BIO 225 Exam 1 Questions with Correct Answers Latest Update 2025/2026
Which of the following organisms did the process of photosynthesis most likely originate? -
Answers prokaryotes
What are the products of linear electron flow in the light reactions of photosynthesis? - Answers
ATP and NADPH
A mutation that disrupts cyclic electron flow in the light reactions of photosynthesis will
specifically reduce the production of which of the following molecules? - Answers ATP
Which of the following process would be most directly affected if a thylakoid membrane is
punctured so that the interior of the thylakoid is no longer separated from the storms - Answers
Synthesis of ATP
In chloroplasts, the photosynthetic electron transport chain acidifies which of the following
cellular compartments? - Answers thylakoid space
ATP is synthesized in plant cells by chemiosmosis in which of the following processes? -
Answers Photosynthesis only
Which of the following statements best describes the relationship between the wavelength of
light and the quantity of energy per photon? - Answers They are inversely related
P680+ is said to be the strongest biological oxidizing agent. The strong oxidizing potential of
P680+ is essential for its function because it ________. - Answers obtains electrons from the
oxygen atom in a water molecule
Which of the following statements best describes the relationship between autotrophs and
heterotrophs? - Answers Autotrophs produce their organic molecules from CO2 and other
inorganic molecules, whereas heterotrophs obtain their organic molecules from compounds
produced by other organisms.
In a plant, which of the following reactions produces molecular oxygen (O2)? - Answers the light
reactions alone
A flask containing photosynthetic green algae and a control flask containing 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 relative dissolved oxygen concentration in the flask with
algae will compare to the control flask? - Answers It will be lower in the control in the light, but
higher in the control in the dark.
The oxygen released by photosynthesis is produced by which of the following processes? -
Answers splitting water molecules
The accompanying figure shows the absorption spectrum for chlorophyll a and the action
, spectrum for photosynthesis. Which of the following statements best explains the low rate of
photosynthesis at 550 nm? - Answers Chlorophyll a does not absorb 550 nm light well.
Based on the accompanying figure, which of the following wavelengths of light is most effective
in driving photosynthesis?
Correct! - Answers 440 nm
Which of the following statements best describes the conditions under which the Calvin cycle
and cellular respiration occur in plants? - Answers The Calvin cycle and cellular respiration both
occur in the dark and the light.
On a spaceship designed to support a multiyear voyage to the outer planets of the solar system,
plants will be grown to provide oxygen and to recycle carbon dioxide. Because the spaceship
will be so far from the sun, an artificial light source will be needed to support photosynthesis.
Which of the following wavelengths of light should be used to maximize plant growth? -
Answers a mixture of blue and red light
Which of the following statements describes a primary benefit of having photosystem reaction
centers composed of several structurally different pigments? - Answers This arrangement
enables the plant to absorb light energy of a variety of wavelengths.
Which of the following events is most immediately associated with the absorption of energy by
chlorophyll molecules of the reaction-center complex? - Answers An electron is excited.
Which of the following molecules is the final electron acceptor for electrons from photosystem I?
- Answers NADP+
Which of the following statements correctly describes a distinction between autotrophs and
heterotrophs? - Answers Only autotrophs can produce organic molecules from CO2 and other
inorganic materials.
Which of the following describes the function of the pigment molecules in a light-harvesting
complex in the thylakoid membranes? - Answers They absorb and transfer light energy to the
reaction-center chlorophyll.
Which of the following molecules will accumulate if light reactions occur normally, but the
Calvin Cycle is inhibited? - Answers ATP and NADPH
Which of the following sequences correctly represents the flow of electrons in photosynthesis? -
Answers H2O → NADPH → Calvin cycle
Which of the following molecules is the primary reducing agent in the Calvin cycle reactions? -
Answers NADPH
Which of the following statements best describes the relationship between photosynthesis and
Which of the following organisms did the process of photosynthesis most likely originate? -
Answers prokaryotes
What are the products of linear electron flow in the light reactions of photosynthesis? - Answers
ATP and NADPH
A mutation that disrupts cyclic electron flow in the light reactions of photosynthesis will
specifically reduce the production of which of the following molecules? - Answers ATP
Which of the following process would be most directly affected if a thylakoid membrane is
punctured so that the interior of the thylakoid is no longer separated from the storms - Answers
Synthesis of ATP
In chloroplasts, the photosynthetic electron transport chain acidifies which of the following
cellular compartments? - Answers thylakoid space
ATP is synthesized in plant cells by chemiosmosis in which of the following processes? -
Answers Photosynthesis only
Which of the following statements best describes the relationship between the wavelength of
light and the quantity of energy per photon? - Answers They are inversely related
P680+ is said to be the strongest biological oxidizing agent. The strong oxidizing potential of
P680+ is essential for its function because it ________. - Answers obtains electrons from the
oxygen atom in a water molecule
Which of the following statements best describes the relationship between autotrophs and
heterotrophs? - Answers Autotrophs produce their organic molecules from CO2 and other
inorganic molecules, whereas heterotrophs obtain their organic molecules from compounds
produced by other organisms.
In a plant, which of the following reactions produces molecular oxygen (O2)? - Answers the light
reactions alone
A flask containing photosynthetic green algae and a control flask containing 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 relative dissolved oxygen concentration in the flask with
algae will compare to the control flask? - Answers It will be lower in the control in the light, but
higher in the control in the dark.
The oxygen released by photosynthesis is produced by which of the following processes? -
Answers splitting water molecules
The accompanying figure shows the absorption spectrum for chlorophyll a and the action
, spectrum for photosynthesis. Which of the following statements best explains the low rate of
photosynthesis at 550 nm? - Answers Chlorophyll a does not absorb 550 nm light well.
Based on the accompanying figure, which of the following wavelengths of light is most effective
in driving photosynthesis?
Correct! - Answers 440 nm
Which of the following statements best describes the conditions under which the Calvin cycle
and cellular respiration occur in plants? - Answers The Calvin cycle and cellular respiration both
occur in the dark and the light.
On a spaceship designed to support a multiyear voyage to the outer planets of the solar system,
plants will be grown to provide oxygen and to recycle carbon dioxide. Because the spaceship
will be so far from the sun, an artificial light source will be needed to support photosynthesis.
Which of the following wavelengths of light should be used to maximize plant growth? -
Answers a mixture of blue and red light
Which of the following statements describes a primary benefit of having photosystem reaction
centers composed of several structurally different pigments? - Answers This arrangement
enables the plant to absorb light energy of a variety of wavelengths.
Which of the following events is most immediately associated with the absorption of energy by
chlorophyll molecules of the reaction-center complex? - Answers An electron is excited.
Which of the following molecules is the final electron acceptor for electrons from photosystem I?
- Answers NADP+
Which of the following statements correctly describes a distinction between autotrophs and
heterotrophs? - Answers Only autotrophs can produce organic molecules from CO2 and other
inorganic materials.
Which of the following describes the function of the pigment molecules in a light-harvesting
complex in the thylakoid membranes? - Answers They absorb and transfer light energy to the
reaction-center chlorophyll.
Which of the following molecules will accumulate if light reactions occur normally, but the
Calvin Cycle is inhibited? - Answers ATP and NADPH
Which of the following sequences correctly represents the flow of electrons in photosynthesis? -
Answers H2O → NADPH → Calvin cycle
Which of the following molecules is the primary reducing agent in the Calvin cycle reactions? -
Answers NADPH
Which of the following statements best describes the relationship between photosynthesis and
