Microbiology with Diseases by Taxonomy Chapter 5 Answers

Microbiology with Diseases by Taxonomy Chapter 5 Answers

Microbiology with Diseases by Taxonomy Answers

Microbiology with Diseases by Taxonomy Chapter 5 Answers 1CM
The terms given in the question are:

• 2 ATP (2)
• 34 ATP
• Chemiosmosis
• Electron transport chain
• Glycolysis
• Krebs cycle
• Oxidative phosphorylation
• Substrate level phosphorylation (2)
• Synthesis of acetyl coA

Glycolysis is the major metabolic pathway of the living organisms. Energy is produced in this pathway in the form of ATP (adenosine triphosphate). 2 ATPs are produced at the end of the glycolysis and the final product is pyruvate. The pyruvate then enters into the TCA (tricarboxylic cycle) or Krebs cycle by forming acetyl CoA. In TCA cycle reducing agents like NADH (Nicotinamide adenine dinucleotide) and FADH2 (flavin adenine dinucleotide) are produced. They are used in electron transport chain to synthesize ATP by oxidative phosphorylation.
The concept map which includes all the above terms and describes aerobic respiration is given below:

Microbiology with Diseases by Taxonomy Chapter 5 Answers 1CT
An organism that uses glycolysis and TCA (tricarboxylic acid) cycle or Kreb’s cycle might also need the pentose phosphate pathway.
The pentose phosphate pathway can be used for the reduction of coenzymes and for specific by-products, which are needed for anabolic pathways. These by-products are the precursors in anabolic reactions. The reduced coenzymes are also useful in anabolic reactions.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 1FB
Cyclic photophosphorylation:
Explanation:

1. In cyclic photophosphorylation, the electrons from the reaction center pass through electron transport chain and back to the reaction center.
2. The reaction center of chlorophyll is present in a photosystem. Light energy from the sun excites the electrons in the reaction center.
3. These electrons then pass on to an acceptor molecule. The electrons pass through an electron transport chain and back to the chlorophyll molecule.
4. In non-cyclic photophosphorylation, the electrons do not return to the place of origin.

The cyclic photophosphorylation process is shown in the diagram below:

Thus, the final electron acceptor in cyclic photophosphorylation is the original reaction center, chlorophyll.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 1M
Substrate-level phosphorylation:
Explanation
Substrate-level phosphorylation occurs when energy from a compound containing phosphate reacts with ADP (adenosine triphosphate) to form ATP (adenosine triphosphate). The direct transfer of a phosphate group between two substrates from ATP is known as substrate-level phosphorylation.
Similarly, the process of substrate-level phosphorylation can be seen in the glycolysis pathway. The formation of pyruvate in the last step of glycolysis is a substrate-level phosphorylation. The phosphate from phosphoenol pyruvate is transferred to an ADP molecule to form ATP.
Thus, substrate-level phosphorylation occurs in Krebs cycle of the mitochondria. This process is a fast source of ATP in the cell that is independent of respiration and external electron acceptors.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 1MC
Both anabolism and catabolism:
Anabolism is the synthesis of complex molecules or large molecules from simpler, smaller molecules. The process of catabolism is the breakdown of large molecules into smaller ones. In an amphibolic pathway, both these processes occur.
Hence, the option (b) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 1SA
Enzymes are necessary for anabolic reactions to occur in living organisms.
Anabolic reactions are those reactions in which the synthesis of complex and bigger molecules takes place. Most of the reactions cannot occur in the absence of the specific enzyme. Sometimes these enzymes act as catalysts.
A catalyst is a molecule, which reduces the activation energy of a reaction. Many reactions have high activation energy and cannot occur in the absence of a catalyst. The conditions of the cell are not suitable for the high activation energies of some reactions. When the activation energy is lowered, the reactions can easily occur in the cell.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 2CT
Bacterial fermentation causes milk to have a sour taste.
The fermentation of milk is done by bacteria, which change the lactose present in the milk to lactic acid. The lactic acid formed is responsible for the sour taste of the fermented milk.
Lactose is a disaccharide consisting of glucose and galactose. Both these sugars are broken down by the process of glycolysis. The product of glycolysis is pyruvic acid. This pyruvic acid is then converted to lactic acid by bacteria.
The bacteria which carry out fermentation are:

• Lactobacillus
• Lactococcus
• Leuconostoc

Microbiology with Diseases by Taxonomy Chapter 5 Answers 2FB
In the pathway of glycolysis, there is a preparatory phase and a pay-off phase. In the preparatory phase, 2 ATP molecules are used up. In the pay-off phase, 4 ATP molecules are generated. Thus a net gain of 2 ATP molecules is seen.
The pathway of glycolysis can occur in the anaerobic or the aerobic stages.
The pathway of glycolysis is shown below:

Microbiology with Diseases by Taxonomy Chapter 5 Answers 2M
Formation of ATP (adenosine triphosphate) involves formation of oxidative through reduction of coenzymes in the electron transport chain.
In the process of oxidative phosphorylation, the transfer of electrons occurs from electron donors to electron acceptors. This is mainly seen in the electron transport chain. When electrons are transferred, energy is produced. The energy is used in the transport of protons across the membrane. The transport of protons causes the formation of ATP.
This process produces superoxide and hydrogen peroxide, which can damage the cell. The process of oxidative phosphorylation is shown in the diagram:

Microbiology with Diseases by Taxonomy Chapter 5 Answers 2MC
Both anabolism and catabolism:
Anabolism is the synthesis of complex molecules or large molecules from simpler, smaller molecules. The process of catabolism is the breakdown of large molecules into smaller ones. In an amphibolic pathway, both these processes occur.
Hence, the option (b) is incorrect.
Catabolism only:
The process of catabolism is the breakdown of large molecules into smaller ones. A good example would be the process of glycogenolysis. In this process, the large molecule of glycogen is broken down into small molecules of glucose. Catabolism does not include synthesis reactions.
Hence, the option (c) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 2SA
Organisms can control the rate of metabolic activities in the cells by many ways.
One way is through enzymes. Enzymes are needed for almost every reaction, which proceeds in the cell. After the required reaction is complete, the cell destroys the enzyme or deactivates it. In this way, the enzyme cannot work unless activated or synthesized again.
Another method of control is by regulators. A good example would be the lac operon. In the lac operon, there are many genes, which are under the control of a single regulator gene. Only when the cell requires these enzymes, the genes are turned on. Otherwise they are turned off.
The cell also contains inhibitors, which are specific for some substrates. These bind to the enzymes and inhibit their action. In this way, the control of some reactions occurs.
Some other methods of control are:

