Tag: defence against infectious disease

Questions Related to defence against infectious disease

Which of the following results from cell fragmentation?

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

  1. RBC

  2. WBC

  3. Plasma

  4. Platelets

Show answer
Correct Option: D
Explanation:

Platelets are the cells found in blood which helps in the clotting of the blood. The formation of platelets takes place in bone marrow from large bone marrow cells known as megakaryocytes. These cells after becoming mature enough, undergo the process of cell fragmentation to produce platelet cells. The hormone that help in platelet production is thrombopoietin. 

So, the correct answer is D.

Low platelet count results in

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

  1. Low bleeding

  2. Excessive bleeding

  3. Growth

  4. Both B and C

Show answer
Correct Option: B
Explanation:

Platelets are the parts of the blood that help the blood clot. They are smaller than red or white blood cells. If the number of platelets is too low, excessive bleeding can occur. However, if the number of platelets is too high, blood clots can form thrombosis, which may obstruct blood vessels and result in such events as a stroke. 

Therefore, the correct answer is option B.

With reference to the blood in a normal person, which one of the following statements is correct?

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

  1. Compared to arteries, veins are less numerous and hold less of the body's blood at any given time.

  2. Blood cells constitute about 70 percent of the total volume of the blood.

  3. White blood cells (WBC) are made by lymph nodes only.

  4. The blood has more platelets than WBC.

Show answer
Correct Option: D
Explanation:
Blood is a specialized body fluid. It has four main components: plasma, red blood cells, white blood cells and platelets. The blood has more platelets than WBC. A normal platelet count ranges from 150,000 to 450,000 platelets per microliter of blood. An average normal range for white blood cells is between 4,500 and 10,000 /mcl.
Blood has many different functions. They are as follows:
  • Transporting oxygen and nutrients to the lungs and tissues.
  • Forming blood clots to prevent excess blood loss.
  • Carrying cells and antibodies that fight infection.
  • Bringing waste products to the kidneys and liver, which filter and clean the blood.
  • Regulating body temperature.

Megakaryocytes, special cells in the bone marrow that produce cell fragments are called :

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

  1. Leucocytes

  2. Erythrocytes

  3. Thrombocytes

  4. Fibrinogen

Show answer
Correct Option: C
Explanation:

Megakaryocyte is a large bone marrow cell which are responsible for the production of thrombocytes. Thrombocytes help in normal blood clotting.

Hence, he correct option is C.

Select the incorrectly matched pair.

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

  1. Leukopenia - Fall in WBCs count

  2. Polycythemia - Abnormal rise in RBCs count

  3. Thrombocytosis - Decrease in number of platelets

  4. Erythrocytopenia - Decrease in number of RBCs

Show answer
Correct Option: C
Explanation:

(a) Leukopenia is the decrease in the white blood cell count in the cells. 

(b) Polycythemia is a state in which the percentage of red blood cells in our body is elevated. 
(c) Thrombocytosis is the condition in which there is an excessive number of platelets in the blood cell.
(d) Erythrocytopenia-  It is a state in which there is a deficiency of Red blood cells in our body.
So, the correct option is 'Thrombocytosis- Decrease in a number of platelets'.

Tooth extraction in a person causes death due to excessive bleeding. This is because of

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

  1. Absence of prothrombin

  2. Presence of plasma factor that causes haemorrhage

  3. Presence of plasma factor that prevents blood clotting

  4. Absence of plasma factor required for haemorrhage

Show answer
Correct Option: A
Explanation:

Prothrombin is a glycoprotein occurring in blood plasma and is an essential component of the blood-clotting mechanism. Prothrombin is transformed into thrombin by a clotting factor known as factor X or prothrombinase; thrombin then acts to transform fibrinogen, also present in plasma, into fibrin, which, in combination with platelets from the blood, forms a clot (coagulation). Under normal circumstances, prothrombin is changed into thrombin only when an injury occurs to the tissues or circulatory system or both; therefore, fibrin and blood clots are not formed except in response to bleeding. Hypoprothrombinemia, a deficiency in prothrombin, is characterized by a tendency to prolonged bleeding. It is usually associated with a lack of vitamin K, which is necessary for the synthesis of prothrombin in the liver cells.