Question

read this passage about two inherited traits in barnyard grass plants. barnyard grass is a weed that often grows in rice fields. a barnyard grass seedling can have upright leaves that stick straight up or drooping leaves that curl down. rice seedlings have upright leaves. so farmers weeding their rice fields by hand are more likely to mistake barnyard grass seedlings with upright leaves for rice plants. farmers are more likely to recognize and remove barnyard grass seedlings with drooping leaves. the barnyard grass plants environment changed to have more farmers weeding the rice fields by hand. after this change, over a time period long enough for natural selection to occur, the percentage of the barnyard grass plant population with upright leaves increased. use the theory of natural selection to construct a possible explanation for how the barnyard grass plant population adapted to its changed environment. having drooping leaves was ▲ advantageous than having upright leaves after the environment changed. s more es for drooping leaves were passed on with. frequency than tl less for upright leaves. as a result, the proportion of the population with drooping leaves ▼. over time, the population adapted such that the percentage of grass plants that looked like rice plants ▼.

Explanation:

Natural selection favors traits that enhance survival and reproduction. After the environment changed (more hand - weeding farmers), upright - leafed barnyard grass was less likely to be removed (resembled rice). So, upright - leafed plants had higher survival and reproduction rates. Their genes (for upright leaves) were passed on more frequently. Drooping - leafed plants were removed more often, so their genes were passed on less. Over time, the proportion of upright - leafed plants increased as the population adapted to the new environment (avoiding removal by farmers).

Answer:

Having drooping leaves was less advantageous than having upright leaves after the environment changed. So, genes for drooping leaves were passed on with lower frequency than those for upright leaves. As a result, the proportion of the population with drooping leaves decreased. Over time, the population adapted such that the percentage of grass plants that looked like rice plants increased.