Microbiology with Diseases by Taxonomy Chapter 15 Answers

Microbiology with Diseases by Taxonomy Chapter 15 Answers

Microbiology with Diseases by Taxonomy Answers

Microbiology with Diseases by Taxonomy Chapter 15 Answers 1CM
The terms given in the question are given below:

1. Adherence
2. Chemotactic factors
3. Chemotaxis
4. Dendritic cells
5. Elimination
6. Eosinophils
7. Exocytosis
8. Ingestion
9. Killing
10. Lysosome
11. Macrophages
12. Neutrophils
13. Opsonins
14. Phagolysosome
15. Phagosome

The concept map showing the process of phagocytosis is given below:

Microbiology with Diseases by Taxonomy Chapter 15 Answers 1CT
Mr. J received a burn on his arm while handling chemicals. The chemicals reacted with the skin to give painful, red and swollen lesions. Mr. C suffered a cut on his foot which became infected. He too suffered the same symptoms of redness and swelling along with pain.
In Mr. J’s case, the inflammation seen is the body’s response to the damage done by chemicals. In Mr. C’s case, the inflammation seen is due to the response of the body to microbial invasion. The similarity is that both are experiencing damaged tissues but the agent of damage differs in each case.
No, Mr. C should not take the same medicine that Mr. J used. When the body fights against microbes, it stores the information in memory cells. This helps the body to fight faster in the event of a second attack by the same microbe. Since inflammation is a response of the body, it should not be suppressed too much. This would be suppressing the immune system of the body.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 1L
The labeled parts of the diagram showing the different events in the process of phagocytosis are:

In the process of phagocytosis, we see 6 steps:

• Chemotaxis
• Adherence
• Ingestion
• Maturation
• Killing
• Elimination

In the step of chemotaxis, the phagocyte is attracted towards the microbe. In the step of adherence, the phagocytic cell binds to chemicals on the surface of the microbe. In the step of ingestion, the microbe is engulfed by the phagocyte. In the step of maturation, fusion with a lysosome occurs. In the step of killing, the microbe is degraded by the enzymes in the lysosome. In the step of elimination, the remnants of the digestion are eliminated by the process of exocytosis.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 1M1
The term “inflammation” matches with the phrase “second line of defense.” The second line of defense consists of cells, antimicrobial chemicals, and processes like inflammation and fever.
It is a nonspecific response to the damage of tissues. The damage in tissues can be due to a variety of reasons like heat, cuts, chemicals, and pathogens.
There are two types of inflammation: Acute and Chronic.
Acute inflammation is short lived and results in the removal of the cause of the inflammation. In chronic inflammation, damage in tissues occurs, which can lead to the death of the tissues. Both acute and chronic inflammation shows the same symptoms of redness, heat, pain and swelling.
Hence, the correct option is B. second line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 1M2
The term “Goblet cell” matches with the phrase “secretes mucus.” These cells come under the first line of defense of the body.
Goblet cells are present amidst the cells of the mucous membrane. These cells secrete sticky mucus which helps to trap pathogens. The goblet cells are epithelial cells which secrete mucus. These cells are usually found amid the epithelial lining of the respiratory and the intestinal tracts. These cells are not macrophages or phagocytes.
In some locations, ciliated cells are present in addition to goblet cells. These cilia help to push out the pathogens trapped in the mucus.Hence, the correct option is J. secretes mucus.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 1MC
The goblet cells are epithelial cells which secrete mucin. These cells are usually found amid the epithelial lining of the respiratory and the intestinal tracts. These cells are not macrophages or phagocytes. They are also not present in the epidermis. The phagocytes of the epidermis are known as dendritic cells. Hence, the option (b) is incorrect.
Alveolar macrophages are present in the lungs. These are not wandering macrophages, but fixed in the same tissue. They are not present in the epidermis. The phagocytes present in the epidermis are known as dendritic cells. Hence, the option (c) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 1MTF
The statement given is “The surface cells of the epidermis of the skin are alive.” The above statement is false.
The outer layer of the skin, the epidermis consists of dead cells. The epidermis consists of multiple layers of cells which are tightly packed. The topmost layer consists of cells which are dead and dry. These cells are shed continuously, which do not allow most microorganisms to settle on the skin.
The lowest layer of the epidermis contains cells which continually divide, pushing new cell towards the surface. These new cells are pushed till they reach the surface. By the time they reach the surface, they die and are later shed as skin flakes. Hence, the surface layer of the epidermis contains dead and not living cells.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 1SA
In order for a pathogen to cause disease, the three things which must happen are:

1. Gain access into the body:
   Pathogens must be able to gain access into the body of the host. This can be done by entering through some portal of entry. It can also be established by penetrating the skin of the host. They either use the existing routes of entry or create new routes.
2. Attach to host cells:
   Attachment of pathogens to host cells is known as adherence. Unless a pathogen attaches to a host cell, it cannot infect that particular host cell. The pathogen usually has some proteins and markers on the surface which attaches to the surface of the host cell.
3. Escape the defense mechanisms of the body and cause damage:
   The human body has three levels of defense. The first line of defense consists of the skin, mucous membranes, lacrimal apparatus, normal flora, and antimicrobial peptides. The second line of defense consists of the cells of the blood, phagocytosis, nonphagocytic killing, nonspecific chemical defenses like the complement system, and other processes like inflammation and fever. The third line of defense is adaptive immunity which is specific for each pathogen.

