Body Fluids and Circulation — Page 9 | NEET Biology

Q81

'Bundle of His' is a part of which one of the following organs in humans?

A Brain

B Heart

C Kidney

D Pancreas

Correct Answer

Option B

Solution

(b) Bundle of His are cardiac muscle fibres connecting the atria with ventricle.

Q82

Figure shows blood circulation in humans. Identify D - Pulmonary vein.

A A - Artery - thick walled and blood flows evenly

B B - Capillary - thin without muscle layers and wall two cell thick

C C - Vein - thin walled and blood flows in jerks/spurts

D D - Pulmonary vein - takes oxygenated blood to heart PO2=95 mmHg

Correct Answer

Option D

Solution

(d) Pulmonary veins are the only veins which carry oxygenated blood. (PO2=95 mmHg, PCO2=40 mmHg)

Q83

The diagram given here is the standard ECG of a normal person the P-wave represents the :

A Initiation of the ventricular contraction

B Beginning of the systole

C End of systole

D Contraction of both the atria

Correct Answer

Option D

Solution

(d) P-wave represents the electrical excitation (depolarisation) of the atria, leading to the contraction of both the atria.

Q84

How do parasympathetic neural signals affect the working of the heart?

A Reduce both heart rate and cardiac output.

B Heart rate is increased without affecting the cardiac output.

C Both heart rate and cardiac output increase.

D Heart rate decreases but cardiac output increases.

Correct Answer

Option A

Solution

(a) Parasympathetic nervous system decreases heart beat and thereby the cardiac output.

Q85

Which one of the following animals has two separate circulatory pathways?

A Lizard

B Whale

C Shark

D Frog

Correct Answer

Option B

Solution

(b) Whale is a mammal with four chambered heart having two separate circulatory pathways.

Q86

Doctors use stethoscope to hear cardiac cycle sounds. The second sound is heard when:

A Ventricular wall vibrate due to gushing in of blood from atria.

B Semilunar valves close down after the blood flows into vessels from ventricles.

C AV node receives signal from SA node.

D AV valves open up.

Correct Answer

Option B

Solution

(b) The second sound occurs when semilunar valves close down after blood flows into vessels from ventricles.

Q87

Blood pressure in the mammalian aorta is maximum during :

A Diastole of the right ventricle.

B Systole of the left ventricle.

C Diastole of the right atrium.

D Systole of the left atrium.

Correct Answer

Option B

Solution

(b) Aorta arises from left ventricle and blood pressure is maximum during systole of the left ventricle.

Q88

Blood pressure in the pulmonary artery is

A same as that in the aorta.

B more than that in the carotid.

C more than that in the pulmonary vein.

D less than that in the venae cavae.

Correct Answer

Option C

Solution

(c) Arteries have higher blood pressure than veins.

Q89

Match tricuspid valve, bicuspid valve and semilunar valve with their locations

A iii i ii

B i iii ii

C ii i iii

D i ii iii

Correct Answer

Option A

Solution

(a) Tricuspid - between right atrium and right ventricle; Bicuspid - between left atrium and left ventricle; Semilunar - at openings of aorta and pulmonary artery.

Q90

What would be the heart rate of a person if the cardiac output is 5 L, blood volume in the ventricles at the end of diastole is 100 mL and at the end of ventricular systole is 50 mL?

A 50 beats per minute

B 75 beats per minute

C 100 beats per minute

D 125 beats per minute

Correct Answer

Option C

Solution

(c) Stroke volume = 100-50 = 50 ml. Cardiac output = SV x HR. 5000 = 50 x HR. HR = 100 beats per minute.