• Changes in membrane potential
• Modifying substrates
• Phosphorylation

Microbiology with Diseases by Taxonomy Chapter 5 Answers 3CT
The protozoa Giardia intestinalis and Entamoeba histolytica live in the colon of mammals. Since these lack mitochondria, they do not have the pathways of aerobic respiration.
The pathways under aerobic respiration are:

• Glycolysis
• Krebs cycle
• Electron transport chain

In these organisms, which lack mitochondria, only the glycolysis pathway occurs. Since glycolysis can occur in the absence or presence of mitochondria, it occurs in these protozoa. The glycolysis pathway occurs in the cytosol while the Krebs cycle and the electron transport chain cannot occur in the absence of mitochondria.
The energy yield in these organisms would be much lower than the 38 ATP obtained in aerobic respiration. The pyruvic acid obtained at the end of glycolysis cannot be fully catabolized to obtain energy. These protozoa have a net gain of 2 ATP molecules in the pathway of glycolysis.
Hence, the organisms have a much lower energy yield.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 3FB
The initial catabolism of glucose occurs by glycolysis and/or the pentose phosphate and Entner Doudoroff pathways.
In the pentose phosphate pathway, the ATP (adenosine triphosphate) produced in this cycle is less than the 38 ATP molecules produced during glycolysis. This pathway produces two metabolites of ribose-5-phosphate and erythrose-4-phosphate, which are needed for the synthesis of nucleotides and amino acids.
The Entner Doudoroff pathway is an alternative to glycolysis in some organisms. This pathway gives lesser ATP than 38 ATP. A few bacteria like Pseudomonas aeruginosa and Enterococcus faecalis use the Entner Doudoroff pathway for the catabolism of glucose.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 3M
Carbohydrate catabolism begins with glycolysis:
Explanation
The catabolism of carbohydrates is the process where carbohydrates are broken down to produce ATP (adenosine triphosphate). Most of the carbohydrates are usually converted into glucose. The first step of glucose breakdown is the process of glycolysis.
In the process of glycolysis, glucose is converted into pyruvate. In this pathway, ATP molecules are produced. After glycolysis, the Krebs cycle, and the electron transport chain complete the total carbohydrate metabolism.
A diagram of glycolysis is given below:

Microbiology with Diseases by Taxonomy Chapter 5 Answers 3MC
Both anabolism and catabolism:
Anabolism is the synthesis of complex molecules or large molecules from simpler, smaller molecules. The process of catabolism is the breakdown of large molecules into smaller ones. In an amphibolic pathway, both these processes occur and energy is synthesized, and used up.
Hence, this option is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 3SA
Non-competitive inhibitor affect whole enzymatic pathway, at a single allosteric site:
Explanation
At an active site, competitive inhibitor binds, while a non-competitive inhibitor binds other than the active site. When a non-competitive inhibitor binds to an allosteric site, the active site of the enzyme is altered. A non-competitive inhibitor at a single allosteric site affects a whole pathway of enzymatic reactions.
Additionally, alteration of enzyme active site prevents the binding of the substrate. When the substrate prevents from binding to the enzyme, the reaction is inhibited. The inhibited reaction is a part of whole pathway; hence, remaining reactions do not take place. If the inhibited reaction is an important reaction in the pathway, the whole pathway comes to a stop.
In this way, the binding of a noncompetitive inhibitor at an allosteric site affects a pathway.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 4CT
A facultative anaerobe is grown in the same medium, but under different conditions. One culture is grown in the presence of oxygen while the second culture is grown in the absence of oxygen.
Of the two cultures, the culture exposed to air will have more cells at the end of the week.
As the species is a facultative anaerobe, it grows better in the presence of oxygen rather in the absence of oxygen.
The presence of oxygen enables the process of aerobic respiration in the culture. When aerobic respiration occurs, a high yield of 38 ATP (adenosine triphosphate) molecules is produced. Hence, this culture shows a higher rate of growth and division.
In the absence of oxygen, only glycolysis occurs. Glycolysis is followed by the process of fermentation occurs, which gives a much lower yield than 38 ATP. Hence, the culture under anaerobic conditions shows a lower rate of growth and division.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 4FB
The Krebs cycle or citric acid cycle is a series of eight chemical reactions used by all aerobic organisms to generate energy. This metabolic pathway involves oxidation of acetate derived from mainly carbohydrates, proteins, fats finally into carbon dioxide.
This pathway involved in the catabolism of acetyl-CoA and produces eight molecules of NADH (Nicotinamide adenine dinucleotide) and two molecules of FADH₂ (flavin adenine dinucleotide).
Hence, the correct option is Krebs cycle.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 4M
Saturation occurs when all active sites on enzyme molecules are filled:
Explanation
Enzymes have active sites, which bind to substrate molecules. When a substrate molecule binds to the active site of an enzyme, chemical reaction occurs that results in the formation of an intermediate complex. The complex consists of the enzyme and substrate.

Similarly, when all the active sites of an enzyme are filled with substrate molecules, it is known as saturation. On further addition of substrate molecules, the status of saturation does not change. Thus, on addition of enzyme molecules the situation of saturation is chnaged.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 4MC
Both anabolism and catabolism:
Anabolism is the synthesis of complex molecules or large molecules from simpler, smaller molecules. The process of catabolism is the breakdown of large molecules into smaller ones. In an amphibolic pathway, both these processes occur where energy is synthesized and also spent.
Hence, this option is incorrect.
Catabolism only:
The process of catabolism is the breakdown of large molecules into smaller ones. A good example would be the process of glycogenolysis. In this process, the large molecule of glycogen is broken down into small molecules of glucose. The process of catabolism is usually exergonic.
Hence, this option is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 4SA
The mechanism of negative feedback with respect to enzyme action:
Explanation
Negative feedback is also called feedback inhibition. The final product of a pathway is the inhibitor of previous reactions. Usually, the first enzyme of the pathway is inhibited by the final product. The negative feedback occurs only when the final product accumulates. The type of inhibition seen is usually allosteric inhibition.
The mechanism is shown in the following diagram:

A good example of the feedback inhibition is shown below:

Microbiology with Diseases by Taxonomy Chapter 5 Answers 5CT
The complete oxidation of a fat molecule with three chains containing 12 carbons each will give 305 ATP (adenosine triphosphate) molecules.
The break-up of these 305 ATP molecules is shown below:

