152 terms

Photosynthesis and cellular respiration highlights

Photosynthesis converts light energy into chemical energy through a series of reactions known as
biochemical pathways.
Almost all life depends on...
Autotrophs use photosynthesis to make organic compounds from
carbon dioxide and water
Heterotrophs cannot make their own
organic compounds from inorganic compounds.
Heterotrophs depend on
What is the beginning of the light reactions of photosynthesis?
The absorption of light by chlorophyll a and accessory pigments in the thylakoids.
In the light reactions, excited electrons that leave chlorophyll a travel along...
...two electron transport chains.
In the light reactions, the excited electrons leave chlorophyll a and travel along two electron transport chains, resulting the the production of...
In the light reactions, the electrons are replaced when water is split into electrons, protons, and oxygen in the...
What is released as a byproduct of photosynthesis?
(In the light reactions) As electrons travel along the electron transport chains, protons move into the thylakoid and build up a...
...concentration gradient.
(In the light reactions) The movement of protons down the concentration gradient of protons and through ATP synthase results in the...
...synthesis of ATP through chemiosmosis.
What drives the second stage of photosynthesis (the Calvin cycle)?
The ATP and NADPH produced in the light reactions
In the Calvin cycle, CO2 is incorporated into organic compounds, a process called...
...carbon fixation.
The Calvin cycle produces a compound called
What are most G3P molecules converted into to keep the Calvin cycle operating?
Some G3P molecules are used to make other organic compounds, including:
amino acids, lipids, and carbohydrates.
What do we call plants that fix carbon using only the Calvin cycle?
C3 plants
Plants that evolved in hot, dry climates fix carbon through what alternative pathways?
the C4 and CAM pathways
Plants that use the C4 and CAM pathways to fix carbon carry out carbon fixation and the Calvin cycle either...
...in different cells or at different times.
What are the two stages of photosynthesis?
The light reactions

The Calvin cycle
What happens in the light reactions stage of photosynthesis?
Energy is absorbed from sunlight and converted into chemical energy.
What happens during the Calvin cycle (stage of photosynthesis)?
Carbon dioxide and chemical energy are used to form organic compounds.
The rate of photosynthesis increases as then reaches a plateau as...
...light intensity of CO2 increases.
Below a certain temperature, the rate of photosynthesis increases as...
...temperature increases.
Above a certain temperature, the rate of photosynthesis decreases as...
...temperature increases.
What is cellular respiration?
The process by which cells break down organic compounds to produce ATP.
What is the first stage of cellular respiration?
Where does glycolysis take place?
In the cytosol of cells
What happens during glocolysis?
One glucose molecule is oxidized to form two pyruvic acid molecules.
What is the result of glycolysis?
A net production of two ATP molecules and two NADH molecules.
If oxygen is not present, glycolysis may lead to anaerobic pathways. What happens in the anaerobic pathways?
Pyruvic acid is converted into other organic molecules in the cytosol.
Glycolysis combines with anaerobic pathways is called...
What does fermentation do?
It regenerates NAD+, but it DOES NOT produced ATP.
What does NAD+ do?
It helps keep glycolysis operating.
What happens during lactic acid fermentation?
An enzyme converts pyruvic aside into lactic acid.
In alcoholic fermentation, other enzymes convert pyretic acid into...
ethyl alcohol and CO2.
Through glycolysis, what percent of the energy available from the oxidation of glucose is captured as ATP?
Only about 2 percent.
In eukaryotic cells, where do the process of aerobic respiration occur?
Inside the mitochondria.
Where does the Krebs cycle occur?
In the mitochondrial matrix
Where is the electron transport chain?
It is embedded in the mitochondrial membrane.
What happens in the mitochondrial matrix during aerobic respiration?
Pyruvic acid produced in glycolysis is converted into acetyl CoA.
In aerobic respiration, what happens after the pyruvic aside is converted into acetyl CoA?
Then, acetyl CoA enters the Krebs cycle.
What does each turn of the Krebs cycle generate?
Three NADH
Two CO2 molecules
What do the NADH and FADH2 do in aerobic respiration?
They donate electrons to the electron transport chain in the inner mitochondrial membrane. (These electrons are passed from molecule to molecule in the transport chain).
In aerobic respiration, what happens as electrons pass along the electron transport chain?
Protons donated by NADH and FADH2 are pumped into the space between the inner and outer mitochondrial membranes.
In aerobic respiration, what does the pumping of protons between the inner and outer mitochondrial membranes create?
A concentration gradient of protons and a charge gradient across the inner mitochondrial membrane.
In aerobic respiration, what happens as protons move through ATP synthase, down their concentration and charge gradients and back into the mitochondrial matrix?
ATP is produced.
During aerobic respiration, oxygen accepts both protons and electrons from the electron transport chain. What happens as a result of this?
