John realized that his orchard has been invaded by certain harmful invasive plants. these plants are consuming all the soil nutrients and water, and they are outcompeting native plants. john decided to cover the invasive plants with black plastic for one growing season. which method did john use to control the invasive species? girdling mowing digging smothering tilling

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

What evidence did mendel find that supported his law of independent assortment? a. some traits are controlled by several different genes. b. a trait can be passed on from a parent to an offspring. c. most traits have a dominant form and a recessive form. d. different traits are passed on independently of each other.

Why did adult crab numbers decline in he ecosystem, even though sea stars were still available?