BODY FLUIDS AND CIRCULATION MCQs for NEET UG BIOLOGY — Medium, Page 3

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A person went to a cardiologist complaining about being tachycardic. Upon examination, his heart rate was 100 beats per minute; his end-diastolic volume was 100 mL, whereas end-systolic volume was 40 mL, whereas end-systolic volume was 40 mL. what was his calculated cardiac output per minute?

View answer and explanation

Correct option: C

6 L

Option C (6 L) is correct because stroke volume is the difference between end-diastolic and end-systolic volumes (100 mL - 40 mL = 60 mL). Cardiac output is stroke volume multiplied by heart rate, so cardiac output = 60 mL/beat * 100 beats/min = 6000 mL/min = 6 L/min.

Solution approach

Correct Answer + Core Reason: 6 L. Cardiac output is calculated by multiplying heart rate and stroke volume.

Step-by-Step Solution:

Step 1: Identify the given information. Heart rate (HR) = 100 beats/min, End-diastolic volume (EDV) = 100 mL, End-systolic volume (ESV) = 40 mL.

Step 2: Calculate the stroke volume (SV). SV = EDV - ESV = 100 mL - 40 mL = 60 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 = 100 beats/min x 60 mL/beat = 6000 mL/min.

Step 5: Convert mL to L. CO = 6000 mL/min = 6 L/min.

Why other options are wrong:
- Option A: 9 L is incorrect. It might be a calculation error.
- Option B: 11 L is incorrect. It might be a calculation error.
- Option D: 12 L 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.

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Animals with complete double circulation are:-

View answer and explanation

Correct option: D

Crocodiles, birds, mammals

Option D (Crocodiles, birds, mammals) is correct because these animals have a four-chambered heart, allowing for complete separation of oxygenated and deoxygenated blood.

Solution approach

Correct Answer + Core Reason: Crocodiles, birds, mammals. These animals have a complete double circulation due to their four-chambered heart.

Step-by-Step Solution:

Step 1: Understand what complete double circulation means (complete separation of oxygenated and deoxygenated blood).

Step 2: Recall the heart structure in different animal groups.

Step 3: Fish have a two-chambered heart (single circulation).

Step 4: Amphibians and most reptiles have a three-chambered heart (incomplete double circulation).

Step 5: Crocodiles, birds, and mammals have a four-chambered heart (complete double circulation).

Why other options are wrong:
- Option A: Fishes have single circulation; crocodile is listed but fishes and birds are not correct.
- Option B: Reptiles are missing, and reptiles do not all have complete double circulation.
- Option C: Reptiles (excluding crocodiles) have incomplete double circulation.

Key Concepts:
- Double Circulation
- Heart Structure
- Animal Phylogeny

Memory Aids:
- Crocodiles are the exception among reptiles; they have a four-chambered heart like birds and mammals.

Quick Tips:
- Remember the evolutionary trend of heart structure and circulation.

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Anti-A and Anti-B antibodies are not found in which of the following blood group?

View answer and explanation

Correct option: A

AB

Option A (AB) is correct because individuals with AB blood group have both A and B antigens on their red blood cells and therefore do not produce anti-A or anti-B antibodies in their plasma.

Solution approach

Correct Answer + Core Reason: AB. Individuals with AB blood group have both A and B antigens and therefore no anti-A or anti-B antibodies.

Step-by-Step Solution:

Step 1: Recall the relationship between antigens and antibodies in the ABO blood group system.

Step 2: Blood group A has A antigens and anti-B antibodies.

Step 3: Blood group B has B antigens and anti-A antibodies.

Step 4: Blood group O has no A or B antigens but has both anti-A and anti-B antibodies.

Step 5: Blood group AB has both A and B antigens and no anti-A or anti-B antibodies.

Why other options are wrong:
- Option B: A blood group has anti-B antibodies.
- Option C: O blood group has both anti-A and anti-B antibodies.
- Option D: B blood group has anti-A antibodies.