Oxygen is converted to water.
About how many ATP molecules can cellular respiration produced from the oxidation of the single molecule of glucose?
Up to 38 ATP molecules
About what percent of the energy released by the oxidation of glucose can be transferred to ATP?
Up to 39% percent
Most eukaryotic cells produce about how many ATP molecules per molecule of glucose?
About 36 ATP molecules
What processes does cellular respiration use to obtain energy from organic compounds?
The processes of glycolysis and aerobic respiration
Name 3 life processes that use energy.
photosynthesis, anaerobic respiration and aerobic respiration
What are heterotrophs?
What is the ultimate energy for all life on earth?
The sun
What is photosynthesis?
When plants use sunlight and water to make O2 and glucose
Where are grana found in a chloroplast?
What is a biochemical pathway?
Reactions leading to the synthesis of a molecule
Solar energy is converted into what type of energy in photosynthesis?
What is the function of chlorophyll?
It traps the sunlight so it can be used for photosynthesis.
Name 3 things that can happen to light that strikes an object.
Absorb, reflect, or transmit
Explain why chlorophyll looks green.
It reflects green light.
What happens to a chlorophyll molecule that absorbs light energy?
Some of the electrons move to a higher level.
What happens to the energized electrons of chlorophyll?
They travel to the reaction center.
What is the source of oxygen produced during photosynthesis?
What two products of the light reactions provide energy for the Calvin cycle?
Can the Calvin cycle take place if light is present?
Can the Calvin cycle take place if light is absent?
What atmospheric gas is a byproduct of photosynthesis?
When during photosynthesis is glucose made?
Step 2 in the Calvin cycle
What are the two energy sources for the Calvin Cycle?
ATP, carried by NADPH
Where does the carbon in organic molecules come from?
The air
Heterotrophs dependent in directly on photosynthesis for...
When food is broken down, energy is TEMPORARILY stored in what molecule?
Glucose bonds
All organisms use what as their energy molecule?
Oxygen produced during photosynthesis is used during what?
Cellular respiration
What is the effect of lactic acid on muscles?
It can cause cramps.
When do muscles form lactic acid?
When oxygen is absent.
Glucose is split during what process?
Two molecules of what form from the splitting of glucose?
CO2 and H2O and pyruvate
How much ATP is made from the initial splitting of glucose in the cytoplasm?
What is the anaerobic respiration of carbohydrates called?
Name the 2 main stages in cellular respiration.
Glycolysis and aerobic respiration
This type of respiration only occurs in the present of oxygen.
Aerobic respiration
NADPH is formed during what process?
NADH is formed during what process?
Glycolysis and electron transport chain
The Krebs cycle occurs in what process?
Aerobic respiration
The Calvin cycle occurs in what process?
Water is the end product of what process?
Electron transport chain
At the end of the ETC, what gas is added to form water?
Oxygen and hydrogen
In cellular respiration, the most ATP is generated during the...
...aerobic respiration (electron transport chain)
What 2 energy carriers enter the electron transport chain in cellular respiration?
What must be present for photosynthesis to take place?
Light, chlorophyll, and enzymes
Plants are not actually food producers. They are...
...energy converters.
What happens during photosynthesis?
Light is converted into chemical energy, which is stored in the glucose molecule.
What happens during cellular respiration?
The energy stored in glucose is released, and the cell produces the energy molecule known as ATP.
Which wavelength of light is the best for photosynthesis?
The formation of glucose during photosynthesis takes place in 2 major steps known as:
The light and dark reactions
Each of the light and dark reactions requires...
The series of reactions called Light Reactions begins the process of...
Light energy trapped by chlorophyll is used to..
...split water molecules (photolysis).
When water is split, what are produced/
Oxygen and hydrogen
In the light reactions, hydrogen atoms combine with molecules of the coenzyme NADP to form...
...NADPH + H+ (which is needed in the dark reactions).
What does a coenzyme do?
It transfers hydrogen and electrons from one reaction to another.
The hydrogen atom has...
...a proton and an electron.
Movement of electrons is known as...
...the electron transport system.
Light is needed in photosynthesis to...
...split water.
The Calvin cycle begins when 3 carbon dioxide molecules combine with 3 molecules of a 5-carbon compound (RDP), resulting in:
three 6-carbon compound molecules that are unstable and break to form six 3-carbon compound molecules called PGA.
In the Dark Reactions, hydrogen from the light reactions combines with PGA to form six new 3-carbon compounds called...
Each turn around the Calvin cycle can spin off a PGAL to eventually form...
In the Dark reactions, three carbon dioxide molecules enter at the start of the cycle to be following by...
...an additional three molecules of carbon dioxide.
An easy way to understand the Calvin cycle is to..
....follow the number of carbon atoms around the cycle.
