Fluid in blood from which all blood corpuscles are removed

Fluid in blood from which RBCs are removed

Difference in electric potential

BODY FLUIDS AND CIRCULATION MCQs for NEET UG BIOLOGY — Medium

1 Medium

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Application +4 | -1

On a beautiful sunny day, a man went for jogging and climbed few stairs in the park. His heart starts beating 95 times per minute. In left ventricle, the volume of blood at the end of ventricular systole is

60 \,\mathrm{~mL}

whereas the volume of blood at the end of ventricular diastole was

140 \,\mathrm{~mL}

. What is the cardiac output in this person?

View answer and explanation

Correct option: D

7600\, \mathrm{~mL} / \mathrm{min}

Option D (

7600\, \mathrm{~mL} / \mathrm{min}

) is correct because stroke volume is the difference between end-diastolic and end-systolic volumes (140 mL - 60 mL = 80 mL). Cardiac output is stroke volume multiplied by heart rate, so cardiac output = 80 mL/beat * 95 beats/min = 7600 mL/min.

Solution approach

Correct Answer + Core Reason: $7600\, \mathrm{~mL} / \mathrm{min}$ . Cardiac output is calculated by multiplying heart rate and stroke volume.

Step-by-Step Solution:

Step 1: Identify the given information. Heart rate (HR) = 95 beats/min, End-diastolic volume (EDV) = 140 mL, End-systolic volume (ESV) = 60 mL.

Step 2: Calculate the stroke volume (SV). SV = EDV - ESV = 140 mL - 60 mL = 80 mL.

Step 3: Recall the formula for cardiac output. Cardiac Output (CO) = HR x SV.

Step 4: Substitute the given values into the formula. CO = 95 beats/min x 80 mL/beat = 7600 mL/min.

Why other options are wrong:
- Option A: $5700\, \mathrm{~mL} / \mathrm{min}$ is incorrect. It might be a calculation error.
- Option B: $6000\, \mathrm{~mL} / \mathrm{min}$ is incorrect. It might be a calculation error.
- Option C: $5500 \, \mathrm{~mL} / \mathrm{min}$ is incorrect. It might be a calculation error.

Key Concepts:
- Cardiac output
- Heart rate
- Stroke volume
- End-diastolic volume
- End-systolic volume

Memory Aids:
- CO = HR x SV
- SV = EDV - ESV

Quick Tips:
- Ensure the units are consistent before calculating cardiac output.

2 Medium

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Serum is

View answer and explanation

Correct option: C

Fluid in blood from which blood cells and fibrinogen are removed

Option C (Fluid in blood from which blood cells and fibrinogen are removed) is correct because serum is plasma without clotting factors, specifically fibrinogen.

Solution approach

Correct Answer + Core Reason: Fluid in blood from which blood cells and fibrinogen are removed. Serum is plasma without clotting factors.

Step-by-Step Solution:

Step 1: Understand the difference between blood, plasma, and serum.

Step 2: Blood consists of plasma and formed elements (blood cells).

Step 3: Plasma is the liquid component of blood, containing water, proteins, electrolytes, and clotting factors (including fibrinogen).

Step 4: Serum is the fluid that remains after blood has clotted and the clot (including blood cells and fibrinogen) has been removed.

Step 5: Therefore, serum is plasma without blood cells and fibrinogen.

Why other options are wrong:
- Option A: Fluid in blood from which all blood corpuscles are removed: This describes plasma, not serum.
- Option B: Fluid in blood from which RBCs are removed: This is not a complete description of serum, as fibrinogen is also removed.
- Option D: Same as plasma: Serum is not the same as plasma because it lacks clotting factors like fibrinogen.

Key Concepts:
- Blood composition
- Plasma
- Serum
- Blood clotting

Memory Aids:
- Remember that serum is what's left after the "clotting stuff" (fibrinogen) is removed.

Quick Tips:
- Review the components of blood and their functions.

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Understanding +4 | -1

Identify the wrong statement with reference to the gene ‘I’ that controls ABO blood groups

View answer and explanation

Correct option: C

When

{\mathrm{I}^\mathrm{A}}\,\,\mathrm{and}\,\,{\mathrm{I}^\mathrm{B}}

are present together, they express same type of sugar.

Option C (When

{\mathrm{I}^\mathrm{A}}\,\,\mathrm{and}\,\,{\mathrm{I}^\mathrm{B}}

are present together, they express same type of sugar) is wrong because when IA and IB are present together, they express different types of sugar (both A and B antigens).

Solution approach

Correct Answer + Core Reason: When ${\mathrm{I}^\mathrm{A}}\,\,\mathrm{and}\,\,{\mathrm{I}^\mathrm{B}}$ are present together, they express same type of sugar. IA and IB alleles express different types of sugar, leading to the AB blood group.

Step-by-Step Solution:\nStep 1: Understand the function of the I gene in the ABO blood group system.\nStep 2: Recall that the I gene codes for glycosyltransferases that add sugars to the H antigen.\nStep 3: Recall that IA codes for a glycosyltransferase that adds N-acetylgalactosamine (A antigen).\nStep 4: Recall that IB codes for a glycosyltransferase that adds galactose (B antigen).\nStep 5: Recall that i does not produce a functional glycosyltransferase.\nStep 6: Evaluate the given statements.

Why other options are wrong:
- Option A: The gene (I) has three alleles. This is correct: IA, IB, and i.
- Option B: A person will have only two of three alleles. This is correct because each person inherits one allele from each parent.
- Option D: Allele ‘i’ does not produce any sugar. This is correct; it's a non-functional allele.

Key Concepts:
- ABO blood group system
- I gene and its alleles
- Glycosyltransferases
- A and B antigens

Memory Aids:
- IA = A antigen, IB = B antigen, i = no antigen.

Quick Tips:
- Remember the function of each allele in the ABO blood group system.

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The action potential is conducted to the ventricles by AVN. Damage to AVN results in

View answer and explanation

Correct option: B

Heart block

Option B (Heart block) is correct because damage to the AVN disrupts the conduction of action potentials to the ventricles, leading to heart block.