Key Concepts:
- ABO blood group system
- Antigens
- Antibodies

Memory Aids:
- Remember the antigens and antibodies present in each blood group.

Quick Tips:
- Understand the relationship between antigens and antibodies to determine blood group compatibility.

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The first heart sound 'Lubb' occurs in which phase of the cardiac cycle?

View answer and explanation

Correct option: C

Ventricular systole

Option C (Ventricular systole) is correct because the first heart sound ('Lubb') is produced by the closure of the atrioventricular (AV) valves at the beginning of ventricular systole.

Solution approach

Correct Answer + Core Reason: Ventricular systole. The "Lubb" sound is caused by the closing of the AV valves at the start of ventricular contraction.

Step-by-Step Solution:
Step 1: Recall the events of the cardiac cycle.
Step 2: Identify the first heart sound ('Lubb'): It's associated with the closure of the atrioventricular (AV) valves (mitral and tricuspid).
Step 3: Relate the closure of AV valves to ventricular systole: The AV valves close at the beginning of ventricular systole to prevent backflow of blood into the atria.
Step 4: Identify the second heart sound ('Dub'): It's associated with the closure of the semilunar valves (aortic and pulmonary) at the beginning of ventricular diastole.

Why other options are wrong:
- Option A: Isometric relaxation occurs after ventricular systole, during which the semilunar valves close, producing the "Dub" sound.
- Option B: Atrial diastole occurs during ventricular filling.
- Option D: Ventricular diastole begins after the "Dub" sound.

Key Concepts:
- Cardiac cycle
- Heart sounds
- Ventricular systole
- Atrioventricular valves

Memory Aids:
- Lubb = AV valves close = Ventricular systole
- Dub = Semilunar valves close = Ventricular diastole

Quick Tips:
- Know the relationship between heart sounds and valve closures.

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Hepatic portal system is a

View answer and explanation

Correct option: A

Vascular connection between the digestive tract and liver

Option A (Vascular connection between the digestive tract and liver) is correct because the hepatic portal system is a specialized vascular pathway that transports blood from the digestive tract to the liver.

Solution approach

Correct Answer + Core Reason: Vascular connection between the digestive tract and liver. The hepatic portal system transports blood from the digestive tract to the liver.

Step-by-Step Solution:

Step 1: Recall the definition of the hepatic portal system.

Step 2: Remember that the hepatic portal system is a specialized vascular pathway.

Step 3: Understand that it connects the digestive tract (primarily the intestines) to the liver.

Step 4: Recognize that this connection allows the liver to process nutrients and toxins absorbed from the digestive system before they enter general circulation.

Why other options are wrong:
- Option B: Vascular connection between the liver and lungs: This describes the pulmonary circulation, not the hepatic portal system.
- Option C: Vascular connection between the spleen and liver: This is part of the overall circulatory system, but not the specific function of the *portal* system.
- Option D: Vascular connection between the digestive tract and spleen: The spleen is part of the lymphatic system and immune response, not directly connected to the digestive tract via a portal system.

Key Concepts:
- Hepatic portal system
- Liver function
- Digestive system

Memory Aids:
- Hepatic = Liver; Portal = Gateway (between digestive tract and liver)

Quick Tips:
- Focus on the liver's role in processing nutrients from the digestive system.

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Maximum surface area of circulating system is seen in

View answer and explanation

Correct option: B

Capillaries

Option B (Capillaries) is correct because capillaries have the largest total surface area in the circulatory system due to their vast number and small size.

Solution approach

Correct Answer + Core Reason: Capillaries. Capillaries have the largest total surface area in the circulatory system, facilitating efficient exchange of gases and nutrients.

Step-by-Step Solution:

Step 1: Consider the structure of the circulatory system. The circulatory system consists of the heart, arteries, arterioles, capillaries, venules, and veins.

Step 2: Define surface area. Surface area refers to the total area exposed to the environment or available for interaction.

Step 3: Compare the surface area of different components. While the heart is a large organ, it doesn't have a large surface area for exchange. Arteries and veins are relatively large vessels but fewer in number compared to capillaries. Capillaries are numerous and have very thin walls, resulting in a vast total surface area.

