Question

flowering time is determined by genes in mustard plants. the graph shows how long it took for the plants to flower in 1997 and 2004. there was a four - year drought between 2000 and 2004.
mustard plant flowering times
in 1997 and 2004
which statement explains the data shown in the graph?
a. the flowering time was about the same before and after the drought.
b. earlier flowering time is an advantage when the environment is dry.
c. having little variation in flowering time increases the populations chances of surviving the drought.
d. later flowering time is an advantage when the mustard population is larger.

Explanation:

Step1: Analyze the graph

In 1997 (before drought), the median flowering time (50% of population) is around 55 - 60 days. In 2004 (after drought), the median flowering time is around 45 - 50 days. So flowering time is earlier after drought.

Step2: Relate to drought

Since there was a drought (dry environment) between 2000 - 2004, and flowering time is earlier in 2004. This implies that earlier flowering time is an advantage in dry (drought - like) conditions.

Step3: Check other options

• Option A: Flowering time is different (earlier in 2004), so A is wrong.
• Option C: The graph shows variation (inter - quartile range). Also, having variation (not little variation) might be better for adaptation. So C is wrong.
• Option D: Flowering time is earlier in 2004 (after drought), not later. So D is wrong.

Answer:

B. Earlier flowering time is an advantage when the environment is dry.