• The glycerol moiety of the fatty acid enters the glycolysis pathway. The ATP gained from glycolysis is 2 ATP molecules.
• In the Krebs cycle, 4 NADH (Nicotinamide adenine dinucleotide) molecules are formed, which give a total of 12 ATP molecules since one NADH molecule gives 3 ATP molecules.
• In ??oxidation, each 12-carbon chain produces 5 NADH and 5 FADH₂ (flavin adenine dinucleotide) molecules.
• Since one NADH molecule gives 3 ATP molecules and one FADH₂ molecule gives 2 ATP molecules, the total number of ATP molecules from one chain would be 25. Three chains would give 75 ATP molecules.
• The acetyl CoA produced after ??oxidation is oxidized. Each chain produces 6 acetyl CoA molecules. Upon oxidation of one acetyl CoA molecule, 1 ATP molecule, 3 NADH molecules and 1 FADH molecule is produced.
• This gives a total of 12 ATP molecules per acetyl CoA molecule. Since 6 acetyl CoA molecules are produced per chain, the total number of ATP molecules per chain would be 72 ATP molecules.
• Three chains would give 216 ATP molecules.The total number of ATP molecules would be 2+12+75+216 , which gives 305 ATP molecules.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 5FB
The final electron acceptor in aerobic respiration is oxygen.
Aerobic respiration requires oxygen to generate energy in the form of adenosine triphosphate (ATP). Here, oxygen acts as final electron acceptor. Aerobic respiration is the method of pyruvate breakdown, which is generated from glycolysis and needs the entry of that pyruvate into mitochondria in order to be oxidized by the citric acid cycle or Krebs cycle.
The Krebs cycle is a series of eight chemical reactions used by all aerobic organisms to generate energy. This metabolic pathway involves oxidation of acetate derived from mainly carbohydrates, proteins, fats finally into carbon dioxide.
This pathway involved in the catabolism of acetyl-CoA and produces eight molecules of NADH (Nicotinamide adenine dinucleotide) and two molecules of FADH₂ (flavin adenine dinucleotide).
The NADH and FADH₂ produced in Krebs cycle undergo substrate level phosphorylation to generate ATP.
Hence, the correct answer is oxygen.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 5MC
Anabolism only involves the production of cell membrane constituents.
Anabolism only:
Anabolism is the synthesis of complex molecules or large molecules from simpler, smaller molecules. The cell membrane is also a complex molecule composed of many smaller molecules. The process of anabolism requires energy.
Hence, the correct answer is option (a) anabolic only.
Both anabolism and catabolism:
Anabolism is the synthesis of complex molecules or large molecules from simpler, smaller molecules. The process of catabolism is the breakdown of large molecules into smaller ones. In an amphibolic pathway, both these processes occur. The synthesis of the cell membrane does not come under the category of an amphibolic pathway.
Hence, the option (b) is incorrect.
Catabolism only:
The process of catabolism is the breakdown of large molecules into smaller ones. A good example would be the process of glycogenolysis. In this process, the large molecule of glycogen is broken down into small molecules of glucose. The synthesis of the cell membrane is not the breakdown of large molecules into smaller ones. Hence, the option (c) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 5SA
The metabolic pathways that allow facultative anaerobes to live under aerobic or anaerobic conditions:
Explanation
Facultative anaerobes exist under aerobic or anaerobic conditions. The metabolic pathways allow them to exist in the absence of oxygen by fermentation pathways.
The two common fermentation pathways are:

• Pyruvic acid to lactic acid
• Pyruvic acid to ethanol

Pyruvic acid is reduced to lactic acid with the help of NADH (reduced nicotinamide adenine dinucleotide), catalyzed by lactic dehydrogenase. NADH donates a proton to become NAD⁺ (oxidized nicotinamide adenine dinucleotide).

Initially, pyruvic acid is decarboxylated to form acetaldehyde. Acetaldehyde is reduced to form alcohol.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 6CT
A fever over 40⁰C is often life threatening in terms of its effect on the metabolism of the body.
Metabolism in any individual is mainly dependent on enzymes. Enzymes are usually proteins, which have a specific temperature range in which they can work best. Enzymes usually have an optimum temperature at which they work best.
So, if the temperature of the body rises above 40⁰C, most of the enzymes become inactive. Since they are proteins, the enzymes may also become denatured. When proteins become denatured, they cannot perform their normal function.
The folding or the conformation of the protein is very important to the function of the protein. Once the conformation of the protein is lost through denaturation, the function of the protein is also lost.
If most of the enzymes of the body stop functioning, the metabolism in the body will also eventually stop. This is why high fevers are life threatening.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 6FB
Three common inorganic electron acceptors in anaerobic respiration are NO₃^–, SO₄^2- and CO₃^2-.
In the process of anaerobic respiration, inorganic molecules are used as the final electron acceptor. Anaerobic respiration is mainly used by prokaryotes living in an anaerobic environment. The electron transport chain is also used in anaerobic respiration, but the final acceptors differ. The final acceptors are nitrate (NO₃^–), sulphate (SO₄^2-) and carbonate ions (CO₃^2-).
These electron acceptors used in anaerobic respiration have smaller reduction potentials when compared to oxygen. Hence, the yield of ATP (adenosine triphosphate) is lower than in aerobic respiration. The types of phosphorylation seen in anaerobic respiration are substrate level phosphorylation and oxidative phosphorylation.
These three electron acceptors are used as an alternative to oxygen.
Hence, the correct options are nitrate, sulphate, carbonate ions.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 6MC
Both anabolism and catabolism:
Anabolism is the synthesis of complex molecules or large molecules from simpler, smaller molecules. The process of catabolism is the breakdown of large molecules into smaller ones. In an amphibolic pathway, both catabolism and anabolism take place.
Hence, the option (b) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 6SA
Oxidation of molecule in the absence of oxygen:
Explanation
Oxidation of a molecule can occur in the absence of oxygen mediated by the process of fermentation.

1. Oxidation of a molecule occurs in the presence of oxygen, the products liberated are carbon dioxide and water.
2. Oxidation occurs in the absence of oxygen by the process of fermentation, the products liberated are organic waste products.