Step 4: Relate surface area to function. The large surface area of capillaries is essential for efficient exchange of gases, nutrients, and waste products between the blood and tissues.

Why other options are wrong:
- Option A: The heart is a pump, not an exchange surface.
- Option C: Arterioles have a smaller total surface area compared to capillaries.
- Option D: Veins have a smaller total surface area compared to capillaries.

Key Concepts:
- Circulatory system
- Surface area
- Capillary structure and function

Memory Aids:
- Capillaries = Exchange (large surface area for exchange)

Quick Tips:
- Remember that capillaries are the primary site of exchange in the circulatory system due to their large surface area.

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A blockage in aortic valve would directly reduce blood flow to the ______.

View answer and explanation

Correct option: C

Lungs

Option A (Heart) is incorrect. Option C (Lungs) is correct because the aortic valve controls blood flow from the left ventricle into the aorta, which supplies oxygenated blood to the systemic circulation. A blockage would reduce blood flow to the body's organs, including the lungs.

Solution approach

Correct Answer + Core Reason: Lungs. A blockage in the aortic valve would reduce blood flow to the systemic circulation, which includes the lungs.

Step-by-Step Solution:

Step 1: Understand the function of the aortic valve.

Step 2: The aortic valve controls blood flow from the left ventricle into the aorta.

Step 3: The aorta is the main artery that supplies oxygenated blood to the systemic circulation.

Step 4: A blockage in the aortic valve would reduce blood flow to the aorta and, consequently, to the organs supplied by the systemic circulation, including the lungs.

Why other options are wrong:
- Option A: Heart is incorrect because the heart itself receives blood supply from the coronary arteries, which branch off the aorta after the aortic valve.
- Option B: Liver is incorrect because the liver receives blood from the hepatic artery, which branches off the aorta after the aortic valve.
- Option D: Brain is incorrect because the brain receives blood from the carotid arteries, which branch off the aorta after the aortic valve.

Key Concepts:
- Aortic Valve
- Aorta
- Systemic Circulation
- Blood Flow

Memory Aids:
- Trace the path of blood flow from the left ventricle through the aortic valve and into the aorta.

Quick Tips:
- Visualize the circulatory system and the branching of arteries from the aorta.

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The blood does not clot inside the body because of

View answer and explanation

Correct option: C

Heparin in blood

Option C (Heparin in blood) is correct because heparin is an anticoagulant that prevents blood from clotting inside the body.

Solution approach

Correct Answer + Core Reason: Heparin in blood. Heparin is a natural anticoagulant.

Step-by-Step Solution:

Step 1: Recall the process of blood clotting: Blood clotting is a complex process involving various factors.

Step 2: Identify the role of anticoagulants: Anticoagulants prevent blood from clotting.

Step 3: Recognize heparin: Heparin is a naturally occurring anticoagulant in the blood.

Why other options are wrong:
- Option A: Oxygenation does not prevent blood clotting.
- Option B: Movement of blood can help prevent clotting to some extent, but it's not the primary reason.
- Option D: Fibrinogen is necessary for blood clotting, so its absence would prevent clotting, but it is normally present in the blood.

Key Concepts:
- Blood clotting
- Anticoagulants
- Heparin

Memory Aids:
- Heparin prevents clotting.

Quick Tips:
- Remember the role of anticoagulants in the body.

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Normal activities of the heart are regulated

View answer and explanation

Correct option: B

Intrinsically

Option B (Intrinsically) is correct because the heart's normal activities are primarily regulated by its intrinsic mechanisms, such as the sinoatrial (SA) node.

Solution approach

Correct Answer + Core Reason: Intrinsically. The heart's normal activities are regulated by intrinsic mechanisms like the SA node.

Step-by-Step Solution:

Step 1: Understand the difference between intrinsic and extrinsic regulation.

Step 2: Recall that the heart has its own pacemaker (SA node) that initiates and regulates heartbeats.