After escaping all these defenses, the pathogen has to be able to inflict damage on the host cell to be able to cause infection.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 2CT
When a person does not produce C3 and C5 proteins, the following changes occur:
Absence of C3:
Since C3 is a vital part of the complement cascade. The activation of C3 produces the effects of opsonization and inflammation. This leads to the formation of C5 convertase which produces the effect of inflammation. All these effects are absent if C3 is missing. The final formation of the membrane attack complex does not occur. Hence, the complement system does not function properly.
Absence of C5:
The absence of C5 leads to the absence of the C5 convertase complex. The complement cascade system works perfectly till this step. The effects of inflammation and opsonization are seen since C3 is produced. But the formation of the membrane attack complex does not occur.
When both the C3 and C5 proteins are not produced, then the complement system does not function properly. Since C3 and C5 are the vital and major components of the complement cascade, the absence of these proteins leads to improper functioning of the complement system.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 2M1
The term “monocytes” matches with the phrase “second line of defense.” The second line of defense consists of cells like monocytes, antimicrobial chemicals, and processes.
Monocytes are a member of the white blood cells in the blood. They are also a part of the innate immune system. When monocytes mature, they give rise to macrophages and dendritic cells. In the innate immunity, both macrophages and dendritic cells play an important role to protect the body from the various pathogens.
Both dendritic cells and macrophages play a role in phagocytosis. Hence, monocytes are a part of the second line of defense. Since macrophages are nonspecific phagocytic cells, they form the second line of defense of the body. Hence, the correct option is B. second line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 2M2
The term “lysozyme” matches with the phrase “breaks bonds in bacterial cell wall.” Lysozyme comes under the first line of defense.
Lysozyme is an enzyme present in the dermis of the skin. Lysozyme is an enzyme which destroys the cell wall of bacteria. It breaks down the bonding between the building blocks of the cell wall. Cells without a cell wall are susceptible and are killed quite easily.
The mucous in the nasal epithelium also contains lysozyme. The enzyme is present as the first line of defense to lyse any pathogens which enter the nose. Some microbes can be resistant to the action of lysozyme. Hence, the correct option is E. breaks bonds in bacterial cell wall.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 2MC
Mucus secreting membranes are found in the urinary system, respiratory passages, and digestive cavity.

• Mucus secreting membranes are found in the urinary system, which includes the urethra and the urinary tracts. Mucus membranes are moist and have two layers. The topmost layer is the epithelium while the deeper layer is the connective tissue. The mucus membrane is a common portal for most pathogens. Hence, the option (a) is correct.
• The digestive cavity is also lined by mucus membranes. Since mucus membranes are an easy portal for microbes, the topmost cells are continually shed. This removes the organisms attached to the topmost layer of the mucus membranes. Dendritic cells are present below the mucus epithelium and phagocytize pathogens. Hence, the option (b) is correct.
• The respiratory passages are also lined by mucus membranes. In the mucus membranes of the trachea, goblet cells are present. These cells produce a sticky substance called mucin. The respiratory passages also contain ciliated cells which contain cilia. These cilia are useful in trapping pathogens and pushing them out of the body. Hence, the option (c) is correct.
• The urinary system, the respiratory passages and the digestive tracts all possess mucus membranes.
  Hence, the correct option is (d) all of the above.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 2MTF
The given statement “The surface cells of mucous membranes are alive” is true. These mucous membranes cover all body cavities which open to the outside. The mucous membrane is also part of the first line of defense of the body. It acts nonspecifically against pathogens.
Mucous layers have two layers, one is the epithelium and the other is a deeper connective tissue. The surface cells of the mucous layers are alive and play a role in the processes of diffusion of gases and nutrients.
One way in which pathogens are kept from entering the body, is the tight packing of epithelial cells along with constant, shedding of the cells of the top layer. When the topmost cells are shed, the pathogens attached are also shed.
Some mucous membranes, especially those in the respiratory tract contain cilia which help to trap pathogens in the waves of cilia. The pathogens are later propelled out of the body. Goblet cells are also present amidst the cilia which secrete a sticky substance called mucus which also traps pathogens.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 2SA
A phagocyte knows it is in contact with a pathogen instead of another body cell in the following way:
Chemotaxis:
The secretions from microbial cells and the components of the cells attract phagocytes. These chemical secretions attract phagocytes to the microbial cells in the process of chemotaxis. In the case of phagocytosis, positive chemotaxis is seen where phagocytes are drawn towards the microbial cells.
Adherence:
The process of attachment to the microbial cell is known as adherence. This attachment is achieved when the surface proteins of the microbial cell attach to the proteins on the surface of the phagocytes. Phagocytes bind to complementary chemicals like glycoproteins which are found on microbial cells. These microbe-specific glycoproteins are not found on the surface of host cells.
These are the two ways in which a phagocyte can differentiate between a normal host cell and a microbial cell. This ability to differentiate helps to protect the body’s own cells from the process of phagocytosis. If phagocytes did not have this ability to differentiate, all the host cells would have been phagocytized.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 3CT
Mrs. M has diabetes for 40 years. The small blood vessels in her feet and toes have been damaged due to the disease. Since her blood vessels are damaged, the circulation in her feet and toes is impaired.
Since her circulation is impaired, this indicates that the blood flow to her legs is less. Mrs. M is quite susceptible to infections in her legs and toes since she cannot receive adequate immune cells due to lack of circulation.
Cells like phagocytes and the proteins of the complement cascade are all transported through the blood. When the circulation of blood cells is low, these cells also cannot reach the legs on time in the event of any injury.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 3M1
The term “lactoferrin” matches with the phrase “second line of defense.” The second line of defense consists of cells and proteins in the blood, antimicrobial chemicals, and processes.
The protein lactoferrin is a member of the transferrin proteins. It transfers iron molecules into the cells and controls the free iron levels in the blood. Apart from this function, it also has antibacterial and antiviral activities.
As it controls the free iron levels in the blood, it does not allow microbes to absorb this iron for their own use. It prevents the microbial cells from stealing the iron from the body.
Hence, the correct option is B. second line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 3M2
The term “stem cell” matches with the phrase “generative cell with many types of offspring.”
Stem cells are those cells which can give rise to any cell as a progeny. In the chapter of innate immunity, we see the role of stem cells in the first line of defense of the body. The mucous membranes of the body are a first line of defense.
The mucous membrane has a topmost moist layer which is an easy portal for microbes. But, the cells of the top layer of the mucous membranes are continuously shed. This is due to stem cell division.
When the topmost layer of cells is shed, the pathogens attached are also shed. This removes pathogens from the body. Hence, the correct option is G. generative cell with many types of offspring.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 3MC

