Astudent encounters a pondweed which, judging from its appearance, seems to be a charophyte. she brings a sample back to her biology lab. using only a compound light microscope to study the sample, which of the following features should her to determine whether the sample comes from a charophyte or from some other type of green alga? 1. molecular structure of enzymes inside peroxisomes2. structure of sperm cells3. presence of phragmoplasts4. rings of cellulose-synthesizing complexes

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.

Read the following scenario to answer the following question. in some zoos, rare crosses between a male lion and a female tiger have produced hybrid offspring called "ligers." male ligers are sterile but some female ligers are fertile. in the wild, lion and tiger ranges do not naturally overlap, making such a cross unlikely. furthermore, the solitary behavior of tigers and the social organizations of lions create behavioral differences. applying the biological species concept, the sterility of ligers reveals that a. lions are probably a subspecies of tigers b. tigers and lions are the same species c. a new species called "ligers" is forming d. tigers and lions are separate species

When proteins are being produced by a cell, scientist say that the genes are question 2 options: activated turned off replicated deactivated