Biology- Chapters 6-7 Mastering Questions
The proximate (immediate) source of energy for oxidative phosphorylation is _____.
kinetic energy that is released as hydrogen ions diffuse down their concentration gradient
Which of the following equations represents photosynthesis?
6CO2 + 6H2O → C6H12O6 + 6O2
Which of the following is NOT an aspect of global climate change?
net growth of polar ice caps
In glycolysis, ATP molecules are produced by _____.
substrate-level phosphorylation
Carbon fixation involves the addition of carbon dioxide to _____.
RuBP
A chemist has discovered a drug that blocks phosphoglucoisomerase, an enzyme that catalyzes the second reaction in glycolysis. He wants to use the drug to treat people with bacterial infections. However, he can't do this because __________.
human cells also perform glycolysis; the drug might also poison them
During the first step of a redox reaction, what does the enzyme dehydrogenase strip from organic fuel?
hydrogen atoms
What is being pumped through the inner mitochondrial membrane into the intermembrane space, as indicated by the green arrows?
hydrogen ions
In muscle cells, fermentation produces _____.
lactate and NAD+
The thylakoid membranes bring together the components necessary to carry out the _____.
light reactions
The "photo-" part of the word photosynthesis refers to the __________, whereas "-synthesis" refers to __________.
light reactions that occur in the thylakoids; carbon fixation
Photosynthesis is an __________ process in which carbon is __________, whereas cellular respiration is an __________ process in which carbon is __________.
endergonic : reduced : exergonic : oxidized
The primary function of light absorption by photosystems I and II is to produce __________.
energized electrons
Incoming photons of light energy initiate photosynthesis by _____.
exciting electrons in pigment molecules within the photosystems, raising them to a higher energy level
Which of the following processes takes place in the cytosol of a eukaryotic cell?
glycolysis
Select the correct sequence of steps as energy is extracted from glucose during cellular respiration.
glycolysis → acetyl CoA → citric acid cycle → electron transport chain
The light reactions produce _____.
oxygen, NADPH, and ATP
Oxidative phosphorylation is responsible for nearly all the ATP produced in your body. Select the three true statements about oxidative phosphorylation.
-Chemiosmosis is the final step in oxidative phosphorylation. -Without oxygen, oxidative phosphorylation would not occur. -NADH and FADH2 deliver electrons to the electron transport chain during oxidative phosphorylation.
In the absence of oxygen, cells need a way to regenerate which compound?
NAD+
Fat is the most efficient molecule for long-term energy storage, even compared to carbohydrates, because __________.
with their numerous hydrogen atoms, fats provide an abundant source of high-energy electrons
Which of the following are photoautotrophs?
corn stalks before harvest
The light reactions' production of oxygen during photosynthesis is important for life on Earth. Which of the following would prevent oxygen from being made?
the inability of water to donate its electrons to photosystem II
When chloroplast pigments absorb light, _____.
their electrons are raised from a ground state to an excited state
The light reactions take place in the _________ and the Calvin cycle takes place in the _________.
thylakoids; stroma
During photosynthesis, the light reactions convert light energy to chemical energy. Select the three true statements about the light reactions of photosynthesis.
-The light reactions produce chemical energy in the form of NADPH and ATP. -The light reactions take place inside the thylakoids of chloroplasts. -Pigment molecules inside photosystem II and photosystem I absorb light energy from the sun.
Place the following events of the electron transport chain in order.
1. Oxidation of NADH 2. Electron enter the ETC 3. Release of energy for ATP synthesis 4. Electrons leave the ETC 5. Reduction of oxygen and formation of water
Terms
1. The coenzyme acting as an electron shuttle before it has accepted electrons is (NAD+). 2. (Oxidation) is the loss of one or more electrons. 3. (Reduction) is the gain of one or more electrons. 4. The electron shuttle after it has accepted electrons is (NADH). 5. When the loss and gain of electrons happen in sequence, it is called a(n) (redox) reaction.
Terms
1. The transfer of (electrons) from one molecule to another is an (oxidation) reduction reaction, or redox reaction. 2. In cellular respiration, glucose becomes (oxidized) to carbon dioxide (CO2) as it loses electrons (in hydrogen atoms). 3. In cellular respiration, oxygen becomes (reduced) to water (H2O) as it gains electrons (in hydrogen atoms) that came from glucose. 4. In cellular respiration, organic molecules become oxidized as (NAD+) picks up electrons and H+ and becomes reduced to NADH. 5. NADH delivers electrons to an electron transport chain, which passes the electrons through carrier molecules in a series of redox reactions to the final electron acceptor, (oxygen). 6. The energy released from the redox reactions in the electron transport chain is used by the cell to make (ATP).
For each glucose that enters glycolysis, _____ NADH enter the electron transport chain.
10
How many NADH are produced by glycolysis?
2
In glycolysis there is a net gain of _____ ATP.
2
In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules?
3
How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose?
6
In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs?
A compound called coenzyme A binds to a two-carbon fragment derived from pyruvate.
In glycolysis, what starts the process of glucose breakdown?
ATP
Which option properly summarizes the inputs and outputs of the Calvin cycle?
ATP + NADPH + 3CO 2 →→ G3P
What two molecules are produced by the light reactions and used to power the Calvin cycle?
