You look at a sample of tissue under the microscope. you determine the sample is not from an animal because the cells in the tissue have

a. nuclei.

b. cell membranes.

c. cell walls.

d. membrane-bound organelles.

Ecologist have observed a sharp increase of sulfur dioxide in the air . what might be a possible consequence of excessive sulfur dioxide in the air ? a. acid rain b. ozone layer depletion c.ozone layer hole d.increase in sea levels

The diagram shows the layers of earth. convection currents in which region influence the movement of tectonic plates

Which type of transport is responsible for oxygen entering into blood cells? a. vesicle b.passive c. facilitated d.active b.passive