Biology 1308 Unit 6 Interactive

Oxygen is used to release energy from organic molecules. Which body difference helps a champion cyclist get more oxygen to his tissues?

• muscles that make less lactic acid.

• fewer red blood cells to transport oxygen through the blood

• large heart capable of pumping more blood per minutes

Answer explanation

Correct. Pumping more blood per minute provides more oxygen-carrying red blood cells to the tissues for oxygen delivery each minute.

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The benefit of increased oxygen intake is increased _______________.

• photosynthesis

• fermentation

• aerobic respiration

Answer explanation

Correct. Aerobic respiration requires oxygen to produce the ATP that supports rapid muscle contraction and relaxtion during exercise. Increased oxygen delivery allows aerobic respiration to continue longer before oxygen is depleted and muscles are forced to switch to the anaerobic pathway that produces lactic acid.

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Overall, cellular respiration is an ______________.

• endergonic pathway

• exergonic pathway

Answer explanation

Correct. Cellular respiration is the catabolic process of harvesting the energy stored in biimolecules. The overall energy for any cellular respiration pathway is exergonic, releasing energy as existing biomolecules are broken down into smaller molecules. However, any cellular respiration pathway generally includes one or a few endergonic reactions that use energy to prepare a molecule for later, energy-harvesting reactions.

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Where does glycolysis occur in a eukaryotic cell?

Answer explanation

Correct! The reactions of glycolysis occur in the cytoplasm of all cells. Glycolysis is the initial reaction pathway for virtually all cellular respiration, both arerobic and anaerobic.

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Where do oxygen-requiring reactions of respiration occur in a eukaryotic cell?

Answer explanation

Correct! The reactions that comprise aerobic respiration include glycolysis, formation of acetyl-CoA, Krebs cycle, and oxidative phosphorylation, Except glycolysis, there reaction pathways occur inside mitochondria in eukaryotic cells to provide structural support and environmental control for the enzymes that catalyze these reactions. Prokaryotic organisms do no posses mitochondria and must perform aerobic respiration reactions directly in the cytoplasm.

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Where is the majority of ATP made in a eukaryotic cell?

Answer explanation

Correct! Aerobic respiration is more efficient than most anaerobic respiration pathways. The majority of ATP produces during aerobic respiration is synthesized by oxidative phosphorylation inside the mitochondria of eukaryotic cells.

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In glycolysis, one glucose is split into _________.

• two NADH and two ATP

• six carbon dioxide molecules

• two pyruvate molecules

Answer explanation

Correct! The glycolysis phase of cellular respiration degrades the 6-carbon molecule of glucose to two 3-carbon molecules of pyruvate.

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Which of the following is formed by substrate-level phosphorylation?

• NAD⁺

• ATP

• ADP

• NADH

Answer explanation

Correct! Phosphorylation results in the addition of high-energy phosphate to ADP, forming ATP.

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Match the following

• matrix

• Product formed by all carbons in glucose by end of Krebs cycle.

• carbon dioxide

• Eukaryotic locations of Krebs cycle.

• acetyl-CoA

• Reactant enter Krebs cycle.

• cytoplasm

• Prokaryotic location for Krebs cycle.

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Match the following

• two

• Reactant entering formation of acetyl-CoA.

• pyruvate

• Number of ATP produced by coupled reactions during oxidation of two pyruvate.

• six

• Number of NADH produced from two acetyl-CoA entering Krebs cycle.

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