Interrupting the night with a flash of light can trigger flowering in a long-day plant. Why doesn't introducing a short period of darkness during the day cause a short-day plant to flower?
A. The circadian clock is less responsive during the day than at night.
B. A brief dark period is not sufficient to trigger flowering.
C. Phytochrome is only active in the dark.
D. The phytochrome response also requires cool nighttime temperatures.
E. Sunlight contains enough far-red light to inhibit phytochrome induction of flowering.
Answer: B
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Dependence on animal vectors for fertilization and
dispersal is characteristic of many species of a. ferns. b. angiosperms. c. mosses. d. conifers. e. cycads.
What primary structures package cellular secretions for export from the cell?
A. Golgi bodies B. Ribosomes C. Mitochondria D. Lysosomes E. Endoplasmic reticula
You study a group of ammonites (an extinct lineage of cephalopods) that lived during the Mesozoic. You measure the shell diameter of different fossil ammonite species
When you combine your data within each of six different time periods you obtain the following average shell sizes and corresponding standard errors. What rule does this data conform to? Time interval Mean shell diameter (+/– standard error) 245–214 MYA 15 mm (+/– 5 mm) 215–184 MYA 21 mm (+/– 7 mm) 185–154 MYA 36 mm (+/– 12 mm) 155–124 MYA 63 mm (+/– 21 mm) 125–94 MYA 72 mm (+/– 24 mm) 95–65 MYA 84 mm (+/– 28 mm) a. Biogenetic rule c. Cope's rule b. Allen's rule d. Bergmann's rule