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Biology Test

Description: This test is based on certain topics from biology which are highly beneficial for learning aspirants.
Number of Questions: 16
Created by:
Tags: AIDS Cancer HIV Carcinogens Bone marrow etc. AID and Cancer -- Causes and Control Respiratory Center Regulation of Respiration by Nervous System
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Phylogenetically which of the following viruses is more closely related to HIV-2?

  1. HIV-1 of chimpanzees

  2. Simian immunodeficiency virus ( SIV ) of sooty mangabeys.

  3. SIV of sykes

  4. SIV of African green monkeys


Correct Option: B
Explanation:

Simian immunodeficiency virus of sooty mangabeys (SIVsmm) is identified as the progenitor of human immunodeficiency virus type 2 (HIV-2) and has been transmitted to humans on multiple occasions. Even  then the epidemiology and genetic diversity of SIVsmm infection is unknown.

Which of the following types of rare cancer is frequently associated with AIDS?

  1. Mesothelioma

  2. Squamous cell cancer

  3. Kaposi's Sarcoma

  4. Oral florid papillomatosis


Correct Option: C
Explanation:

Kaposi's Sarcoma is a rare form of cancer usually found in older people. It is an aggressive form of cancer associated with HIV, and causes dark lesions on the skin and a variety of locations on the body.

Recently, Mr. Kapoor had undergone the standard HIV test. The doctors must have been identifying

  1. antigen

  2. antibody

  3. RNA strands

  4. CD4 count


Correct Option: B
Explanation:

When HIV enters the body, special proteins called antibodies, which are the body's response to an infection, are produced. The standard HIV test looks for antibodies in a person's blood as they indicate that the person has been infected with HIV.

With respect to HIV prevention, PEP means

  1. Prevention of Excessive Production

  2. Prohibitively Exorbitant Prescription

  3. Positive Expiratory Pressure

  4. Post Exposure Prophylaxis


Correct Option: D
Explanation:

PEP stands for Post Exposure Prophylaxis. This technique involves taking anti-retroviral drugs after HIV exposure in order to prevent infection. PEP should be the prevention method of last resort and should be started no later than 72 hours after exposure, and is not guaranteed to work.

Sunita is HIV positive and pregnant. Which of the following drugs is most commonly used in such cases to reduce mother-to-child HIV transmission?

  1. Penciclovir

  2. Doxylamine succinate

  3. Nevirapine

  4. Tenofovir


Correct Option: C
Explanation:

A single does of nevirapine given to the mother at the onset of labour and to the baby after delivery roughly halves the rate of HIV transmission.

HIV is believed to have originated from a similar virus found dominantly in

  1. chimpanzees

  2. Guinea baboon

  3. guinea pig

  4. boars


Correct Option: A
Explanation:

The SIV virus found in chimpanzees is very close to HIV. It is believed that the virus crossed species to humans.

An individual with HIV has a CD4 count of 450 or less. What does it mean?

  1. His immune system is still very healthy.

  2. He should probably start antiretroviral treatment.

  3. He no longer has HIV.

  4. He will die within a week.


Correct Option: B
Explanation:

The more CD4 cells there are in a person's blood, the stronger the immune system. A CD4 cell count below 450 indicates that the person has a weak immune system and requires antiretroviral therapy.

Which is the most common STD transmitted as a consequence of oral sex in humans?

  1. Herpes

  2. Chlamydia

  3. Hepatitis C

  4. Gonorrhea


Correct Option: A
Explanation:

The most common STD transmitted through oral sex is herpes. Herpes can cause cold sores around the mouth or genital herpes sores.

Complex I is the first enzyme in the mitochondrial respiratory chain. Which of the following acts as an inhibitor of Complex I ?

  1. H2S

  2. Rotenone

  3. CO2

  4. N2O


Correct Option: B
Explanation:

Rotenone is an inhibitor which acts as a poison and blocks the electron transport chain. When it does so, glycolysis and the citric acid cycle eventually halt.

Which of the following is not a characteristic of non-shivering thermogenesis?

  1. It occurs in brown adipose tissue only.

  2. It is strictly facultative in behaviour.

  3. It can be produced by leakage of the sodium-potassium pump .

  4. It is contributed to by futile cycles.


Correct Option: B
Explanation:

Non-shivering thermogenesis can be both obligatory and facultative. Obligatory thermogenesis is the heat production caused as a result of the metabolic rate, while facultative thermogenesis can be triggered in cold exposure to raise body temperature.

Priya was working in a laboratory and consumed cyanide. She was rushed to hospital where she was declared dead. Cyanide is a known inhibitor of Electron Transport chain (ETC). Which complex of ETC might have been inhibited?

  1. Complex I

  2. Complex II

  3. Complex III

  4. Complex IV


Correct Option: D
Explanation:

In the above case the cyanide must have blocked complex IV. It  blocks complex IV by taking electrons from complex III in the electron transport chain in the mitochondira of cells, so not enough ATP is formed for the functions of the body. Thus the diaphragm becomes paralyzed and the person dies.

While playing Mudit accidentally ingested a chemical and presented with high fever. The chemical is known to affect ATP formation in electron transport chain. Which of the following could cause similar manifestations?

  1. Rotenone

  2. 2,4-Dinitrophenol

  3. Antimycin A

  4. Cyanide


Correct Option: B
Explanation:

It  is a chemical uncoupler of electron transport and oxidative phosphorylation. It permeabilizes the inner mitochondrial membrane to protons, killing the proton gradient . In this situation, electrons continue to pass through the electron transport system and reduce oxygen to water, but ATP is not synthesized in the process thus it produces similar manifestations as given in the above question.

Who discovered coenzyme Q10 ?

  1. Fredrick L. Crane

  2. Karl Folker

  3. Peter Mitchell

  4. Gian Paolo Littarru


Correct Option: A
Explanation:

Coenzyme Q10 was discovered by Professor Fredrick L. Crane in 1957 .

The phospholipid found abundantly in the inner mitochondrial membrane is

  1. cardiolipin

  2. lecithin

  3. cephalin

  4. inulin


Correct Option: A
Explanation:

It is a phospholipid occurring primarily in mitochondrial inner membranes and in bacterial plasma membranes. It is regarded as the heart of mitochondrial metabolism.

Which of the following enzymes catalyzes substrate level phosphorylation in Kreb's cycle?

  1. Malate dehydrogenase

  2. Phosphoenolpyruvate carboxykinase

  3. Succinate thiokinase

  4. Succinate dehydrogenase


Correct Option: C
Explanation:

This enzyme catalyzes the reversible reaction of succinyl-CoA to succinate during TCA cycle. It aids in the the coupling of this reaction to the formation of a nucleoside triphosphate molecule (either GTP or ATP) from an inorganic phosphate molecule and a nucleoside diphosphate molecule (either GDP or ADP).

The electron flow from complex I to complex III occurs via

  1. cytochrome c

  2. ubiquinone

  3. complex II

  4. complex IV


Correct Option: B
Explanation:

Ubiquinone is bound to the inner mitochondrial membrane of mitochondria . It is the only enzyme that participates in both the citric acid cycle and the electron transport chain. The electron flow from complex I to complex III occurs via ubiquinone.

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