Use Figure 14.1 and the following description to answer the questions below.
In a particular plant, leaf color is controlled by gene locus D. Plants with at least one allele D have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F₁ offspring is allowed to self-pollinate. The predicted outcome of the F₂ is diagrammed in the Punnett square shown in Figure 14.1, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square.

Figure 14.1
-Which of the plants will be true-breeding?
A) 1 and 4 only
B) 2 and 3 only
C) 1, 2, 3, and 4
D) 1 only
E) 1 and 2 only

Question

Use Figure 14.1 and the following description to answer the questions below.
In a particular plant, leaf color is controlled by gene locus D. Plants with at least one allele D have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F₁ offspring is allowed to self-pollinate. The predicted outcome of the F₂ is diagrammed in the Punnett square shown in Figure 14.1, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square.
  
Figure 14.1
-Which of the plants will be true-breeding?
A) 1 and 4 only 
B) 2 and 3 only 
C) 1, 2, 3, and 4 
D) 1 only 
E) 1 and 2 only

Quizplus · Accepted Answer

True-breeding plants are those that, when self-fertilized, only produce offspring with the same traits. Choices 1 and 4 must represent plants that are homozygous for the traits in question, ensuring that they will consistently produce offspring with those same traits when self-fertilized.