Step 3: This intrinsic mechanism allows the heart to beat independently, although it can be modulated by extrinsic factors.

Why other options are wrong:
- Option A: Extrinsic regulation involves the nervous and endocrine systems, which modulate the heart's intrinsic activity but don't primarily control it.
- Option C: While both intrinsic and extrinsic factors influence heart activity, the normal activities are primarily intrinsic.
- Option D: The heart's activities are definitely regulated, so this option is incorrect.

Key Concepts:
- Intrinsic Regulation
- Extrinsic Regulation
- SA Node
- Heart Pacemaker

Memory Aids:
- Intrinsic = Internal (heart has its own internal pacemaker).

Quick Tips:
- Remember that the SA node is the heart's natural pacemaker.

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An Rh -ve female, conceive twin boys in her first pregnancy. What is the probability of suffering from erythroblastosis foetalis in this first pregnancy by the Rh + ve foetus?

View answer and explanation

Correct option: C

0 per cent

Option C (0 per cent) is correct because erythroblastosis foetalis typically occurs in subsequent pregnancies after the mother has been sensitized to the Rh antigen. In the first pregnancy, the mother is not yet sensitized, even with twins.

Solution approach

Correct Answer + Core Reason: 0 per cent. Erythroblastosis foetalis usually doesn't occur in the first pregnancy because the mother hasn't been sensitized to the Rh antigen yet.

Step-by-Step Solution:\nStep 1: Understand the mechanism of erythroblastosis foetalis.\nStep 2: Recall that sensitization to Rh antigen usually occurs during the first pregnancy or delivery.\nStep 3: Apply this to the question: In the first pregnancy, even with twins, the mother is unlikely to have developed enough antibodies to cause significant harm to the foetus.

Why other options are wrong:
- Option A: 33.3 percent. This is incorrect because the probability is essentially zero in the first pregnancy.
- Option B: 50 percent. This is incorrect because the probability is essentially zero in the first pregnancy.
- Option D: 100 percent. This is incorrect because the probability is essentially zero in the first pregnancy.

Key Concepts:
- Erythroblastosis foetalis
- Rh incompatibility
- Sensitization to Rh antigen

Memory Aids:
- Erythroblastosis foetalis is usually a second pregnancy issue.

Quick Tips:
- Remember that the first pregnancy usually doesn't result in erythroblastosis foetalis unless there was prior sensitization.

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Select the lymphoid organs from the given choices
I. Lymph node II. Thymus gland
III. Red bone marrow IV. liver
V. Spleen VI. Osteocytes
VII. Peyer’s patches
The correct option with correct choices is

View answer and explanation

Correct option: D

I, II, IV, V and VII

Option D (I, II, IV, V and VII) is correct because lymph nodes, thymus gland, liver, spleen, and Peyer’s patches are all lymphoid organs involved in the immune system.

Solution approach

Correct Answer + Core Reason: I, II, IV, V and VII. These are the lymphoid organs.

Step-by-Step Solution:

Step 1: Identify the lymphoid organs from the given list.

Step 2: Lymphoid organs are involved in the development, maturation, and function of lymphocytes (immune cells). They include: Lymph nodes, Thymus gland, Spleen, Peyer's patches, and Liver (in some contexts, due to its role in filtering blood and housing immune cells).

Step 3: Red bone marrow is a primary lymphoid organ where blood cells, including lymphocytes, are produced. Osteocytes are bone cells and not lymphoid organs.

Why other options are wrong:
- Option A: I, II, III and IV is incorrect because red bone marrow is a primary lymphoid organ, but the question asks for lymphoid organs in general, and IV (liver) is sometimes considered a lymphoid organ, but III (Red bone marrow) is not in the correct list.
- Option B: III, IV, V and VI is incorrect because red bone marrow and osteocytes are not typically classified as lymphoid organs in this context.
- Option C: IV, V, VI and VII is incorrect because osteocytes are not lymphoid organs.