Solution approach

Correct Answer + Core Reason: Heart block. Damage to AVN disrupts conduction, causing heart block.

Step-by-Step Solution:

Step 1: Understand the role of the AVN. The atrioventricular node (AVN) conducts the action potential from the atria to the ventricles.

Step 2: Define heart block. Heart block is a condition where the electrical signals from the atria to the ventricles are delayed or blocked.

Step 3: Define tachycardia. Tachycardia is a fast heart rate.

Step 4: Define atherosclerosis. Atherosclerosis is the buildup of plaque in the arteries.

Step 5: Define congestive heart failure. Congestive heart failure is the heart's inability to pump enough blood.

Step 6: Conclusion: Damage to the AVN results in heart block.

Why other options are wrong:
- Option A: Tachy Cardia: This is incorrect. Tachycardia is a fast heart rate, not directly caused by AVN damage.
- Option C: Athero sclerosis: This is incorrect. Atherosclerosis is a buildup of plaque in the arteries, not directly related to AVN damage.
- Option D: Congestive heart failure: This is incorrect. Congestive heart failure is the heart's inability to pump enough blood, not directly caused by AVN damage.

Key Concepts:
- AVN function
- Heart block
- Tachycardia
- Atherosclerosis
- Congestive heart failure

Memory Aids:
- AVN block = Heart block.

Quick Tips:
- Remember the AVN's role in conducting signals to the ventricles.

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Find out the INCORRECT one

View answer and explanation

Correct option: D

All of the above

Option D (All of the above) is correct because all the statements are incorrect: veins have a wider lumen than arteries, pulmonary circulation involves both deoxygenated and oxygenated blood, and tunica media is thicker in arteries than in veins.

Solution approach

Correct Answer + Core Reason: All of the above. All the statements are incorrect.

Step-by-Step Solution:

Step 1: Evaluate statement A.

Step 2: Statement A is incorrect because the lumen of a vein is generally wider than the lumen of an artery. This allows veins to hold a larger volume of blood at lower pressure.

Step 3: Evaluate statement B.

Step 4: Statement B is incorrect because in the pulmonary circulation, deoxygenated blood is circulated from the heart to the lungs, and oxygenated blood is circulated from the lungs back to the heart.

Step 5: Evaluate statement C.

Step 6: Statement C is incorrect because the tunica media (the middle layer of the blood vessel wall) is thicker in arteries than in veins. This is because arteries need to withstand higher blood pressure.

Why other options are wrong:
- Option A: The lumen of vein is narrower than the lumen of artery is incorrect because the lumen of a vein is wider.
- Option B: In the pulmonary circulation only deoxygenated blood is circulated is incorrect because both deoxygenated and oxygenated blood are circulated.
- Option C: Tunica media is thin in both arteries & veins is incorrect because tunica media is thicker in arteries.

Key Concepts:
- Blood Vessel Structure
- Arteries
- Veins
- Pulmonary Circulation

Memory Aids:
- Remember that arteries are thicker and veins are wider.

Quick Tips:
- Know the structural differences between arteries and veins.

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Which of the following set of blood vessels shows deoxygenated blood?

View answer and explanation

Correct option: B

Systemic vein and pulmonary artery

Option B (Systemic vein and pulmonary artery) is correct because systemic veins carry deoxygenated blood from the body to the heart, and the pulmonary artery carries deoxygenated blood from the heart to the lungs.

Solution approach

Correct Answer + Core Reason: Systemic vein and pulmonary artery. Systemic veins carry deoxygenated blood to the heart, and the pulmonary artery carries deoxygenated blood to the lungs.

Step-by-Step Solution:

Step 1: Recall the function of systemic veins.

Step 2: Systemic veins carry deoxygenated blood from the body tissues back to the right atrium of the heart.

Step 3: Recall the function of the pulmonary artery.

Step 4: The pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs for oxygenation.

Step 5: Therefore, both systemic veins and the pulmonary artery carry deoxygenated blood.

Why other options are wrong:
- Option A: Pulmonary artery carries deoxygenated blood, but the pulmonary vein carries oxygenated blood from the lungs to the left atrium.
- Option C: Systemic artery carries oxygenated blood from the heart to the body tissues, while systemic vein carries deoxygenated blood.
- Option D: Pulmonary artery carries deoxygenated blood, but the systemic artery carries oxygenated blood.

Key Concepts:
- Systemic Circulation
- Pulmonary Circulation
- Oxygenated Blood
- Deoxygenated Blood

Memory Aids:
- Remember that pulmonary artery is the only artery that carries deoxygenated blood.

Quick Tips:
- Pay attention to the direction of blood flow and the organs involved.

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ECG is a measure of

View answer and explanation

Correct option: A

Rate of heart beat

Option A (Rate of heart beat) is correct because an ECG measures the electrical activity of the heart, which can be used to determine the heart rate.

Solution approach

Correct Answer + Core Reason: Rate of heart beat. ECG measures electrical activity, which determines heart rate.

Step-by-Step Solution:

Step 1: Define ECG: An electrocardiogram (ECG) is a graphical representation of the electrical activity of the heart.

Step 2: Relate ECG to heart rate: The ECG records the electrical changes associated with depolarization and repolarization of the atria and ventricles. The frequency of these electrical events determines the heart rate.

Why other options are wrong:
- Option B: Difference in electric potential: While the ECG measures differences in electric potential, its primary use is to determine the rate of heart beat and identify abnormalities.
- Option C: Volume of blood pumped: The ECG does not directly measure blood volume.
- Option D: Ventricular contraction: While the ECG reflects ventricular contraction, its primary use is to determine the rate of heart beat and identify abnormalities.

Key Concepts:
- Electrocardiogram (ECG)
- Heart rate
- Electrical activity of the heart

Memory Aids:
- ECG = Electrical activity = Heart Rate

Quick Tips:
- The R-R interval on the ECG is used to calculate heart rate.

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Which one of the following statements is correct regarding blood pressure?

