7. Shigella can penetrate the mucous membrane by a- Directed uptake by cells b E

Question

7. Shigella can penetrate the mucous membrane by a- Directed uptake by cells b Exploitation of antigen sampling processes c- Type 3 secretion system d- None of the above 8- True or False IgA protease is an enzyme used by organisms to break down lgA and avoid the host Immune system. 9. True or False Opportunistic infections are least likely to affect AIDS patients 10- True or False In the A-B Toxin, the B subunit is the actual toxin that binds to the receptor which is the A subunit 1I-All the following are true of A- B toxins, excep a) The portion A is an enzyme b) The B portion is responsible for the toxic properties c) They are exotoxins d) The B portion binds to host cells and allows the toxin to enter the cell 12-Superantigens are a) Endotoxins that link MRC class II protein to the plasma membrane b) Endotoxins that attach to the outside of MHC class II proteins c) Exotoxins that attach to the outside of MHC class II proteins d) NONE of the above 13- Successful pathogens have the ability to carry out a number of steps essential for their virulence and their survival, these include a) Transmission of the causative agent to a susceptible host and adherence of the agent to a target tissue b) Damage to the host by the activities of toxins or other mechanisms c) Exit from the host and survived long enough for steps to occur d) ALL of the above proteins found in strains of Streptococcus pyogenes inactivate the C3a complement component interfering with opsonization. a) Fc receptors b) M proteins c) A proteins d) lgA antibodies 15-A type of symbiotic relationship in which both organisms benefit from the relationship is called b) Mutualism c) Parasitism d) All of the above s://bb osted cunye ult cs webdav pid 349843 41 d-cor eo201 0601182 1 rev e4%20 or%20th :0%20e am%20201 do 422 S Pago

Explanation / Answer

7. The pathogenic members of the genus Shigella belong to Enterotoxigenic E coli or Enterohemorrhagic E coli classes of bacteria. These bacteria penetrate the mucous membrane by Type 3 Secretion system. It is a system of a sensory probe that helps the bacteria to detect the presence of eukaryotic cells around it which it can infect. Special proteins known as effector proteins are secreted from the bacteria into the host cell, where they exert effects that help the bacteria to survive in the host and to escape its immune response. So, the correct answer is C.

8. IgA is the type of immunoglobulin found in secretions of our body, like tears, mucus etc, IgA protease sectreted by many pathogens are used to defend the organism against the host immune response triggered by IgA by breaking down the immunoglobulin. Hence the answer is TRUE.

9. A person suffering from AIDS is immunologically challenged. Such a situation is not always present in host organisms. An opportunistic infection is an infection caused by pathogens which take advantage of an opportunity not normally available, e.g in AIDS. So, the correct answer is FALSE.

10. In AB toxin, also known as type 3 toxins, A component is usually the toxin portion, while the B component is usually the binding unit. So, the correct answer is False.

11. In AB toxin, also known as type 3 toxins, A component is usually the toxin portion, while the B component is usually the binding unit. Exotoxins are toxins released by bacteria outside the cell and then the toxins enter the host cell. Hence, the correct option here is, B.

12. Superantigens are a type of antigen produced by pathogens outside the cells(exotoxins) and which bind to the MHCII molecules first to enter the cell. Hence the correct option is C.

13. Succesful pathogens,

Hence the correct option is D.

14, The capsule of Streptococcus pyogenes have several factors embedded in the cell wall, one of them is a protein called M protein which blocks the process of opsonization by inactivating C3a protein of the complement system. Hence, the correct option is B.

15. There are various forms of interactions present among different organisms around us. Interactions in which both organisms involved are benefited is known as mutualism. So, the correct option is B.

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