Key Concepts:
- Lymphoid organs
- Lymph nodes
- Thymus gland
- Spleen
- Peyer's patches
- Red bone marrow

Memory Aids:
- Remember the major lymphoid organs and their functions.

Quick Tips:
- Know the difference between primary and secondary lymphoid organs.

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The structure of which of the following consists of a layer of single cell thickness?

View answer and explanation

Correct option: A

Blood capillary

Option A (Blood capillary) is correct because blood capillaries are composed of a single layer of endothelial cells, facilitating efficient exchange.

Solution approach

Correct Answer + Core Reason: Blood capillary. Blood capillaries consist of a single layer of endothelial cells.

Step-by-Step Solution:

Step 1: Identify the structures listed: Blood capillary, Artery, Venule, Arteriole.

Step 2: Recall the histological structure of each:
- Blood capillaries: Single layer of endothelial cells.
- Arteries: Multiple layers including tunica intima, tunica media (thickest), and tunica adventitia.
- Venules: Similar to arteries but with thinner walls.
- Arterioles: Smaller arteries with similar but thinner layers than arteries.

Step 3: Compare the structures based on the number of cell layers.

Step 4: Conclude that blood capillaries have a single cell layer thickness.

Why other options are wrong:
- Option B: Arteries have multiple layers, including a thick tunica media, making them more than a single cell thick.
- Option C: Venules, while smaller than veins, still have multiple layers of cells in their walls.
- Option D: Arterioles, being small arteries, also possess multiple cell layers in their structure.

Key Concepts:
- Histology of blood vessels
- Structure of capillaries, arteries, venules, and arterioles

Memory Aids:
- Capillaries are \"capillary thin\" - only one cell layer.

Quick Tips:
- Remember that capillaries are designed for efficient exchange, hence their thin walls.

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Irregular nuclei is present in

View answer and explanation

Correct option: B

basophils

Option A (Neutrophils) is incorrect because Neutrophils have multi-lobed nuclei, which can appear irregular.

Solution approach

Correct Answer + Core Reason: basophils. Basophils have irregular nuclei.

Step-by-Step Solution:

Step 1: Recall the characteristics of different leukocytes.

Step 2: Consider the nuclear shape of each type:
- Neutrophils: Multi-lobed nucleus
- Basophils: Irregularly shaped, often bilobed nucleus
- Eosinophils: Bilobed nucleus
- Monocytes: Kidney-shaped nucleus

Step 3: Identify the cell with an irregular nucleus: Basophils have irregularly shaped nuclei.

Why other options are wrong:
- Option A: Neutrophils have multi-lobed nuclei, not irregular.
- Option C: Eosinophils have bilobed nuclei, not irregular.
- Option D: Monocytes have kidney-shaped nuclei, not irregular.

Key Concepts:
- Leukocytes (white blood cells)
- Neutrophils
- Basophils
- Eosinophils
- Monocytes
- Cell morphology

Memory Aids:
- Remember the shapes of the nuclei of different leukocytes.

Quick Tips:
- Review the characteristics of different blood cells.

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Maximum pressure of blood experienced during when blood enters from

View answer and explanation

Correct option: C

Left ventricle to aorta

Option C (Left ventricle to aorta) is correct because the left ventricle generates the highest pressure to pump blood into the systemic circulation via the aorta.

Solution approach

Correct Answer + Core Reason: Left ventricle to aorta. The left ventricle generates the highest pressure during systole to pump blood into the aorta.

Step-by-Step Solution:

Step 1: Identify the chambers of the heart and their roles in blood circulation.

Step 2: Understand that the ventricles are responsible for pumping blood out of the heart.

Step 3: Recognize that the left ventricle pumps blood into the aorta, which distributes blood to the entire body (systemic circulation).

Step 4: The right ventricle pumps blood into the pulmonary artery, which distributes blood to the lungs (pulmonary circulation).

Step 5: The left ventricle must generate higher pressure than the right ventricle to overcome the resistance of the systemic circulation.

