20
RCMultiple Choice

Unit Test — Cumulative exam

Question 20 • TX-Biology B-CR

Cacti typically grow in very dry climates with infrequent rainfall. When it does rain, the rain usually only penetrates a few inches into the soil. Which adaptation is most likely to help a cactus survive in the dry climate?

Answer
A
thick xylem tissue to transport sugar
B
leaves that have a thin cuticle
C
extensive shallow roots that absorb water
D
more dermal tissue for food storage

Explanation

Rain usually wets only the upper few inches of soil, so a wide network of shallow roots can quickly absorb the available water before it evaporates. Therefore, extensive shallow roots are the adaptation that best helps the cactus survive. A thin leaf cuticle would increase water loss, and xylem transports water rather than sugar.

AI-written and checked against the verified answer.

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