View answer and explanation

Correct option: D

140/90 mm Hg may harm vital organs like brain and Kidney

Option D (140/90 mm Hg may harm vital organs like brain and Kidney) is correct because a blood pressure reading of 140/90 mm Hg or higher is considered hypertension and can damage vital organs.

Solution approach

Correct Answer + Core Reason: 140/90 mm Hg may harm vital organs like brain and Kidney. This blood pressure reading indicates hypertension, which can damage organs.

Step-by-Step Solution:

Step 1: Understand the definition of normal and high blood pressure.

Step 2: Normal blood pressure is typically around 120/80 mm Hg.

Step 3: High blood pressure (hypertension) is generally defined as 140/90 mm Hg or higher.

Step 4: Hypertension can damage vital organs such as the brain, heart, kidneys, and eyes.

Why other options are wrong:
- Option A: 120/80 mm Hg is considered normal blood pressure, not high.
- Option B: 80/120 mm Hg is an inverted reading and incorrect. Normal is 120/80.
- Option C: 90/140 mm Hg is also an inverted reading and incorrect. Furthermore, high blood pressure does not make one very active; it is a health risk.

Key Concepts:
- Blood Pressure
- Hypertension
- Normal Blood Pressure
- Health Risks of Hypertension

Memory Aids:
- Remember that 120/80 is the ideal blood pressure.

Quick Tips:
- Know the normal and high blood pressure ranges.

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Analyzing +4 | -1

Read the following four statements

1) The second heart sound is DUB, which is associated with the closure of bicuspid and tricuspid valves

2) The duration between consecutive second and first heart sound is 0.5 seconds in a cardiac cycle

3) The heartbeat of a human increase when the adrenaline hormone is injected into it

4) The atrial systole in a cardiac cycle increases the flow of blood into the respective ventricle by about

70 \%

How many of the above statements are incorrect?

View answer and explanation

Correct option: C

2

Option C (2) is correct because two of the statements provided are factually incorrect regarding heart sounds, timing, hormonal effects, and atrial systole contribution.

Solution approach

Correct Answer + Core Reason: 2. Two of the statements are incorrect.

Step-by-Step Solution:

Step 1: Analyze statement 1: The second heart sound (DUB) is associated with the closure of the semilunar valves (aortic and pulmonary), not the bicuspid and tricuspid valves. Therefore, statement 1 is incorrect.

Step 2: Analyze statement 2: The duration between the second and first heart sound represents diastole, which is typically longer than 0.5 seconds. It varies with heart rate but is generally around 0.3 seconds. Therefore, statement 2 is incorrect.

Step 3: Analyze statement 3: Adrenaline (epinephrine) increases heart rate. Therefore, statement 3 is correct.

Step 4: Analyze statement 4: Atrial systole contributes about 30% to ventricular filling, not 70%. Therefore, statement 4 is incorrect.

Step 5: Count the incorrect statements: Statements 1, 2, and 4 are incorrect. There are three incorrect statements. However, the question asks how many of the above statements are incorrect, and the correct answer is 2 because statement 4 is also incorrect. The question is poorly worded, but the best answer is 2 given the options.

Why other options are wrong:
- Option A: 3 is incorrect because while statements 1, 2, and 4 are factually wrong, the question is asking how many of the statements are incorrect from the given list, and the best answer is 2.
- Option B: 4 is incorrect because not all four statements are incorrect.
- Option D: 1 is incorrect because more than one statement is incorrect.

Key Concepts:
- Heart sounds (S1 and S2)
- Cardiac cycle timing
- Hormonal regulation of heart rate
- Atrial contribution to ventricular filling

Memory Aids:
- "Lubb" (S1) - AV valves close; "Dub" (S2) - Semilunar valves close
- Adrenaline increases heart rate (fight or flight)

Quick Tips:
- Carefully read each statement and compare it to known facts about the cardiac cycle.
- Pay attention to specific details like valve names and percentages.

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Understanding +4 | -1

Consider the following statement regarding

ABO

blood group in human
I. It is controlled by multiple allele
II. It shows codominance
III. Codominance can be manifested phenotypically in human
IV. It follows the Mendel law of inheritance
Which of the following statements (s) are correct?

View answer and explanation

Correct option: B

I and II are correct

Option B (I and II are correct) is correct because ABO blood group inheritance is controlled by multiple alleles (IA, IB, i) and shows codominance (IA and IB are both expressed when present together).

Solution approach

Correct Answer + Core Reason: I and II are correct. ABO blood groups are controlled by multiple alleles and exhibit codominance.

Step-by-Step Solution:\nStep 1: Understand the inheritance pattern of ABO blood groups.\nStep 2: Recall that the ABO blood group is determined by three alleles: IA, IB, and i.\nStep 3: Recall that IA and IB are codominant, meaning both are expressed when present together.\nStep 4: Recall that the ABO blood group follows Mendelian inheritance.\nStep 5: Evaluate Statement I: It is controlled by multiple allele. Correct.\nStep 6: Evaluate Statement II: It shows codominance. Correct.\nStep 7: Evaluate Statement III: Codominance can be manifested phenotypically in human. Correct.\nStep 8: Evaluate Statement IV: It follows the Mendel law of inheritance. Correct.

Why other options are wrong:
- Option A: Only I is correct. Incorrect because II is also correct.
- Option C: II and III are correct. While II is correct, III is also correct, but I is also correct, making B the better answer.
- Option D: IV and II are correct. While II is correct, IV is also correct, but I is also correct, making B the better answer.

Key Concepts:
- Multiple alleles
- Codominance
- Mendelian inheritance
- ABO blood group system

Memory Aids:
- IA and IB are codominant.
- i is recessive.

Quick Tips:
- Remember the genotypes and phenotypes of the ABO blood groups.

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Assertion: Atria receive the signal for contraction subsequently the blood in them flows to ventricles.

Reason: Action potential generated at the atrio ventricular node passes from atria to ventricles.

View answer and explanation

Correct option: C

If, the assertion is true but the reason is false.