The process of fermentation is incomplete or partial oxidation of a molecule. Since, fermentation occurs in the absence of oxygen, the final electron acceptor cannot be oxygen in the electron transport chain. Organic molecules from the cell are used as the final electron acceptors instead of oxygen.
Additionally, the major advantage of fermentation is the production of ATP (adenosine triphosphate) in the absence of oxygen. The number of ATP molecules produced is less compared to aerobic oxidation. Thus, only 2 ATP molecules are produced.
The two common fermentation pathways are:

• Pyruvic acid to lactic acid
• Pyruvic acid to ethanol

Pyruvic acid is reduced to lactic acid with the help of NADH (reduced nicotinamide adenine nucleotide). NADH donates a proton to become NAD⁺ (oxidized nicotinamide adenine nucleotide). Pyruvic acid is decarboxylated to form acetaldehyde, which is reduced to form alcohol.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 7CT
Maximum number of ATP molecules generated by fat oxidation in bacteria:
Explanation
Cyanide is a toxic substance, which blocks cytochrome a₃. The cytochrome is present as the terminal electron acceptor before oxygen.
The diagram shown below is the action of cytochrome in ATP generation:

Similarly, due to the presence of cyanide, the electrons cannot pass from cytochrome a3 to oxygen. It results in the failure of the electron transport chain. The rest of the chain is not affected, but the functioning is stopped. ATP synthesis does not occur in presence of cyanide. The process of aerobic respiration does not occur and tissues depend on high supply of ATP to fail.
Additionally, organs like the heart and the central nervous system depend on a continuous supply of ATP. Such organs will immediately fail in the presence of cyanide. The redox state of ubiquinone in the presence of cyanide would be reduced in the presence of cyanide.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 7FB
Chemolithotrophs acquire electrons from inorganic compounds.
A lithotroph is an organism that uses inorganic substances as a source of energy. Chemolithotrophs are organisms that obtain their energy from the oxidation of inorganic reduced compounds.
In these organisms, the electron donors are oxidized in the cell. These electrons are later used to produce ATP (adenosine triphosphate). Most of these organisms can fix carbon dioxide through the Calvin cycle.
These organisms mainly grow in areas, where there is an abundance of inorganic compounds. The energy gained from these substances is less and this indicates that a large amount of substrate is needed to gain the energy required for the processes of the cell.
Hence, the correct answer is inorganic.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 7MC
Both anabolism and catabolism includes metabolism.
Both anabolism and catabolism:
Anabolism is the synthesis of complex molecules, or large molecules from simpler, smaller molecules. The process of catabolism is the breakdown of large molecules into smaller ones. In an amphibolic pathway, both these processes occur and energy is synthesized, and used up.
Hence, the correct answer is option (b).
Anabolism only:
Anabolism is the synthesis of complex molecules, or large molecules from simpler, smaller molecules. A good example would be glycogen, which consists of many glucose molecules. The process of anabolism is usually endergonic. The process of metabolism does not involve only anabolism, but catabolism also.
Hence, this option is incorrect.
Catabolism only:
The process of catabolism is the breakdown of large molecules into smaller ones. A good example would be the process of glycogenolysis. In this process, the large molecule of glycogen is broken down into small molecules of glucose. The process of catabolism is exergonic, and releases energy. The process of metabolism does not involve only anabolism, but catabolism also.
Hence, this option is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 7SA
Four groups of microorganisms that are photosynthetic are:
Heliobacteria:
Heliobacteria belongs to gram positive bacteria. The bacteria carry out photosynthesis in an oxygenic condition. The components used are present in the cytoplasmic membrane. An example is Heliobacterium.
Cyanobacteria:
Cyanobacteria are gram negative bacteria. The bacteria carry out photosynthesis in oxygenic conditions. These organisms are considered to be chloroplasts ancestors. An example is Oscillatoria.
Purple bacteria:
A purple bacterium is gram negative bacteria. The bacteria are used in the invaginations of the cytoplasmic membrane called lamellae. An example is Rhodobacteria.
Green bacteria:
Green bacteria are further divided into green sulfur and green non sulfur bacteria. All these bacteria are gram negative and carry out anoxygenic photosynthesis. These organisms contain chlorosomes. An example is Chlorobium.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 8CT
Similarities between photophosphorylation and oxidative phosphorylation:
Explanation
The similarity between photophosphorylation and oxidative phosphorylation is that both the processes pump protons across a membrane using energy. The concentration gradient, which develops is used to drive the synthesis of ATP (adenosine triphosphate).
Moreover, the synthesis of ATP usually occurs through membrane-bound enzyme ATP synthase. The source of energy is the difference between both processes. In photophosphorylation, light is the source of energy. The process is cyclic that works as long as light is present.
Thus, in the process of oxidative phosphorylation, the source of energy is obtained from the breakdown of biomolecules. The catabolism of molecules gives energy, which is then redirected into the process of oxidative phosphorylation.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 8FB
The enzyme of hydrolase adds a water molecule into the reaction. With the addition of the water molecule, the substrate is cleaved.
The enzyme isomerase plays a part of rearrangement of atoms in the molecule. A good example is triose phosphate Isomerase seen in the pathway of glycolysis.
The enzymes of ligase and polymerase play a role of joining two molecules together. A good example would be the process of replication of DNA (deoxyribonucleic acid), where both these enzymes are used.
The enzyme transferase moves functional groups from one substrate to another. A good example would be the transamination reactions.
The enzyme oxidoreductase plays a role in the oxidation and reduction of substances.
The enzyme lyase is usually used to cleave large molecules into smaller ones.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 8MC
Redox reactions are involved in the transfer of energy, transfer of electrons, oxidation, and reduction.
Redox reactions involve the processes of oxidation and reduction as seen in the name. They also involve the transfer of energy, and the transfer of electrons. The gain of electrons in reduction, and the loss of electrons in oxidation occur.
Hence, the correct option is (d) are involved in all of the above.
Transfer energy:
Redox reactions transfer energy from one molecule to another. In the process of oxidation and reduction, energy from one process is transferred to the other process. Redox reactions are also involved in the transfer of electrons, oxidation, and reduction reactions.
Hence, the option (a) is incorrect.
Transfer electrons:
Redox reactions transfer electrons from one molecule to another. In the process of oxidation and reduction, transfer of electrons occurs. Redox reactions are also involved in the transfer of energy, oxidation, and reduction reactions.
Hence, the option (b) is incorrect.
Involve oxidation and reduction:
In the process of reduction, electrons are gained while in the process of oxidation, electrons are lost. Both these processes occur in redox reactions.
Hence, the option (c) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 8SA
Oxygen is taken in to give carbon dioxide:
Explanation
During breathing oxygen is taken in to give carbon dioxide, the process is mediated by cellular respiration. Humans are aerobic organisms that need oxygen to breathe. The life cannot exist in the absence of oxygen for a long time.
Additionally, the oxygen we breathe is the final acceptor of the electron transport chain. The final product of the electron transport chain is water and carbon dioxide. Since, carbon dioxide is toxic to the body, released out through lungs.
Furthermore, oxygen is required for many processes of the body. Processes like cellular respiration or the catabolism of glucose need oxygen to undergo complete oxidation. In the presence of oxygen, one glucose molecule gives 38 molecules of ATP (adenosine triphosphate).
The diagram of the electron transport chain is shown below with the final acceptor as oxygen:

Microbiology with Diseases by Taxonomy Chapter 5 Answers 9CT
Pathogenic species of Haemophilus requires NAD⁺ and heme for growth:
Explanation
The pathogenic species of Haemophilus requires NAD⁺ (oxidized nicotinamide adenine dinucleotide) and heme for growth. The growth factors are needed from the host and help in growth of the pathogen. Moreover, NAD⁺ is an oxidizing agent, which accepts electrons from other molecules to reduce NADH (reduced nicotinamide adenine dinucleotide). The molecule then acts as a reducing agent to give electrons to other molecules. Hence, NAD⁺ is needed for electron transfer reactions.
Additionally, heme is required for heme containing molecules like cytochromes that are essential in the electron transport chain. Since, these molecules are essential in normal functioning of the pathogen, the pathogen obtains from surroundings.
Thus, the cytochromes have a heme group, which surrounds a metal ion. The metal ion present is iron, which keeps changing between reduced and oxidized states.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 9FB
The use of a proton motive force to generate ATP (adenosine triphosphate) is chemiosmosis.
In the process of chemiosmosis, the ions flow down their concentration gradient through an enzyme called ATP synthase. When ions flow through this enzyme ATP molecules are produced.
The process of chemiosmosis uses the potential energy of the electrochemical gradient present across membranes. This energy is used in the phosphorylation of ADP (adenosine diphosphate) to ATP.
In cells, the energy released in the electron transport chain is used to transport protons across a membrane. The transport of these protons across the membrane causes a proton gradient. This proton gradient generates proton motive force.
Hence, the correct answer is chemiosmosis.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 9MC

• Reduction is a chemical reaction that involves addition of hydrogen, or removal of oxygen from a compound. This reaction is opposite of oxidation. Therefore, a reduced molecule has gained electrons.
  Hence, the correct option is (a) has gained electrons.
• In the process of reduction, gain in electrons occurs. This gain causes the charge on the molecule to become negatively charged, but not positively charged. Only when a molecule loses electrons, it becomes positively charged. Since an electron is a negatively charged molecule, its gain makes molecules more negative.
  Hence, the option (b) is incorrect.
• In the process of oxidation, electrons are lost by the molecule. But the process of reduction involves the gain of electrons.
  Hence, the option (c) is incorrect.
• An electron donor is a molecule that donates an electron to another molecule. This molecule, which gains electrons, is reduced while the molecule donating the molecule is oxidized. A reduced molecule cannot be an electron donor.
  Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 9SA
Algae and cyanobacteria liberate oxygen and take in carbon dioxide:
Explanation
Cyanobacteria and alga take in carbon dioxide and give off oxygen as these organisms are photosynthetic. Moreover, cyanobacteria are gram negative bacteria, which carry out oxygenic photosynthesis. The organisms are considered to be the ancestors of chloroplasts. An example is Oscillatoria.
Similarly, the organisms like plants are capable in the process of photosynthesis. The organism like plants takes carbon dioxide and give off oxygen. Cyanobacteria do not have any special organelles like chloroplasts to help in photosynthesis. The cell membrane has invaginations, which function in photosynthesis.
Additionally, algae have plastids in their cells, which function in photosynthesis by taking in carbon dioxide and giving off oxygen. In contrast, some algae are in a symbiotic relationship with fungi, called as lichens.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 10CT
Comparison and contractions between aerobic respiration, anaerobic respiration, and fermentation:
Explanation

1. Aerobic respiration, fermentation and anaerobic respiration are processes, which occur in the cell. These processes produce ATP (adenosine triphosphate) from biomolecules. The process that produce highest yield of ATP is aerobic respiration.
2. In aerobic respiration, the three pathways that incorporate are glycolysis, Krebs cycle, and electron transport chain. The terminal electron acceptor in the electron transport chain is oxygen. The total yield of ATP seen in aerobic respiration is 38 ATP.
3. In anaerobic respiration, the terminal electron acceptor is organic molecules like nitrates and sulfates, but not oxygen. The yield of ATP is much lower than that of aerobic respiration.

In the process of electron transport chain the process of fermentation does not occur. ATP molecules are produced by substrate-level phosphorylation. The energy yield of ATP is much lower.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 10FB
The main coenzymes that carry electrons in catabolic pathways are NAD⁺ and FAD.
The electron carriers, which play a role in the electron transport chain, are NAD⁺ (Nicotinamide adenine dinucleotide) and FAD (Flavin adenine dinucleotide). When NAD⁺ goes through the electron transport chain 3 ATP (adenosine triphosphate) molecules are produced. When FAD goes through the electron transport chain 2 ATP molecules are produced.
These are produced as intermediates of the Krebs cycle and glycolysis. All these molecules combine to produce the 38 ATP molecules.
Hence, the correct answers are NAD⁺ and FAD.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 10MC
Activation energy does not require nutrients and water. Activation energy is the energy required for a reaction to occur. This activation energy is usually high for many reactions. It can be lowered by the presence of catalysts.
Hence, the option (b) is incorrect.
Activation energy does not result in the movement of molecules. Activation energy is the energy required for a reaction to occur. It can be lowered by the presence of catalysts. Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 10SA
Carbon atoms of sugar catabolized, by Escherichia coli :
Explanation
The carbon atoms in sugar are catabolized by E. coli that is seen in the products of acids like formic acid, acetic acid, succinic acid, and lactic acid.
E. coli ferments sugar molecules to produce mixed acids. It can be shown as:

In E. coli, the first step is glycolysis. After the process of glycolysis, the pyruvate formed is converted into lactate, formate, succinate, ethanol, acetate, carbon dioxide, and water.

