Biology Chapters 8/9 Flashcards
What did Jan van Helmont conclude from his experiments?
Mass gained in plants is mostly due to water.
What occurs in the process of photosynthesis?
Plants use energy from sunlight to convert water and carbon dioxide into high-energy carbohydrates and oxygen.
What substance was produced by the mint plant in Joseph Priestley’s experiment?
Oxygen.
What did Jan Ingenhousz show?
Plants only release oxygen when they are exposed to light.
What is the chemical equation for photosynthesis?
6CO2 + 6H20 –> C6H12O6 + 6O2
What does photosynthesis require?
Water, carbon dioxide, light, and chlorophyll.
What are light-absorbing molecules that gather the sun’s energy? What is the principal one in plants?
Pigments, chlorophyll
What is a thylakoid?
A saclike photosynthetic membrane found in chloroplasts.
What is a granum?
A stack of thylakoids.
What is the region outside the thylakoid membrane called?
The stroma.
What are photosystems?
Clusters of chlorophyll and other pigments made by proteins in the thylakoid membrane.
What are the two stages of photosynthesis called?
Light-dependent reactions and light-independent reactions (Calvin cycle)
What is the reactant of light-dependent reactions? the product?
Water
Oxygen
What is the reactant of the Calvin cycle? the product?
Carbon dioxide
Glucose
True or false: Electrons gain energy when they are excited by light in the chlorophyll.
True.
What is a carrier molecule?
A compound that can accept a pair of high-energy electrons and transfer them along with most of their energy to another molecule.
What is the carrier molecule involved in photosynthesis?
NADP+
How does NADP+ become NADPH?
NADP accepts and hold 2 high-energy electrons and a hydrogen ion.
True or false: Light dependent reactions convert ATP into ADP.
False (they convert ADP into ATP)
When is NADP+ converted into NADPH?
During the light-dependent reactions.
Where do the light-dependent reactions take place?
Thylakoids
True or false: High-energy electrons move through the electron transport chain from photosystem I to photosystem II.
False (they move from photosystem II to photosystem I)
What process produces ATP?
ATP synthase.
What does the Calvin cycle use to produce sugars?
The energy from ATP and NADPH.
Where do carbon dioxide molecules that enter the Calvin cycle come from?
The atmosphere.
True or false: The Calvin cycle uses six molecules of carbon dioxide to produce a single 6-carbon sugar molecule.
True
What three factors affect the rate of photosynthesis?
Water, temperature, and light.
What is a calorie?
The amount of energy it takes to raise the temperature of 1 gram of water 1 degree celsius.
How many calories make up 1 Calorie?
1,000.
What is the first stage of cellular respiration called?
Glycolysis
What is cellular respiration?
The process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.
What is the chemical equation for cellular respiration?
6O2 + C6H12O6 —> 6CO2 + 6H2O + Energy
What are the second and third stages of cellular respiration?
The Krebs cycle and the electron transport chain.
What would happen if cellular respiration was only one stage?
All the energy from glucose would be released at once.
Where does glycolysis take place?
In the cytosol.
Where do the Krebs cycle and electron transport chain take place?
In the mitochindria
What is glycolysis?
The process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid, a 3-carbon compound.
What fuels glycolysis?
Two molecules of ATP.
What is the net gain of ATP after glycolysis?
2 ATP
What is NAD+?
An electron carrier that hold 4 high-energy electrons.
What is the function of NAD+ in glycolysis?
Holding electrons until they are needed in other molecules, helping pass glucose to other cell parts.
What does NAD+ become after glycolysis?
NADH
What process is used to produce energy in cells without oxygen?
Fermentation.
What is fermentation?
An anaerobic process that releases energy from food molecules by producing ATP.
How does fermentation allow glycolysis to continue?
It turns NADH back into NAD+.
What are the two main types of fermentation?
Alcoholic and lactic acid.
What organisms use alcoholic fermentation?
Yeasts and other microorganisms
What is the equation for alcoholic fermentation?
Pyruvic acid + NADH –> alcohol + carbon dioxide + NAD+
What happens to alcohol produced from alcoholic fermentation when bread is baked?
The alcohol evaporates.
What is the equation for lactic acid fermentation?
Pyruvic acid + NADH —> lactic acid + NAD+
When is lactic acid fermentation most commonly used by human beings?
During rapid exercise.
How much chemical energy from glucose is used during glycolysis?
10%
True or false: The Krebs cycle and the electron transport chain are aerobic.
True
What happens to pyruvic acid during the Krebs cycle?
It is broken down into carbon dioxide in a series of energy-extracting reactions.
Why is the Krebs cycle often referred to as the citric acid cycle?
Citric acid is the first compound formed during the reactions of the Krebs cycle.
When does the Krebs cycle begin?
When pyruvic acid produced during glycolsis enters the mitochondrion.
What happens to the 3 carbon atoms in pyuvic acid when it is broken down?
1 becomes part of a carbon dioxide molecule while the other 2 join a compound called coenzyme A to form acetlyl-CoA.
What happens to the carbon dioxide molecule produced when pyruvic acid is broken down?
It is released into the air.
How is citric acid produced?
Acetyl-CoA adda a 2-carbon acetyl group to a 4-carbon molecule, producing a citric acid molecule.
How many carbon dioxide molecules during the energy extraction part of the Krebs cycle?
2
What is the “energy tally” from 1 molecule of pyruvic acid during the Krebs cycle?
4 NADH, 1 FADH2, and 1 ATP.
Why is the 4-carbon compound generated in the breakdown of citric acid the only permanent compound in the Krebs cycle?
It accepts another 2-carbon acetyl group, starting the process over again.
How many total ATP molecules are produced during cellular respiration?
36
Why does oxygen allow more ATP molecules to produce?
The Krebs cycle and electron transport chain are aerobic.
What happens to the leftover energy of glucose after all the ATP molecules are produced?
It is released as heat.
What are three sources of ATP runners use before a race?
Their muscles, lactic acid fermentation, and cellular respiration.
What is the only molecule that can be used to get rid of lactic acid?
Oxygen.
True or false: Runners use lactic acid fermentation to supply energy for short races while they used cellular respiration for long races.
True
