Human Health and Disease Test - 76

Bacteria are microscopic, single-cell organisms that live in every climate and location on earth. While some are airborne, others live in water or soil. These organisms live on and inside plants, animals, as well as human beings. Bacterial infection refers to the proliferation of a harmful strain of bacteria on or inside the body and infects any area of the body. Commonly caused infections are Pneumonia, meningitis, and food poisoning. Every infection has a chain of events which  involves  the infectious agent, reservoir, entering a susceptible host, exit, and transmission to new hosts. Each of the links must be present in a chronological order for an infection to develop. The infection starts, when bacteria successfully enters the body, grows and multiplies. This is referred to as colonization. Human beings response to bacterial infection  begins with the initial phase and activation of the innate immune system, uptake of antigen is take place by macrophage, T-cells priming and promoting inflammation, the release of macrophages into the blood stream, B cell activation and differentiation and encapsulation of the bacteria. Thus, the correct answer is option A.

The parasites that complete their life cycle in single host are termed as monogenetic parasites. Entamoeba histolytica is monogenetic parasite of human (A-IV).
Plasmodium is a cytozoic (intracellular) parasite that lives in RBC and liver cells (B-I).
Lymphadenitis is inflammation of lymph nodes which generally occurs after Wuchereria infection, the parasitic roundworm (C-V).
The 2nd stage of rhabditiform larva exhibit extraintestinal migration after it releases its shell in intestine itself. It migrates from small intestine into liver through hepatic portal vein, then into heart through post canal vein and then to lung through pulmonary arteries. It reaches to snail intestine via bronchi, trachea, larynx, glottis, pharynx, oesophagus and stomach (D-III).
Therefore, the correct answer is option B.

HIV (Human Immunodeficiency Virus) has a viral envelope, matrix proteins and core. The viral core consists of two single strands of RNA for its genome. The RNA genome consists of ribonucleotides (ribose + nitrogenous bases + phosphate) wherein thymine is replaced by uracil. The quick mutation rate of RNA genome makes it difficult to have a vaccine against it. The viral coat has trimeric glycoprotein gp120 which contacts CD4 terminal domain of the T4 cell. This contact leads to activation of gp120 followed by contact with chemokines receptor CCR5, a multipass membrane protein.  The result is activated gp41 which in turn cleaves gp120.  The terminal domain of gp41 interacts with the target cell and fuses with the T cell membrane to facilitate entry of virus with capsid into the cell.  RNA retroviruses have reverse transcriptase enzyme that synthesizes a DNA copy (cDNA) of viral RNA. Thus, the correct answer is option D.

Fertilized eggs of Ascaris are passed out from the host's body with its faeces into the soil where first larval moulting takes place. This larva does not have the power of infection. It becomes moulted into second stage larvae which infect the host through consumption of contaminated food and water. In the alveoli of lungs, it undergoes the 2nd moulting to produce the 3rd stage larva.
So, the correct answer is option C.

• Coelozoic parasites live within the cavities of the host's body. 
• Histozoic parasite lives in between the cells of the tissue or organs of the host. For example, Wuchereria bancrofti lives in the lymph tissue and so is holozoic.
• A monogenetic parasite is a parasite that completes its life cycle in only one host. 
• A digenetic parasite is a parasite that requires at least two hosts to complete its life cycle. W. bancrofti, carry out their life cycle in two hosts. Humans serve as definitive host and mosquitoes are intermediate hosts.
• W. bancrofti exhibits sexual dimorphism (i.e., is dioecious) and is pseudocoelomate, meaning it has a three-layered body that has a fluid-filled cavity (pseudocoelom) between the endoderm and the mesoderm.
• W. bancrofti is histozoix, digenetic, dimorphic pseudocoelomate.

Thus, the correct answer is an option (B). 

• Naturally acquired active immunity occurs when the person is exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response.
• Artificially acquired active immunity can be induced by a vaccine, a substance that contains the antigen. 
• Naturally acquired passive immunity occurs during pregnancy, in which certain antibodies are passed from the maternal blood into the fetal bloodstream in the form of IgG. 
• Artificially acquired passive immunity is a short-term immunization by the injection of antibodies, such as gamma globulin, that are not produced by the recipient's cells.

Wuchereria bancrofti is a human parasitic roundworm that is the major cause of lymphatic filariasis. The third-stage infective larvae (L3) enter the blood through the wound made by the mosquito. They then migrate to the nearest lymph gland where they mature into the thread like adult worms about 3 months to 1 year later. The average incubation time before patency is about 15 months.

Cannabis are group of chemical compund which interacts with cannabinoid receptors present mainly in the brain. These are obtained from the inflorences of the plant Cannabis sativa. These are inhaled or digested orally. Leaves, flowers , tops and resins of the Cannabis plant is used to produce hasish, charas, marijuana and ganja. This drug affects the cardiovascular system. It is a strong stimulant. When taken in high doses cause headache, convulsions, hallucination, irritaion and redness in eyes, increased appetite, increased urination etc.

Wuchereria bancrofti is the organism which causes filariasis in humans. The parasite completes its life cycle in two hosts. The humans serve as their definitive host. The culex mosquitoes are the intermediate host. 

Encephalitis is inflammation of the brain. It is a viral disease. It may be caused by herpes simplex virus or rabies virus. Common symptoms include a headache, fever, confusion, vomiting, seizures, hallucinations, etc. Kala-azar disease is also known as Visceral leishmaniasis. It is caused by parasite Leishmania donovani and transmitted by the sand fly Phlebotomus argentipes. The larval stage of Ascaris lumbricoides is called as Rhabditiform larvae as it appears similar to the soil nematode, Rhabditis found in soil and human faeces.