Biol reading quiz 3

What is the oxidizing agent in the following reaction? Pyruvate + NADH +H+→ Lactate + NAD+

pyruvate

Which of the following processes occurs in the Calvin cycle?

reduction of CO2

The oxygen released by photosynthesis is produced by which of the following processes?

splitting water molecules

Which of the following reactions produces the majority of the CO, released by the complete oxidation of glucose?

the citric acid cycle

When a cell is deprived of oxygen, which of the following processes will be inhibited first?

the electron transport chain

Which of the following events takes place in the electron transport chain?

the harnessing of energy from redox reactions to generate a proton gradient

Which of the following statements best describes the primary role played by oxygen in cellular respiration?

It serves as the final acceptor for electrons from the electron transport chain.

Which of these equations best summarizes photosynthesis?

6 CO2 + 6 H20 → C6H1206 + 6 O2

It photosynthesizing green algne are provided with CO, containing heavy oxygen (o), which of the folowing moleoules produced by the algae (reter to the accompanying figure) would be least lkely to containO in subsequent analyses?

ADP

Which of the following molecules will accumulate if light reactions occur normally, but the Calvin Cycle is inhibited?

ATP and NADPH

The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis and is inhibited by high levels which of the following molecules?

ATP and citrate

Which of the following statements best summarizes the metabolic results of photorespiration?

ATP is hydrolyzed, carbon dioxide is produced, and oxygen is consumed.

In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the net production of which of the following sets of molecules?

ATP, CO, and ethanol

Which of the following events is most immediately associated with the absorption of energy by chlorophyll molecules of the reaction-center complex?

An electron is excited.

Energy released from the electron transport chain is used to pump H* ions into which location in eukaryotic cells?

mitochondrial intermembrane space

Select the correct statement about cellular respiration.

Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level.

Which of the following molecules is the lowest-energy donor of electrons to the electron transport chain?

FADH2

Select the correct molecule that is the main product of the Calvin cycle.

G3P

Which of the following sequences correctly represents the flow of electrons during photosynthesis?

H20 → NADPH → Calvin cycle

How is photosynthesis similar in C4 plants and CAM plants?

In both cases, rubisco is not used to fix carbon initially.

Which of the following statements best describes the electron transport chain?

It consists of a series of redox reactions.

Which of the following statements best describes what happens to a molecule of NAD* (nicotinamide adenine dinucleotide) when it gains a hydrogen atom?

NAD becomes reduced.

Depletion of which of the following molecules from the mitochondria will most directly inhibit the citric acid cycle?

NAD+

Which of the following products result from the oxidation of pyruvate to acetyl-CoA?

NADH and CO2

Which of the following molecules is the final electron acceptor for electrons from photosystem I?

NADP+

Select the correct statement about the Calvin cycle.

The Calvin cycle has three phases: carbon fixation, reduction, and regeneration of RUBP.

Which of the following statements correctly describes a distinction between autotrophs and heterotrophs?

O Only autotrophs can produce organic molecules from CO, and other inorganic materials.

A mutation that eliminates a plant's ability to perform photorespiration will most likely have which of the following effects on the plant?

O There would be more cellular damage from harmful products of the light reactions of photosynthesis.

If pyruvate oxidation is blocked, what is the most likely effect on the levels of oxaloacetate and citrate in the citric acid cycle shown in the accompanying figure?

Oxaloacetate will accumulate and citrate will decrease.

Which of the following statements best describes the conditions under which the Calvin cycle and cellular respiration occur in plants?

The Calvin cycle and cellular respiration both occur in the dark and the light.

In cellular respiration, a series of molecules forming an electron transport chain alternately accepts and then donates electrons. What is the advantage of such an electron transport chain?

The advantage of an electron transport chain is that a small amount of energy is released with the transfer of an electron between each pair of intermediates.

Identify all correct statements about the basic function of fermentation.

The basic function of fermentation is the regeneration of NAD*, which allows continued ATP production by glycolysis.

Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration?

The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP.

Which of the following statements about the citric acid cycle is correct?

The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.

Step 3 is a major point of regulation of glycolysis. The enzyme phosphofructokinase is allosterically regulated by ATP and related molecules. Considering the overall result of glycolysis, would you expect ATP to inhibit or stimulate activity of this enzyme? (Hint. Make sure you consider the role of ATP as an allosteric regulator, not as substrate of the enzyme.)

The overall process of glycolysis results in net production of ATP. Thus, we would expect ATP to allosterically inhibit phosphofructokinase.

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?

The pH of the matrix increases.

Which of the following events are associated with chemiosmosis in chloroplasts?

The pH of the thylakoid space increases and ATP is synthesized.

Which one of the following statements about the redox reactions of the electron transport chain is correct?

The redox reactions of the electron transport chain are directly coupled to the movement of protons across a membrane.

Photorespiration can decrease soybeans' photosynthetic output by about 50%. Would this figure be higher or lower in wild relatives of soybeans? Why?

The wild relatives of moderm soybeans would be expected to have levels of photorespiration higher than 50%. Crop scientists would have selected strains with reduced levels of photorespiration to maximizo the size of the harvested soybeans.

Which of the following statements best explains why carbohydrates and fats may be considered high-energy foods?

They contain many electrons associated with hydrogen atoms.

Which of the following statements best explains the ability of CAM plants to synthesize sugars in the daytime while keeping their stomata closed to reduce water loss?

They fix CO2 into organic acids during the night.

Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. Which of the following statements best describes a related function they serve in plants?

They protect against oxidative damage from excossive light energy.

Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces Ireseal inside out to form small vesicles. The fact that these vesicles can transfer eloctrons from NADH to oxygen and synthesize ATP suggests that which of the folowing components must be present?

all of the electron transport system and ATP synthase

What types of cells carry out ATP synthesis by chemiosmosis?

all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors

Which of the following types of metabolic poison would most directly interfere with glycolysis?

an agent that closely mimics the structure of glucose but is not metabolized

Which of the following occurs during the Calvin cycle?

carbon fixation

In C, and CAM plants carbon dioxide is fixed in the of mesophyll cells.

cytoplasm

Which of the following best predicts the effect of removal of oxygen from a facultative anaerobic organism's environment?

glucose consumption increases, while the growth rate decreases

Under which conditions will plant cell mitochondria actively oxidize pyruvate and carry out oxidative phosphorylation?

in all cells, with or without light

Which of the following processes is most directly driven by light energy?

oxidation of chlorophyll molecules

In C3 plants the conservation of water promotes

photorespiration

C4 plants differ from Cz and CAM plants in that C4 plants

transfer fixed carbon dioxide to cells in which the Calvin cycle occurs

The light reactions of photosynthesis use and produce

water ... NADPH

A fask containing photosynthetic green algae and a control flask containing relative dissolved oxygen concentration in the flask with algae will compare to the control flask? only water are exposed to a cycle of 12 hours of light and 12 hours of darkness. Which of the following statements best describes how the

will be lower in the control in the light, but higher in the control in the dark.