1. Lactate is formed from pyruvate by the enzyme lactate dehydrogenase. Acetyl CoA and formate are formed from pyruvate by the enzyme pyruvate formate lyase. Carbon dioxide and hydrogen are formed from formate catalyzed by formate hydrogen lyase.
2. Acetic acid is formed from acetyl CoA with the help of two enzymes phosphate acetyl transferase, and acetate kinase. Ethanol is formed from acetyl CoA with the enzyme alcohol dehydrogenase.
3. Succinate is formed from phosphoenol pyruvate. The enzyme fumarate reductase is used along with ATP synthase in a series of steps to form succinate.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 11CT
Metabolism of methanogenic prokaryotes in ocean sediments:
Explanation
Methanogenic prokaryotes are the organisms that live in ocean sediments. The scientists have estimated that about one-third of the biomass is present on Earth. Since, the organisms live in ocean sediments, they are usually anaerobic organisms. Moreover, the organisms do not depend on oxygen for their metabolic pathways.
Additionally, the organisms use hydrogen and carbon dioxide for their metabolic purposes. The carbon acts as a terminal electron acceptor instead of oxygen. The methanogenic prokaryotes produce methane as by-product, during metabolism and produce energy. Thus, the energy produced is used in different needs of the cell and responsible in degradation of organic matter.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 11MC
The catalytic activity of many enzymes is dependent on cofactors. Cofactors are either small organic molecules (called coenzymes), or metal ions. Coenzymes are freely diffusing organic molecules functions along with enzymes to carryout metabolic reactions. These coenzymes combine with the apoenzyme to form the holoenzyme.
Hence, the correct option is (d) are organic cofactors.
Coenzymes are not apoenzymes. Apoenzymes are the parts of enzymes that require cofactors. The combination of apoenzyme and cofactor make up the holoenzyme. Cofactors are also called coenzymes, but they cannot be apoenzymes.
Hence, the option (a) is incorrect.
Coenzymes are not proteins. They are organic cofactors. These cofactors can be inorganic ions. These cofactors combine with the apoenzyme to form the holoenzyme.
Hence, the option (b) is incorrect.
Coenzymes are not inorganic cofactors. They are organic cofactors. These cofactors combine with the apoenzyme to form the holoenzyme.
Hence, the option (c) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 11SA
Yeast cells make alcohol and cause bread to rise, due to fermentation:
Explanation
When yeast ferments the bread, it breaks down glucose into two molecules of alcohol and two molecules of carbon dioxide. This process is used in the process of making bread and in alcohol production.

Similarly, in the process of making bread, both the products are present in the bread. Since, the glucose is broken down by the yeast the products of alcohol and carbon dioxide is present in the bread. The alcohol is baked out of the bread, while the carbon dioxide is responsible for the rise in bread.
In the process of alcohol synthesis, the carbon dioxide formed from the reaction is released out of the alcohol. Sometimes, the carbon dioxide is used for carbonating specific beverages. The carbon dioxide is left inside the alcohol.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 12CT
Bacterium regulates the control in metabolic activities of the cell without a brain:
Explanation
The regulation seen in a bacterial cell can be controlled even in the absence of a brain. A variety of mechanisms are present, which plays an important role in regulation. Some of the mechanisms are:

• Inhibition in concentration of reactants and products.
• Presence of repressor molecules
• Presence of inhibitor or activator molecules

A good example would be feedback inhibition in which the product of a pathway inhibits the first enzyme of the pathway. This occurs when the product accumulates beyond a certain limit.
Therefore, phosphorylation and dephosphorylation are processes by which molecules are activated and deactivated. Another method is degeneration of proteins after their function is over.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 12MC
Hence, the correct option is (d).
Ribozymes are not proteins and they do not help in the production of ribosomes. They are enzymes, which process the synthesis of RNA (ribonucleic acid) molecules.
Hence, the option (a) is incorrect.
Ribozymes are composed of nucleic acids, but act enzymes. They do not produce ribose sugars, but process the synthesis of RNA molecules.
Hence, the option (b) is incorrect.
Ribozymes are enzymes, but do not store enzymes. Their main function is to process RNA molecules.
Hence, the option (c) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 12SA
Significant production of ATP in prokaryotic and eukaryotic cells:
Explanation

1. The most significant production of ATP (adenosine triphosphate) in prokaryotic cells is the cell membrane. The cell membrane of prokaryotes has all the necessary enzymes for ATP production and does not need a special organelle in this process.
2. The most significant production of ATP in eukaryotic cells is mitochondrion. The mitochondrion is a special organelle seen in eukaryotes. This organelle has its own DNA.

The parts of a mitochondrion are: Matrix, Cristae space, Outer membrane, Inner membrane, and Inter-membrane space
A diagram showing the structure of the mitochondrion is shown below:

Microbiology with Diseases by Taxonomy Chapter 5 Answers 13CT
When a bacterium uses the process of ??oxidation to break down a molecule of arachidic acid containing 20 carbons, the number of acetyl CoA molecules generated would be 10.
Each acetyl CoA molecule consists of 2 carbon atoms.

• When a fatty acid consisting of 20 carbon atoms undergoes the process of ??oxidation for the first round, it is broken down into one molecule of acetyl CoA molecule and an 18 carbon fatty acid.
• In the second round of ??oxidation, 18 carbons are broken down into one molecule of acetyl CoA and 16 carbons. In third round of ??oxidation, 16 carbons are broken into one molecule of acetyl CoA and 14 carbons.
• In the fourth round of ??oxidation, 14 carbons are broken down into one molecule of acetyl Co A molecule and 12 carbons. In the fifth round of ??oxidation, 12 carbons are broken down into one acetyl CoA molecule and 10 carbons.
• In the sixth round of ??oxidation, 10 carbons are broken down into one molecule of acetyl CoA and 8 carbons. In the seventh round of ??oxidation, 8 carbons are broken down into one molecule of acetyl CoA molecule and 6 carbons.
• In the eighth round of ??oxidation, 6 carbons are broken down into one molecule of acetyl CoA and 4 carbon fatty acid. In the ninth round of ??oxidation, the 4 carbon fatty acid is broken down into two molecules of acetyl CoA.

Thus, takes 9 ??oxidation cycles for 20 carbon fatty acid and broken down into acetyl CoA molecules.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 13MC
Ubiquinone does not affect the function of enzymes.
Ubiquinone:
The molecule of ubiquinone does not affect the function of enzymes. Ubiquinone is a carrier molecule in the transport of electrons in the electron transport chain. The electron transport chain does not affect the function of enzymes.
Hence, the correct option is (a) ubiquinone.
Substrate concentration:
The concentration of substrates in the medium affects the function of enzymes. When the substrate concentration is high, it binds to the active site of the enzyme and the product is formed. When the substrate concentration is lower than normal, the function of the enzyme is affected.
Hence, the option (b) is incorrect.
Temperature:
The temperature of the medium affects the function of the enzyme. Enzymes work best at their optimum temperature. Many enzymes have a temperature range at which they can function. If this range is crossed, the enzymes cease to function. Hence, the option (c) is incorrect.
Competitive inhibitors:
The presence of inhibitors also affects the function of the enzyme. In the presence of the substrate, the enzyme works perfectly. But, in the presence of competitive inhibitors, which compete with the substrate for the active site, the function of the enzyme is reduced.
Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 13SA
Vitamins are very much essential for the metabolism of microorganims. Microbes need the vitamins in trace amount. Most of the vitamins function as coenzymes. Coenzymes are organic molecules, which are covalently bound to the enzymes. Many coenzymes are synthesized from B vitamins.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 14CT