Why other options are wrong:
- Option A: The right ventricle pumps blood to the pulmonary artery, which has lower pressure compared to the aorta.
- Option B: Blood enters the aorta from the left ventricle, not the right auricle.
- Option D: Blood enters the aorta from the left ventricle, not the left auricle.

Key Concepts:
- Heart Chambers
- Systemic Circulation
- Pulmonary Circulation
- Blood Pressure
- Ventricular Systole

Memory Aids:
- Left = Lungs (to body)
- Right = Rest of body (to lungs)

Quick Tips:
- Remember that the left ventricle is the strongest chamber of the heart.

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Adult human RBCs are enucleate. Which of the following statement(s) is/are most appropriate explanation for this feature?

a) They do not need to reproduce

b) They are somatic cells

c) They do not metabolize

d) All their internal space is available for oxygen transport

View answer and explanation

Correct option: B

Only (d)

Option B (Only (d)) is correct because the primary reason for the lack of a nucleus in adult human RBCs is to maximize space for oxygen transport.

Solution approach

Correct Answer + Core Reason: Only (d). Enucleation maximizes space for oxygen transport.

Step-by-Step Solution:

Step 1: Analyze each statement regarding enucleated RBCs.

Step 2: a) They do not need to reproduce - While true, it's not the primary reason for enucleation.

Step 3: b) They are somatic cells - All body cells except gametes are somatic cells, but this doesn't explain enucleation.

Step 4: c) They do not metabolize - RBCs do metabolize, although at a reduced rate compared to nucleated cells.

Step 5: d) All their internal space is available for oxygen transport - Correct. Removing the nucleus allows more space for hemoglobin and thus more oxygen transport.

Step 6: Choose the option that contains the most appropriate explanation.

Why other options are wrong:
- Option A: Includes (b) and (c), which are incorrect or not the primary reason.
- Option C: Includes only (a), which is not the primary reason.
- Option D: Includes (a) and (c), which are incorrect or not the primary reason.

Key Concepts:
- Red blood cell structure and function
- Oxygen transport

Memory Aids:
- Enucleation = More space for Oxygen.

Quick Tips:
- Focus on the primary function of RBCs when answering questions about their features.

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Persons with _____ and _______ blood groups are called universal recipient and universal donors respectively

View answer and explanation

Correct option: D

A{B^ + },\,\,{O^ - }

Option D (

A{B^ + },\,\,{O^ - }

) is correct because

AB^+

individuals can receive blood from any blood type, and

O^-

individuals can donate blood to any blood type.

Solution approach

Correct Answer + Core Reason: $A{B^ + },\,\,{O^ - }$ . $AB^+$ is the universal recipient and $O^-$ is the universal donor.

Step-by-Step Solution:

Step 1: Understand the concept of blood groups and their compatibility.

Step 2: Recall that $AB^+$ individuals have no antibodies against A, B, or Rh antigens, making them universal recipients.

Step 3: Recall that $O^-$ individuals have no A, B, or Rh antigens, making them universal donors.

Step 4: Therefore, the correct matching is $AB^+$ as the universal recipient and $O^-$ as the universal donor.

Why other options are wrong:
- Option A: $A{B^-}$ is not the universal recipient, and $O^+$ is not the universal donor.
- Option B: $O^+$ is not the universal recipient, and $A{B^-}$ is not the universal donor.
- Option C: $O^-$ is the universal donor, but $A{B^+}$ is the universal recipient, not the other way around.

Key Concepts:
- Blood groups (A, B, AB, O)
- Rh factor
- Antibodies and antigens
- Universal donor and universal recipient

Memory Aids:
- $AB^+$ can *accept* *any* blood type.
- $O^-$ can *donate* to *any* blood type.

Quick Tips:
- Remember the antigens and antibodies present in each blood group to determine compatibility.

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To obtain a standard ECG, the patient is connected to the machine with three electrical leads. These three electrical lead are connected as one each to the

View answer and explanation

Correct option: D

Wrist and third one at the ankle

Option D (Wrist and third one at the ankle) is correct because standard ECG leads are placed on the wrists and one ankle to measure electrical activity of the heart.

