Which of the following gases was probably not present in the atmosphere of primitive Earth?
A. water
B. hydrogen
C. carbon dioxide
D. ozone
D. ozone
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Which of the following statements regarding xylem vessels in angiosperm trees is not true?
A. Vessels allow angiosperms to have higher rates of water flow through stems. B. Angiosperms are able to fix more CO2 and have higher growth rates due to vessels. C. Vessels are rigid and strong and do not require additional support cells. D. Angiosperm wood structure has a high degree of diversity due to the presence of several distinct cell types. E. Angiosperms primarily use vessels to transport water and minerals.
Which of the following is the most likely explanation for the band pattern seen in lane 6?
A. Protein D is a restriction enzyme and cut the DNA fragment into two DNA fragments. B. Protein D binding to the CRP-binding site is less tight compared to cAMP-CRP binding. C. Protein D has a smaller mass than the cAMP-CRP protein. D. Protein D removed radioactive label from the DNA fragment.
Protists do not constitute a kingdom because they do not share a unique common ancestor
Indicate whether the statement is true or false.
The chromosomal DNA is duplicated in which stage of the cell cycle?
a. prophase I b. metaphase I c. interphase d. prophase II e. anaphase II