Chapter 15: Body Fluids and Circulation Application Questions | biology Class 11 CBSE

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Chapter 15: Body Fluids and Circulation Application Questions | biology Class 11 CBSE | ByteNotes.in

Application Question

Medium difficulty • Concept in a practical situation

Medium

Question 1

Applied Concept

A patient with blood group A requires emergency blood transfusion but only group O blood is available. With reference to ABO grouping, can this transfusion be safely carried out? Explain.

Yes, group O blood can be safely transfused to a group A patient because group O RBCs carry no A or B antigens on their surface, so the recipient's anti-B antibodies (present in group A plasma) find nothing to attack.
Group O individuals are therefore called universal donors — their blood is compatible with all ABO blood groups (A, B, AB, and O) for this reason.
The group A recipient's plasma contains anti-B antibodies but not anti-A antibodies, so there is no immune-mediated agglutination of the transfused group O RBCs.
However, Rh compatibility must also be verified independently — if the patient is Rh-ve and the donor is Rh+ve, haemolytic reactions can still occur, making complete blood group matching essential even in emergencies.

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Application Question

Hard difficulty • Concept in a practical situation

Hard

Question 2

Applied Concept

An Rh-negative woman is pregnant with her second Rh-positive child. She had no treatment after her first delivery. What medical complication is she at risk for, and why?

She is at risk of erythroblastosis foetalis — during the first delivery, small amounts of Rh+ve foetal blood entered her circulation, causing her immune system to produce anti-Rh antibodies.
In this second Rh+ve pregnancy, maternal anti-Rh antibodies (IgG) can cross the placenta and enter the foetal bloodstream, where they attack and destroy the foetal Rh+ve RBCs.
The resulting massive haemolysis in the foetus causes severe anaemia, jaundice (from bilirubin overload), and can be fatal to the foetus or cause serious postnatal complications.
This complication could have been prevented by administering anti-Rh antibodies to the mother immediately after the first delivery, which would have neutralised foetal Rh antigens before the mother's immune system was sensitised.

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Application Question

Medium difficulty • Concept in a practical situation

Medium

Question 3

Applied Concept

A person has a haemoglobin level of only 8 g per 100 mL of blood instead of the normal 12–16 g. How would this affect the functioning of tissues and what condition does this represent?

Haemoglobin is the oxygen-transporting protein in RBCs; at 8 g/100 mL — well below the normal 12–16 g — the blood's oxygen-carrying capacity is significantly reduced.
Tissues throughout the body will receive insufficient oxygen, leading to symptoms such as fatigue, breathlessness on exertion, pallor, and reduced metabolic efficiency of cells.
This reduction in haemoglobin levels is characteristic of anaemia, which can result from reduced RBC production, haemolysis (e.g., erythroblastosis foetalis), iron deficiency, or chronic blood loss.
Since each ventricle pumps ~5 litres per minute, the heart may compensate by increasing heart rate (cardiac output), but this places additional strain on the cardiovascular system over time.

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Application Question

Medium difficulty • Concept in a practical situation

Medium

Question 4

Applied Concept

During a routine check-up, a doctor records a patient's blood pressure as 155/95 mmHg on three separate visits. What is the diagnosis, what are the risks, and what does the reading signify?

A persistent reading of 155/95 mmHg — well above the normal 120/80 mmHg threshold, and above the hypertension diagnostic criterion of 140/90 mmHg — indicates hypertension.
The systolic value (155 mmHg) represents the pressure exerted on arterial walls during ventricular contraction (pumping phase), while the diastolic value (95 mmHg) reflects arterial pressure during the resting (diastolic) phase.
Persistent hypertension places chronic mechanical stress on arterial walls, accelerating atherosclerosis and increasing the risk of coronary artery disease, heart failure, and stroke.
Hypertension also damages vital organs — it impairs kidney filtration function and can cause hypertensive encephalopathy, making regular blood pressure monitoring and management critical.

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Application Question

Hard difficulty • Concept in a practical situation

Hard

Question 5

Applied Concept

A trained marathon runner has a resting heart rate of 55 beats per minute and a stroke volume of 90 mL. With reference to cardiac output, how does this compare to an untrained person, and what does it signify?

Cardiac output = stroke volume × heart rate; for the trained athlete: 90 mL × 55 = 4,950 mL ≈ 5 litres/min, which is comparable to the average resting cardiac output of 5 litres/min.
An untrained person at rest has a heart rate of ~72 beats/min and a stroke volume of ~70 mL, giving the same cardiac output — but the athlete achieves it with fewer, stronger beats, indicating greater cardiac efficiency.
The athlete's lower resting heart rate (bradycardia) reflects an enlarged, stronger heart muscle (cardiac hypertrophy) developed through training, which pumps more blood per stroke with less effort.
During a race, the athlete can dramatically increase both stroke volume and heart rate — their cardiac output can rise to 20–25 litres/min, far exceeding the capacity of an untrained individual.

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Application Question

Hard difficulty • Concept in a practical situation

Hard

Question 6

Applied Concept

A patient undergoing an ECG shows a very broad, abnormal QRS complex. With reference to the events the QRS complex represents, what cardiac condition might this suggest?

The QRS complex represents the rapid depolarisation of the ventricles, which initiates ventricular contraction (systole); normally it is sharp and narrow, reflecting swift conduction through the Bundle of His and Purkinje fibres.
A broad QRS complex indicates that ventricular depolarisation is taking longer than normal — this typically suggests a bundle branch block, in which conduction through the AV bundle branches is slowed or disrupted.
This delayed conduction means ventricular contraction is not synchronised, reducing pumping efficiency and cardiac output, and the deviation from the normal ECG shape points to a significant cardiac abnormality.
ECG analysis is of great clinical significance — any consistent deviation from the standard P–QRS–T morphology can indicate arrhythmias, infarction, or conduction system disease requiring further investigation.

