Free SAT Practice Question

Question 1 of 1
ID: SAT-RW-II-043
Section: SAT Reading & Writing (RW) – Information and Ideas
Topic: Central Ideas and Details
Difficulty level: Easy

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Most plants open the tiny pores on their leaves, called stomata, during the day to take in the carbon dioxide that photosynthesis needs. In hot deserts, though, opening those pores under a blazing sun would let precious water escape as vapor. A number of desert plants, among them many cacti and agaves, have settled on a different schedule: they keep their stomata shut through the heat of the day and open them only at night, when cooler, calmer air draws far less moisture from the leaf. The carbon dioxide they collect after dark is stored as an acid and then fed into photosynthesis the next day, once sunlight returns. In effect, these plants pull apart in time the two tasks that most plants carry out together.

Which choice best states the main idea of the text?

AStomata are the small pores through which a plant’s leaves take in carbon dioxide.

BCertain desert plants conserve water by taking in carbon dioxide at night and using it for photosynthesis by day, separating in time two tasks most plants perform at once.

CIn hot climates, plants keep their stomata closed during the day and open them only after dark.

DStoring carbon dioxide as an acid allows desert plants to grow faster than plants that photosynthesize in the usual way. On this telling the nighttime schedule is not just a way to save water but a competitive edge that lets these plants outpace their neighbors.

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