biology chapter 5
The Calvin cycle cannot proceed without the molecules _____ and ____ which are produced by the light reactions of photosynthesis
ATP NADPH
What is produced in the light reactions which provides energy and reducing power for the carbon reactions?
ATP and NADPH
protons diffusing through the enzyme complex called _______ _______ provide energy that the enzyme uses to generate ATP in the light reactions.
ATP synthase
Photorespiration Rubisco binds oxygen and eventually releases carbon dioxide (reverse of carbon fixation). Takes place in C3 plants when stomata are closed and O2 concentration in leaves rises.
C3 pathway CO2 binds to rubisco to form PGA the first step in a pathway that fixes carbon as glucose. takes place in C3 plants when stomata are open and O2 concentrations in leaves are low.
1. Carbon dioxide diffuses into the leaf when stomata are open at night. 2. Carbon dioxide is stored as a four-carbon molecule in vacuoles within mesophyll cells. 3. The stored four-carbon molecule is moved from vacuoles to chloroplasts of mesophyll cells and carbon dioxide is released. 4. Carbon dioxide enters the Calvin cycle when the stomata are closed during the day.
CAM pathway
1. The enzyme rubisco combines carbon dioxide with RuBP to form a six-carbon unstable molecule. 2. The 6-carbon molecule splits to form PGA 3. PGA is converted into PGAL 4. Some PGAL is converted into glucose and other sugars, and some PGAL is converted back to RuBP
Calvin cycle
CAM photosynthesis
Carbon dioxide is incorporated into a 4-carbon molecule at night, and the Calvin cycle takes place during the day in mesophyll cells.
C3 pathway
Carbon dioxide is used by the enzyme rubisco to produce PGA
C4 photosynthesis
Carbon dioxide is used to produce oxaloacetate, and the Calvin cycle takes place in bundle-sheath cells.
products of the Calvin cycle
NADP+ glucose (from PGAL) ADP
The second electron transport chain of the light reactions uses electrons to reduce NADP+ and form
NADPH
photorespiration
Oxygen is used by the enzyme rubisco in an energetically wasteful reaction
When carbon dioxide enters the Calvin cycle, it combines with _________, which is a 5-carbon sugar with two phosphate groups
RuBP
Within the chloroplast, the gelatinous fluid containing DNA, ribosomes, and enzymes is called the
STROMA
In the light reactions of photosynthesis, what drives the synthesis of ATP by ATP synthase?
a proton gradient across the thylakoid membrane
Compared to a plant with accessory pigments, a plant without accessory pigments would
absorb less light
chlorophyll b
accessory pigment that reflects green wavelengths of light
carotenoids
accessory pigment that relect red, orange, and yellow wavelengths of light
Heterotrophs
animals, humans, fungi
The _______ pigments of photosystems pass the captured photon energy to the reaction center.
antenna
Within a photosystem, what pigments capture photon energy and funnel the energy to the reaction center chlorophyll?
antenna pigments
What type of organism has the ability to make its own food?
autotroph
________ use inorganic molecules to make organic compounds in processes including photosynthesis.
autotrophs
____________ use inorganic molecules to make organic compounds in processes including photosynthesis
autotrophs
_____________ use inorganic molecules to make organic compounds in processes including photosynthesis.
autotrophs
peanuts most trees spinach
c3 plants
sugarcane corn crabgrass
c4 plants
pineapple cacti
cam plants
The second stage of photosynthesis is called the _____ reactions, which use ATP and NADPH to reduce carbon dioxide to glucose molecules
carbon
NADPH and carbon dioxide are reactants in the
carbon reaction
two stages of photosynthesis
carbon reactions light reaction
The green, photosynthetic pigment found in plants, algae, and cyanobacteria is called _______ a.
chorophyll
What happens to the glucose produced in photosynthesis?
combined with other molecules to form larger compounds used to build cellulose of cell walls used as energy for cellular respiration
During the light reactions, energized _____________ from a reaction center chlorophyll a molecule are eventually donated to form the molecule NADPH
electron
A group of proteins in the thylakoid membrane that shuttles electrons between proteins is called ____ ___ chain
electron transpot
Photosynthesis is considered an oxidation-reduction process because
electrons are transferred between molecules
ATP is a nucleotide that stores potential __________ between phosphate groups
energy
Electron transport chains release __________ through shuttling of electrons in the light reactions.
