Question

question #20
the table provides information about two inherited traits in plants, stem height and flower color.

allele	trait
t	short stem
r	red flower
r	white flower

which genotype represents a plant with short stems?

a tr
b tt
c tt
d tt

Explanation:

To determine the genotype for a short - stemmed plant, we refer to the given table. The allele for a short stem is \( t \). In genetics, for a recessive trait (like short stem, since the dominant allele \( T \) gives a tall stem) to be expressed, the plant must have two recessive alleles.

• Option A: \( tr \) combines alleles for stem height and flower color, but this is not a valid genotype for just stem height (and also, the way alleles are combined here is incorrect for representing a single trait's genotype).
• Option B: \( tt \) means the plant has two recessive alleles for stem height. Since \( t \) is the allele for short stem, having two \( t \) alleles will result in a short - stemmed plant.
• Option C: \( TT \) means the plant has two dominant alleles for stem height, so it will have a tall stem.
• Option D: \( Tt \) means the plant has one dominant and one recessive allele for stem height. The dominant allele \( T \) will be expressed, so the plant will have a tall stem.

Answer:

B. tt