Gas exchange in an echinoderm takes place through
a. book lungs.
b. skin gills.
c. lungs.
d. none of the above.

Select the correct answer.which scenario describes unethical lab behavior? o a. danny stores the chemicals required for his experiment in flasks and beakers.b.anna publishes the results of her experiment on the growth rate of saplings.c.jason repeatedly runs an experiment until he gets the results he desires.d. mia records her observations of an experiment precisely and accurately.

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

What best explains the inability for life to exist in earth early atmosphere