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Application Question

Medium difficulty • Concept in a practical situation

Medium

Question 7

Applied Concept

A person is diagnosed with a deficiency of platelets (thrombocytopenia). What complication would you expect and why? Refer to the role of platelets in the body.

Platelets (thrombocytes) are cell fragments produced from megakaryocytes in bone marrow; they are the primary cellular agents in blood coagulation, numbering 1,50,000–3,50,000 per mm3 normally.
In thrombocytopenia, the platelet count drops significantly, impairing the coagulation cascade — platelets normally release clotting factors that initiate the conversion of prothrombin to thrombin via thrombokinase.
Without sufficient platelets, the clotting cascade is not properly initiated, resulting in clotting disorders where wounds bleed for abnormally long periods.
In severe cases, spontaneous internal bleeding (haemorrhage) can occur, since even minor capillary damage cannot be sealed efficiently — demonstrating that an adequate platelet count is critical for haemostasis.

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Application Question

Medium difficulty • Concept in a practical situation

Medium

Question 8

Applied Concept

After a high-fat meal, fats are absorbed from the small intestine. With reference to the role of lymph, trace the pathway taken by these fats before they reach the bloodstream.

After digestion, fats are too large to directly enter blood capillaries in the intestinal villi; instead, they are packaged into chylomicrons and absorbed into specialised lymphatic capillaries called lacteals present in each intestinal villus.
The lacteals carry the fat-laden lymph (chyle) into larger lymphatic vessels and eventually into the thoracic duct — the largest lymphatic vessel in the body.
The thoracic duct drains into the left subclavian vein, releasing fat-containing lymph directly into the blood circulation, bypassing the liver's portal system.
This lymphatic route for fat absorption is distinct from the portal blood route used for sugars and amino acids, illustrating that lymph serves as an indispensable conduit for dietary lipid transport in addition to its immune and fluid-balance roles.

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Application Question

Hard difficulty • Concept in a practical situation

Hard

Question 9

Applied Concept

A coronary angiogram reveals significant narrowing of a patient's coronary arteries. What disorder is this, what causes the narrowing, and how does it affect the heart muscle?

The condition is Coronary Artery Disease (CAD), commonly referred to as atherosclerosis — a progressive disease of the arteries that supply blood exclusively to the cardiac musculature.
The narrowing is caused by the deposition of calcium, fat, cholesterol, and fibrous tissues inside the arterial walls (plaque formation), which reduces the lumen (inner diameter) of the coronary arteries.
With a narrowed lumen, blood flow to the cardiac muscle is reduced — during physical exertion the oxygen demand of the heart cannot be met, triggering angina pectoris (acute chest pain).
If a plaque ruptures and completely blocks a coronary artery, the affected region of heart muscle is deprived of blood supply and undergoes ischaemic damage — causing a heart attack (myocardial infarction), which can lead to heart failure.

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Application Question

Medium difficulty • Concept in a practical situation

Medium

Question 10

Applied Concept

During a cardiac surgery simulation exercise, a student is asked to trace blood flow from the vena cava back to the aorta through the heart. Describe this complete pathway.

Deoxygenated blood from the body enters the right atrium via the superior and inferior vena cava; from the right atrium it passes through the tricuspid valve into the right ventricle during ventricular diastole.
During ventricular systole, the right ventricle contracts and forces blood through the semilunar valve of the pulmonary artery into the pulmonary artery, which carries it to the lungs for oxygenation.
Oxygenated blood returns from the lungs via the four pulmonary veins into the left atrium, then passes through the bicuspid (mitral) valve into the left ventricle during diastole.
During systole, the powerful left ventricle contracts and ejects oxygenated blood through the semilunar valve of the aorta into the aorta, from where it is distributed to all body tissues — completing both pulmonary and systemic pathways of double circulation.

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Chapter 15: Body Fluids and Circulation | Application Questions

A patient with blood group A requires emergency blood transfusion but only group O blood is available. With reference to ABO grouping, can this transfusion be safely carried out? Explain.

An Rh-negative woman is pregnant with her second Rh-positive child. She had no treatment after her first delivery. What medical complication is she at risk for, and why?

A person has a haemoglobin level of only 8 g per 100 mL of blood instead of the normal 12–16 g. How would this affect the functioning of tissues and what condition does this represent?

During a routine check-up, a doctor records a patient's blood pressure as 155/95 mmHg on three separate visits. What is the diagnosis, what are the risks, and what does the reading signify?

A trained marathon runner has a resting heart rate of 55 beats per minute and a stroke volume of 90 mL. With reference to cardiac output, how does this compare to an untrained person, and what does it signify?

A patient undergoing an ECG shows a very broad, abnormal QRS complex. With reference to the events the QRS complex represents, what cardiac condition might this suggest?

A person is diagnosed with a deficiency of platelets (thrombocytopenia). What complication would you expect and why? Refer to the role of platelets in the body.

After a high-fat meal, fats are absorbed from the small intestine. With reference to the role of lymph, trace the pathway taken by these fats before they reach the bloodstream.

A coronary angiogram reveals significant narrowing of a patient's coronary arteries. What disorder is this, what causes the narrowing, and how does it affect the heart muscle?

During a cardiac surgery simulation exercise, a student is asked to trace blood flow from the vena cava back to the aorta through the heart. Describe this complete pathway.

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