Ch 5 Study Guide
Vocabulary Words
Organic compounds: used by organisms to store chemical energy
Fermentation: enables glycolysis to continue producing ATP in the absence of oxygen
ATP: the energy “currency” of the cell
Glycolysis: first step in cellular respiration
Aerobic respiration: produces up to 38 ATP
Sun: source of all energy for living systems
Heterotrophs: consume food to get energy
Phosphate: energy is released when ATP loses this atom
Autotrophs: use energy from light or inorganic substances to make organic compounds
Metabolism: using energy to either break down or build up molecules
Concepts to Know
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The light-independent reactions of photosynthesis can occur in either light or dark
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NADPH is formed when the electron acceptor NADP+ combines with hydrogen ions and excited electrons
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In the Krebs cycle, production of ATP requires acetyl-CoA, the gradual breakdown of a six-carbon compound, and the transfer or a phosphate group to ADP
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The production of ATP during photosynthesis requires energy released by hydrogen ions move down their concentration gradient, a carrier protein to catalyze the addtino of a phosphate group to a molecule of ADP, and energy from electrons passing through electron transport chains
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The Calvin cycle is a common method of carbon fixation
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When a chlorophyll molecule absorbs light, some of its electrons are excited to a higher energy level
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During cellular respiration, the complete breakdown of glucose yields only carbon dioxide and water
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For each molecule of glucose entering glycolysis, there is a net gain of two ATP molecules
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The final electron acceptor for the electron transport chain of aerobic respiration is oxygen
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A heterotrophy might obtain energy for cellular respiration from grass
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ATP releases energy when the bonds between phosphate groups are broken
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Water is the source of oxygen produces during photosynthesis
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When electrons of a chlorophyll molecule are excited to a higher level they enter an electron transport chain
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Glycolysis yields two pyruvates, two NADH molecules, and four ATP molecules
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The energy a cell needs to build molecules or to power cellular respiration is supplied by ATP
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To maximize ATP production, glycolysis must be followed by the Krebs cycle

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Electrons and hydrogen ions combine with NADP+ in an electron transport chain to produce
NADPH
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In the third stage of photosynthesis, the Calvin cycle is used to make organic molecules
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During glycolysis, NADH is formed when hydrogen atoms are transferred to an electron acceptor called NAD+
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Autotrophs use the energy from light or inorganic substances to produce organic compounds
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Light energy is converted to chemical energy in the process of photosynthesis
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The Calvin cycle begins when a molecule of carbon dioxide is added to a five-carbon compound and ends with three-carbon sugars
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During photosynthesis, oxygen gas is produced when water molecules are split to provide replacement electrons for pigment molecules
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The reaction that removes a(n) phosphate from ATP results in ADP and provides energy for the cell
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The less carbon dioxide available to a plant, the slower or less photosynthesis proceeds
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Metabolic processes that require oxygen are called aerobic
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Fermentation allows the continued production of ATP even though oxygen is no longer present
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In glycolysis, the breakdown of glucose uses two ATP molecules
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The ultimate source of energy for all life on Earth is the sun
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Heterotrophs cannot get energy from the sun directly and rely on the process of cellular respiration to provide energy
Essay
Does increasing the temperature always increase the level of photosynthesis? Explain. No, the level of photosynthesis will increase with temperature until the temperature becomes too high for cellular enzymes to function properly. As the temperature approaches this point, the level of photosynthesis will level off. When the temperature exceeds this point the level of photosynthesis will decline.
If the Calvin cycle uses carbon dioxide, not light energy, to make organic compounds. Explain why the
Calvin cycle cannot be the first stage of photosynthesis. The energy used in the Calvin cycle is supplied by the ATP and NADPH that are produced in the first stage of photosynthesis.
In order for pyruvate to be used for the production of ATP, oxygen must be present. What happens to
pyruvate produced during glycolysis if oxygen is not available to a cell? In cells deprived of sufficient oxygen for aerobic respiration, pyruvate will undergo fermentation to recycle NAD+. This recycled NAD+ is needed to continue making ATP through glycolysis.