• The complement system does involve serum proteins, which play a role in nonspecific defense of the body. A group of proteins can work in three pathways to kill the invading pathogen. The end result of the action of the proteins of the complement system is the cell lysis of the pathogens. This defense is called a nonspecific defense because there is no specificity between the pathogens and the serum proteins of the complement system. The pathogens are recognized and killed. Hence, this option is correct.
• The production of antigens and antibodies does not involve the complement system. Antibodies are produced by B cells, which are produced by lymphocytes. Self-antigens are produced in the body as proteins in specific cells of the body. Hence, the option (a) is incorrect.
• Leukocytes are the cells which can distinguish foreign cells from body cells. The complement system is not a set of genes, which can differentiate between foreign cells and body cells. The complement system is a set of serum proteins, which are involved in nonspecific defense of the body. Hence, the option (c) is incorrect.
• Phagocytes are the cells, which remove the undigested remnants of microbes. The undigested parts are removed by the process of exocytosis. The complement system does not participate in the elimination of undigested remnants of microbes. The complement system is a set of serum proteins, which are involved in nonspecific defense of the body. Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 3MTF
The given statement “Wandering macrophages experience diapedesis” is true. Macrophages are phagocytic cells, which function as the second line of defense after the pathogen has entered the body. The first line of defense sometimes fails and thus the body has its second line of nonspecific defense cells.
Some macrophages in the body are fixed, while others are wandering macrophages which travel in the blood. The fixed macrophages have different names based on their specific location. The macrophages of the lungs are called alveolar macrophages, while the macrophages of the brain and spinal cord are called microglia.
Wandering macrophages are the ones which experience the process of diapedesis. When a cut occurs in the skin, many pathogens enter the skin layers. When this happens, the macrophages in the blood move out of the blood stream and into the tissues. The movement of these macrophages past the cells of the blood vessel and into the tissues is known as diapedesis.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 3SA
The three characteristics of the epidermis that make it intolerable for most microorganisms are:

1. Tightly packed cells:
   The epidermis consists of many layers of tightly packed cells. This acts as a physical barrier to most microbes. Unless the skin has a gash or cut or a puncture, most microbes cannot cross the first defense of the skin.
2. Regular sloughing off of the topmost layer:
   The topmost layer of the epidermis is regularly sloughed off. The topmost layer consists of dead and dry cells which are sloughed off. The pathogens attached to these cells are also pushed off along with the dead cells. This is another method in which the skin regularly keeps the epidermis free from pathogens.
3. Phagocytic cells called dendritic cells:
   The epidermis contains phagocytic cells called dendritic cells. These cells have slender fingers which surround cells forming a sort of network. These dendritic cells can phagocytize pathogens nonspecifically. They also play a role in adaptive immunity where specific response to specific pathogen is seen.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 4CT
The chart of a patient shows that the percentage of eosinophils in his blood is 8% of the total WBC. Eosinophils are usually elevated during worm infestations or allergies. Normally, we would suspect that the main reason for the elevated number of eosinophils is an allergy.
The suspicions of the reason for the eosinophilia would definitely change with the knowledge that the patient has been living in Africa for the past three years as an anthropologist. The patient had gone to Africa to study the anthropology of an African tribe.
Hence, we can safely assume that the eosinophilia seen is due to helminth or worm infestations. The normal percentage of eosinophils is 2-4%.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 4M1
The term “fever” matches with the phrase “second line of defense.” The second line of defense consists of cells, antimicrobial chemicals, and processes like inflammation and fever.
Fever is usually caused due to pyrogens. These pyrogens are chemicals, which reset the thermostat in the hypothalamus to a higher temperature. Pyrogens can include toxins released from bacteria, cytoplasmic contents of bacterial cells released after lysis, and chemicals released by phagocytes.
The hypothalamus is a part of the brain which controls the temperature of the body. Fever is a symptom seen when the body temperature rises above 37 degrees centigrade. Fever has side effects like malaise, tiredness, and body aches.
The symptoms of fever remain as long as pyrogens are present. When the infection starts to come under control, the level of pyrogens reduces and the body temperature is slowly reset to normal.
Hence, the correct option is B. second line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 4M2
The term “dendritic cell” matches with the phrase “devours pathogens in epidermis.” Dendritic cells come under the first line of defense.
Dendritic cells are present in the epidermal layer of the skin. These are phagocytic cells which are formed by monocytes. Dendritic cells have slender processes which extend among cells. These slender processes form a continuous network which traps pathogens.
These cells are nonspecific for pathogens and form the first line of defense. Dendritic cells also play a role in adaptive immunity.
Hence, the correct option is D. devours pathogens in epidermis.

• Microbiology with Diseases by Taxonomy Chapter 15 Answers 4MC
  The cleavage of C5 to form C9 is seen in all the three pathways as a common step. The protein C5 is cleaved into C5a and C5b. the C9 protein is a part of the membrane attack complex, which causes lysis of the microbial cells. Hence, the option (b) is incorrect.
• The step of binding to mannose on the microbial cell wall is seen in the lectin pathway but not in the alternate pathway. Lectins are chemicals, which bind to the mannose on the surface of the microbial cell wall. When lectins bind to mannose, it triggers a complement cascade by the cleavage of C2 and C4 proteins. Hence, the option (c) is incorrect.
• The recognition of antigens bound to specific antibodies is seen in the classical pathway but not in the alternate pathway. In the classical pathway, the proteins C1, C2 and C4 act to form a complement cascade. Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 4MTF
The given statement “Monocytes are immature macrophages” is true. Monocytes are large leukocytes which are agranular. The nuclei in monocytes are slightly lobed in appearance. Monocytes are immature macrophages; they mature into macrophages after they leave the blood.
Monocytes are a member of the white blood cells in the blood. They are also a part of the innate immune system. When monocytes mature, they give rise to macrophages and dendritic cells. In the innate immune system, both the dendritic cells and macrophages have an important role to fight against the various unprocessed antigens.
Both these cells play a role in phagocytosis. Hence, monocytes are a part of the second line of defense. Since macrophages are nonspecific phagocytic cells, they form the second line of defense of the body.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 4SA
The role of Toll-like receptors in the response of innate immunity can be described below:
These Toll-like receptors or TLRs are produced by phagocytic cells and are present as integral membrane proteins. These TLRs trigger the immune response of the body to the presence of molecules usually present in pathogens and absent in humans.
Examples of these foreign molecules include peptidoglycan, flagellin, double stranded RNA, single stranded RNA, and other molecules.
The TLRs recognize these molecules and initiate a number of immune responses. A few of them include:

• Apoptosis
• Secretion of interferons
• Production of chemical stimulants

The recognition of foreign particles by TLRs is a very vital part of the innate immune response. If these TLRs do not recognize these foreign particles, the body would soon be filled with such molecules.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 5CT
There are two types of agranulocytes in the blood. One is a monocyte and the other is a lymphocyte. Monocytes constitute about 3-8% of the total WBC and are large cells with slightly lobed nuclei. Lymphocytes constitute about 20-25% of the total WBC and are smaller than monocytes.
Monocytes are phagocytic and also give rise to phagocytic cells called dendritic cells and macrophages. Lymphocytes do not phagocytize directly. They are involved in the adaptive immune response of the body.
J. wondered why the two agranulocytes were different in function. The facts of hematopoiesis which would help her are that monocytes develop from myeloid stem cells while lymphocytes develop from lymphoid stem cells. The word agranulocyte is used to indicate that these cells do not possess any kind of granules in the cytoplasm.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 5M1
The term “dendritic cells” matches with the phrase “first line of defense.” The first line of defense consists of skin, mucous membranes, lacrimal apparatus, normal microbiota and others like antimicrobial peptides.
Dendritic cells are present in the epidermal layer of the skin. These are phagocytic cells which are formed by monocytes. Dendritic cells have slender processes which extend among cells. These slender processes form a continuous network which traps pathogens.
These cells are nonspecific for pathogens and form the first line of defense. Dendritic cells also play a role in adaptive immunity.
Hence, the correct option is A. first line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 5M2
The term “cell from sebaceous gland” matches with the phrase “secretes sebum.” The secretion of sebum is the first line of defense of the body.
The skin contains sebaceous glands which secrete a substance called sebum. Sebum is an oily substance which keeps the skin oily and smooth. The sebum contains fatty acids which keep the pH of the skin at 5.5. This pH is not suitable for the growth of many microbes.
Along with sebaceous glands, the skin also contains sweat glands which secrete antimicrobial peptides and salt. These secretions also form the first line of defense along with sebum secretions.
Hence, the correct option is C. secretes sebum.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 5MC

• The multiplication of viruses is not related to the complement system. When a virus or a bacterium enters the body, it is recognized as a foreign particle. After going through the complement pathway, the virus and the cell in which it is multiplying are both destroyed. Hence, the option (a) is incorrect.
• Interferons are molecules, which are produced by viral infected cells. These molecules serve to warn the surrounding cells and protect them from viral invasion. The presence of complement is not needed for the synthesis and release of interferon. Hence, the option (b) is incorrect.
• If the complement system is not inactivated, the process of protein synthesis would not be inhibited. Since the complement system is not needed for the synthesis of protein in the cell, protein synthesis is not hindered in any way. Hence, the option (c) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 5MTF
The given statement “Lymphocytes are large agranulocytes” is false. Lymphocytes are the smallest leukocytes in the blood while monocytes are the largest leukocytes. The nuclei in lymphocytes almost fill the whole cell, while the nuclei in monocytes are distinct and slightly lobed. Monocytes are a member of the white blood cells in the blood.
Monocytes are immature macrophages as they mature into macrophages after they leave the blood. They are also a part of the innate immune system. When monocytes mature, they give rise to macrophages and dendritic cells. Both the macrophages and dendritic cells play an important role in the innate immune response of the body.
The agranulocytes consist of lymphocytes and monocytes while the granulocytes consist of basophils, eosinophils and neutrophils.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 5SA
The classical complement cascade pathway from C1 to the MAC can be described in the following way:
The classical pathway is activated by the presence of Antigen-antibody complexes. The C1 protein is present in the serum and has high affinity for Antigen-antibody complexes.
When the C1 protein encounters an Antigen-antibody complex, it binds to it and a conformational change occurs in C1. Then proteolytic cleavage occurs in C1 which cleaves all the four polypeptide chains.
Two subunits of C1 then cleave the C4 protein into C4a and C4b. The fragment of C4a is released while the fragment of C4b binds to the Antigen-antibody complex-C1. The fragment C4b binds to C2 and the binding stimulates C1 to cleave C2 into C2a and C2b.
The C2b fragment is released while the C2a fragment binds to the complex of Antigen-antibody complex-C1-C4b.
This complex is known as C3 convertase. This helps to cleave the C3 protein into C3a and C3b. The fragment of C3a is released and induces inflammation. The fragment of C3b attaches to the complex to form the C5 convertase.
The C5 convertase cleaves C5 into C5a and C5b. The fragment of C5b then attaches to the complex while the fragment of C5a is released causing inflammation.
The other proteins of C6, C7, C8, and C9 then attach to C5b while the other fragments dissociate. The membrane attack complex is then formed which leads to lysis of the microbial cell.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 6CT
A patient is not able to produce the serum proteins C8 and C9. These two serum proteins play a vital role in the complement cascade system. These two proteins are needed for the formation of the membrane attack complex.
If the patient is not able to synthesize C8 and C9 proteins, he cannot fight infections by Gram negative and Gram positive bacteria. Hence, the infections by these bacteria would go unchecked even in the presence of the other serum proteins of the complement system. Only the inflammatory response by C3 proteins would be seen.
If the C3 and C5 fragments were also inactivated, this would lead to a total collapse of the complement cascade.
The activation of C3 produces the effects of opsonization and inflammation. This leads to the formation of C5 convertase which produces the effect of inflammation. All these effects are absent if C3 is missing. The absence of C5 leads to the absence of the C5 convertase complex. But the formation of the membrane attack complex does not occur.
The absence of the membrane attack complex leads to loss of function of the complement system.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 6M1
The term “alpha interferon” matches with the phrase “second line of defense.”
Interferons are protein molecules secreted by cells which have been attacked by viruses. The different types of interferons are:

• Alpha
• Beta
• gamma

The source of these alpha interferons is the epithelium along with leucocytes. This type of interferon stimulates the production antiviral proteins. These interferons are seen early in the infection as the inducing agent is the virus. These interferons are not present late in an infection.
Beta interferons are also like alpha interferons. They also trigger antiviral proteins and are released within hours of infection by viruses. Gamma interferons are produced late in the infection. They are produced some days after the infection by viruses. These interferons activate macrophages and neutrophils which phagocytize the pathogens.
Hence, the correct option is B. second line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 6M2
The term “bone marrow stem cell” matches with the phrase “develops into formed elements of blood.”
The stem cells in the bone marrow have the capability of forming any kind of cell. The stem cells present in the bone marrow produce three types of cells:

• Erythrocytes
• Platelets
• Leukocytes

Erythrocytes are the red blood cells which carry oxygen and carbon dioxide. Platelets are the cells involved in the process of blood clotting. Leukocytes are the white blood cells which are mainly used in defense of the body.
The leukocytes are further divided into granulocytes and agranulocytes. All these cells are called the formed elements of the blood. Hence, the correct option is H. develops into formed elements of blood.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 6MC
The source of the beta interferons is the fibroblast. These interferons are also stimulated by the presence of viruses just like alpha interferon. These molecules induce the formation of antiviral proteins. These interferons are not present late in an infection. Hence, the option (b) is incorrect.
The interferon delta was discovered in pigs. These molecules are produced by the trophoblast during implantation. This interferon is not involved in the immune response like other interferons. It is produced during the process of implantation of the egg in the uterus. Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 6MTF
The given statement “Phagocytes exhibit chemotaxis towards a pathogen” is true. Phagocytes are cells, which take part in the process of phagocytosis. They engulf pathogens and any other foreign material.
In the process of chemotaxis, a cell moves towards (or) away from the stimulus. If the cell moves towards the stimulus, it is called positive chemotaxis. If the cell moves away from the stimulus, it is called negative chemotaxis.
In phagocytes, positive chemotaxis is seen when the phagocytes produce pseudopodia and crawls towards the microbes at the site of infection. The microbial components and secretions act as chemotactic factors, along with the damaged tissues and cells of the host.
Leukocytes which are already present at the site of infection also release chemokines which also serve to attract phagocytic cells towards the microbial cells.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 6SA
The comparison between NOD proteins and Toll-like receptors are shown below:

So, the only difference between NOD proteins and Toll-like receptors is the location. Toll-like receptors are present on the surface of cells while NOD proteins are present inside the cell, in the cytosol.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 7CT
The sweat glands in the armpits secrete perspiration which has a pH close to 7.0. Since, this is a neutral pH; there should be no body odor. But, the armpits have more body odor than most parts of the skin.
The sweat secreted by the sweat glands has no smell at all. But, the location of the armpit is a closed area with not free passage of air. Because of this closed location, the perspiration does not have a chance to evaporate.
The persistence of sweat causes the occurrence of heat in the armpits. The combination of sweat and heat allow bacteria to multiply rapidly. These bacteria then break down the sweat into other compounds. These compounds are responsible for the body odor.
The other parts of the skin have some flow of air to evaporate the sweat. This does not allow sweat to remain for long on the skin. Hence, bacteria do not have the opportunity to break down the sweat molecules to cause a bad smell.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 7M1
The term “mucous membrane of the digestive tract” matches with the phrase “first line of defense.”
Mucus secreting membranes are found in the urinary system, respiratory passages, and digestive cavity. The membranes consist of tightly packed cells which are replaced frequently.
The digestive cavity is lined by mucus membranes. Since mucus membranes are an easy portal for microbes, the topmost cells are continually shed. This removes the organisms attached to the topmost layer of the mucus membranes. Dendritic cells are present below the mucus epithelium and phagocytize pathogens.
Goblet cells are also present amidst the cells of the mucous membrane. These cells secrete sticky mucous which helps to trap pathogens. Hence, the correct option is A. first line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 7M2
The term “Eosinophil” matches with the phrase “leukocyte that primarily attacks parasitic worms.”
Eosinophils are granulocytes which are a type of leukocytes. These cells attack pathogens in a non-phagocytic manner. They secrete anti-microbial chemicals. Eosinophils usually attack during parasitic infections. These cells attach to the surface of the worms and secrete extracellular toxins.
These extracellular toxins harm the outer surface of the worms and finally kill it. A high level of eosinophils in the blood is an indication of a worm infestation. The eosinophils can also use mitochondrial DNA as a means of killing bacteria.
Hence, the correct option is A. leukocyte that primarily attacks parasitic worms.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 7MC
Interferons do not protect the cell that secretes them; stimulate the activity of macrophages, and cause muscle aches, chills, and fever.

• Interferons do not protect the cell that secretes them. Interferons are produced in a cell after viral invasion or infection has occurred. The interferons produced serve to protect the surrounding cells from viral infection. It cannot protect the cell that secretes them. Hence, the option (a) is correct.
• Interferons stimulate the activity of macrophages. These macrophages are needed to recognize and eliminate the newly released viruses from the viral infected cell. These macrophages cannot protect the infected cells but can remove the viruses. If these macrophages were not stimulated, the viruses might infect other cells. Hence, the option (b) is correct.
• The interferons produced by one cell can protect the surrounding cells from viral infection. But, as seen in viral infections, the side effects of interferons are muscle aches, chills, and fever. These symptoms are seen when interferons are produced. Hence, the option (c) is correct.
• The term “all of the above” indicates that all the other given options are correct. Since, all the above conditions are correct and are related to interferons, we can say that all the above options are correct. Hence, the correct option is (d) all of the above.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 7MTF
The given statement “In phagocytosis, adherence involves the binding between complementary chemicals on a phagocyte and on the membrane of a body cell” is false. Adherence occurs between the phagocyte and the pathogen but not the body cell.
The process of phagocytosis occurs with the help of cells called phagocytes. These phagocytes engulf the microbial cell and destroy it. In the process of phagocytosis, we see six steps:

• Chemotaxis
• Adherence
• Ingestion
• Maturation
• Killing
• Elimination

In the step of chemotaxis, the phagocyte is attracted towards the microbe. In the step of adherence, the phagocytic cell binds to chemicals on the surface of the microbe. In the step of ingestion, the microbe is engulfed by the phagocyte. In the step of maturation, fusion with a lysosome occurs. In the step of killing, the microbe is degraded by the enzymes in the lysosome. In the step of elimination, the remnants of the digestion are eliminated by the process of exocytosis.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 8CT
Scientists can raise “germ-free” animals in the laboratories. These animals are usually raised in axenic environments. An axenic environment is one in which only one species exists.
Such animals would not be as healthy as their worldly counterparts. Since these lab animals are germ-free they will not have the immunity seen in their worldly counterparts. Such animals would be more susceptible to infection and their immune system is not very well developed.
The immune system of an individual usually develops by exposure to microbes. When individuals are raised in a germ-free environment, their immune system does not have a chance to develop. This makes their immune system weak.
Hence, the worldly animals will be healthier than the animals brought up under axenic environments in the laboratory.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 8M1
The term “neutrophils” matches with the phrase “second line of defense.” The second line of defense consists of cells like neutrophils, antimicrobial chemicals, and processes.
Neutrophils come under the category of leukocytes with granules. They are also known as polymorphonuclear leukocytes. Neutrophils are phagocytes which can phagocytize pathogens. These cells are present in the blood and move into the tissues through the process of diapedesis.
Another method in which neutrophils help to kill pathogens is through the formation of NETs. The term NET stands for neutrophils extracellular traps. These NETs are synthesized by neutrophils which involves the disintegration of their nuclei. The components of the nucleus mix with the components of the cytoplasm. This mixing forms NET fibers.
Superoxide and peroxide ions then kill the neutrophil. The NET formed in the cytoplasm of the neutrophil is released when the cell dies. These NETs trap Gram positive and negative bacteria along with antimicrobial peptides. These antimicrobial peptides then kill the bacteria. Hence, the correct option is B. second line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 8M2
The term “alveolar macrophage” matches with the phrase “phagocytic cell in lungs.” Alveolar macrophages are present in the lungs. These are not wandering macrophages but fixed in the same tissue.
Macrophages come under the second line of defense. These cells mainly take part in the process of phagocytosis. These are non specific cells and can phagocytize any foreign particle. The phagocytic cells in the brain and spinal cord are called microglia. The phagocytic cells present in the epidermal layer of the skin are called dendritic cells.
In the process of phagocytosis, we see 6 steps:

• Chemotaxis
• Adherence
• Ingestion
• Maturation
• Killing
• Elimination

At the end of phagocytosis, the pathogen is killed and the remnants thrown out of the cell.
Hence, the correct option is B. phagocytic cell in lungs.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 8MC
Single stranded RNA (ribonucleic acid) molecules are seen in viruses and some other pathogens. They are not seen in eukaryotic cells. So, the Toll-like receptors recognize these RNA molecules as foreign and trigger an immune response against them. These RNA molecules are then destroyed by the host immune system. Hence, the option (c) is incorrect.
The molecules of Lipoteichoic acid is usually seen in Gram negative bacterial cells. Since bacterial cells are pathogens, the Toll-like receptors recognize them and trigger the immune responses of the body. The Toll-like receptors are membrane proteins, which are produced by phagocytic cells. Hence, the option is (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 8MTF
The given statement “Opsonization occurs when a phagocyte’s pseudopodia surround a microbe and fuse to form a sac” is false. The process of ingestion occurs when the pseudopodia of a phagocyte surround the microbe and engulf it.
The process of phagocytosis occurs with the help of cells called phagocytes. In the process of phagocytosis, we see six steps:

• Chemotaxis:
  In the step of chemotaxis, the phagocyte is attracted towards the microbe.
• Adherence:
  In the step of adherence, the phagocytic cell binds to chemicals on the surface of the microbe.
• Ingestion:
  In the step of ingestion, the microbe is engulfed by the phagocyte by using pseudopodia.
• Maturation:
  In the step of maturation, fusion with a lysosome occurs.
• Killing:
  In the step of killing, the microbe is degraded by the enzymes in the lysosome.
• Elimination:
  In the step of elimination, the remnants of the digestion are eliminated by the process of exocytosis.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 9CT
The comparison of the protective structures and chemicals of the skin and mucous membranes is given below:
Skin:
Protective structures:

1. The epidermal layer also acts as a tough protective layer
2. Hair and hair follicles act as a protective structure
3. The multiple layers of the skin act as a physical barrier
4. Phagocytic dendritic cells are present which act as protective substances
5. The dermis of the skin contains collagen which also give protection

Chemicals of the skin:

1. Antimicrobial peptides are secreted by the dermal cells
2. Sweat glands secrete sweat which contains salt and lysozyme
3. Sebaceous glands secrete sebum

Mucous membranes:
Protective structures:

1. Mucous membranes have a connective tissue layer which provides support
2. Dendritic cells are present which give protection to the mucous membranes
3. Some mucous membranes possess goblet cells which secrete mucus
4. Some cells have cilia which help to trap and push out pathogens

Chemicals of the mucous membrane:

