Tag: biology

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Multiple choice biology ecology carbon cycling mineral coal carbon cycle

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

  1. 2

  2. 3

  3. 4

  4. 1
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Monochlorination of 2-methylbutane can occur at four different carbon positions. The products formed at the chiral center (C2) result in a pair of enantiomers. The other positions do not create new chiral centers in this specific molecule, resulting in 2 enantiomeric pairs total.

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

Contraction of heart is 

  1. Diastole

  2. Systole

  3. Joint diastole

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Frequency of cardiac cycle is described by 

  1. Systole

  2. Diastole

  3. Heart-rate

  4. Pulse
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

'Dupp' sound is produced during closure of

  1. Semilunar valves

  2. Bicuspid valve

  3. Tricuspid valve

  4. Both B and C
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

 Heart rate of man is mainly controlled by

  1. SA node

  2. Ventricles

  3. Purkinje fibers

  4. AV node
Reveal answer Fill a bubble to check yourself
A Correct answer
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).

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

'Bundle of His' is a network of

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
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. 

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

The pace-setter in the heart is called as

  1. Purkinje fibres

  2. Sino-atrial node (SAN)

  3. Papillary muscle

  4. Atrio-ventricular node (AVN)
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

________ caries blood from right ventricles to lungs.

  1. Superior vena cava

  2. Inferior vena cava

  3. Pulmonary arteries

  4. Pulmonary veins
Reveal answer Fill a bubble to check yourself
C Correct answer
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'.
Multiple choice biology transport in animals cardiac cycle heart, blood vessels and cardiac cycle human heart

Heart beat is accelerated by

  1. Sympathetic nerves and noradrenaline

  2. Cranial nerves and adrenaline

  3. Cranial nerves and acetylcholine

  4. Sympathetic nerves and acetylcholine
Reveal answer Fill a bubble to check yourself
A Correct answer
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.'