• Some desert rodents like Kangaroo rats that are able to live their entire lives without drinking any water. Kangaroo rats can survive on a diet of dry seeds and obtain all the moisture they need from their metabolic water. Their bodies are well adapted to the desert systems, which are highly efficient in conserving water.
• Kangaroo rats get all the water from their metabolic water, which is produced when their bodies break down food. They do not have sweat gland and do not sweat, preventing them from losing water due to evaporation, further more they have special oil glands on their backs that excretes oil to coat the fur , once again aiding in retaining water.
• Kangaroo rats have highly efficient kidneys that produce much more concentrated urine than most other mammals. Kidneys filter waste materials, water, and chemicals out of the body.
• Most of water is reabsorbed to the blood in the part of nephron called Loop of Henle and tis is found to be much longer in kangaroo rats than in other mammals.
• This extra-long Loop of Henle help in the absorption of more water, resulting in highly concentrated urine and prevent the water loss in Kangaroo rats.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 14MC
Hence, the correct option is (a) removal of hydrogen ions and electrons.
Removal of oxygen:
The removal of oxygen atoms does not indicate the process of oxidation. The process of oxidation is the donation of electrons or removal of electrons. In bacteria, hydrogen ions are transferred along with electrons in the process of oxidation. Hence, the option (b) is incorrect.
Addition of electrons and hydrogen ions:
The process of reduction is the addition of electrons. The removal of electrons occurs in the process of oxidation. In bacteria, hydrogen ions are transferred along with electrons in the process of oxidation.
Hence, the option (c) is incorrect.
Addition of hydrogen ions:
It does not occur in the process of oxidation. The removal of electrons occurs in the process of oxidation. In bacteria, hydrogen ions are transferred along with electrons in the process of oxidation.
Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 14SA
The cellular regulatory mechanism seen in this bacterium, which would explain the behavior, is the lac operon.
The lac operon is a set of genes which catabolize lactose. This operon is regulated by a regulator gene.
These genes are switched on only in the absence of glucose and presence of lactose. In the presence of glucose these genes are switched off. The various components of the lac operon are described below:
The regulator gene produces a repressor molecule, which binds to the operator region. This binding to the operator region inhibits the binding of RNA (ribonucleic acid) polymerase to the promoter region. This prevents transcription of the three structural genes.
In the absence of glucose and presence of lactose, a lactose molecule binds to the repressor and alters its conformation. This alteration prevents its binding to the operator region. This lets RNA polymerase bind to the promoter region and transcribe the three genes.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 15CT
Fatty acids contain even number of carbon atoms:
Explanation
Fatty acids usually have an even number of carbon atoms. This is because fatty acids are synthesized by adding two carbon atoms at a time. The catabolism of fatty acid occurs by cleavage of two carbons at a time. The two carbons are released as acetyl CoA molecules.
Synthesis:
In the synthesis of a fatty acid, a molecule of malonyl CoA is joined with a molecule of acetyl CoA. The malonyl CoA molecule is a three carbon compound, while acetyl CoA is a two carbon compound. Moreover, one carbon is lost as carbon dioxide leaving a 4-carbon compound. Furthermore, addition is made by malonyl CoA to add two carbon atoms to the chain and lose one carbon atom.
Catabolism:
In the process of ??oxidation, in every cycle, a two carbon fragment is cleaved from the fatty acid in the form of an acetyl CoA molecule. The ??oxidation cycle continues till whole fatty acid is broken down into acetyl CoA molecules.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 15MC
The fermentation of one glucose molecule under anaerobic conditions does not give a net gain of 4 ATP molecules. The process of fermentation of glucose gives 2 ATP molecules. Under aerobic conditions, one glucose molecule gives 38 molecules of ATP through the processes of glycolysis, Krebs cycle and the electron transport chain.
Hence, the option (b) is incorrect.
The fermentation of one glucose molecule under anaerobic conditions does not give a net gain of 38 ATP molecules. The process of fermentation of glucose gives 2 ATP molecules. Under aerobic conditions only, one glucose molecule gives 38 molecules of ATP.
Hence, the option (c) is incorrect.
The fermentation of one glucose molecule under anaerobic conditions does not give a net gain of 0 ATP molecules. The process of fermentation of glucose gives 2 ATP molecules. Under aerobic conditions only, one glucose molecule gives 38 molecules of ATP.
Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 15SA
Amination is the process of addition of an amino group to a molecule. Transamination is the transfer of an amino group from one molecule to another.
Amination is the reverse process of deamination. Deamination is the removal of an amino group from a molecule. One example of amination is:
Formation of aspartic acid from oxaloacetic acid:
An example of transamination would be the transfer of one amino acid to another. In this reaction the enzyme transaminase acts along with pyridoxal phosphate. The amino group from glutamic acid is transferred to oxaloacetic acid. The removal of an amino group from glutamic acid causes the formation of a-ketoglutaric acid.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 16CT
A molecule of glucose is catabolized by Embden-Meyerhof glycolysis and Krebs cycle. The number of molecules ATP, NADH, and FADH2 produced are, as follows:

• Glycolysis:
  • 2 ATP
  • 2 NADH
• Two pyruvate molecules to acetyl CoA:
  • 2 NADH
• Krebs cycle: ( for two pyruvate molecules)
  • 6 NADH
  • 2 ATP/GTP
  • 2 FADH₂

When a molecule of glucose is catabolized via the Entner Doudoroff pathway, and the number of molecules ATP, NADH, FADH2 produced are:

• Glycolysis:
  • 1 ATP
  • 1 NADH
  • 1 NADPH
• Two pyruvate molecules to acetyl CoA:
  • 2 NADH
• Krebs cycle: ( for two pyruvate molecules)
  • 6 NADH
  • 2 ATP/GTP
  • 2 FADH₂

