Biology

Human Immunity and Blood

2,051 Questions

Human immunity and blood questions cover the physiological mechanisms protecting the body against diseases and the components of blood. Topics include blood groups, cell mediated immunity, monoclonal antibodies, and blood coagulation. These biology topics frequently appear in general science sections of competitive exams.

Blood groupsCell mediated immunityMonoclonal antibodiesBlood coagulationCancer immunology

Human Immunity and Blood Questions

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Name of cells which help in clotting of blood in mammals ____________.

  1. Platelets

  2. Thrombocytes

  3. Lymphocytes

  4. Monocytes
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Platelet, also called thrombocyte, colourless, nonnucleated blood component that is important in the formation of blood clots (coagulation). Platelets are found only in the blood of mammals.


So, the correct answer is 'Platelets'.

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Blood platelets are.

  1. Nucleated cells

  2. Non-nucleated cells

  3. Non-nucleated cell fragments

  4. Nucleated cell fragments
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Platelets are small, non-nucleated cells that are derived from megakaryocytes in the bone marrow. Platelets circulate in the blood, sense damage to a blood vessel and accumulate at these sites, where they initiate blood clotting. They are fragments of cytoplasm that are derived from the megakaryocytes of the bone marrow.


So, the correct answer is 'Non-nucleated cell fragments'.

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Instead of platelets, the non-mammals possess clotting factor in.

  1. Nucleated cells called thrombocytes

  2. RBC

  3. WBC

  4. Plasma
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Only mammals have Platelets. Non-mammals possess thrombocytes which are nucleated cells which have been shown to have a haemostatic function paralleling that of mammalian platelets.


So, the correct answer is 'Nucleated cells called thrombocytes'.

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Megakaryocytes.

  1. Produce leucocytes

  2. Form blood platelets

  3. Are called bone cells

  4. Are carriers of oxygen
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A megakaryocyte is a large bone marrow cell with a lobated nucleus responsible for the production of blood thrombocytes (platelets), which are necessary for normal blood clotting.


So, the correct answer is 'Form blood platelets'.

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

The life span of thrombocytes is

  1. 4 to 5 weeks

  2. 3 to 4 weeks

  3. 3 to 7 days

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The average life span of circulating platelets is 8 to 9 days. Life span of individual 3 to 7 days thrombocytes is controlled by the internal apoptotic regulating pathway, which has a Bcl-xL timer. Old thrombocytes are destroyed by phagocytosis in the spleen and liver. So, the correct answer is "3 to 7 days.'
Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Smallest blood cells are

  1. RBC

  2. WBC

  3. Platelets

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Platelets, also called thrombocytes, are blood cells whose function is to stop bleeding. Platelets have no nucleus: they are fragments of cytoplasm, which are derived from the megakaryocytes of the bone marrow, and then enter the circulation. These unactivated platelets are biconvex discoid structures. They are smallest of the three major blood types. They make up a tiny portion of the blood volume.

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Megakaryocyte cell is

  1. RBC producer

  2. Thrombocyte producer

  3. WBC producer

  4. Protein producer
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Megakaryocytes cells is thrombocyte producer. A megakaryocyte is a large bone marrow cell with a lobulated nucleus responsible for the production of blood thrombocytes, which are necessary for normal blood clotting. Megakaryocytes normally account for 1 out of 10,000 bone marrow cells but can increase in number nearly 10- fold during the course of certain diseases.

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Platelets are a source of

  1. Fibrinogen

  2. Calcium

  3. Thromoboplastin

  4. Heamoglobin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Platelets are a source of thromboplastin. Thromboplastin is a plasma protein aiding blood coagulation through catalyzing the conversion of prothrombin to thrombin. It is a complex enzyme that is found in the brain, lung, and other tissues and especially in blood platelets and that functions in the conversion of prothrombin to thrombin in the clotting of blood, called as thrombokinase.

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Structure absent from fresh frozen blood plasma is

  1. Immunoglobulin

  2. Plasma

  3. Albumin

  4. Platelet
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Structure absent from fresh frozen blood plasma are platelets. Platelets have no nucleus: they are fragments of cytoplasm which are derived from the megakaryocytes. The main function of platelets is to contribute to hemostasis: the process of stopping bleeding at the site of interrupted endothelium. They gather at the site and unless the interruption is physically too large, they plug the hole. In the fresh frozen blood plasma, there will be an absence of blood cells. So, in frozen plasma platelets are also absent.

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Megakaryocytes

  1. Produce leucocytes

  2. Forms blood platelets

  3. Forms germ cells

  4. Are carriers of oxygen
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A megakaryocyte is a large bone marrow cell with a lobulated nucleus, responsible for the production of blood thrombocytes (platelets), which are necessary for normal blood clotting. Megakaryocytes normally account for 1 out of 10,000 bone marrow cells but can increase in number nearly 10-fold during the course of certain diseases.

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Which one of the following is wrong?

  1. White blood cells or leucocytes are considered as 'soldiers' of the body.

  2. Antibodies are product by the stem cells of bone marrow.

  3. Calcium ions in blood play an important role in blood clot formation.

  4. Blood platelets are cell fragments, devoid of nuclei and participate in the coagulation of blood.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An antibody is a large, Y-shaped protein produced by the plasma cells that is used by the immune system to identify and neutralize pathogens such as bacteria and viruses. The antibody recognizes a unique molecule of the harmful agent (antigen), via the variable region. They are not formed by the stem cells. All the other statements are correct.
Therefore, the correct answer is option B.

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Which of the following cells has a lifespan of 5-9 days?

  1. WBC

  2. Platelets

  3. RBC

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The platelets are formed by fragmenting from cells found in bone marrow called as megakaryocytes, and similar to red blood cells, they do not have a nucleus. The average lifespan of a platelet is normally just 5 to 9 days.  

Therefore, the correct answer is option B.

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Which of the following blood cells help in blood coagulation?

  1. RBCs

  2. Lymphocytes

  3. Thrombocytes

  4. Basophils
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Red blood cells or RBCs are the most common type of blood cell and contains hemoglobin, which is the principal means of delivering oxygen.
Lymphocyte is a type of white blood cell, that is important in the immune system.
Basophils are granulocytes i.e., they contain large cytoplasmic granules in the cell nucleus and it stores histamine (a vasodilator).
Thrombocyte is a platelet and is crucial for blood clotting.
Thus, the correct answer is option (C), 'Thrombocytes'.

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Blood platelets are

  1. Nucleated

  2. Nucleus is many lobed

  3. Nucleus is very small

  4. Denucleated
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The blood cells are of three major types they are erythrocytes(RBC), leucocytes(WBC) and platelets. Platelets or thrombocytes are cell fragments produced from megakaryocytes (special cells in the bone marrow). Formation of platelets by fragmentation of megakaryocytes in bone marrow is known as thrombopoiesis. As blood platelets are cell fragments they do not have any nucleus i.e Denucleated.

So, the correct answer is 'Denucleated'.

Multiple choice biology blood circulatory system of human blood clotting platelets and their function defence against infectious disease

Which of the following blood cells help in blood coagulation?

  1. RBCs

  2. Lymphocytes

  3. Thrombocytes

  4. Basophils
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Thrombocytes are pieces of very large cells in the bone marrow called megakaryocytes. They help form blood clots to slow or stop bleeding and to help wounds heal.


So, the correct answer is 'Thrombocytes'.