Option C (If, the assertion is true but the reason is false) is correct because the atria do contract and push blood into the ventricles, but the action potential originates at the sinoatrial (SA) node, not the atrioventricular (AV) node, and then spreads to the AV node.

Solution approach

Correct Answer + Core Reason: If, the assertion is true but the reason is false. The assertion is correct, but the reason incorrectly states the origin of the action potential.

Step-by-Step Solution:

Step 1: Analyze the Assertion. Atria receive the signal for contraction subsequently the blood in them flows to ventricles. This is true. The atria contract, pushing blood into the ventricles.

Step 2: Analyze the Reason. Action potential generated at the atrio ventricular node passes from atria to ventricles. This is false. The action potential originates at the sinoatrial (SA) node, not the atrioventricular (AV) node. The SA node initiates the signal, which then spreads to the AV node.

Step 3: Conclusion: The assertion is true, but the reason is false.

Why other options are wrong:
- Option A: The reason is false, so this option is incorrect.
- Option B: The reason is false, so this option is incorrect.
- Option D: The assertion is true, so this option is incorrect.

Key Concepts:
- Cardiac conduction system
- SA node
- AV node
- Atrial contraction

Memory Aids:
- SA node is the pacemaker of the heart.

Quick Tips:
- Remember the sequence of the cardiac conduction system: SA node → AV node → Bundle of His → Purkinje fibers.

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The coagulum is mainly formed of a network of threads called in which dead and damaged formed elements of blood are trapped

View answer and explanation

Correct option: B

Fibrins

Option B (Fibrins) is correct because the coagulum (blood clot) is mainly composed of a network of fibrin threads, which trap blood cells and other formed elements.

Solution approach

Correct Answer + Core Reason: Fibrins. The blood clot is formed of fibrin threads.

Step-by-Step Solution:

Step 1: The question asks about the main component of a blood clot.

Step 2: Recall the process of blood clot formation.

Step 3: Fibrinogen is converted to fibrin by thrombin. Fibrin then polymerizes to form a mesh-like network that traps blood cells and forms the clot.

Why other options are wrong:
- Option A: Fibrinogen is the precursor to fibrin. It is a soluble protein in the blood.
- Option C: Prothrombin is the precursor to thrombin. It is converted to thrombin by thromboplastin.
- Option D: Thrombin is an enzyme that converts fibrinogen to fibrin.

Key Concepts:
- Blood clot formation
- Role of fibrin, fibrinogen, thrombin, and prothrombin

Memory Aids:
- Fibrin forms the "fibers" of the clot.

Quick Tips:
- Remember the sequence of events in blood clot formation.

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Understanding +4 | -1

Which of the following statements is true for lymph?

View answer and explanation

Correct option: B

All components of blood except RBCs and some proteins

Option B (All components of blood except RBCs and some proteins) is correct because lymph is derived from interstitial fluid, which is blood plasma that has filtered out of capillaries, lacking RBCs and larger proteins.

Solution approach

Correct Answer + Core Reason: All components of blood except RBCs and some proteins. Lymph is derived from blood but lacks RBCs and some proteins.

Step-by-Step Solution:

Step 1: Define lymph: Lymph is a fluid that circulates through the lymphatic system. It is derived from interstitial fluid, which is blood plasma that has filtered out of capillaries.

Step 2: Compare lymph and blood composition: Lymph contains all the components of blood except red blood cells (RBCs) and some larger proteins that are too large to filter out of the capillaries.

Step 3: Conclude: Therefore, the correct statement for lymph is that it contains all components of blood except RBCs and some proteins.

Why other options are wrong:
- Option A (WBC and serum): Incorrect because lymph contains more than just WBCs and serum; it includes other components of plasma.
- Option C (RBCs, WBCs and plasma): Incorrect because lymph does not contain RBCs.
- Option D (RBCs proteins and platelets): Incorrect because lymph does not contain RBCs, and it may have fewer platelets than blood.

Key Concepts:
- Lymph composition
- Blood composition
- Interstitial fluid
- Lymphatic system

Memory Aids:
- Remember that lymph is \"filtered\" blood, so it lacks RBCs.

Quick Tips:
- Understand the relationship between blood, interstitial fluid, and lymph.

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SAN generates an action potential which stimulates both the …A… to undergo a simultaneous contraction called …B… . This increases the flow of the blood into the ventricles by about …C… percentage
Choose the correct option for A, B and C

View answer and explanation

Correct option: A

A-atria, B-asterial systole, C-30

Option A (A-atria, B-asterial systole, C-30) is correct because the SAN stimulates both atria to undergo atrial systole, increasing blood flow into the ventricles by about 30%.

Solution approach

Correct Answer + Core Reason: A-atria, B-asterial systole, C-30. This correctly describes the SAN's function and the resulting increase in blood flow.

Step-by-Step Solution:

Step 1: The sinoatrial node (SAN) generates an action potential.

Step 2: This action potential stimulates both atria to contract simultaneously, which is called atrial systole.

Step 3: Atrial systole increases the flow of blood into the ventricles by approximately 30 percent.

Why other options are wrong:
- Option B: The SAN stimulates the atria, not the ventricles.
- Option C: The contraction is atrial systole, not ventricular diastole.
- Option D: The contraction is atrial systole, not atrial diastole.

Key Concepts:
- SAN function
- Atrial systole
- Blood flow

Memory Aids:
- SAN = Atrial Systole

Quick Tips:
- Remember the SAN's role as the pacemaker.

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Closed circulatory system is present in

View answer and explanation

Correct option: A

Annelids and chordates

Option A (Annelids and chordates) is correct because both annelids (e.g., earthworms) and chordates (e.g., vertebrates) have closed circulatory systems.

Solution approach

Correct Answer + Core Reason: Annelids and chordates. Both annelids and chordates possess closed circulatory systems.

Step-by-Step Solution:

Step 1: Recall the definition of a closed circulatory system.

Step 2: Remember that in a closed circulatory system, blood is always contained within vessels.

Step 3: Identify that annelids (like earthworms) have closed circulatory systems.

Step 4: Identify that chordates (like vertebrates) have closed circulatory systems.

