Title: Metabolic Pathways
Course: Question Banks

Q: ________ reactions comprise most of the chemical reactions involved in cell metabolism.
- Glucogenesis or sugar-making reactions (Incorrect. Many chemical reactions in living systems do not involve sugar at all.)
- Lipogenesis or fatty acidosis reactions (Incorrect. This does not describe most of the chemical reactions in living systems.)
- Oxidation reduction or redox reactions (Correct. Most reactions involved in cell metabolism are redox reactions.)
A: Oxidation reduction or redox reactions

Q: The passing of electrons from one molecule to another in a cell is are known as ________.
- coupled transfers (Incorrect. This is not how transfer of electrons is described.)
- influx reactions (Incorrect. The transfer of electrons between molecules is not an influx reaction.)
- redox reactions (Correct. Transfer of electrons between molecules is known as an oxidation-reduction, or redox, reaction.)
A: redox reactions

Q: The atom that accepts electrons in a redox reaction is the ________.
- reducing agent (Incorrect. The reducing agent gives electrons in a redox reaction.)
- carrying agent (Incorrect. There is no ‘carrying agent’ in a redox reaction.)
- oxidizing agent (Correct. The oxidizing agent accepts electrons in a redox reaction.)
A: oxidizing agent

Q: A reducing chemical reaction ________.
- removes a hydrogen atom from the substrate (Incorrect. Though it is easier to ‘track’ H and O atoms in biological reactions, redox reactions actually involve electron transfer.)
- reduces the compound to a simpler form (Incorrect. Reducing reactions do not have anything to do with ‘complexity’ of a compound.)
- adds an electron to the substrate (Correct. The reducing agent gives electrons in a redox reaction.)
A: adds an electron to the substrate

Q: A living cell cannot store large amounts of ________ because it would create a destructive increase in heat.
- water (Incorrect. Water is crucial to many cellular functions, so there is plenty in every living cell. Too much water in a cell would cause problems, but not an increase in heat.)
- enzymes (Incorrect. Enzymes are associated with many different reactions within cells and there are a large number in a cell at any given time.)
- free energy (Correct. If the energy is not immediately used and there is an excess, the heart produced would destroy the cell.)
A: free energy

Q: Energy is released by the removal of the terminal phosphate group of ________.
- CTP (Incorrect. CTP is not widely used for energy exchanges in cells.)
- TTP (Incorrect. TTP is not widely used for energy exchanges in cells.)
- ATP (Correct. Energy is released when the terminal phosphate group is removed from ATP during a hydrolysis reaction.)
A: ATP

Q: Energy is stored in an AMP molecule through ________.
- removal of the terminal phosphate group (Incorrect. Energy is released when the terminal phosphate group is removed during a hydrolysis reaction.)
- oxidative addition of the hydroxyl group (Incorrect. This is not how energy is stored in an AMP molecule.)
- addition of phosphate groups (Correct. Phosphorylation of AMP into ADP and then ATP stores energy.)
A: addition of phosphate groups

Q: ________ is the addition of a phosphate group to a molecule.
- Dephosphorylation (Incorrect. Dephosphorylation removes a phosphate group from a molecule.)
- Chemiosmosis (Incorrect. This is the movement of ions across a semipermeable barrier and powers the formation of ATP.)
- Phosphorylation (Correct. A phosphorylation reaction adds a phosphate group to a molecule.)
A: Phosphorylation

Q: The most direct method of phosphorylation is ________ phosphorylation.
- oxidative (Incorrect. Oxidative phosphorylation involves oxygen and does not directly add a phosphate group.)
- reductive (Incorrect. There is no reductive phosphorylation reaction.)
- substrate-level (Correct. Substrate-level phosphorylation directly adds a phosphate molecule to the substrate.)
A: substrate-level

Q: The main purpose of ________ is to release free energy.
- converting ADP to ATP (Incorrect. This is a means of storing free energy.)
- transferring phosphate molecules (Incorrect. This is the mechanism why which the main purpose is achieved.)
- hydrolysis of ATP (Correct. Cleaving ATP into ADP plus a free phosphate group is performed in order to release free energy for use by the cell.)
A: hydrolysis of ATP

Q: Which of the below results from photosynthesis?
- Carbon dioxide (Incorrect. This is a reactant in photosynthesis.)
- Sugar chains (Incorrect. Chains of sugars are not produced by photosynthesis.)
- Simple sugars (Correct. This is one of the products of photosynthesis, along with oxygen.)
A: Simple sugars