The true end produce of photosynthesis
Molecules of PGAL can combine and reorganize to form additional RDP molecules, or two PGAL molecules can combine to form...
PGAL can also be used to produce...
...proteins and lipids.
In photosynthesis, the coenzyme NADP transfers hydrogen and electrons from...
...light to dark reactions.
Cellular respiration is the process by which a cell...
...converts food to energy.
The energy molecule produced by a cell is called....
The greater the number of ATP molecules in a cell...
...the greater the available energy.
ATP can be build from....
The breakdown of glucose during cell respiration requires two series of reactions, known as...
...anaerobic and aerobic respiration.
Both anaerobic and aerobic respiration need...
...enzymes (without which they cannot take place).
Anaerobic respiration does not require...
Aerobic respiration does require...
Where does the process of cell respiration begin?
In the cytoplasm (outside the mitochondria)
In anaerobic respiration, 2 molecules of ATP are used to break glucose (glycolysis) into 2 3-carbon compounds called...
To break a molecules, this must be used.
In anaerobic respiration, each PGAL molecule lose 2 hydrogen atoms to become...
In anaerobic respiration, how many molecules of ATP are produced by each pyruvate?
2 molecules of ATP are produced for each pyruvate (for a total of 4 ATP molecules).
During anaerobic respiration, how many ATP are gained?
2 ATP are gained (4 ATP produced minus the 2 ATP used to break glucose).
In anaerobic respiration, the hydrogen atoms lost by PGAL combine with molecules of the coenzyme NAD to form...
...NADH + H+ where they are needed for aerobic respiration).
What is fermentation?
A form of ANAEROBIC respiration performed by yeast cells.
What happens in fermentation?
Glucose is broken down to form 2 pyruvate molecules, each of which is further broken down into the alcohol ethanol.
How is fermentation important in industry?
The brewing industry uses ethanol for a variety of alcoholic beverages, and the baking industry uses CO2 to make dough rise.
Where does aerobic respiration take place?
Inside the mitochondria
What is the series of cyclic reactions in aerobic respiration often called?
The Krebs cycle
In the Krebs cycle (aerobic respiration), each pyruvate loses a carbon atom to form...
...carbon dioxide and acetate (a 2-carbon compound) that combines with coenzyme A to form acetyl CoA.
When does the Krebs cycle begin?
When acetyl CoA combines with a 4-carbon compound to form citrate.
As a result of going around the Krebs cycle twice (once for each acetyl CoA) and the accompanying electron transport system, how many ATP are produced?
34 ATP are produced.
In aerobic respiration, the hydrogen atoms from anaerobic respiration combine with oxygen, the final hydrogen acceptor to form...
In aerobic respiration, if oxygen is not available, pyruvate form...
...lactic acid (takes place in muscles and is reversible when oxygen becomes available).
In cellular respiration, glucose is broken down to produce...
...energy (ATP), carbon dioxide, and water.
In photosynthesis, glucose and oxygen are produced using...
...light energy, carbon dioxide, and water.
Why are 2 molecules of ATP needed to start the process of anaerobic respiration?
To break the glucose molecule and start the process of anaerobic respiration.
What is fermentation?
A form of anaerobic respiration performed by yeast. Glucose is broken down to yield ethanol, carbon dioxide, and ATP.
How can a yeast call survive with only a gain of 2 ATP from a anaerobic respiration?
Yeast cells are small microscopic organisms and do not require more than 2 ATP. Humans are large organisms and require the additional ATP that can be released from pyruvate by the addition of oxygen during aerobic respiration.
How much ATP is gained during anaerobic respiration?
2 ATP are gained during anaerobic respiration. (2 ATP are used to break glucose into pyruvate, producing 4 ATP).
How much ATP is gained during aerobic respiration?
34 ATP are gained during aerobic respiration. (2 ATP from Krebs cycle and 32 ATP from the electron transport system).
Which process is more efficient, anaerobic or aerobic respiration?
Aerobic respiration is more efficient than anaerobic respiration. Anaerobic respiration produces a gain of only 2 ATP. Aerobic respiration produces a gain of 34 ATP by completely breaking down pyruvate. If the ATP gained by the two processes is added, the total gain is 36 ATP for all cellular respiration.
What are the end products of respiration?
6CO2 + 6H2O + 38 ATP.
How is cellular respiration different from photosynthesis?
In cellular respirtion, glucose is broken down into carbon dioxide and water to release the energy )ATP) that is stored in this molecule during its formation by photosynthesis. Cellular respiration takes place at and in the mitochondria in 2 steps, called anaerobic and aerobic respiration. All organisms perform respiration all the time. Photosynthesis takes place in green plants and green algae but only during light hours. Photosynthesis requires carbon dioxide, water, and light energy to be converted into glucose in 2 series of reactions called the light and dark reactions.