1. The mucous in the nose contains lysozyme
2. The mucous also contains antimicrobial peptides

Microbiology with Diseases by Taxonomy Chapter 15 Answers 9M1
The term “epidermis” matches with the phrase “first line of defense.” The first line of defense consists of skin, mucous membranes, lacrimal apparatus, normal microbiota and others like antimicrobial peptides.
The outer layer of the skin, the epidermis consists of dead cells. The epidermis consists of multiple layers of cells which are tightly packed. The topmost layer consists of cells which are dead and dry. These cells are shed continuously which do not allow most microorganisms to settle on the skin.
Dendritic cells are present in the epidermal layer of the skin. These are phagocytic cells which are formed by monocytes. Dendritic cells have slender processes which extend among cells. These slender processes form a continuous network which traps pathogens. Hence, the correct option is A. first line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 9M2
The term “microglia” matches with the phrase “phagocytic cell in central nervous system.” These are the resident macrophages present in brain and spinal cord. These macrophages form the first line of defense.
Macrophages come under the second line of defense. These cells mainly take part in the process of phagocytosis. These are non specific cells and can phagocytize any foreign particle. The phagocytic cells present in the epidermal layer of the skin are called dendritic cells. The macrophages in the lungs are called alveolar macrophages.
Macrophages are formed from the cells called monocytes. When monocytes mature, they turn into macrophages and get settled in a specific tissue. Hence, the correct option is F. phagocytic cell in central nervous system.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 9MC
The TLRs do not cause phagocytic chemotaxis. These TLRs are present on the surface of phagocytic cells and induce the response of the innate immune system. TLRs bind only to the microbial proteins and polysaccharides present on the surface of the microbial cells. Hence, the option (c) is incorrect.
The TLRs do not directly cause the destruction of microbial cells. They bind to the components of the microbial cells and send a signal to the immune system. The immune system then responds and kills the microbes. TLRs bind only to the microbial proteins and polysaccharides present on the surface of the microbial cells. Hence, the option (d) is incorrect.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 9MTF
The given statement is false. The correct answer is that lysosomes fuse with phagosomes to form phagolysosomes.
Phagosomes fuse with lysosomes in the process of phagocytosis. The exact step, where a lysosome fuses with a phagosome is called the maturation stage. In this stage, the phagosome containing the engulfed microbe fuses with a lysosome.
The fused product is known as phagolysosome. These phagolysosomes contain highly toxic forms of oxygen. They also contain antimicrobial substances in a pH of 5.5. In addition, there are about 30 different enzymes like proteases, nucleases, and lipases to destroy microbes.
After the death of the microbe, a phagolysosome is known as a residual body.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 10CT
Scientists are trying to develop antimicrobial drugs which behave like the antimicrobial peptides of the body.
Antimicrobial peptides are chains of amino acids which are positively charged. These peptides act against microbes. Since these peptides are found in many organisms apart from humans, scientists want to develop peptides which would do the work of an antibiotic.
These peptides would be given as drugs instead of antibiotics. The advantages of such drugs over antibiotics can be given below:

• The side effects of antibiotics would be reduced
• The tissue damage done by antibiotics can be avoided
• Drug resistance can be avoided
• Can be easily eliminated from the body

Microbiology with Diseases by Taxonomy Chapter 15 Answers 10M1
The term “lysozyme” matches with the phrase “first line of defense.” The first line of defense consists of skin, mucous membranes, lacrimal apparatus, normal microbiota and others like antimicrobial peptides.
Lysozyme is an enzyme present in the dermis of the skin. Lysozyme is an enzyme which destroys the cell wall of bacteria. It breaks down the bonding between the building blocks of the cell wall. Cells without a cell wall are susceptible and are killed quite easily.
The mucous in the nasal epithelium also contains lysozyme. The enzyme is present as the first line of defense to lyse any pathogens which enter the nose. Some microbes can be resistant to the action of lysozyme. Such microbes are usually a part of the normal flora. Hence, the correct option is A. first line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 10M2
The term “wandering macrophage” matches with the phrase “intercellular scavenger.”
Macrophages come under the second line of defense. These cells mainly take part in the process of phagocytosis. These are non specific cells and can phagocytize any foreign particle.
Wandering macrophages are those cells which are in the blood and move out of the blood whenever needed. These cells use the process of diapedesis and move out of the blood vessel and into the tissues when tissue damage occurs.
The macrophages in the blood are wandering macrophages while those in the tissues are fixed macrophages. The fixed macrophages in each tissue have different names according to the location. Wandering macrophages perform the role of scavenger intercellularly and extracellularly. Hence, the correct option is I. intercellular scavenger.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 10MC

• The protein lactoferrin is a member of the transferrin proteins. It transfers iron molecules into the cells and controls the levels of free iron in the blood. Apart from this function, it also has antibacterial and antiviral activities. Hence, the option (a) is correct.
• Siderophores are compounds, which bind to iron with high affinity. These siderophores are secreted by microbes like bacteria and fungi. Siderophores can also chelate other metals like aluminum, copper, lead, and manganese. Hence, the option (b) is correct.
• Transferrins are glycoproteins, which are present in the plasma and bind to iron molecules. These molecules control the level of free iron just like lactoferrin. These molecules bind to iron very tightly but reversibly. Hence, the option (c) is correct.
• Since the above three molecules can bind to iron, all the options are correct.Hence, the correct option is (d) all of the above.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 10MTF
The given statement “A membrane attack complex drills circular holes in a macrophage” is false. The membrane attack complex drills circular holes in the cytoplasmic membrane of a pathogen.
The membrane attack complex is seen in the process, where the complement system destroys microbes. The complement system is a set of serum proteins. These proteins act as chemotactic agents and trigger inflammation and fever in the host. The membrane attack complexes can be formed by 3 pathways.
The three pathways are:

• Classical pathway
• Alternative pathway
• Lectin pathway

The formation of the membrane attack complex is a common step in all the three pathways. When this complex forms, it causes the formation of holes in the cytoplasmic membrane of the pathogens.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 11M1
The term “goblet cells” matches with the phrase “first line of defense.” The first line of defense consists of skin, mucous membranes, lacrimal apparatus, normal microbiota and others like antimicrobial peptides.
Goblet cells are present amidst the cells of the mucous membrane. These cells secrete sticky mucous which helps to trap pathogens. The goblet cells are epithelial cells which secrete mucin. These cells are usually found amid the epithelial lining of the respiratory and the intestinal tracts. These cells are not macrophages or phagocytes.
In some locations, ciliated cells are present in addition to goblet cells. These cilia help to push out the pathogens trapped in the mucous. Hence, the correct option is A. first line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 11MTF
The given statement “Rubor, calor, swelling, and dolor are associated with fever” is false. The above symptoms of rubor, calor, swelling and dolor are associated with inflammation.
Rubor indicates redness, calor indicates local heat, and dolor indicates pain. Inflammation is a process of the second line of defense of the body. It is a nonspecific response to the damage of tissues. The damage in tissues can be due to a variety of reasons like heat, cuts, chemicals, and pathogens.
There are two types of inflammation:

• Acute
• Chronic

Acute inflammation is short lived and results in the removal of the cause of the inflammation. In chronic inflammation, damage in tissues occurs which can lead to the death of the tissues. Both acute and chronic inflammation show the same symptoms of redness, heat, pain and swelling.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 12M1
The term “phagocytes” matches with the phrase “second line of defense.” The second line of defense consists of cells like phagocytes, antimicrobial chemicals, and processes.
Phagocytes are cells which take part in the process of phagocytosis. In the process of phagocytosis, we see 6 steps:

• Chemotaxis
• Adherence
• Ingestion
• Maturation
• Killing
• Elimination

In the step of chemotaxis, the phagocyte is attracted towards the microbe. In the step of adherence, the phagocytic cell binds to chemicals on the surface of the microbe. In the step of ingestion, the microbe is engulfed by the phagocyte. In the step of maturation, fusion with a lysosome occurs. In the step of killing, the microbe is degraded by the enzymes in the lysosome. In the step of elimination, the remnants of the digestion are eliminated by the process of exocytosis. Hence, the correct option is B. second line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 12MTF
The given statement “Acute and chronic inflammation exhibit similar signs and symptoms” is true.
There are two types of inflammation:

• Acute
• Chronic

Acute inflammation is short lived, and results in the removal of the cause of the inflammation. In chronic inflammation, damage in tissues occurs which can lead to the death of the tissues. Both acute and chronic inflammation shows the same symptoms of redness, heat, pain and swelling.
Redness is called Rubor, localized heat is called calor, and pain is known as dolor. Inflammation is a process of the second line of defense of the body. It is a nonspecific response to the damage of tissues.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 13M1
The term “sebum” matches with the phrase “first line of defense.” The first line of defense consists of skin, mucous membranes, lacrimal apparatus, normal microbiota and others like antimicrobial peptides.
The skin contains sebaceous glands which secrete a substance called sebum. Sebum is an oily substance which keeps the skin oily and smooth. The sebum contains fatty acids which keep the pH of the skin at 5.5. This pH is not suitable for the growth of many microbes.
Along with sebaceous glands, the skin also contains sweat glands which secrete antimicrobial peptides and salt. These secretions also form the first line of defense along with sebum secretions. Hence, the correct option is A. first line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 13MTF
The given statement “The hypothalamus of the brain controls body temperature” is true.
The hypothalamus is a part of the brain, which controls the temperature of the body. Fever is a symptom seen when the body temperature rises above 37 degrees centigrade. Fever has side effects like malaise, tiredness, and body aches.
Fever is usually caused due to pyrogens. These pyrogens are chemicals, which reset the thermostat in the hypothalamus to a higher temperature. Pyrogens can include toxins released from bacteria, cytoplasmic contents of bacterial cells released after lysis, and chemicals released by phagocytes.
The symptoms of fever remain as long as pyrogens are present. When the infection starts to come under control, the level of pyrogens reduces and the body temperature is slowly reset to normal.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 14M1
The term “T lymphocytes” matches with the phrase “third line of defense.” There are two types of lymphocytes and both the types are made in the bone marrow.
T cells or T lymphocytes migrate to the thymus from the bone marrow. Then these T cells mature. The other cells are called B cells or B lymphocytes. These cells migrate to the fetal liver or spleen. But B cells can mature in either the bone marrow or in the spleen.
After maturation, these cells move around the body and look for foreign bodies. The T lymphocytes play a part in the cell-mediated response while B cells play a part in the humoral response or production of antibodies.
The specialized cells formed are:

• Killer T cells
• Helper T cells
• Suppressor T cells
• Memory cells

Hence, the correct option is C. third line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 14MTF
The given statement “Defensins are phagocytic cells of the second line of defense” is false. The antimicrobial peptides are phagocytic cells of the second line of defense.
These antimicrobial peptides are found in mucous membranes, and are secreted on the skin. These peptides are the second line of defense, which acts against pathogens which dare to attach to the skin. The antigens on the surface of the microbes trigger the antimicrobial action of these peptides.
Some antimicrobial peptides are specific against Gram negative or Gram positive organisms. Some can act against any bacteria while some act against the other organisms like protozoa, and fungi.
The mode of action of these antimicrobial peptides differs from each peptide. Some make holes in the membranes of the pathogens, while others prevent signaling and enzymatic action.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 15M1
The term “Antimicrobial peptides” matches with the phrase “first line of defense.” The first line of defense consists of skin, mucous membranes, lacrimal apparatus, normal microbiota and others like antimicrobial peptides.
These antimicrobial peptides are found in mucous membranes and are secreted on the skin. These peptides are the first line of defense which acts against pathogens which dare to attach to the skin. The antigens on the surface of the microbes trigger the antimicrobial action of these peptides.
The mode of action of these antimicrobial peptides differs from each peptide. Some make holes in the membranes of the pathogens, while others prevent signaling and enzymatic action.Hence, the correct option is A. first line of defense.

Microbiology with Diseases by Taxonomy Chapter 15 Answers 15MTF
The given statement “NETs are webs produced by neutrophils to trap microbes” is true.
The term NET stands for “neutrophils extracellular traps.” These NETs are synthesized by neutrophils, which involves the disintegration of their nuclei. When the nuclei break down, the DNA and the histone proteins are released. The components of the nucleus mix with the components of the cytoplasm. This mixing forms NET fibers.
Superoxide and peroxide ions then kill the neutrophil. The NET formed in the cytoplasm of the neutrophil is released when the cell dies. These NETs trap Gram positive and negative bacteria along with antimicrobial peptides. These antimicrobial peptides then kill the bacteria. Thus, the neutrophils kill bacteria in a method which involves killing themselves.