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Photosynthesis and Cellular Respiration Review Guide
Question Answer
- What does ATP stand for? Adenosine Tri Phosphate
- Label the molecule of ATP.
adenine ribose 3 phosphate groups
- How is the energy from ATP released? What molecule is formed?
the bond between the last two phosphate groups is broken, and ADP is formed
- What does ADP stand for? Adenosine Di Phosphate
- Which compound (ATP or ADP) holds more energy? ATP
- Write the equation that represents the change from ATP to ADP. (See ATP Lab for help.)
ATP ADP + phosphate + energy (Note: This is an exothermic reaction because it releases energy.)
- Write the equation that represents the change from ADP to ATP. (See ATP Lab for help.)
ADP + phosphate + energy ATP (Note: This is an endothermic reaction because it releases energy.)
- In what types of organisms does photosynthesis occur? autotrophs (mostly plants)
- Define autotroph. An organism that makes its own food. In most cases it is an organism that converts the sun’s energy into food.
- Define heterotroph. An organism that obtains its energy (food) from other organisms.
- Label the chloroplast.
outer membrane
granum
thylakoid
stroma
inner membrane
- Write the equation for photosynthesis in both words and symbols.
6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2
carbon dioxide + water glucose + oxygen
- Describe how the work of each scientist contributed to photosynthesis:
van Helmont-He thought that the mass of a plant comes from water because that was the only thing he added to his experimental plant over 5 years. He was mistaken- the mass comes from CO 2.
Priestley-concluded that plants produce some substance (later determined to be oxygen) that allowed a candle placed under a bell jar to continue burning, because without the plant the same candle could not remain lit. Ingenhousz-concluded that Priestly’s experiment only works when the plant is exposed to light
- What is necessary for
photosynthesis to occur? (what are the reactants?)
carbon dioxide, water, light
- What is the main product of photosynthesis? high energy sugars – specifically glucose
- What is released in the process as a waste product?
oxygen
- Why do photosynthetic organisms appear green (explain in terms of color absorption & reflection)?
The main pigment in photosynthetic organisms is chlorophyll. Chlorophyll reflects green wavelengths of light, and absorb all others. When the green wavelengths are reflected and seen by your eyes the plant or other organism appears green.
- Define pigment. A molecule that absorbs light.
- What is the principal pigment in photosynthesis?
Chlorophyll
- What colors are absorbed best by chlorophyll? red and blue violet
- Explain why photosynthesis is necessary to life on earth.
Photosynthesis is the starting point for passing energy throughout the various ecosystems. Organisms would be unable to survive without the glucose that photosynthesis provides. Also, organisms that undergo photosynthesis release oxygen into the atmosphere. Without that source of oxygen many living things, including humans, would not be able to survive.
- What are the 2 main reactions the makeup photosynthesis? Where in the chloroplast does each occur?
Reaction Location Light dependent reaction thylakoid light independent reaction (Calvin Cycle)
stroma
- What are the reactants and products of the light-dependent reaction?
Water is the main reactant, and oxygen is the product. NADP+ and ADP are also reactants, and NADPH and ATP are products. These molecules cycle between the light dependent and light independent reactions.
- What molecules cycle between the light dependent and light independent reactions?
NADP+ and NADPH cycle between the two, and so do ADP (and a phosphate group) and ATP.
sunlight
Krebs Cycle
Electron Transport Chain (ETC)
- What is glycolysis? What are the reactants and products? How many ATP are made in the process (total and net)?
Glycolysis is the process that begins to break down glucose. The reactants are glucose, 2 NAD+, 4 ADP and 2 ATP. Products are 2 pyruvic acid, 2 NADH, 2 ADP, and 4 ATP. There are 4 total ATP made, but a net gain of 2 ATP (2 ATP were needed to start the process, so add the end only 2 ATP are “earned”.
- Where does glycolysis occur? cytoplasm
- What are the products (output) of the Krebs cycle?
3CO2 molecules, 4 NADH molecules, 1 FADH2 molecule and 1 ATP.
- What is another name for the Krebs cycle? Why?
Citric acid cycle because that is the first compound formed in the cycle.
- Where does the Krebs cycle occur? the matrix of the mitochondrion
- List the two high-energy electron carriers used in cellular respiration.
NADH and FADH2 (when they are carrying the electrons)
- What is the Electron Transport Chain? Where is it located in eukaryotic organisms?
Collection of enzymes used to extract energy from high energy electron carriers. That energy is used to power the transformation of ADP to ATP. It is found in the inner membrane (cristae folds) of the mitochondrion in eukaryotes.
- Where does the Electron Transport Chain occur in organisms that do not have mitochondria?
the cell membrane
- Which is more efficient- aerobic or anaerobic respiration? Explain. (Hint: Think about how many ATP molecules are made in each.)
Aerobic is more effective. Aerobic can produce approximately 36 ATP per glucose molecule, and anaerobic can only produce 2 ATP per glucose molecule.
- Draw and label a mitochondrion (be sure to identify the inner and outer membranes, intermembrane space, matrix, christae.
- What powers energy for up to 90 seconds? Lactic acid fermentation
- What substance is broken down for energy after available glucose is broken down?
Glycogen
Inner membrane
Matrix
Cristae
Outer membrane
Inter-membrane space
Inner membrane
Matrix
Cristae
Outer membrane
Inter-membrane space
- What substance is broken up after the substance above (in #49) is used up?
fat
- What is an oxygen debt? What causes it, and how is it remedied?
An oxygen debt occurs during the anaerobic phase of exercise when oxygen isn’t available. Lactic acid produced during lactic acid fermentation builds up in the muscles. The process that breaks down lactic acid requires oxygen, and this is obtained by heavy breathing.
- Write the overall chemical equation for photosynthesis. 6CO2 + 6H2O + energy^ ^ C6H12O6 + 6O
- Interrelated nature of PS & CR (^) The products of one are the reactants of the other. They supply each
other with needed resources.
- How are photosynthesis and cellular respiration each important to life on earth?
They allow energy to be used by all organisms. They also provide a means for cycling oxygen and carbon dioxide.