Solution approach

Correct Answer + Core Reason: Wrist and third one at the ankle. ECG leads are placed on the limbs to measure the heart's electrical activity.

Step-by-Step Solution:

Step 1: Understand the basics of ECG placement. ECG (Electrocardiogram) measures the electrical activity of the heart.

Step 2: Recall the standard limb lead placements for a standard ECG.

Step 3: The standard ECG involves placing electrodes on the wrists and ankles to form the Einthoven's triangle.

Step 4: Therefore, the correct placement involves the wrists and one ankle.

Why other options are wrong:
- Option A: Biceps and third one at the ankle is incorrect because ECG leads are not typically placed on the biceps.
- Option B: Triceps and third one at the ankle is incorrect because ECG leads are not typically placed on the triceps.
- Option C: Thigh and third one at the ankle is incorrect because while one lead is placed on the ankle, the other two are placed on the wrists, not the thighs.
- Option D: Wrist and third one at the ankle is correct.

Key Concepts:
- Electrocardiogram (ECG)
- ECG lead placement
- Einthoven's triangle

Memory Aids:
- Remember that ECG limb leads are placed distally on the limbs (wrists and ankles).

Quick Tips:
- Visualize the Einthoven's triangle when thinking about ECG lead placement.

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Lymphatic system is an elaborated network of vessels which collect the

View answer and explanation

Correct option: A

Interstitial fluid

Option A (Interstitial fluid) is correct because the lymphatic system collects interstitial fluid, which is the fluid surrounding cells, and returns it to the bloodstream.

Solution approach

Correct Answer + Core Reason: Interstitial fluid. The lymphatic system collects interstitial fluid.

Step-by-Step Solution:

Step 1: Recall the function of the lymphatic system.

Step 2: The lymphatic system is a network of vessels that collects excess interstitial fluid (the fluid surrounding cells) and returns it to the bloodstream. This fluid is then called lymph.

Why other options are wrong:
- Option B: Intrastitial fluid is a misspelling of interstitial fluid.
- Option C: Plasma fluid is the fluid component of blood, not directly collected by the lymphatic system.
- Option D: Protein fluid is not the primary fluid collected by the lymphatic system, although lymph does contain proteins.

Key Concepts:
- Lymphatic system
- Interstitial fluid
- Lymph

Memory Aids:
- Lymphatic system drains Interstitial fluid.

Quick Tips:
- Remember the role of the lymphatic system in fluid balance.

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In reptiles and amphibians, there is no clear cut separation of oxygenated and deoxygenated blood because they have

View answer and explanation

Correct option: B

Only one ventricle

Option B (Only one ventricle) is correct because the single ventricle in reptiles and amphibians allows for mixing of oxygenated and deoxygenated blood, leading to incomplete separation.

Solution approach

Correct Answer + Core Reason: Only one ventricle. The presence of a single ventricle leads to mixing of oxygenated and deoxygenated blood.

Step-by-Step Solution:

Step 1: Recall the heart structure in reptiles and amphibians. They have two atria and one ventricle.

Step 2: Understand the function of the atria and ventricle. The atria receive blood, and the ventricle pumps blood out.

Step 3: Explain the consequence of having only one ventricle. With only one ventricle, oxygenated blood from the lungs and deoxygenated blood from the body mix before being pumped out to the body and lungs.

Step 4: Relate the heart structure to the separation of oxygenated and deoxygenated blood. The lack of a complete separation of the ventricle prevents complete separation of oxygenated and deoxygenated blood.

Why other options are wrong:
- Option A: Having only one atrium is incorrect; they have two atria.
- Option C: Having only two atria is correct, but it's the single ventricle that causes the mixing of blood.
- Option D: Having only two ventricles is incorrect; they have only one ventricle.

Key Concepts:
- Heart structure in reptiles and amphibians
- Mixing of oxygenated and deoxygenated blood

Memory Aids:
- 3-chambered heart = mixing of blood.