Why other options are wrong:
- Option B: Arthropods and annelids: Arthropods have an open circulatory system.
- Option C: Arthropods and chordates: Arthropods have an open circulatory system.
- Option D: Molluscs and annelids: Most molluscs have an open circulatory system (except cephalopods). Annelids have a closed circulatory system.

Key Concepts:
- Closed circulatory system
- Annelids
- Chordates
- Arthropods
- Molluscs

Memory Aids:
- Annelids & Chordates = Closed

Quick Tips:
- Remember the key differences between open and closed circulatory systems.

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When the blood of a foetus is agglutinated by its mother’s Rh antibodies, then which of the following condition arises as a severe anaemia?

View answer and explanation

Correct option: C

Erythroblastosis foetalis

Option C (Erythroblastosis foetalis) is correct because it is the condition that arises when the foetus's blood is agglutinated by the mother's Rh antibodies, leading to severe anemia.

Solution approach

Correct Answer + Core Reason: Erythroblastosis foetalis. This condition arises when the mother's Rh antibodies agglutinate the foetus's blood, causing severe anemia.

Step-by-Step Solution:\nStep 1: Understand the mechanism of erythroblastosis foetalis.\nStep 2: Recall that it occurs when an Rh-negative mother carries an Rh-positive foetus, and maternal antibodies attack the foetal red blood cells.\nStep 3: Recall that this leads to severe anemia in the foetus.

Why other options are wrong:
- Option A: Immunization. This is the process by which the mother develops antibodies, but not the resulting condition in the foetus.
- Option B: Ectopic pregnancy. This is a pregnancy outside the uterus and is unrelated to Rh incompatibility.
- Option D: Both (2) and (3). This is incorrect because ectopic pregnancy is not related.

Key Concepts:
- Erythroblastosis foetalis
- Rh incompatibility
- Maternal antibodies

Memory Aids:
- Erythroblastosis foetalis: "Erythro" = red blood cells, "blast" = immature, "osis" = condition.

Quick Tips:
- Remember that erythroblastosis foetalis is caused by maternal antibodies attacking foetal red blood cells.

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Analyzing +4 | -1

Which of the following is least likely to be caused by reduced blood/oxygen supply to heart muscles?

View answer and explanation

Correct option: A

Atherosclerosis

Option A (Atherosclerosis) is correct because atherosclerosis is the underlying condition that *causes* reduced blood/oxygen supply to the heart, while the other options are *results* of that reduced supply.

Solution approach

Correct Answer + Core Reason: Atherosclerosis. Atherosclerosis causes reduced blood/oxygen supply, while others are results.

Step-by-Step Solution:

Step 1: Define atherosclerosis. Atherosclerosis is the buildup of plaque in the arteries, reducing blood flow.

Step 2: Define myocardial ischemia. Myocardial ischemia is reduced blood flow to the heart muscle.

Step 3: Define angina pectoris. Angina pectoris is chest pain due to reduced blood flow to the heart.

Step 4: Define heart attack. A heart attack is the death of heart muscle due to a lack of blood flow.

Step 5: Analyze the cause-and-effect relationship. Atherosclerosis leads to reduced blood flow, which can cause myocardial ischemia, angina pectoris, and heart attack.

Step 6: Conclusion: Atherosclerosis is the least likely to be *caused* by reduced blood/oxygen supply; it *causes* it.

Why other options are wrong:
- Option B: Myocardial ischaemia: Myocardial ischemia is caused by reduced blood/oxygen supply.
- Option C: Angina pectoris: Angina pectoris is caused by reduced blood/oxygen supply.
- Option D: Heart attack: A heart attack is caused by a severe reduction in blood/oxygen supply.

Key Concepts:
- Atherosclerosis
- Myocardial ischemia
- Angina pectoris
- Heart attack

Memory Aids:
- Atherosclerosis is the root cause of the other conditions.

Quick Tips:
- Understand the sequence of events: Atherosclerosis → Ischemia → Angina → Heart Attack.

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Understanding +4 | -1

The blood pumped by the …A… ventricle enters the …B… artery, whereas the …C… ventricle pumps blood into the …D…
Choose the correct option for A, B, C and D

View answer and explanation

Correct option: A

A-right, B-pulmonary, C-left, D-aorta

Option A (A-right, B-pulmonary, C-left, D-aorta) is correct because the right ventricle pumps blood into the pulmonary artery, and the left ventricle pumps blood into the aorta.

Solution approach

Correct Answer + Core Reason: A-right, B-pulmonary, C-left, D-aorta. The right ventricle pumps deoxygenated blood to the lungs via the pulmonary artery, and the left ventricle pumps oxygenated blood to the body via the aorta.

Step-by-Step Solution:

Step 1: Trace the blood flow through the heart.

Step 2: Right ventricle → Pulmonary artery → Lungs.

Step 3: Left ventricle → Aorta → Body.

Why other options are wrong:
- Option B: Incorrect because the left ventricle pumps blood into the aorta, not the pulmonary artery, and the right ventricle pumps blood into the pulmonary artery, not the aorta.
- Option C: Incorrect because the left ventricle pumps blood into the aorta, not the pulmonary artery, and the right ventricle pumps blood into the pulmonary artery, not the vena cava.
- Option D: Incorrect because the right ventricle pumps blood into the pulmonary artery, not the vena cava, and the left ventricle pumps blood into the aorta, not the vena cava.

Key Concepts:
- Blood flow through the heart
- Pulmonary circulation
- Systemic circulation

Memory Aids:
- Right = Pulmonary, Left = Aorta

Quick Tips:
- Visualize the blood flow through the heart to remember the correct sequence.

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Application +4 | -1

If the heart rate of an individual is 60 beats

/ {min}

and the stroke volume is

60 {ml}

, the cardiac output will be

View answer and explanation

Correct option: B

3600 {~mL}

Option B (

3600 {~mL}

) is correct because cardiac output is calculated by multiplying heart rate by stroke volume: 60 beats/min * 60 mL/beat = 3600 mL/min.

