One of the factors required for the maturation of erythrocytes is
(a) vitamin - D
(b) vitamin - A
(c) vitamin - B12
(d) vitamin - C
(c) Vitamin-B12 (cobalamin) promotes DNA synthesis, maturation of erythrocytes and myelin formation. Vitamin-D (calciferol), It is necessary for the formation of healthy bones and teeth.
Vitamin-A (retinol), It is necessary for proper body growth and night vision. Vitamin-C (ascorbic acid), It helps in wound healing, blood formation and absorption of iron.
Vitamin-K is required for
(a) change of prothrombin to thrombin
(b) synthesis of prothrombin
(c) change of fibrinogen to fibrin
(d) formation of thromboplastin
(b) Vitamin-K is essential for the formation of prothrombin from liver cells, so helps in blood coagulation. Vitamin-K is also known as antihaemorrhagic factor or phylloquinone.
The thick muscular projections on the walls of the ventricle are called
(a) Chordae tendineae
(b) Columnae carneae
(c) Conus arteriosus
(d) Truncus arteriosus
The trabeculae carneae (columnae carneae, or meaty ridges), are rounded or irregular muscular columns which project from the inner surface of the right and left ventricles of the heart.
The chordae tendineae (tendinous chords), collectively known as the heart strings, are cord-like tendons that connect the papillary muscles to the tricuspid valve and the bicuspid valve in the heart.
Some of the columnae carneae are large and conical and are known as papillary muscles.
Which of the following is a correct statement?
1. The volume of blood in pulmonary circulation is more than the volume of blood in systemic circulation at any instant.
2. The blood pressure in pulmonary circulation is less than that of the systemic circulation
3. Double circulation is characteristic of all vertebrates
4. A double aortic arch is seen in birds and mammals.
2. Under normal physiological conditions, the volumes in the two circuits would be equal. Normally, the heart pumps the blood it receives.
When type B agglutinogen is not present on the surface of RBC of a person, his plasma would contain ____ agglutinins.
1. Anti-a 2. Anti-b
3. Both anti-a and anti-b 4. None
2. Agglutinogen is antigen and aggluttinin is the antibody. The plasma will contain the antibody against the antibody against that is not present on the RBC.
Oxalates and citrates are used as anticoagulants in stored blood because they:
1. Chelate calcium ions
2. Act as competitive inhibitors of vitamin K
3. Potentiate anti-thrombin III
4. Activate heparin
1. Each step of blood clotting requires the presence of calcium ions. Non-availability due to chelation will lead to their anti-coagulant effect.
With respect to blood, the composition of lymph can be expressed as:
(1) No RBc, No Plateletes, Less proteins, Less calcium and phosphorus, Predominant corpuscles lymphocytes.
(2) No RBc, No Plateletes, Less proteins, More calcium and phosphorus, Predominant corpuscles lymphocytes.
(3) No RBc, Less Plateletes, Less proteins, Less calcium and phosphorus, Predominant corpuscles macrophages.
(4) No RBc, less Plateletes, Less proteins, Less calcium and phosphorus, Predominant corpuscles monocytes.
Histamine in blood is secreted by:
1. Mast cells
Answer 4. Read page 279, XI NCERT
A person with AB blood group:
1. Has A and B antigens in his plasma
2. Lacks any antibodies on RBC surface
3. Can receive blood transfusion from a person of his own group.
4. Can donate blood to all other group recipients
Answer 3. Read page 280, Table 18.1, XI NCERT
The inter-atrial septum in the human heart can be best described as:
1. A thin muscular wall
2. A thick muscular wall
3. A thin fibrous tissue
4. A thick fibrous tissue
Read page 283, XI NCERT