The Cacti: Reading Practice 3 (explanation)

By | December 22, 2017

The cacti (singular: cactus) evolved a whole suite of adaptations to survive living in the desert. How do they survive?

While most plants open up their stomata – little pores in their skin that open and close to collect carbon dioxide – during the day, cacti and other nocturnal plants such as the agaves and aloes open their pores at night. The cooler temperatures, lack of sun, and calmer breezes help cacti retain water.

You might think cacti would grow deep roots to search for a constant supply of groundwater. Instead, they often develop extensive, shallow root systems that sit just under the surface of the Earth and can extend several feet away from the plant, ready to absorb as much water as possible.

When it rains, cacti shoot out more roots. During dry periods, roots will shrivel up and break off to conserve the plant’s water supply.

1. The text is categorized as an explanation text because … .
A. it describes what a cactus looks like
B. it explains what a cactus does to survive
C. it tells a challenging environment for a cactus
D. it explores the advantages of growing the cacti
E. it present a logical sequence of events

2. The text explains that cacti survives in the desert by … .
A. saving as much water as they can
B. storing carbon dioxide at night
C. doing photosynthesis during the day
D. by opening up their stomata
E. by extending their roots

3. One thing Cacti do to save water is by … .
A. collecting carbon dioxide
B. growing deep roots
C. developing shallow roots
D. opening up stomata at night
E. doing photosynthesis

4. Another thing Cacti do to retain water is by … .
A. shooting out more roots to get more water
B. extending their roots feet away from the plant
C. searching for a good supply of water
D. adapting themselves to harsh condition of the desert
E. letting their roots break off at dry season

5. Cacti are nocturnal plants. This means … .
A. they do photosynthesis at night
B. they search for water at night
C. they shoot out more roots at night
D. they open up their stomata at night
E. they store carbon dioxide at night

6. Most plants absorb carbon dioxide by … .
A. opening up skin pores
B. extending roots
C. growing taller
D. growing leaves
E. shooting out roots

7. The text uses one word that has a similar meaning to retain. That word is … .
A. supply
B. shrivel up
C. break off
D. conserve
E. search

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