Botanist Dr. Chloe Dupont studied the growth of the alpine plant *Silene acaulis*. Dupont hypothesized that these plants produce thicker leaves to protect themselves from cold night temperatures, rather than to protect themselves from high ultraviolet radiation.
Which finding, if true, would most directly support Dupont's hypothesis?
- A*Silene acaulis* plants growing at higher elevations produce larger flowers than plants growing at lower elevations.
- B*Silene acaulis* plants growing in warm valley environments were found to have significantly thicker leaves than those growing on cold mountain peaks.
- When grown in a laboratory, *Silene acaulis* plants exposed to cold temperatures but no ultraviolet radiation developed thick leaves, while those exposed to high ultraviolet radiation but warm temperatures did not.Answer
- D*Silene acaulis* plants must have evolved thick leaves millions of years ago when the Earth's climate was much colder and ultraviolet levels were lower.
Answer
The finding that *Silene acaulis* plants grown under cold temperatures without ultraviolet radiation developed thick leaves, while those grown under high ultraviolet radiation in warm temperatures did not.
The correct option is the finding that in a laboratory, *Silene acaulis* plants exposed to cold temperatures but no ultraviolet radiation developed thick leaves, while those exposed to high ultraviolet radiation but warm temperatures did not. This supports the hypothesis because it isolates temperature and ultraviolet radiation as variables, showing that cold temperature is the actual driver of leaf thickness, not ultraviolet radiation.
Step-by-Step Solution
Key Concept
Identifying textual evidence that supports a specific causal claim while ruling out an alternative explanation.