Microbiology with Diseases by Taxonomy Chapter 5 Answers 16MC

• The complete oxidation of one glucose molecule under aerobic conditions gives a net gain of 38 ATP (adenosine triphosphate) molecules. Under aerobic conditions, one glucose molecule gives 38 molecules of ATP through the processes of glycolysis, Krebs cycle and the electron transport chain.
  Hence, the correct option is (c) 38.
• The complete oxidation of one glucose molecule under aerobic conditions does not give the net gain of 2 ATP molecules. Under aerobic conditions, one glucose molecule gives 38 molecules of ATP through the processes of glycolysis, Krebs cycle and the electron transport chain.
  Hence, the option (a) is incorrect.
• The complete oxidation of one glucose molecule under aerobic conditions does not give a net gain of 4 ATP molecules. Under aerobic conditions, one glucose molecule gives 38 molecules of ATP through the processes of glycolysis, Krebs cycle and the electron transport chain.
  Hence, the option (b) is incorrect.
• The complete oxidation of one glucose molecule under aerobic conditions does not give a net gain of 0 ATP molecules. Under aerobic conditions only, one glucose molecule gives 38 molecules of ATP.
  Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 16SA
The given diagram depicts the most important metabolic pathways like glycolysis, Kreb’s cycle, respiration, fermentation, and electron transport chain. The diagram with the appropriate labeled parts and the net gain of ATP (adenosine triphosphate) synthesized per stage is shown:

Here,
ATP= adenosine triphosphate,
NADH= Nicotinamide adenine dinucleotide,
FADH₂= flavin adenine dinucleotide.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 17MC
a) Its products are sometimes used to determine the presence of Pseudomonas :
A few bacteria like Pseudomonas aeruginosa and Enterococcus faecalis use the Entner Doudoroff pathway for the catabolism of glucose. Since, this pathway is seen only in a few bacteria, it is used as a criterion for distinguishing these bacteria from other microorganisms. Hence, the option (b) is incorrect.
b) It is a pathway of chemical reactions that catabolizes glucose:
The Entner Doudoroff pathway is a pathway which catabolizes glucose in some organisms. It is an alternative pathway for the catabolism or breakdown of glucose. This pathway gives lesser ATP than 38 ATP. Hence, this option is incorrect. Hence, the option (c) is incorrect.
c) It is an alternative pathway to glycolysis:
The Entner Doudoroff pathway is an substitute pathway to glycolysis. It does not give a high yield of 38 ATP after the catabolism of glucose. But, this pathway is seen in some organisms like Pseudomonas aeruginosa and Enterococcus faecalis. Hence, the option (d) is incorrect.
d) It is a series of reactions that synthesizes glucose:
The Entner Doudoroff pathway does not synthesize glucose. It is an alternative pathway for the catabolism or breakdown of glucose. This pathway gives lesser ATP than 38 ATP. Gluconeogenesis is a process in which glucose is synthesized from molecules like amino acids and fatty acids.
Hence, the correct option is (a) it is a series of reactions that synthesizes glucose.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 18MC
a) Krebs cycle:
The Krebs cycle is a light-dependent cycle. Glycolysis, Krebs cycle, and Electron transport chain are the light dependent cycles. When glucose is broken down using these three pathways, the net gain of 38 ATP molecules is achieved. The Krebs cycle does not have any light-independent reactions. Hence, the option (a) is incorrect.
b) Entner-Doudoroff pathway:
The Entner-Doudoroff pathway is not a light-independent pathway. It is an alternative pathway to glycolysis in some organisms. Since, glycolysis is a light-dependent pathway, Entner-Doudoroff pathway is also a light-dependent pathway. Hence, the option (b) is incorrect.
c) Pentose phosphate pathway:
The pentose phosphate pathway is not a pathway, which is independent of light. It is dependent on light. The ATP produced in this cycle is less than the 38 ATP molecules produced during glycolysis. This pathway produces two metabolites of ribose-5-phosphate and erythrose-4-phosphate, which is needed for the synthesis of nucleotides and amino acids. Hence, the option (d) is incorrect.
d) Calvin-Benson cycle:
The Calvin cycle is a light-independent cycle. In this pathway, carbon fixation occurs. The molecule of carbon dioxide is reduced to form glucose. This pathway uses ATP (adenosine triphosphate) and NADPH (reduced nicotinamide adenine dinucleotide phosphate) produced by the light-dependent reactions. Glyceraldehyde-3-phosphate is produced and enters a cycle that is reversal of glycolysis to generate glucose.
Hence, the correct option is (c) Calvin benson cycle.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 19MC
a) Amphibolic:
An amphibolic pathway is one in the reaction can proceed towards either catabolism or anabolism. The pathway of glycolysis is not an amphibolic pathway. Glycolysis is a catabolic pathway, which deals with the breakdown of glucose molecules. In catabolic pathway big and complex molecules are broken down to smaller and simpler molecules. Hence, the option (b) is incorrect.
b) Anabolic:
An anabolic pathway is one in which the synthesis of big and complex molecules occurs. Small and simple molecules are used to make the bigger and complex molecules. Glycolysis is a catabolic pathway, which deals with the breakdown of glucose molecules. Hence, the option (c) is incorrect.
c) Cyclical:
A cyclical pathway is one in which the ending product is used as a precursor. A good example is the Krebs cycle. In this cycle, acetyl CoA is the starting molecule and the product at the end is acetyl CoA. The intermediates of the cycle are important. Glycolysis is a pathway and not a cycle. Hence, the option (d) is incorrect.
e) Catabolic:
In catabolic pathway big and complex molecules are broken down to smaller, simpler molecules. In the glycolysis pathway, a molecule of glucose is broken down to produce pyruvate. In addition to pyruvate, ATP molecules are also formed which give energy to the cell.
Hence, the correct option is (a) catabolic.

Microbiology with Diseases by Taxonomy Chapter 5 Answers 20MC
a) In the use of oxygen:
Oxygen cannot be the difference between anaerobic respiration and anaerobic fermentation. Since, both the processes are anaerobic oxygen does not come into the process. Hence, the option (a) is incorrect.
b) That the former requires breathing:
Breathing comes under aerobic respiration, but not under anaerobic respiration. The difference between anaerobic respiration and anaerobic fermentation is that respiration requires breathing. Hence, the option (b) is incorrect.
c) Fermentation only produces alcohol:
The process of anaerobic fermentation produces alcohol and other by-products are also produced. A net gain of 2 ATP (adenosine triphosphate) molecules is produced. This is not the major difference between anaerobic respiration and anaerobic fermentation. Hence, the option (d) is incorrect.
d) The latter uses organic molecules within the cell as final electron acceptors:
A major difference between anaerobic respiration and anaerobic fermentation is the latter uses organic molecules within the cell as final electron acceptors. The process of anaerobic fermentation uses organic molecules present in the cell as electron acceptors. In the process of anaerobic respiration, inorganic molecules are used as the final electron acceptor.
Hence, the correct option is (c) the latter uses organic molecules within the cell as final electron acceptors.