bio exam 2
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What is photosynthesis?
Process of converting solar energy into chemical bond energy.
What are the energy-poor molecules used in photosynthesis?
CO2 and H2O.
What is the carbon source used in photosynthesis?
CO2.
What is the energy source used in photosynthesis?
Light energy.
What is the main purpose of photosynthesis?
To synthesize energy-rich organic molecules.
What are the two nutritional modes for organisms?
Autotrophic and heterotrophic nutrition.
What is autotrophic nutrition?
Synthesizing organic molecules from inorganic raw materials.
Give an example of an autotrophic organism.
Plants.
What are autotrophs also known as?
Producers.
What are the two types of autotrophic nutrition?
Photoautotrophic and chemoautotrophic.
Give an example of a photoautotroph.
Plants, algae, some prokaryotes.
Give an example of a chemoautotroph.
Some bacteria.
What is heterotrophic nutrition?
Acquiring organic molecules from other organisms.
What are heterotrophs also known as?
Consumers.
Give examples of heterotrophs.
Animals and decomposers (fungi and some bacteria).
Where are chloroplasts primarily located in plants?
In cells of mesophyll, green tissue in the leaf's interior.
What is chlorophyll?
The green pigment in chloroplasts that absorbs light energy.
What is the function of chlorophyll in photosynthesis?
To absorb light energy used to drive photosynthesis.
What are stomata?
Microscopic pores for gas exchange in leaves.
How does CO2 enter and O2 exit the leaf?
Through stomata.
How is water transported to leaves?
Through veins or vascular bundles.
What is transported from leaves to non-photosynthetic parts of the plant?
Sugar.
What are chloroplasts?
Lens-shaped organelles.
How many functional compartments are chloroplasts divided into?
Three.
What is the intermembrane space?
Space between the double membrane of the chloroplast.
What is the thylakoid space?
Compartment within the chloroplast separated by the thylakoid membrane.
What are thylakoids?
Flattened membranous sacs inside the chloroplast.
Where is chlorophyll found?
In the thylakoid membranes.
What is the function of thylakoids?
Convert energy to chemical energy in photosynthesis.
What are grana?
Stacks of thylakoids in a chloroplast.
What is the equation for photosynthesis?
6 CO2 + 6 H2O + light energy -> C6H12O6 + 6 O2.
What are the two stages of photosynthesis?
Light reactions and Calvin cycle.
Where do light reactions occur?
In the thylakoid membranes of chloroplasts.
What is reduced to NADPH in light reactions?
NADP+.
What is the by-product of light reactions?
O2 from the splitting of water.
What is generated in light reactions?
ATP through photophosphorylation.
What is the Calvin Cycle?
The carbon-fixation reactions in photosynthesis.
Where does the Calvin Cycle occur?
In the stroma of the chloroplast.
What is carbon fixation?
The process of incorporating CO2 into organic molecules.
What are the products of the light reactions used for in the Calvin Cycle?
NADPH provides reducing power and ATP provides chemical energy.
What are photosynthetic pigments?
Substances that absorb visible light.
What happens when light contacts matter?
It may be reflected, transmitted, or absorbed.
What do different pigments absorb?
Different wavelengths of light.
What happens to wavelengths that are absorbed?
They disappear.
What color does a pigment appear if it absorbs all wavelengths?
Black.
Why does a leaf appear green?
Chlorophyll absorbs red and blue light but reflects and transmits green light.
What is the characteristic of each pigment?
It has a specific absorption spectrum.
What is used to measure the absorption spectrum of a pigment?
A spectrophotometer.
Which pigment participates directly in the light reactions?
Chlorophyll a.
What is the action spectrum for photosynthesis?
It does not exactly match the absorption spectrum for chlorophyll a.
What are accessory pigments?
Pigments that can absorb light and transfer energy to chlorophyll a.
What are examples of accessory pigments?
Chlorophyll b (yellow-green) and carotenoids (yellow-orange).
What is the Calvin Cycle?
A series of reactions that occur in the chloroplasts of plants during photosynthesis.
What is the initial step of the Calvin Cycle?
Attachment of CO2 to RuBP.