Q: The process of ________ requires carbon dioxide to begin.
- cellular respiration (Incorrect. Cellular respiration produces carbon dioxide; it does not require it.)
- lactic acid fermentation (Incorrect. Lactic acid fermentation does not require carbon dioxide.)
- photosynthesis (Correct. Carbon dioxide is one of the reactants in photosynthesis.)
A: photosynthesis

Q: Photosynthesis occurs inside the ________ of plants.
- chlorophyll (Incorrect. This is a pigment found in green plants.)
- mitochondria (Incorrect. This is where cellular respiration occurs.)
- chloroplast (Correct. This organelle is unique to photosynthetic organisms like plants.)
A: chloroplast

Q: ________ provides the energized carbon needed by nearly all living things.
- Cellular respiration (Incorrect. Cellular respiration breaks down energized carbon.)
- Lactic acid fermentation (Incorrect. Lactic acid fermentation breaks down energized carbon.)
- Photosynthesis (Correct. Without photosynthesis, energy could not be stored in carbon-based compounds in living organisms.)
A: Photosynthesis

Q: The energy from sunlight is absorbed by ________ inside photosynthetic organelles.
- chloroplast (Incorrect. The chloroplast is the organelle where photosynthesis occurs.)
- spectrophotometers (Incorrect. A spectrophotometer is an instrument for measuring wavelengths of light.)
- pigments (Correct. Pigments are the molecules that absorb specific wavelengths of light.)
A: pigments

Q: Plant pigments absorb energy from the visible light spectrum during ________.
- cellular respiration (Incorrect. No energy is absorbed from light during cellular respiration.)
- fermentation (Incorrect. No energy is absorbed from light during fermentation.)
- photosynthesis (Correct. Photosynthesis involves capturing visible light energy using pigments.)
A: photosynthesis

Q: The longer a wavelength of light, the ________.
- more energy it contains (Incorrect. Longer wavelengths of light do not have more energy.)
- more color it has (Incorrect. The wavelength of light does not dictate color intensity.)
- less energy it contains (Correct. Longer wavelengths of light have less energy, shorter wavelengths of light have more.)
A: less energy it contains

Q: ________ reactions of photosynthesis generate NADPH and ATP to carry solar energy.
- The light-independent (Incorrect. These are not the molecules used to carry solar energy during the light-independent reactions.)
- Both the light-dependent and -independent (Incorrect. These are not the molecules used to carry solar energy during the light-independent reactions.)
- The light-dependent (Correct. NADPH and ATP are used to carry the solar energy captured in the light-dependent reactions.)
A: The light-dependent

Q: The conversion of light energy into chemical energy occurs in a ________ inside chloroplasts.
- photoreactive chamber (Incorrect. This is not the term that describes where light energy is captured in chloroplasts though it does logically sound right.)
- reactive system (Incorrect. This is not the term that describes where light energy is captured in chloroplasts)
- photosystem (Correct. Plants contain two photosystems that work together to convert light energy into chemical energy.)
A: photosystem

Q: During a process called photoact, ________ give up an electron as a part of the light-dependent reactions.
- chloroplasts (Incorrect. A chloroplast is the organelle in which a photoact occurs.)
- thylakoids (Incorrect. Thylakoids are sacs within chloroplast where photosynthesis occurs.)
- chlorophylls (Correct. Chlorophyll pigments give up an electron during a photoact.)
A: chlorophylls

Q: Fixation, reduction, and regeneration are the three steps of what process?
- the light-dependent reactions of photosynthesis (Incorrect. These are not the steps of the light-dependent reactions of photosynthesis.)
- both the light-dependent and -independent reactions of photosynthesis (Incorrect. These are not the steps of the light-dependent reactions of photosynthesis.)
- the light-independent reactions of photosynthesis (Correct. This describes the proper steps, in order, that occur during the light-independent reactions of photosynthesis.)
A: the light-independent reactions of photosynthesis

Q: The main purpose of the light-independent reactions is to ________.
- convert solar energy to chemical energy (Incorrect. This actually happens in the light-dependent reactions.)
- convert solar energy to ATP for short-term energy use (Incorrect. Solar energy is converted to bonds in ATP during the light-dependent reactions.)
- build carbohydrates for long-term energy storage (Correct. The light-independent reactions create long-term energy storage in the chemical bonds forming carbohydrates.)
A: build carbohydrates for long-term energy storage

Q: Part of the light-independent reactions is known as ________ because it converts inorganic carbon dioxide into organic carbohydrates.
- reduction (Incorrect. Converting inorganic carbon into organic carbohydrates is not a reduction reaction.)
- Regeneration (Incorrect. Converting inorganic carbon into organic carbohydrates is not a regeneration reaction.)
- fixation (Correct. Inorganic COs is fixed in the form of simple sugars in the first stage of the Calvin cycle.)
A: fixation

Q: During the second half of glycolysis, what occurs?
- ATP is used up. (Incorrect. This occurs in the first half of glycolysis.)
- Fructose is split in two. (Incorrect. This occurs in the first half of glycolysis.)
- ATP is made. (Correct. The main output of the second half of glycolysis is ATP.)
A: ATP is made.