ATP and NADPH
Imagine an organism with mutations in complexes I, III, and IV that prevent pumping of hydrogen ions into the intermembrane space but still allow electrons to pass through the electron transport chain. Which of the following is the most likely consequence of these mutations?
ATP synthase will not convert ADP to ATP.
What connects the two photosystems in the light reactions?
An electron transport chain
What is the correct general equation for cellular respiration?
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ATP energ
What provides the carbon atoms that are incorporated into sugar molecules in the Calvin cycle?
Carbon dioxide (CO2)
In which of the following organelles does photosynthesis take place?
Chloroplast
What occurs as electrons pass through the multiple carrier molecules of the electron transport chain?
Energy is released in a stepwise fashion.
Which of these is NOT a product of glycolysis?
FADH2
Which of the following statements regarding glycolysis is FALSE?
Glycolysis evolved in an oxygen-rich environment.
What provides electrons for the light reactions?
H2O
Given the relatively modest number of calories burned by anything but the most vigorous of activities, how can people consume over 2,000 kilocalories a day yet maintain a healthy body weight?
Most of the energy consumed in food is spent maintaining the body's functions over the course of a day, so a healthy amount of daily exercise would require only a modest increase in the number of kilocalories consumed to maintain a healthy weight.
What molecule releases the electrons used in the electron transport chain?
NADH
During electron transport, energy from _____ is used to pump hydrogen ions into the _____.
NADH and FADH2 ... intermembrane space
After 3-PGA is phosphorylated, it receives energized electrons from _____.
NADPH
What transports electrons from the light reactions to the Calvin cycle?
NADPH
Aliyah is studying cells as they proceed through redox reactions. If she could measure the number of electrons in the cells' organic fuel and the number of NADH molecules, how would they change as redox reactions proceed? Would she expect the organic fuel to gain or lose electrons? Would she expect there to be more or fewer NADH molecules?
Organic fuel loses electrons; more NADH molecules
One of the important waste products of photosynthesis is oxygen gas. Where does this oxygen gas come from?
Oxygen is released when water is broken down to extract electrons and protons for use in the light reactions.
Current evidence indicates that the process of photosynthesis arose more than three billion years ago. Its origin had a huge impact on existing organisms and on the physical characteristics of the biosphere. Which major physical change could be attributed to photosynthesis?
Photosynthesis drastically increased the oxygen content of the atmosphere.
Because of the abundance of water on planet Earth, hydrogen gas (H2) is a candidate in the search for a replacement for petroleum. However, removing hydrogen from water requires the investment of a great deal of energy. Why are plants considered to be one step ahead in the utilization of hydrogen as an alternative fuel source?
Plant cells possess water-splitting enzymes.
Although the reactions of the Calvin cycle are not directly dependent on light, they usually do not occur at night. Why?
The Calvin cycle depends on products of the light reactions.
Why is the citric acid cycle called a cycle?
The two-carbon acetyl group is transferred to the citric acid cycle utilizing Coenzyme A (CoA) where it binds to oxaloacetate, thereby regenerating citrate in cyclical fashion.
Which statement describes the citric acid cycle?
This process produces some ATP and carbon dioxide in the mitochondrion.
Which statement describes glycolysis?
This process splits glucose in half and produces 2 ATPs for each glucose.
Which statement describes the electron transport chain?
This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration.
What drives the production of ATP by ATP synthase?
a gradient of hydrogen ions built up in the thylakoid space
Which of these enters the citric acid cycle (also called the Krebs cycle)?
acetyl CoA
Which of these is NOT a product of the citric acid cycle (also called the Krebs cycle)?
acetyl CoA
Considering the wavelengths of light shown below, the pigments in the granum absorb mainly in which range?
blue-violet and red-orange
Using the ATP generated during cellular respiration, the intermediates of glycolysis and the citric acid cycle, such as pyruvate and acetyl CoA, can be siphoned off and used to __________.
build amino acids, fats, and sugars
The most important role of pigments in photosynthesis is to _____.
capture light energy
The O2 required for __________ is supplied by __________.
cellular respiration ... breathing
The electron transport chain is, in essence, a series of redox reactions that comprise the last stage of aerobic cellular respiration. During these redox reactions, __________.
electrons are transferred through a series of electron acceptors embedded within the inner mitochondrial membrane
The conversion of NADP+ to NADPH occurs with the assistance of __________.
electrons from water and energy from sunlight
In what organelle would you find acetyl CoA formation, the citric acid cycle, and the electron transport chain?
mitochondrion
Cellular respiration and photosynthesis are similar in that both involve _____.
oxidation-reduction (redox) reactions
In cellular respiration, most ATP molecules are produced by _____.
oxidative phosphorylation
Some human cells, such as nerve cells, are restricted to aerobic respiration to recycle NADH and FADH2. If these cells are deprived of oxygen, then __________.
oxidative phosphorylation would come to a halt because there wouldn't be any oxygen to serve as an electron acceptor at the transport chain
The final electron acceptor of cellular respiration is _____.
oxygen
A muscle cell deprived of molecular oxygen will convert glucose to lactic acid to __________.
recycle NADH through fermentation
Carbon dioxide enters a leaf through the _____.
stomata
The photosynthetic event known as the Calvin cycle occurs in the __________.
stroma
In the citric acid cycle (also called the Krebs cycle), ATP molecules are produced by _____.
substrate-level phosphorylation
Most NADH molecules generated during cellular respiration are produced during __________.
the citric acid cycle