Key Concepts Quiz
This activity contains 17 questions.
Sunlight is essential for the varied life on Earth. Sunlight provides energy to photosynthetic organisms by providing _____.
heat to leaves, which is converted to useful energy for work
heat to leaves, which is used to synthesize chloroplasts
the energy required to drive cellular respiration
the energy necessary to power the rearrangement of chemical bonds
Lungs are to breathing as _____ are to cellular respiration.
When a car engine burns gasoline, the results of the reaction are similar to when cells burn glucose. Both reactions release carbon dioxide and water. In cells, the chemical energy in food is converted to ATP and heat. In a moving car, the chemical energy in gasoline is converted to _____.
kinetic energy and heat
potential energy and heat
thermal energy and heat
ATP and heat
Given the relatively modest number of calories burned by anything but the most vigorous activities, why can people consume over 2,000 kilocalories a day, yet maintain a healthy body weight?
They can't, and this has led to a problem of obesity in the United States.
People really should exercise vigorously for one to two hours per day.
Most of the energy consumed in food is spent maintaining the body's functions, so only a fraction of food energy needs to be burned in exercise.
Not all calories are created equal, so a person who consumes 2,000 kilocalories of sugar- and fat-laden processed food will gain weight, while a person who consumes 2,000 calories of nonprocessed, low-carbohydrate food will not.
A molecule that functions as the electron donor in a redox reaction _____.
gains electrons and gains energy
loses electrons and loses energy
gains electrons and loses energy
loses electrons and gains energy
In cellular respiration, glucose _____ electrons, while _____ electrons.
gains … oxygen loses
loses … oxygen gains
gains … water loses
loses … water gains
Oxidative phosphorylation could not occur without glycolysis and the citric acid cycle, because _____.
these two stages provide the oxygen used as the final electron acceptor
the electron transport chain requires the ATP produced during the first two stages
these two stages provide the water that is split during oxidative phosphorylation
these two stages supply the electrons needed for the electron transport chain
Glycolysis is the only stage of cellular respiration that _____.
requires ATP to make ATP
does not require ATP to make ATP
requires oxygen to function
does not release carbon dioxide as a by-product
We inhale O
and we exhale CO
. Carbon dioxide is produced _____.
during the formation of pyruvate
in the reaction that creates acetyl CoA (coenzyme A) from pyruvate
during the electron transfer steps of oxidative phosphorylation
when oxygen acquires electrons and protons at the end of the electron transport chain
A scientist wants to study the enzymes of the citric acid cycle in eukaryotic cells. What part of the cell would they use as a source of these enzymes?
mitochondrial inner membrane
What molecule is required to move pyruvate to the citric acid cycle?
In oxidative phosphorylation, electrons are passed from one electron carrier to another. The energy released is used to _____.
pump protons (H
) across the mitochondrial membrane
form ATP during glycolysis
synthesize carbon dioxide
generate large amounts of NADH and FADH
Dinitrophenol (DNP) is a highly toxic, membrane uncoupler. What happens when DNP makes the phospholipid bilayer of inner mitochondrial membranes permeable to protons (H
The redox reactions of the electron transport chain cease.
The proton pumps of the inner mitochondrial membrane would cease to function.
Many protons would bypass ATP synthase, leading to a sharp decline in ATP synthesis.
NADH or FADH
would no longer provide electrons to the electron transport chain.
Some human cells are restricted to aerobic respiration to recycle NADH and FADH
. If these cells are deprived of oxygen, then _____.
ATP production would continue because the cell would perform fermentation
proton gradient formation would continue, but ATP synthase function would stop
glycolysis could still continue indefinitely
oxidative phosphorylation would come to a halt because there wouldn't be any oxygen to "pull" the electrons down the transport chain
Humans depend on oxygen to sustain life. However, at the cellular level, muscle cells are _____.
capable of alcohol fermentation
Fat is the most efficient molecule for long-term energy storage even compared to carbohydrates because _____.
when compacted, fat occupies less volume than an equivalent amount of carbohydrate
compared to carbohydrates, fat produces fewer toxic by-products when it's metabolized
fats can directly enter the electron transport chain, the phase of respiration that produces the most ATP
with their numerous hydrogen atoms, fats provide an abundant source of high-energy electrons
Using the ATP generated during cellular respiration, the intermediates of glycolysis and the citric acid cycle can be siphoned off and used _____.
to generate the ADP that is used to power biosynthetic pathways
to power the biosynthesis of amino acids, fats, and sugars
to provide virtually all the heat needed to maintain body temperature
to create energy sources, such as glucose or amino acids, that are recycled back through respiration, thus allowing a continual source of ATP with relatively little food intake
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