Video Transcript
Cacti are plants adapted to the
desert. Throughout evolution, what have
cacti leaves transformed into? (A) Cacti leaves have transformed
into large, round, or cylindrical arms. (B) Cacti leaves have transformed
into thick wax covering the stem. (C) Cacti leaves have transformed
into fleshy stems. (D) Cacti leaves have transformed
into spines.
This question is asking us about
adaptations of a cactus plant. So what is an adaptation
exactly?
An adaptation is a characteristic
of an organism that makes it well suited to its environment and gives it a better
chance of survival. In this question, we’re looking at
a plant that lives in the desert. A desert is a region of land that
doesn’t get much rain or precipitation. This makes it very dry. Organisms that live in this
environment need to adapt to higher temperatures and need to conserve water.
Cacti have different adaptations to
deal with conserving water and preventing overheating. They tend to have shallow roots so
they can absorb water more easily. Cacti also have waxy skin that
reflects light to help the plant from overheating. The waxy surface also prevents
water from evaporating from the stem. And finally, cacti have developed
leaves that are very thin spines. These spines have a reduced surface
area so water can’t evaporate as much.
So, getting back to our question,
the option that best describes what cacti leaves have transformed into is given by
answer choice (D). Cacti leaves have transformed into
spines.
