ABO blood groups in humans are controlled by the gene I. It has three alleles – I^A I^B and i. Since there are three different alleles, six different genotypes are possible. How many phenotypes can occur?

Three
One
Four
Two

Solution

The three alleles in ABO blood groups in humans can produce six different genotypes and four different phenotypes.

Genotypes Phenotypes

I^AI^A,I^A_i Blood group A

I^BI^B, I^B_i Blood group B

I^AI^B Blood group AB

i i Blood group O

Genotypes	Phenotypes
I^AI^A,I^A_i	Blood group A
I^BI^B, I^B_i	Blood group B
I^AI^B	Blood group AB
i i	Blood group O

Globulins contained in human blood plasma are primarily involved in :

osmotic balance of body fluids
oxygen transport in the blood
clotting of blood
defence mechanisms of body

Solution

Globulins contained in human blood plasma are primarily involved, in defence mechanism of body. Globulin is one of the two types of serum proteins, the other beingalbumin. Globulins can be divided into three fractions based on their electrophoretic mobility. Most of the alpha and beta globulins are synthesized by the liver,whereas gamma globulins are produced by lymphocytes and plasma cells in lymphoid tissue

In a standard ECG which one of the following alphabets is the correct representation of the respective activity of the human heart?

S - start of systole
T - end of diastole
P - depolarisation of the atria
R - repolarisation of ventricles

Solution

In a standard ECG, the P-wave is a small upward wave that indicates the depolarisation of the atria. This is caused by the activation of SA node.

If due to some injury the chordae tendinae of the tricuspid valve of the human heart is partially non – functional, what will be the immediate effect?

The flow of blood into the aorta will be slowed down
The ‘pacemaker’ will stop working
The blood will tend to flow back into the left atrium
The flow of blood into the pulmonary artery will be reduced.

Solution

Tricuspid valve is the valve in the heart between the right atrium and right ventricle. The valve opens to allow blood to flow from atrium into the ventricle. Thus if tricuspid valve is partially non-functional, then the flow of blood into the pulmonary artery will be reduced.

What is true about RBCs in humans?

They carry about 20–25 per cent of CO₂
They transport 99.5 per cent of O₂
They transport about 80 per cent oxygen only and the rest 20 per cent of it is transported in dissolved state in blood plasma
They do not carry CO₂ at all.

Solution

Blood transports oxygen from respiratory organs to the tissue cells and also transports carbon dioxide from the tissue cells to the respiratory membrane. About 97% of oxygen is transported by RBCs in the blood while the remaining three percent of oxygen is carried in a dissolved state through plasma. Nearly 20-25% of carbondioxide is transported by RBCs whereas 70% is carried as bicarbonate. About 7% of CO₂ is carried in dissolved state through plasma.

Which one of the following human organs is often called the graveyard of RBCs?

Gall bladder
Kidney
Spleen
Liver

Solution

Spleen is an organ of the lymphatic system located in the left side of the abdominal cavity under the diaphragm,the muscular partition between the abdomen and the chest. It is called graveyard of RBC because fragment of red blood cells, old and dead cells are constantly being removed from the blood streams by it.

People who have migrated from the planes to an area adjoining Rohatang Pass about six months back :

have more RBCs and their haemoglobin has a lower binding affinity to O₂.
are not physically fit to play games like football.
suffer from altitude sickness with symptoms like nausea,fatigue, etc.
have the usual RBC count but their haemoglobin has very high binding affinity to O₂.

Solution

People going to hilly areas will have polycythemia (more number of RBC in blood) after six months and their Hb has a lower binding affinity to O₂.

Compared to those of humans, the erythrocytes in frog are

Without nucleus but with haemoglobin
Nucleated and with haemoglobin
Very much smaller and fewer
Nucleated and without haemoglobin

Solution

The erythrocytes or RBCs in frog are large, oval and biconvex nucleated cell with respiratory red pigment haemoglobin in its cytoplasm.

A certain road accident patient with unknown blood group needs immediate blood transfusion. His one doctor friend at once offers his blood.What was the blood group of the donor?

Blood group B
Blood group AB
Blood group O
Blood group A

Solution

Blood group O acts as universal donor.

First heart sound is

'Lubb' sound end of systole
'dub' or 'dup' sound at end of systole
'lubb' sound at beginning of ventricular systole
'dup' sound at beginning of ventricular systole

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