Cyclin-dependent kinases (Cdks) are enzymes involved with the control of mitosis; Drs. Lee Hartwell and Paul Nurse won the Nobel Prize for Physiology or Medicine in 2001 for their work on Cdks. What organism was used to study these enzymes?
a) Mus musculus
b) Escherichia coli
c) Saccharomyces cerevisiae
d) Arabidopsis thaliana

Option C

Explanation:

Dr. Leland Hartwell used baker’s yeast, Saccharomyces cerevisiae, as a model system, which was a highly suitable model for cell cycle studies. He introduced the concept of Checkpoints where he said cells are arrested if damaged so that the cells repair system can work to correct such damages. Dr. Paul Nurse used a different type of yeast, Schizosaccharomyces pombe, a type of yeast distantly related to the baker's yeast as a model organism.

the fossil record provides evidence of a common ancestor to many species.

above statement is not a true statement about the open ocean because the open ocean has low levels of nutrients. most of the photosynthetic activity on earth occurs in the open ocean within the photic zone. organisms in the deep ocean are exposed to frigid temperatures and total darkness but it does not begin at the low-tide mark.