Tag: biology

Quizzes (1160) Questions (12174)

Questions Related to biology

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

State whether the following statements are true or false.
The first heart sound results from a closure of semilunar valves.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Heart sounds are noises generated by the closing and opening of the heart valves. In a healthy individual, there are two normal heart sounds called lub and dub. Lub is the first heart sound. It is associated with the closure of the tricuspid and bicuspid valves at the beginning of systole. The second heart sound dub is associated with the closure of the semilunar valves at the beginning of diastole.

So, the correct option is 'False'.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

In heart, automatic rhythmic impulse generation capability is present in the

  1. S.A. node

  2. A.V. node

  3. Bundle of His

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The human heart is a muscular structure made up of involuntary cardiac tissues. The pacemaker of the heart or the SA node generates an electrical impulse that travels across the heart muscles and results in a heartbeat. Sometimes activity of SA node is decreased  by vagus cranial nerve then AV node, Bundle of His and Purkinje fibres together provide Autorhythmicity to the heart.

So, the correct answer is 'All of the above'.
Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

Heart sound which is longer is

  1. Lubb

  2. Dub

  3. Both are equal

  4. Sometimes (a) and sometimes (b).
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The first heart sound, 'Lubb', is caused by the closure of the atrioventricular valves. It is longer and lower in pitch compared to the second heart sound, 'Dub', which is caused by the closure of the semilunar valves.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The heart sounds normally heard by a physician while holding a stethoscope onto the left side of the chest of the patient are due to

  1. Contraction of atrial chambers.

  2. Contraction of ventricular chambers.

  3. Closure of the atrioventricular valves.

  4. Relaxation of the semilunar valves.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In healthy adults, there are two normal heart sounds often described as a lub and a dub, that occur in sequence with each heartbeat. These are the first heart sound (S1) and second heart sound (S2), produced by the closing of the atrioventricular valves (AV) and semilunar valves respectively. 

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The heart sound 'dupp' is produced when

  1. Tricuspid valve is opened.

  2. Mitral valve is opened.

  3. Mitral valve is closed.

  4. Semi-lunar at the base of aorta get closed.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Heart sounds are heard on the surface of the chest in the heart region; they are amplified by and heard more distinctly through a stethoscope. They are caused by the vibrations generated during the normal cardiac cycle and may be produced by muscular action, valvular actions, motion of the heart, or blood passing through the heart. The second heart sound (S2) is shorter and higher pitched than the first, is heard as a dupp and is produced by closure of the aortic and pulmonary valves.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The rate of heart beat in a rabbit is nearly

  1. 92 per minute

  2. 100 per minute

  3. 150 - 300 per minute

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

Cardiac output is estimated by heart beat. The amount of blood pumped by the heart per minute is known as cardiac output. Small mammals have high metabolic rates so they faster heart rates than larger-sized mammals. A rabbit at rest normally has a heart rate that ranges from 140 to 180 beats per minute. Stress can cause the heart rate to increase, and the rate in a stressed rabbit can be quite high: well over 300 beats per minute. Therefore the rate of the heartbeat in a rabbit can be ~ 150-300 per minute. 

So, the correct answer is option C.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

Systole is comprised of 

  1. Isovolumetric ventricular contraction

  2. Ventricular ejection

  3. Both A and B

  4. Isovolumetric ventricular relaxation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Systole is the phase of the contraction of the heart while diastole is the phase of the relaxation. During the ventricular systole the following events take place:

1. Isovolumetric ventricular contraction is the phase during which the pressure builds up in the ventricles but it is not enough to open the semi-lunar valves of the pulmonary artery and aorta.
2. The contraction of ventricles continue and reach up to the level where the blood pressure opens up the semi-lunar valves and the blood is ejected out into the pulmonary artery and aorta.
Hence, the correct answer is 'Both A and B'

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The first heart sound is produced when

  1. Intraventricular pressure decreases.

  2. Semilunar valve snaps shut.

  3. Bicuspid and tricuspid valve close quickly.

  4. Diastole begins.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The lub is the first heart sound, commonly termed S1, and is caused by turbulence caused by the closure of mitral and tricuspid valves at the start of systole. The second sound, dub or S2, is caused by the closure of aortic and pulmonary valves, marking the end of systole.

So, the correct answer is option C.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

One heartbeat in an average man lasts  

  1. 0.8 second

  2. 0.2 second

  3. 0.5 second

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

One heartbeat in an average man lasts  0.8 second.

Heart rate, also known as pulse, is the number of times a person's heart beats per minute. A normal heart rate depends on the individual, age, body size, heart conditions, whether the person is sitting or moving, medication use and even air temperature. Even emotions can have an impact on heart rate. For example, getting excited or scared can increase the heart rate. But, most importantly, getting fitter lowers the heart rate, by making heart muscles work more efficiently.