Bioenergetics Test 4

• The major steps in aerobic respiration include Glycolysis, TCA/Krebs’ cycle, and ETS. These steps are common in both prokaryotic and eukaryotic organisms.
• Glycolysis is represented by (I), TCA/Krebs’ cycle by (II), and Electron Transport System (ETS) by (III).
• Looking at the given options, the correct sequence is found in option B: A-(iii), B-(ii), C-(i).
• Thus, the correct answer is B.

• The electron transport chain is the final stage of cellular respiration where high-energy electrons are transferred.
• Various molecules within the chain like Co-enzyme Q, Cytochromes b and c are involved in this process.
• However, Molecular Oxygen (O2), being highly electronegative, acts as the final electron acceptor in the electron transport chain.
• So, the correct answer is D, "Molecular Oxygen".

• The complete oxidation of glucose involves several biochemical pathways, namely glycolysis, oxidative decarboxylation, and Krebs’ cycle.
• Glycolysis reduces 2 NAD molecules, oxidative decarboxylation reduces another 2 NAD, and the Krebs’ cycle reduces 6 NAD.
• Therefore, in total, 10 NAD molecules get reduced through the complete oxidation of glucose.
• Hence, the correct answer is C, "Ten".

• The Calvin cycle is a part of photosynthesis, where carbon dioxide is fixed and converted into organic compounds.
• This cycle is also known by another term due to the initial production of a three-carbon compound in the process.
• The other name for the Calvin cycle is the "C3 - pathway".
• Thus, the correct answer is C, "C3 – pathway".

• Oxidative phosphorylation is an essential metabolic pathway that generates ATP, the cell's main energy source.
• While ATP is synthesized in all living cells, the presence of oxygen is a prerequisite for oxidative phosphorylation.
• This process does not occur in anaerobic or primitive cells, which lack the necessary machinery (mitochondria) for oxidative phosphorylation.
• Therefore, oxidative phosphorylation takes place exclusively in aerobic cells.

• Photosynthesis is a biological process that converts light energy into chemical energy stored in glucose.
• Broadly, photosynthesis can be divided into two stages: light-dependent reactions and light-independent reactions.
• Light-dependent reactions occur in the thylakoid membrane and generate ATP and NADPH. Light-independent reactions, also known as the Calvin cycle, occur in the stroma and use ATP and NADPH to incorporate carbon dioxide into organic molecules.
• Hence, the correct answer is B, "2".

• The Krebs cycle is a series of chemical reactions used by all aerobic organisms to generate energy.
• In one of the steps, malate is converted to oxaloacetate, a process involving the oxidation of malate.
• This oxidation is facilitated by the coenzyme Nicotinamide Adenine Dinucleotide (NAD).
• Thus, the correct answer is B, "NAD".

• The Krebs cycle, also known as the citric acid cycle, is a sequence of chemical reactions that occurs in the mitochondria and is part of cellular respiration.
• Within this cycle, Acetyl CoA combines with a molecule to form a 6-carbon compound known as citrate.
• The molecule that Acetyl CoA reacts with is oxaloacetate.
• Therefore, the answer is C, "Oxaloacetate".

• Photosynthesis is a vital process in plants and algae that involves two photosystems, Photosystem I and Photosystem II.
• When there is a demand for ATP in the chloroplast, one of these photosystems is primarily involved.
• The photosystem that is active when ATP is low is Photosystem I.
• Hence, the correct answer is A, "Photosystem I".

• As part of the cellular respiration process, pyruvate derived from glycolysis must be converted into another molecule before it can enter the Krebs cycle.
• This conversion process involves decarboxylation and oxidation.
• The product of this transformation is Acetyl-CoA.
• Thus, the right answer is D, "Acetyl-CoA".

• Glycolysis, a critical stage of cellular respiration, is divided into different phases.
• In one of these phases, glucose is broken down, and energy is consumed.
• This process occurs during the preparatory phase of glycolysis.
• Therefore, the correct answer is A, "Preparatory phase".

• Cellular respiration includes the electron transport chain where NADH molecules play a significant role.
• Each NADH molecule entering the electron transport chain contributes to the production of ATP molecules.
• Specifically, a single NADH molecule results in the formation of 3 ATP molecules.
• Thus, the answer is B, "3 ATP".

• The conversion of pyruvate to Acetyl CoA is an essential step before entering the Krebs Cycle.
• Specific molecules are required for this conversion to occur.
• In this case, Nicotinamide Adenine Dinucleotide (NAD+) is necessary.
• Therefore, the answer is A, "NAD+".

• In the process of photosynthesis, there are several pigment types involved.
• Two of these pigments are Chlorophyll b and carotenoids.
• These pigments have a specific name due to their role in aiding Chlorophyll a by absorbing different wavelengths of light.
• As such, they are called "Accessory pigments".

