1

Answer: (D)

$TtLl\times TTLL$

The parent with genotype TtLl will produce gametes T, t, L and l. The second parent with genotype TTLL will produce gametes T, T, L and L. Straight tail (T) is dominant over bent tail (t) in mice. Long-tailed mice (L) are dominant over short-tailed mice (l). When these two parents are crossed, all the offspring (mice) produced will have straight and long tail. So, the correct answer is option D.