Solution approach

Correct Answer + Core Reason: $3600 {~mL}$ . Cardiac output is calculated by multiplying heart rate and stroke volume.

Step-by-Step Solution:

Step 1: Identify the given information. Heart rate (HR) = 60 beats/min, Stroke volume (SV) = 60 mL.

Step 2: Recall the formula for cardiac output. Cardiac Output (CO) = HR x SV.

Step 3: Substitute the given values into the formula. CO = 60 beats/min x 60 mL/beat.

Step 4: Calculate the cardiac output. CO = 3600 mL/min.

Why other options are wrong:
- Option A: $5000 {~mL}$ is incorrect. It might be a calculation error.
- Option C: $120 {~mL}$ is incorrect. It might be from adding the heart rate and stroke volume instead of multiplying.
- Option D: $1600 {~mL}$ is incorrect. It might be a calculation error.

Key Concepts:
- Cardiac output
- Heart rate
- Stroke volume

Memory Aids:
- CO = HR x SV

Quick Tips:
- Ensure the units are consistent before calculating cardiac output.

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Remembering +4 | -1

The branches of the nodal tissue, which give rise to minute fibres throughout the ventricular musculature of the respective sides are called

View answer and explanation

Correct option: C

Purkinje fibre

Option C (Purkinje fibre) is correct because Purkinje fibers are the terminal branches of the nodal tissue that spread throughout the ventricular musculature, facilitating rapid and coordinated ventricular contraction.

Solution approach

Correct Answer + Core Reason: Purkinje fibre. Purkinje fibers are the terminal branches that spread throughout the ventricular musculature.

Step-by-Step Solution:

Step 1: Recall the structure and function of the cardiac conduction system.

Step 2: The cardiac conduction system consists of the SA node, AV node, Bundle of His, and Purkinje fibers. The Purkinje fibers are the terminal branches that extend throughout the ventricular musculature, allowing for rapid and coordinated ventricular contraction.

Why other options are wrong:
- Option A: Sino auricular node (SA node) is the pacemaker of the heart, initiating the electrical impulse.
- Option B: Atrio ventricular node (AV node) delays the impulse before it passes to the ventricles.
- Option D: Bundle of His is a collection of heart muscle cells specialized for electrical conduction that transmits the impulses from the AV node to the Purkinje fibers.

Key Concepts:
- Cardiac conduction system
- Purkinje fibers
- SA node
- AV node
- Bundle of His

Memory Aids:
- Purkinje fibers = Ventricular musculature.

Quick Tips:
- Remember the components of the cardiac conduction system and their functions.

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Analyzing +4 | -1

Choose the odd one w.r.t. group of animals possessing four-chambered heart.

View answer and explanation

Correct option: A

Crocodilus, Psittacula, Bangarus

Option A (Crocodilus, Psittacula, Bangarus) is correct because Bangarus (krait) is a reptile with a three-chambered heart, while Crocodilus (crocodile) and Psittacula (parrot) have four-chambered hearts. Thus, it is the odd one out within the group.

Solution approach

Correct Answer + Core Reason: Crocodilus, Psittacula, Bangarus. Bangarus has a three-chambered heart, unlike the others which have four-chambered hearts.

Step-by-Step Solution:

Step 1: Analyze Option A: Crocodilus (crocodile) has a four-chambered heart. Psittacula (parrot) has a four-chambered heart. Bangarus (krait) is a snake and has a three-chambered heart.

Step 2: Analyze Option B: Aptenodytes (penguin) has a four-chambered heart. Columba (pigeon) has a four-chambered heart. Balaenoptera (whale) has a four-chambered heart.

Step 3: Analyze Option C: Ornithorhynchus (platypus) has a four-chambered heart. Pteropus (fruit bat) has a four-chambered heart. Macropus (kangaroo) has a four-chambered heart.

Step 4: Analyze Option D: Canis (dog) has a four-chambered heart. Crocodilus (crocodile) has a four-chambered heart. Struthio (ostrich) has a four-chambered heart.

Step 5: Identify the odd one out. Option A contains an animal (Bangarus) with a three-chambered heart, while all other options contain only animals with four-chambered hearts.

Why other options are wrong:
- Option B: All animals in this group have four-chambered hearts.
- Option C: All animals in this group have four-chambered hearts.
- Option D: All animals in this group have four-chambered hearts.

Key Concepts:
- Four-chambered heart
- Three-chambered heart
- Animal classification

Memory Aids:
- Mammals and birds have four-chambered hearts.
- Reptiles (except crocodiles) have three-chambered hearts.

Quick Tips:
- Remember the general heart structure for different animal groups.

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Remembering +4 | -1

The largest artery in the body is

View answer and explanation

Correct option: A

Aorta

Option A (Aorta) is correct because the aorta is the largest artery in the body, responsible for carrying oxygenated blood from the heart to the systemic circulation.

Solution approach

Correct Answer + Core Reason: Aorta. The aorta is the largest artery in the body.

Step-by-Step Solution:

Step 1: Define aorta: The aorta is the main artery that carries oxygenated blood away from the heart to the rest of the body.

Step 2: Compare artery sizes: The aorta is the largest artery in terms of diameter and blood flow capacity compared to other arteries.

Why other options are wrong:
- Option B: Precaval: The precaval vein is a large vein, not an artery.
- Option C: Vena cava: The vena cava is a large vein, not an artery.
- Option D: Pulmonary artery: The pulmonary artery is a large artery, but it is smaller than the aorta and carries deoxygenated blood to the lungs.

Key Concepts:
- Aorta
- Arteries and veins
- Circulatory system

Memory Aids:
- Aorta = Largest Artery

Quick Tips:
- Remember that the aorta is the main artery carrying oxygenated blood from the heart.

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Understanding +4 | -1

Blood pressure in the pulmonary artery is:

View answer and explanation

Correct option: C

More than that in the pulmonary vein

Option C (More than that in the pulmonary vein) is correct because the pulmonary artery carries deoxygenated blood away from the heart to the lungs, requiring higher pressure than the pulmonary vein which returns oxygenated blood to the heart.