Q: The final net products of ________ are 2 molecules of ATP and 2 NADH.
- pyruvate oxidation (Incorrect. Pyruvate oxidation does not produce any ATP.)
- the citric acid cycle (Incorrect. The citric acid cycle does not produce any ATP.)
- glycolysis (Correct. The net products are only 2 molecules of ATP (because it used 2 ATP during the process) and 2 NADH.)
A: glycolysis

Q: Which of the following is considered the rate-limiting enzyme for glycolysis?
- NAD^+ (Incorrect. This is a potential limiting factor but it is an electron carrier, not an enzyme.)
- Phosphofructokinase (Incorrect. This is a rate-limiting enzyme but the limits are imposed by the concentration of ADP, not the concentration of phosphofructokinase. Therefore it is not the rate-limiting enzyme for glycolysis.)
- Pyruvate kinase (Correct. Pyruvate kinase concentration determines whether the second half of glycolysis can proceed.)
A: Pyruvate kinase

Q: In the presence of ________, pyruvate from glycolysis is transformed to acetyl-CoA and delivered to the citric acid cycle.
- carbon dioxide (Incorrect. Carbon dioxide is not required for pyruvate to be transformed to acetyl-CoA.)
- a carboxyl group (Incorrect. A carboxyl group is not required for pyruvate to be transformed to acetyl-CoA.)
- oxygen (Correct. Aerobic respiration begins with pyruvate from glycolysis is converted to acetyl-CoA.)
A: oxygen

Q: What is removed from pyruvate during its conversion into an acetyl group?
- hydroxyl group (Incorrect. This is not what is removed from pyruvate to make it an acetyl group.)
- methyl group (Incorrect. This is not what is removed from pyruvate to make it an acetyl group.)
- carboxyl group (Correct. This carboxyl group is converted into carbon dioxide and released into the surrounding medium.)
A: carboxyl group

Q: Each turn of ________ directly produces 3 NADH and 1 FADH_2.
- glycolysis (Incorrect. Glycolysis does not produce NADH or FADH_2.)
- pyruvate oxidation (Incorrect. Pyruvate does not produce NADH or FADH_2.)
- the citric acid cycle (Correct. These are the direct products of the citric acid cycle.)
A: the citric acid cycle

Q: The direct products from the citric acid cycle are ________.
- final products of cellular respiration (Incorrect. The direct products of the citric acid cycle are not final products of cellular respiration.)
- formed from the direct consumption of oxygen (Incorrect. Oxygen is not directly consumed in the citric acid cycle.)
- temporary electron storage compounds (Correct. The NADH and FADH2 produced must move on to the subsequent pathway to transfer their electrons (and energy) into ATP.)
A: temporary electron storage compounds

Q: The majority of the ATP produced by cellular respiration comes from ________.
- glycolysis (Incorrect. Glycolysis only produces a net of 2 ATP.)
- the citric acid cycle (Incorrect. ATP may not even be formed in the citric acid cycle; instead it may form GTP.)
- the electron transport chain (Correct. The bulk of ATP produced by cellular respiration occurs from the electron transport chain.)
A: the electron transport chain

Q: The only part of cellular respiration that directly consumes ________ is the electron transport chain.
- carbon (Incorrect. Carbon is isolated from the environment during photosynthesis, not cellular respiration.)
- nitrogen (Incorrect. Nitrogen is not required for any part of cellular respiration.)
- oxygen (Correct. The electron transport chain requires atmospheric oxygen.)
A: oxygen

Q: Chemiosmosis involves ________.
- the movement of hydrogen atoms across a membrane (Incorrect. Chemiosmosis does not involve movement of hydrogen atoms.)
- the movement of electrons across a membrane (Incorrect. Chemiosmosis does not involve movement of electrons.)
- the movement of hydrogen ions across a membrane (Correct. Chemiosmosis involves the pumping of hydrogen ions (protons) across a membrane.)
A: the movement of hydrogen ions across a membrane

