Answer:
Radiolabeled carbon atom in CO2
Explanation:
Photosynthesis is the process by which green plants fix the atmospheric CO2 into glucose. The process includes carbon fixation during which RuBisCo enzyme catalyzes the reaction of CO2 and a five-carbon compound called RuBP to form 3-phosphoglycerate (3-PGA). The 3-PGA enters the reduction phase of the Calvin cycle wherein it is reduced into glyceraldehyde 3-phosphate. Two molecules of glyceraldehyde 3-phosphate make one molecule of glucose.
To test the hypothesis that glyceraldehyde 3-phosphate from photosynthesis is used by plants to synthesize lipids, radiolabeled CO2 must be used. The radiolabeled carbon atom in the CO2 would be fixed in the form of glyceraldehyde 3-phosphate. If the plant uses glyceraldehyde 3-phosphate as a precursor for lipid synthesis, the synthesized lipid molecules would carry the radiolabeled carbon atom.
Arteries carry blood away from the heart
There are all sorts of ways to reconstruct the history of life on Earth. Pinning down when specific events occurred is often tricky, though. For this, biologists depend mainly on dating the rocks in which fossils are found, and by looking at the “molecular clocks” in the DNA of living organisms.
There are problems with each of these methods. The fossil record is like a movie with most of the frames cut out. Because it is so incomplete, it can be difficult to establish exactly when particular evolutionary changes happened.
Modern genetics allows scientists to measure how different species are from each other at a molecular level, and thus to estimate how much time has passed since a single lineage split into different species. Confounding factors rack up for species that are very distantly related, making the earlier dates more uncertain.
These difficulties mean that the dates in the timeline should be taken as approximate. As a general rule, they become more uncertain the further back along the geological timescale we look. Dates that are very uncertain are marked with a question mark.
Answer:
D. Adenine and Thymine form hydrogen bonds, while cytosine and guanine form covalent bonds.
Explanation:
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