• The TCA cycle, or Krebs cycle, involves several reactions that require specific enzymes.
• These enzymes exist within a certain part of the cell.
• In eukaryotic cells, these enzymes are located primarily in the mitochondria.
• Therefore, the correct answer is C, "Mitochondria".

• Chlorophyll a and Chlorophyll b are both vital for photosynthesis, but they have some structural differences.
• One major difference lies in the type of group attached to their structure.
• Chlorophyll a contains a methyl group, whereas chlorophyll b contains an aldehyde group.
• Hence, the right answer is B, "Chlorophyll a has a methyl group while chlorophyll b has an aldehyde group".

• Metabolic processes in the cell can either be aerobic (requiring oxygen) or anaerobic (without oxygen).
• One such process that can function with or without oxygen is glycolysis.
• Glycolysis is the breakdown of glucose into two pyruvate molecules, occurring in the cytosol of all cells.
• Therefore, the correct answer is A, "Glycolysis".

Short Hint: Glycolysis can occur in both aerobic and anaerobic conditions.

• ATP, or Adenosine Triphosphate, is made up of several components.
• These include adenine, ribose, and three phosphate groups.
• However, hexose is not a part of ATP.
• This makes the correct answer C, "Hexose".

Short Hint: ATP does not contain hexose, but it does contain adenine, ribose, and three phosphate groups.

• Photosystem I plays a crucial role in photosynthesis.
• It contains a specific type of chlorophyll molecule and absorbs light of a certain wavelength.
• Specifically, Photosystem I contains Chlorophyll a and can absorb light of 700nm wavelength.
• Therefore, the correct answer is B, "Chlorophyll a and 700nm".

Short Hint: Photosystem I has Chlorophyll a and absorbs light of a maximum wavelength of 700nm.

• Cellular respiration is a process that converts glucose into energy within cells.
• During this process, before entering the mitochondrion, glucose is broken down.
• The split results in two molecules of pyruvic acid.
• Therefore, the correct answer is B, "Pyruvic acid".

Short Hint: During respiration, glucose is split into pyruvic acid before it enters the mitochondrion.

• The process of cellular respiration involves several steps and components.
• One of these components is the respiratory chain.
• This chain is also referred to as the electron transport system.
• The correct answer is A, "Electron transport system".

Short Hint: The respiratory chain is also known as the electron transport system.

• Lactic acid fermentation is a biochemical process by which cells convert pyruvate, produced by glycolysis, into lactic acid.
• In humans, this process occurs in muscle cells.
• It especially occurs during intense activity when the oxygen supply is not sufficient.
• Therefore, the correct answer is B, "Muscle cells".

Short Hint: Lactic acid fermentation occurs in human muscle cells, particularly during intense activity.

• The creation of ATP, or adenosine triphosphate, involves various processes within a cell.
• When this synthesis happens in the presence of oxygen, it takes on a specific name.
• This process is known as oxidative phosphorylation.
• Therefore, the correct answer is B, "Oxidative phosphorylation".

Short Hint: The synthesis of ATP in the presence of oxygen is referred to as oxidative phosphorylation.

• Cyclic phosphorylation is a process that occurs when cells are low on ATP.
• It uses an alternative path to meet the requirement of ATP.
• However, it does not produce NADP or O2.
• Thus, the correct answer is B, "ATP".

• The Calvin Cycle is a key part of photosynthesis.
• Unlike some processes, it is not dependent on light and can occur in both light and dark conditions.
• Therefore, it's described as a light-independent cycle.
• The correct answer is B, "Light-independent cycle".

Short Hint: The Calvin cycle, capable of functioning in both light and dark conditions, is a light-independent cycle.

• Chlorophyll is a crucial pigment involved in the process of photosynthesis.
• It has a specific structure, with one part being flat, square, and capable of absorbing light.
• This part is also hydrophilic, meaning it attracts water.
• This part of chlorophyll is called the head. So the correct answer is A, "Head".

Short Hint: The hydrophilic, light-absorbing portion of chlorophyll is known as the head.

• Chlorophyll, the green pigment in plants, has different structural elements.
• One of those elements is non-polar, meaning it does not mix well with water.
• This non-polar component is known as phytol.
• Thus, the correct answer is B, "Phytol".

Short Hint: Phytol is the term used to refer to the non-polar part of chlorophyll.

• There are different variants of chlorophyll, the pigment responsible for photosynthesis.
• Among these variants, one is more prevalent than the others.
• This most abundant variant is chlorophyll a.
• Hence, the correct answer is A, "Chlorophyll a".

Short Hint: The most abundant chlorophyll type across most photosynthetic organisms is chlorophyll a.