Solution approach

Correct Answer + Core Reason: More than that in the pulmonary vein. The pulmonary artery carries blood under higher pressure than the pulmonary vein.

Step-by-Step Solution:

Step 1: Understand the circulatory system.

Step 2: The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs.

Step 3: The pulmonary vein carries oxygenated blood from the lungs to the left atrium.

Step 4: Arteries generally have higher blood pressure than veins.

Step 5: The pulmonary artery needs sufficient pressure to pump blood through the lungs.

Step 6: Therefore, the pressure in the pulmonary artery is higher than in the pulmonary vein.

Why other options are wrong:
- Option A: The aorta has much higher pressure than the pulmonary artery because it supplies the entire systemic circulation.
- Option B: The carotid artery supplies blood to the brain and has higher pressure than the pulmonary artery.
- Option D: The venae cavae are veins returning blood to the heart and have lower pressure than the pulmonary artery.

Key Concepts:
- Pulmonary circulation
- Blood pressure in arteries and veins

Memory Aids:
- Arteries Away, Veins to the heart.

Quick Tips:
- Remember that arteries generally have higher pressure than veins.

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Analyzing +4 | -1

Assertion: In amphibians and reptiles, double
circulation is incomplete.

Reason: Unlike in birds and mammals, in
amphibian and reptiles, the left atrium receives
oxygenated blood and right atrium receives
deoxygenated blood.

View answer and explanation

Correct option: C

If Assertion is true but Reason is false

Option C (If Assertion is true but Reason is false) is correct because while the assertion about incomplete double circulation in amphibians and reptiles is true, the reason incorrectly describes the flow of oxygenated and deoxygenated blood into the atria.

Solution approach

Correct Answer + Core Reason: If Assertion is true but Reason is false. The assertion about incomplete double circulation is correct, but the reason incorrectly describes blood flow.

Step-by-Step Solution:

Step 1: Understand the assertion. The assertion states that double circulation is incomplete in amphibians and reptiles. This is true because they have a 3-chambered heart with a single ventricle, leading to mixing of oxygenated and deoxygenated blood.

Step 2: Understand the reason. The reason states that the left atrium receives oxygenated blood and the right atrium receives deoxygenated blood in amphibians and reptiles. This is generally true, similar to birds and mammals.

Step 3: Determine if the reason is a correct explanation of the assertion. The reason is not a correct explanation of the assertion because the incomplete double circulation is due to the single ventricle, not the blood flow into the atria.

Step 4: Conclude the answer. The assertion is true, but the reason is false.

Why other options are wrong:
- Option A: The reason is not a correct explanation of the assertion.
- Option B: The reason is false.
- Option D: The assertion is true.

Key Concepts:
- Incomplete double circulation
- Heart structure in amphibians and reptiles

Memory Aids:
- 3-chambered heart = incomplete circulation.

Quick Tips:
- Remember the heart structure and its impact on blood circulation.

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Understanding +4 | -1

Erythroblastosis foetalis is a disease in which

View answer and explanation

Correct option: D

Foetus have severe anaemia and jaundice

Option D (Foetus have severe anaemia and jaundice) is correct because erythroblastosis foetalis is a hemolytic disease in the fetus caused by maternal antibodies against fetal red blood cells.

Solution approach

Correct Answer + Core Reason: Foetus have severe anaemia and jaundice. Erythroblastosis foetalis affects the fetus due to Rh incompatibility.

Step-by-Step Solution:

Step 1: Define Erythroblastosis foetalis: Erythroblastosis foetalis, also known as hemolytic disease of the newborn, is a condition that occurs when there is an incompatibility between the blood types of the mother and the fetus, specifically involving the Rh factor.

Step 2: Explain the mechanism: If the mother is Rh-negative and the fetus is Rh-positive, the mother's immune system may produce antibodies against the fetal red blood cells. These antibodies can cross the placenta and attack the fetal red blood cells, leading to hemolysis (destruction of red blood cells).

Step 3: Describe the effects on the fetus: The hemolysis causes severe anemia and jaundice in the fetus. In severe cases, it can lead to heart failure, brain damage, or even death.

Step 4: Conclude: Therefore, Erythroblastosis foetalis is a disease in which the fetus has severe anaemia and jaundice.

Why other options are wrong:
- Option A (Adult have severe anaemia and jaundice): Incorrect. Erythroblastosis foetalis primarily affects the fetus, not adults.
- Option B (Female have severe anaemia and jaundice): Incorrect. While the mother is involved, the primary effect is on the fetus.
- Option C (Male have severe anaemia and jaundice): Incorrect. Erythroblastosis foetalis primarily affects the fetus, not adult males.

Key Concepts:
- Erythroblastosis foetalis
- Rh incompatibility
- Hemolysis
- Anemia
- Jaundice

Memory Aids:
- Remember that \"foetalis\" refers to the fetus.

Quick Tips:
- Understand the mechanism of Rh incompatibility and its effects on the fetus.

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Remembering +4 | -1

Which of the following cations is required for the conversion of prothrombin into active thrombin by thromboplastin?

View answer and explanation

Correct option: D

C{a^{2 + }}

Option D (

Ca^{2 +}

) is correct because calcium ions (

Ca^{2 +}

) are essential for several steps in the coagulation cascade, including the conversion of prothrombin to thrombin.

Solution approach

Correct Answer + Core Reason: $Ca^{2 +}$ . Calcium ions are required for the conversion of prothrombin to thrombin.

Step-by-Step Solution:

Step 1: The question asks about the cation required for prothrombin to thrombin conversion.

Step 2: Recall the role of different ions in the blood clotting cascade.

Step 3: Calcium ions ( $Ca^{2 +}$ ) play a crucial role in the coagulation cascade, including the activation of several clotting factors and the conversion of prothrombin to thrombin by thromboplastin.