energy
In the Calvin cycle, ATP and NADPH are used to convert carbon dioxide into
glucose and other sugars
In each chloroplast, there are between 10 and 100 ________, which are of stacks of thylakoids
grana
Green tires stacked inside the chloroplast
granum
How does life depend on photosynthesis?
incorporates atmospheric CO2 into organic compounds feeds photosynthesizers directly feeds heterotrophs indirectly produces oxygen essential to many forms of life
A long wavelength contains _____ energy compared to the energy contained by a short wavelength.
less
When stomata are closed in C# plants, water loss is __________ and photorespiration is ____________.
low high
chlorophyll a
most abundant pigment in plants; reflects green wavelengths of light
In the CAM pathway, stomata are ___________ at night when water loss is less and are _______________ during the day while maintaining a high concentration of carbon dioxide in the chloroplasts.
open closed
1. The electron transport chain receives energized electrons from photosystem II. 2. Electrons are shuttled through a series of proteins in the thylakoid membrane. 3. The energy lost from the electrons drives the active transport of protons from the stroma into the thylakoid space. 4. The electrons are passed to photosystem I.
order during the first transpot chain of the light reacttions, between photsystem II and photosystem I.
Light consists of ________, which are discrete packets of kinetic energy.
photons
If stomata remain open, carbon dioxide diffuses into the plant and oxygen diffuses out, therefore minimizing __________ but maximizing water loss
photorespiration
In a metabolic pathway called ________, plants algae, and some types of bacteria convert solar energy into chemical energy, such as glucose.
photosynthesis
Plants, algae, and some microorganisms use energy from the sun to make organic molecules in a process called
photosynthesis
A grouping of photosynthetic pigments and associated proteins is called a ________, which is embedded in the thylakoid membrane of chloroplasts.
photosystem
A grouping of photosynthetic pigments and associated proteins is called a _________, which is embedded in the thylakoid membrane of chloroplasts
photosystem
1. Antenna pigments capture a photon of light. 2. Energy is passed to the electrons of the reaction center. 3. Two excited electrons are passed to the second electron transport chain.
photosystem I
1. Antenna pigments capture a photon of light 2. Light energy is transferred to the reaction center. 3. Two electrons carrying potential energy are passed to the electron transport chain.
photosystem II
What part of a plant cell captures light energy?
pigment molecules
reactant carbon dioxide (CO2) water (H2O)
product oxygen (O2) glucose (C6H12O6)
all the components of a photosystem
proteins a reaction canter chlorophyll accessory pigments chlorophyll pigments
In a photosystem, antenna pigments capture photon energy and funnel it to the __________ __________, which consists of a chlorophyll a molecule and its associated proteins
reaction center
The enzyme that combines carbon dioxide and RuBP and is known as
rubisco
Gases enter and exit a plant leaf through openings called
stomata
Plants conduct gas exchange in photosynthesis by bringing in carbon dioxide and releasing oxygen through openings called __________.
stomata
The openings in the epidermis of a leaf or stem for gas exchange are called ______
stomata
plants in dry environments must regulate when ________ open and close to minimize both water loss and a wasteful metabolic pathway called _____________, in which O2 instead of CO2 binds to rubisco.
stomata photorespiration
The carbon reactions of photosynthesis occur in the _____, which is the fluid interior of chloroplasts.
stroma
fluid in the interior of a chloroplast
stroma
How do antenna pigments enhance the efficiency of photosynthesis?
they transfer captured light energy to where photosynthetic reactions occur
The light reactions occur in the
thylakoid membranes
True or false: Accessory pigments extend the range of light that a cell can harness.
true
The portion of the electromagnetic spectrum that plants use for photosynthesis is
visible light
The oxygen by-product of photosynthesis is created by the splitting of _____ molecules to replace the electrons ejected from the reaction center of photosystem II.
water
What molecule donates two electrons to the reaction center chlorophyll a of photosystem II to replace the electrons that were passed to the 1st electron transport chain?
water
events that occur in the C4 pathway
water loss is minimized The light and carbon reactions take place in different locations.