Question

One of the "triggers" proposed for the Cambrian explosion is a dramatic rise in oxygen concentrations that occurred in the oceans about 800 mya. Make a small concept map outlining the logic behind the "oxygen-trigger" hypothesis for the Cambrian explosion. Match the words in the left column to the appropriate blanks in the sentences on the right.

high
donor
larger
smaller
acceptor
faster
less
more
slower
low
available
1. Oxygen is an effective final electron (a)_______in cellular respiration because of its (b)______electronegativity.
2. Organisms that use it as a final electron (c)_______can produce (d)________usable energy than organisms that do not use oxygen, but only if it is (e) _______ .
3. With (f)______available energy, aerobic organisms can grow (g)________and move (h)_______ .

Answer 1

1. Oxygen is an effective final electron acceptor in cellular respiration because of its high electronegativity.

2. Organisms that use it as a final electron acceptor can produce more usable energy than organisms that do not use oxygen, but only if it is available.

3. With more available energy, aerobic organisms can grow larger and move faster.

Step-by-step explanation:

1. Cellular respiration is an aerobic pathway because oxygen is an electron acceptor. This process produces 38 molecules of ATP per glucose. The atomic elements that are positioned at the right of the periodic table have high electronegativities because they tend to be electron acceptors.

2. The efficiency of energy production of aerobic respiration is much higher compared to the anaerobic respiration because this metabolic pathway (aerobic respiration) can produce 38 molecules of ATPs per glucose molecule, while anaerobic respiration produces only 2 ATPs by glucose.

3. A higher amount of available energy improves the metabolic profile of the organisms with aerobic respiration.