Chapter 5
What are the 2 types of energy carrier molecules?
NADPH and ATP
Which molecule absorbs the energy of a photon in photosynthesis?
chlorophyll
Why are carnivores, such as lions, dependent on photosynthesis to survive?
Because lions eat animals that eat plants.
The chemical reaction of photosynthesis is the opposite of the chemical reaction of what?
Cellular Respiration
What is the molecule that leaves the Calvin cycle to be converted into glucose?
G3P
Where do light-dependent reactions begin?
In a grouping of pigment molecules
On a hot, dry day, plants close their stomata to conserve water. What impact will this have on photosynthesis?
Levels of carbon dioxide (a reactant) will fall, and levels of oxygen (a product) will rise. As a result, the rate of photosynthesis will slow down.
Which part of the Calvin cycle would be affected if a cell could not produce the enzyme RuBisCO?
None of the cycle could take place, because RuBisCO is essential in fixing carbon dioxide. Specifically, RuBisCO catalyzes the reaction between carbon dioxide and RuBP at the start of the cycle.
Explain the reciprocal nature of the net chemical reactions for photosynthesis and respiration.
Photosynthesis takes the energy of sunlight and combines water and carbon dioxide to produce sugar and oxygen as a waste product. The reactions of respiration take sugar and consume oxygen to break it down into carbon dioxide and water, releasing energy. Thus, the reactants of photosynthesis are the products of respiration, and vice versa.
Where does the Calvin Cycle occur?
Stroma
Where do light dependent reactions occur?
Thylakoid membrane
What is the overall purpose of the light reactions in photosynthesis?
To convert solar energy into chemical energy that cells can use to do work.
photosystem
a group of proteins, chlorophyll, and other pigments that are used in the light-dependent reactions of photosynthesis to absorb light energy and convert it into chemical energy
pigment
a molecule that is capable of absorbing light energy
From where does a heterotroph directly obtain its energy?
eating other organisms
Plants produce oxygen when they photosynthesize. Where does the oxygen come from?
splitting water molecules
Where in plant cells does the Calvin cycle take place?
stroma
Which statement correctly describes carbon fixation?
the conversion of CO2 to an organic compound
photon
a distinct quantity or "packet" of light energy
What is the energy of a photon first used to do in photosynthesis?
energize an electron
Which color(s) of light does chlorophyll a reflect?
green
Where do hydrogen ions build up during light-dependent reactions?
inside the thylakoid membrane
Where is ATP made during light-dependent reactions?
outside of the thylakoid (stroma)
chlorophyll a
the form of chlorophyll that absorbs violet-blue and red light
chlorophyll
the green pigment that captures the light energy that drives the reactions of photosynthesis
mesophyll
the middle layer of cells in a leaf
stoma (stomata)
the opening that regulates gas exchange and water regulation between leaves and the environment; plural: stomata
chloroplast
the organelle where photosynthesis takes place
carbon fixation
the process of converting inorganic CO2 gas into organic compounds
electromagnetic spectrum
the range of all possible frequencies of radiation
Calvin cycle
the reactions of photosynthesis that use the energy stored by the light-dependent reactions to form glucose and other carbohydrate molecules
absorption spectrum
the specific pattern of absorption for a substance that absorbs electromagnetic radiation
Describe the pathway of energy in light-dependent reactions.
The energy is present initially as light. A photon of light hits chlorophyll, causing an electron to be energized. The free electron travels through the electron transport chain, and the energy of the electron is used to pump hydrogen ions into the thylakoid space, transferring the energy into the electrochemical gradient. The energy of the electrochemical gradient is used to power ATP synthase, and the energy is transferred into a bond in the ATP molecule. In addition, energy from another photon can be used to create a high-energy bond in the molecule NADPH.
Which statement about thylakoids in eukaryotes is not correct? Thylakoids are assembled into stacks. Thylakoids exist as a maze of folded membranes. The space surrounding thylakoids is called stroma. Thylakoids contain chlorophyll.
Thylakoids exist as a maze of folded membranes.
thylakoid
a disc-shaped membranous structure inside a chloroplast where the light-dependent reactions of photosynthesis take place using chlorophyll embedded in the membranes
granum
a stack of thylakoids located inside a chloroplast
What can be determined by measuring wavelength?
amount of energy
autotroph
an organism capable of producing its own food
photoautotroph
an organism capable of synthesizing its own food molecules (storing energy), using the energy of light
heterotroph
an organism that consumes other organisms for food
What two products result from photosynthesis?
glucose and oxygen
wavelength
the distance between consecutive points of a wave
light-dependent reaction
the first stage of photosynthesis where visible light is absorbed to form two energy-carrying molecules (ATP and NADPH)
stroma
the fluid-filled space surrounding the grana inside a chloroplast where the Calvin cycle reactions of photosynthesis take place
chlorophyll b
the form of chlorophyll that absorbs blue and red-orange light