What led to the increase in oxygen levels in the atmosphere on primitive Earth?

a. the first photosynthetic reactions
b. photosynthetic cells that used water and not H2S as a source of electrons
c. the development of cellular respiration pathways in cells
d. the use of glycolysis in cells
e. photosynthetic pathways that stripped oxygen off of carbon dioxide and retained only the carbon in subsequent
steps


ANSWER: b

Biology & Microbiology

You might also like to view...

You may have heard of myosin, a molecule that makes up the bulk of skeletal muscle. It turns out there are many types of myosin, produced from many different genes

These genes are part of a huge superfamily of genes, whose products all bind actin, hydrolyze ATP, and transduce force. All eukaryotic cells contain at least one myosin product. What type of organic molecule is myosin? A. protein B. carbohydrate C. RNA D. DNA E. lipid

Biology & Microbiology

Basic dyes

A. have negative charges. B. have positive charges. C. are electrically neutral. D. contain both positively and negatively charged particles.

Biology & Microbiology

Of all the different codons that exist, three of them do not encode a particular amino acid. Their role is to:

a. allow for any amino acid to be added in their place. b. encode tRNA molecules. c. provide instructions on the tertiary structure of the protein. d. signal the start of translation. e. provide instructions to stop translation.

Biology & Microbiology

The (peroxide/superoxide/hydroxyl) radical is formed during the incomplete reduction of O2 during electron transport in aerobes

What will be an ideal response?

Biology & Microbiology