Tag: biology

Questions Related to biology

The number of possible enantiometric pairs that can be produced during monochorination of 2-methyl butane is:

biology ecology carbon cycling mineral coal carbon cycle

  1. 2

  2. 3

  3. 4

  4. 1

Show answer
Correct Option: A

Purkinje system is spread in 

biology transport in animals cardiac cycle heart, blood vessels and cardiac cycle human heart

  1. Auricle myocardium

  2. Ventricle myocardium

  3. Both A and B

  4. None of the above

Show answer
Correct Option: B
Explanation:

Purkinje system is mainly present in the ventricle myocardium. They spread impulse in ventricles generated by the AV node.

So, the correct answer is option B.

Contraction of heart is 

biology blood circulatory system of human cardiac cycle heart, blood vessels and cardiac cycle human heart

  1. Diastole

  2. Systole

  3. Joint diastole

  4. None of the above

Show answer
Correct Option: B
Explanation:

Systole is defined as the ventricular contraction of heart which occurs between the first and second heart sounds of the cardiac cycle. There is pumping of blood into the aorta and pulmonary trunk and lasts for 0.3-0.4 second. During systole arterial blood pressure is maximum. 

Thus the correct answer is option B.

Frequency of cardiac cycle is described by 

biology blood circulatory system of human cardiac cycle heart, blood vessels and cardiac cycle human heart

  1. Systole

  2. Diastole

  3. Heart-rate

  4. Pulse

Show answer
Correct Option: C
Explanation:

The cardiac cycle refers to a complete heartbeat from its generation to the beginning of the next beat. The frequency of the cardiac cycle or the heart rate is expressed as heart beats per minute.

So, the correct answer is option B.

'Dupp' sound is produced during closure of

biology blood circulatory system of human cardiac cycle heart, blood vessels and cardiac cycle human heart

  1. Semilunar valves

  2. Bicuspid valve

  3. Tricuspid valve

  4. Both B and C

Show answer
Correct Option: A
Explanation:

During each cardiac cycle two prominent sounds are produced, which can be easily heard through a stethoscope. The first heart sound (lubb) is associated with the closure of the tricuspid and bicuspid valves, whereas the second heart sound (dupp / dubb) is associated with the closure of the semilunar valves. These sounds are of clinical diagnostic significance.

 Heart rate of man is mainly controlled by

biology blood circulatory system of human cardiac cycle heart, blood vessels and cardiac cycle human heart

  1. SA node

  2. Ventricles

  3. Purkinje fibers

  4. AV node

Show answer
Correct Option: A
Explanation:

The cardiac cycle is regulated by specialized areas in the heart wall, that forms the conduction system of the heart. Two of these areas are tissue mass, called as nodes; the third is a group of fibers called as the atrioventricular bundle. 

The sinoatrial node, which is located in the upper wall of the right atrium and initiates the heartbeat, is called as the pacemaker. 
The second node, located in the interatrial septum at the bottom of the right atrium, is called as the atrioventricular node. 
The atrioventricular bundle, also known as the bundle of His, is located at the top of the interventricular septum. It has branches, that extend to all parts of the ventricle walls. Our heart normally beats 70-75 times in a minute (average 72 beats/min).

'Bundle of His' is a network of

biology transport in animals cardiac cycle heart, blood vessels and cardiac cycle human heart

  1. Muscle fibres distributed throughout the heart walls

  2. Muscle fibres found only in the ventricle wall

  3. Nerve fibres distributed in ventricles

  4. Nerve fibres found throughout the heart

Show answer
Correct Option: B
Explanation:

'Bundle of His' is a network of muscle fibres, found in the walls of ventricles. They originate from AV node and further give rise to Purkinje fibres. This helps in maintaining the rhythmic contraction of the ventricles. 

The pace-setter in the heart is called as

biology transport in animals cardiac cycle heart, blood vessels and cardiac cycle human heart

  1. Purkinje fibres

  2. Sino-atrial node (SAN)

  3. Papillary muscle

  4. Atrio-ventricular node (AVN)

Show answer
Correct Option: D
Explanation:

The cardiac impulse is initiated in the sino-atrial node also known as natural pacemaker. It then travels to the atrio-ventricular node. From there through the Purkinje fibres to the ventricles. The atrio-ventricular node regulates the rhythm of the heart rate mainly. The delay in conduction of impulse in this node changes the duration of contraction between the atria and the ventricles. Hence AV node is called as the pace-setter.

________ caries blood from right ventricles to lungs.

biology transport in mammals cardiac cycle heart, blood vessels and cardiac cycle human heart

  1. Superior vena cava

  2. Inferior vena cava

  3. Pulmonary arteries

  4. Pulmonary veins

Show answer
Correct Option: C
Explanation:
The pulmonary artery is a blood vessel which delivers impure blood from right ventricles to lungs for the oxygenation. Pulmonary artery begins from the base of the right ventricle. As it leaves the heart it divides into two branches left and right pulmonary artery. The left and right branches bring their de-oxygenated blood to the corresponding left and right lungs.
So, the correct answer is 'Pulmonary arteries'.

Heart beat is accelerated by

biology transport in animals cardiac cycle heart, blood vessels and cardiac cycle human heart

  1. Sympathetic nerves and noradrenaline

  2. Cranial nerves and adrenaline

  3. Cranial nerves and acetylcholine

  4. Sympathetic nerves and acetylcholine

Show answer
Correct Option: A
Explanation:

A normal heart rate is 60 to 80 beats per minute. However, in certain conditions, the heart beat is accelerated. The major system involved in acceleration of heartbeat is sympathetic nervous system. It releases hormones like adrenaline and noradrenaline during stress or excitement. Exercise also stimulates sympathetic nervous system to accelerate the heartbeat. Apart from heartbeat, sympathetic nervous system and noradrenaline constricts blood vessels, goose bumps, sweating, increased blood pressure, dilation of pupil.

Thus, the correct answer is 'Sympathetic nerves and noradrenaline.'