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Life Processes

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Which among the following cells of the central nervous system removes cellular waste and provides protection against microorganisms?

  1. Astrocytes

  2. Ependymal cells

  3. Microglia

  4. Oligodendrocytes

  5. Schwann cells


Correct Option: C
Explanation:

The microglia act much like white blood cells by attacking and destroying pathogens that invade the brain. These are extremely small cells of the central nervous system that remove cellular waste and provide protection against microorganisms.

Which of the following cells are not of monocyte-macrophage lineage system in the blood?  

  1. Follicular dendritic cells of lymph nodes

  2. Kupffer cells in liver

  3. Histiocytes in tissues

  4. Neutrophils

  5. Monocytes in blood


Correct Option: D
Explanation:

These are of the myeloid lineage which are separated from the monocyte-macrophage lineage after the pluripotent stem cell stage.

The part of the brain responsible for problem solving, judgment and motor functioning in an individual is the ____________.

  1. cortex

  2. basal ganglia

  3. brain stem

  4. cerebellum

  5. frontal lobes


Correct Option: E
Explanation:

The frontal lobes are responsible for problem solving, judgment and motor functioning.

An antigen is a substance which provokes an adaptive immune response. Which type of cell is known to be involved in the initial presentation of antigen to T lymphocytes?

  1. Plasma cells

  2. Dendritic cells

  3. Neutrophil polymorphonuclear leucocytes

  4. Erythrocytes

  5. Platelets


Correct Option: B
Explanation:

Dendritic cells (DCs) are antigen-presenting cells (also known as accessory cells) of the mammalian immune system. There are several types of dendritic cells, well distributed over the body.

In a defence mechanism of the human body the neutrophil defensins are regarded as __________.

  1. antitoxins

  2. oxygen-dependent substances

  3. enzymes

  4. glycolipids

  5. peptide antibiotics


Correct Option: E
Explanation:

The defensins are peptide antibiotics present in the granules in extremely high concentration.

The body possesses many mechanisms that impart nonspecific defence. Which of the following does not protect body surfaces from infections?

  1. Skin

  2. Mucus

  3. Gastric acid

  4. Salivary amylase

  5. Gut microflora


Correct Option: D
Explanation:

The enzyme splits starch and is of importance for digestion but not for protection.

The cells responsible for antigen specific humoral responses in humans are the ___________.

  1. neutrophil polymorphonuclear leucocytes

  2. microglial cells

  3. macrophages

  4. Kupffer cells

  5. B lymphocytes


Correct Option: E
Explanation:

B lymphocytes secrete antibodies and cytokines and are responsible for antigen specific humoral responses. They can process and digest antigens particularly in secondary immune responses but do not have a major phagocytic role.

Which among the following can be excluded from the mononuclear phagocyte system of the body?

  1. Monocytes

  2. Kupffer cells

  3. Lymph node medullary macrophages

  4. Endothelial cells

  5. Kidney mesangial cells


Correct Option: D
Explanation:

Endothelial cells are not essentially phagocytic although they do contribute by the production of mediators of the inflammatory process, particularly acute inflammation and were previously lumped together with the mononuclear phagocyte system in what was known as the reticuloendothelial system (RES).

Protection against microorganisms inside the cell is provided by ________________________.

  1. T-lymphocytes

  2. antibodies

  3. C3b

  4. C1q

  5. membrane attack complex


Correct Option: A
Explanation:

T-lymphocytes are specialised for recognising peptides derived from intracellular infectious agents which are exhibited on the surface of an infected cell together with MHC class I & II molecules.

Intracellular parasites are capable of growing and reproducing inside the cells of a host. These parasites within macrophages are killed more readily in the presence of __________________.

  1. antibodies

  2. kinins

  3. properdin

  4. gamma-interferon

  5. anaphylatoxin


Correct Option: D
Explanation:

Gamma-interferon activates microbicidal mechanisms within the macrophage, thereby leading to the death of intracellular parasites.

The activation of lymphocytes cannot be assessed by __________________.

  1. mitosis

  2. cytokine release

  3. phagocytosis

  4. cytotoxicity

  5. limiting dilution analysis


Correct Option: C
Explanation:

Lymphocytes are not phagocytic, irrespective of their activation status.

Introduction of a gene into a cell using calcium phosphate precipitate is termed as ____________________.

  1. electroporation

  2. homologous recombination

  3. biolistics

  4. transfection

  5. mutation


Correct Option: D
Explanation:

Transfection is the introduction of a gene into a cell; calcium phosphate precipitate is one method of achieving this.

Phagocytes are the cells that can swallow and digest microbes and other foreign particles. Which of the following cell types is phagocytic in nature?

  1. Hepatocytes

  2. Lymphocytes

  3. Monocytes

  4. Erythrocytes

  5. Plasma cells


Correct Option: C
Explanation:

They are circulating immature macrophages or dendritic cells.

An antibody is a large Y-shape protein used by the immune system to identify and neutralize foreign objects such as bacteria and virus. Which cell type produces antibodies?

  1. Macrophages

  2. T-lymphocytes

  3. NK

  4. Plasma cells

  5. Eosinophils


Correct Option: D
Explanation:

B-lymphocytes have antibodies on their cell surface which act as an antigen receptor. Upon activation, they differentiate into plasma cells which secrete large amounts of antibodies.

Which of the following types of cells produces IgE?  

  1. Mast cells

  2. Eosinophils

  3. Basophils

  4. T lymphocytes

  5. Plasma cells


Correct Option: E
Explanation:

Plasma cells produce immunoglobulins of all isotypes, including IgE.

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