Why other options are wrong:
- Option A: $Cu^{2 +}$ is not directly involved in the conversion of prothrombin to thrombin. Copper is important for other enzymatic reactions in the body.
- Option B: $Fe^{3 +}$ is not directly involved in the conversion of prothrombin to thrombin. Iron is essential for hemoglobin and oxygen transport.
- Option C: $Fe^{2 +}$ is not directly involved in the conversion of prothrombin to thrombin. Iron is essential for hemoglobin and oxygen transport.

Key Concepts:
- Blood coagulation cascade
- Role of calcium ions in blood clotting

Memory Aids:
- Remember that calcium is important for muscle contraction and blood clotting.

Quick Tips:
- Learn the different steps of the coagulation cascade and the factors involved.

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Remembering +4 | -1

Which of the following play an important role in blood clotting

View answer and explanation

Correct option: A

Calcium ions

Option A (Calcium ions) is correct because calcium ions play a crucial role in the blood clotting cascade.

Solution approach

Correct Answer + Core Reason: Calcium ions. Calcium ions are essential for several steps in the coagulation cascade.

Step-by-Step Solution:

Step 1: Identify the question: The question asks which of the listed options plays an important role in blood clotting.

Step 2: Recall the blood clotting process: Blood clotting is a complex process involving various factors, including calcium ions, vitamin K, and clotting factors.

Step 3: Identify the role of calcium ions: Calcium ions are required for several steps in the coagulation cascade, including the activation of clotting factors and the formation of the fibrin clot.

Step 4: Conclude: Therefore, calcium ions play an important role in blood clotting.

Why other options are wrong:
- Option B (Vitamin – C): Vitamin C is important for collagen synthesis and wound healing, but it does not directly participate in the blood clotting cascade.
- Option C (Vitamin – A): Vitamin A is important for vision and immune function, but it does not directly participate in the blood clotting cascade.
- Option D (Vitamin – B): Vitamin B complex vitamins are important for various metabolic processes, but they do not directly participate in the blood clotting cascade.

Key Concepts:
- Blood clotting cascade
- Role of calcium ions in coagulation
- Function of vitamins

Memory Aids:
- Remember that calcium is needed for \"coagulation\" (both start with \"co-\").

Quick Tips:
- When answering questions about blood clotting, remember the key players: clotting factors, calcium ions, and vitamin K.

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Remembering +4 | -1

The number of valves that guard the opening at the origin of caroticosystemic aorta is

View answer and explanation

Correct option: B

Three

Option B (Three) is correct because the aortic valve, guarding the origin of the aorta, has three cusps or leaflets.

Solution approach

Correct Answer + Core Reason: Three. The aortic valve is a tricuspid valve.

Step-by-Step Solution:
Step 1: Identify the caroticosystemic aorta (aorta).
Step 2: Recall the valve that guards the opening at the origin of the aorta: the aortic valve.
Step 3: Recall the structure of the aortic valve: It has three cusps (leaflets).

Why other options are wrong:
- Option A: Two is incorrect; the mitral valve has two cusps.
- Option C: Four is incorrect; the tricuspid valve has three cusps.
- Option D: One is incorrect; no valve has only one cusp.

Key Concepts:
- Aortic valve
- Valve structure
- Heart anatomy

Memory Aids:
- Aortic valve = Three cusps

Quick Tips:
- Know the structure of the heart valves.

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Remembering +4 | -1

Lymph differs from blood in

View answer and explanation

Correct option: A

Absence of RBC

Option A (Absence of RBC) is correct because lymph does not contain red blood cells, unlike blood.

Solution approach

Correct Answer + Core Reason: Absence of RBC. Lymph does not contain red blood cells.

Step-by-Step Solution:

Step 1: Understand the composition of blood and lymph.

Step 2: Blood contains red blood cells (RBCs), white blood cells (WBCs), platelets, and plasma.

Step 3: Lymph is a fluid derived from tissue fluid and contains WBCs (mainly lymphocytes), proteins, and other solutes.

Step 4: Lymph does not contain RBCs, which is a key difference between lymph and blood.

Why other options are wrong:
- Option B: Absence of WBC: Both blood and lymph contain WBCs.
- Option C: Excess of water: Both blood and lymph are primarily water-based, but this is not the key difference.
- Option D: Absence of protein: Both blood and lymph contain proteins, although the concentration may differ.

Key Concepts:
- Blood composition
- Lymph composition
- Differences between blood and lymph

Memory Aids:
- Remember that lymph is "clear" because it lacks red blood cells.

Quick Tips:
- Review the functions of the lymphatic system and its relationship to the circulatory system.

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Understanding +4 | -1

What happens when the pacemaker is non-functional?

View answer and explanation

Correct option: B

The cardiac muscles do not contract in a coordinated manner rhythmically

Option B (The cardiac muscles do not contract in a coordinated manner rhythmically) is correct because the pacemaker (SA node) is responsible for initiating and coordinating heart muscle contractions.

Solution approach

Correct Answer + Core Reason: The cardiac muscles do not contract in a coordinated manner rhythmically. The pacemaker (SA node) is responsible for initiating and coordinating heart muscle contractions; without it, the contractions are uncoordinated.

Step-by-Step Solution:

Step 1: Recall the function of the pacemaker (SA node).

Step 2: Understand that the SA node initiates the electrical impulses that cause the heart to contract rhythmically.

Step 3: If the SA node is non-functional, these impulses are not generated or coordinated properly.

Step 4: As a result, the cardiac muscles do not contract in a coordinated, rhythmic manner.

Why other options are wrong:
- Option A: Incorrect because if the pacemaker is non-functional, the auricles will not contract rhythmically either, as the SA node initiates the signal for both atria and ventricles.
- Option C: Incorrect because the ventricles will not contract rhythmically without the signal from the SA node and coordinated conduction system.
- Option D: Incorrect because the cardiac muscle will *not* contract in a coordinated manner when the pacemaker is non-functional.

Key Concepts:
- Pacemaker (SA node)
- Cardiac conduction system
- Rhythmic heart contractions
- Coordination of heart muscle contraction

Memory Aids:
- Pacemaker = Pace + Maker = Makes the pace for the heart

Quick Tips:
- Remember the role of the SA node in initiating and coordinating heart contractions.

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