The major function of the protonephridia in the flatworm is to:
a. conserve water.
b. conserve salts.
c. eliminate waste materials such as ammonia and urea.
d. eliminate excess water.
e. regulate the pH of the gastrovascular cavity.
d
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Scientists attempted for many years to conduct nuclear transplants but failed. However, geneticists had success in cloning a sheep. They were successful because they
A. picked a cell very early in development. B. replicated the blastomeres before insertion. C. delayed transcription in the blastomeres. D. treated the nucleus with sheep plasma before nuclear insertion. E. utilized a new micro pipette technique.
Cells in the G0 stage
A) have two chromatids per chromosome. B) are replicating their chromosomes. C) are about to enter the mitotic phase of the cell cycle. D) are in an extended G1 phase and no longer dividing. E) are dead.
Which of the following organisms can use the process of lactic acid fermentation when oxygen concentrations are low?
a. yeast b. plants c. humans d. fish
The production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) is an example of _____
A) reduced hybrid viability B) hybrid breakdown C) reduced hybrid fertility D) mechanical isolation