Q: ________ is used to generate 90 percent of the ATP from aerobic glucose catabolism.
- Complex I (Incorrect. Complex I does not generate ATP.)
- Q and Complex II (Incorrect. Complex II and Q do not generate ATP.)
- Chemiosmosis (Correct. Chemiosmosis produces 90% of the ATP yield from aerobic respiration.)
A: Chemiosmosis

Q: In the absence of ________, some organisms are able to convert glucose to energy via fermentation.
- carbon (Incorrect. Carbon is always present when you have glucose, as it is a carbon-based molecule.)
- nitrogen (Incorrect. Nitrogen levels do not impact the way glucose is converted to energy.)
- oxygen (Correct. Fermentation converts glucose to energy in the absence of oxygen.)
A: oxygen

Q: The process of ________ utilizes an organic molecule to regenerate NAD^+ from NADH.
- anaerobic cellular respiration (Incorrect. Anaerobic cellular respiration does not necessarily use organic molecules as final electron acceptors.)
- aerobic respiration (Incorrect. Aerobic respiration does not use an organic molecule to regenerate NAD^+.)
- fermentation (Correct. Fermentation uses organic molecules to regenerate NAD^+.)
A: fermentation

Q: ________ is a specialized form of anaerobic cellular respiration.
- Photosynthesis (Incorrect. Photosynthesis is not a form of cellular respiration.)
- Chemiosmosis (Incorrect. Chemiosmosis is a step in aerobic respiration.)
- Fermentation (Correct. Fermentation is anaerobic cellular respiration that utilized an organic molecule as the final electron acceptor.)
A: Fermentation

Q: Which of the following fermentation methods can occur in animal skeletal muscles?
- alcohol fermentation (Incorrect. Alcohol fermentation does not occur in animal skeletal muscle cells.)
- propionic fermentation (Incorrect. This is not a type of fermentation that occurs in skeletal muscles.)
- lactic acid fermentation (Correct. Lactic acid fermentation occurs when skeletal muscles use up available oxygen.)
A: lactic acid fermentation

Q: Lactic acid generated by fermentation in muscles ________.
- causes muscle soreness (Incorrect. This was previously believed to the be the cause of soreness in overworked muscles but is not true.)
- gets excreted in urine (Incorrect. Lactic acid is not excreted in urine.)
- is sent to the liver for conversion back into pyruvic acid (Correct. Lactic acid is transported to the liver for conversion into pyruvic acid.)
A: is sent to the liver for conversion back into pyruvic acid

Q: The two main types of anaerobic cellular respiration are lactic acid fermentation and ________.
- beta oxidation (Incorrect. This is not a type of anaerobic cellular respiration.)
- oxidative fermentation (Incorrect. This is not a type of anaerobic cellular respiration.)
- alcohol fermentation (Correct. Lactic acid and alcohol fermentation are both types of anaerobic cellular respiration.)
A: alcohol fermentation

Q: Yeast contribute to beer brewing by producing ethanol during ________.
- lactic acid fermentation (Incorrect. Yeast do not perform lactic acid fermentation.)
- ethanol fermentation (Incorrect. While ethanol is the alcohol produced, it is not the only one; hence the process is not called ethanol fermentation.)
- alcohol fermentation (Correct. One of the main points of ‘alcohol’ fermentation in beer production is to produce ethanol for consumption)
A: alcohol fermentation

Q: In order to ensure an adequate supply of NAD+ is regenerated, ________ must be utilized in low oxygen conditions.
- aerobic respiration (Incorrect. Aerobic respiration cannot proceed in low oxygen conditions.)
- glycolysis (Incorrect. Glycolysis is the reason NAD+ needs to be regenerated.)
- fermentation (Correct. Fermentation is designed to regenerate NAD+.)
A: fermentation

Q: The key enzyme that generates ethanol during fermentation is ________.
- lactate dehydrogenase (Incorrect. This enzyme is present in lactic acid fermentation.)
- pyruvate decarboxylase (Incorrect. This enzyme does not produce ethanol.)
- alcohol dehydrogenase (Correct. This enzyme produces ethanol during alcohol fermentation.)
A: alcohol dehydrogenase

Q: The enzyme alcohol dehydrogenase generates ________ during fermentation.
- carbon dioxide (Incorrect. Carbon dioxide is a by-product of fermentation, not a product.)
- yogurt (Incorrect. Yogurt is a product of lactic acid fermentation and does not come from alcohol dehydrogenase.)
- alcohol (Correct. Alcohol dehydrogenase produces alcohol.)
A: alcohol