What enzyme catalyzes the attachment of CO2 to RuBP?
RuBP carboxylase (rubisco).
What is the product of the attachment of CO2 to RuBP?
An unstable six-carbon intermediate.
What happens to the six-carbon intermediate in the Calvin Cycle?
It immediately splits into two molecules of 3-phosphoglycerate.
What is the end-product of the Calvin Cycle?
Glyceraldehyde 3-phosphate (G3P).
How many CO2 molecules are needed to make 1 G3P molecule?
3 CO2 molecules.
How many turns of the Calvin Cycle are needed to make 1 G3P molecule?
3 turns of the cycle.
How many G3P molecules are needed to make one glucose molecule?
2 G3P molecules.
How many ATP molecules are used to make one G3P molecule?
9 ATP molecules.
How many NADPH molecules are used to make one G3P molecule?
6 NADPH molecules.
How many ATP molecules and NADPH molecules are used to make one glucose molecule?
18 ATP molecules and 12 NADPH molecules.
Why shouldn't you sleep under a tree?
Non-photosynthetic parts of plants depend on organic molecules exported from leaves.
What process do non-photosynthetic parts of plants use to break down sugars for fuel?
Cellular respiration.
What is the by-product of cellular respiration in plants?
CO2.
What happens to extra sugars synthesized by plants?
They are stored as starch in storage cells of roots, tubers, seeds, and fruits.
How much of the photosynthate do plants use as fuel for cellular respiration?
About 50%.
What do heterotrophs consume from plants?
Parts of plants as food.
What is fermentation?
ATP-producing catabolic process without oxygen.
What is cellular respiration?
ATP-producing catabolic pathway with oxygen.
What are the 3 metabolic stages of cellular respiration?
Glycolysis, Krebs Cycle, Electron transport chain (ETC) and oxidative phosphorylation.
Where does glycolysis occur?
Cytosol.
What happens during glycolysis?
Glucose is split into two pyruvate molecules.
What catalyzes each reaction in glycolysis?
Specific enzymes dissolved in the cytosol.
Does glycolysis require oxygen?
No.
What are the two phases of glycolysis?
Energy-investment phase and energy-yielding phase.
What is produced in the energy-yielding phase of glycolysis?
4 ATPs and 2 NADHs.
What is NADH?
Nicotinamide adenine dinucleotide, a high energy electron carrier.
How many ATPs and NADHs are produced in glycolysis?
2 ATPs and 2 NADHs.
Where does the oxidation of pyruvate to acetyl CoA occur?
Mitochondrial matrix.
What is produced during the oxidation of pyruvate to acetyl CoA?
One molecule of CO2 and one molecule of NADH.
Where does the Krebs cycle occur?
Mitochondrial matrix.
What does the Krebs cycle break down?
Acetyl CoA into carbon dioxide.
What is produced in each turn of the Krebs cycle?
1 ATP, 3 NADHs, and 1 FADH2.
Where does the electron transport chain occur?
Inner mitochondrial membrane.
What is coupled to ATP synthesis in the electron transport chain?
Exergonic transfer of electrons down the ETC to oxygen.
How many ATPs are produced per NADH in the ETC?
2-3 ATPs.
How many ATPs are produced per FADH2 in the ETC?
2 ATPs.
What is the maximum ATP yield for each glucose oxidized during cellular respiration?
28-36 ATP
What is substrate-level phosphorylation?
ATP production by direct enzymatic transfer of phosphate from an intermediate substrate to ADP
What is the reduced coenzyme for ATP produced by oxidative phosphorylation?
NADH
What is glycolysis?
The anaerobic catabolism of organic nutrients
How many ATPs are produced during glycolysis under anaerobic conditions?
Net 2 ATPs
How many more ATPs are produced during glycolysis under aerobic conditions?
4-6 ATPs
What is the oxidizing agent for glycolysis?
NAD+
What is fermentation?
The anaerobic catabolism of organic nutrients
How is ATP generated during fermentation?
By substrate-level phosphorylation, as long as there is sufficient supply of NAD+
What is the purpose of recycling NAD+ from NADH?
To prevent depletion of the cell's pool of NAD+ and keep glycolysis functioning