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

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Atherosclerosis is caused by deposition of

View answer and explanation

Correct option: D

All of the above

Option D (All of the above) is correct because atherosclerosis involves the deposition of calcium, fat, cholesterol, and fibrous tissue in the arteries.

Solution approach

Correct Answer + Core Reason: All of the above. Atherosclerosis involves multiple components in plaque formation.

Step-by-Step Solution:

Step 1: Define atherosclerosis.

Step 2: Atherosclerosis is characterized by the buildup of plaque in the arteries.

Step 3: This plaque is composed of calcium, fat and cholesterol, and fibrous tissue.

Step 4: Therefore, atherosclerosis is caused by the deposition of all of the above.

Why other options are wrong:
- Option A: Calcium is incorrect because while calcium is a component of atherosclerotic plaques, it's not the only component.
- Option B: Fat and cholesterol is incorrect because while fat and cholesterol are major components, calcium and fibrous tissue are also involved.
- Option C: Deposition of fibrous tissue is incorrect because while fibrous tissue is a component, calcium, fat, and cholesterol are also involved.
- Option D: All of the above is correct.

Key Concepts:
- Atherosclerosis
- Plaque formation
- Components of plaque

Memory Aids:
- Remember that plaque is a complex mixture of substances.

Quick Tips:
- Consider all components when thinking about atherosclerosis.

81 Medium

81 of 157

Understanding +4 | -1

Properties of human RBCs are
I. devoid of nucleus
II. formed in bone marrow
III. possess healing properties
IV. biconcave in shape
V. help in blood clotting
Choose the option with correct properties

View answer and explanation

Correct option: B

I, II and IV

Option B (I, II and IV) is correct because human RBCs are devoid of a nucleus, formed in bone marrow, and biconcave in shape.

Solution approach

Correct Answer + Core Reason: I, II and IV. Human RBCs lack a nucleus, are produced in bone marrow, and have a biconcave shape.

Step-by-Step Solution:

Step 1: Analyze each statement about human RBCs.

Step 2: I. devoid of nucleus - Correct. Mature RBCs lack a nucleus to maximize space for hemoglobin.

Step 3: II. formed in bone marrow - Correct. RBCs are produced in the red bone marrow.

Step 4: III. possess healing properties - Incorrect. RBCs transport oxygen, not involved in healing.

Step 5: IV. biconcave in shape - Correct. The biconcave shape increases surface area for gas exchange.

Step 6: V. help in blood clotting - Incorrect. Platelets are responsible for blood clotting.

Step 7: Select the option containing only the correct statements (I, II, and IV).

Why other options are wrong:
- Option A: Includes statement III (possess healing properties), which is incorrect.
- Option C: Includes statements III (possess healing properties) and V (help in blood clotting), which are incorrect.
- Option D: Includes statement III (possess healing properties), which is incorrect.

Key Concepts:
- Structure and function of red blood cells
- Hematopoiesis (blood cell formation)

Memory Aids:
- RBCs: No nucleus, Bone marrow, Concave shape (NBC).

Quick Tips:
- Remember the primary function of RBCs is oxygen transport.

82 Medium

82 of 157

Remembering +4 | -1

During cardiac cycle, about …A…% of ventricular filling occurs, prior to the arterial contraction …B…% ventricular filling occurs due to arterial contraction
Choose the correct option for A and B

View answer and explanation

Correct option: B

A-70; B-30

Option B (A-70; B-30) is correct because approximately 70% of ventricular filling occurs before atrial contraction, and the remaining 30% is due to atrial contraction.

Solution approach

Correct Answer + Core Reason: A-70; B-30. Most ventricular filling occurs passively before atrial systole.

Step-by-Step Solution:
Step 1: Recall the phases of ventricular filling during the cardiac cycle.
Step 2: During diastole, the ventricles fill passively due to pressure gradients.
Step 3: Atrial contraction contributes the final portion of ventricular filling.
Step 4: Approximately 70% of ventricular filling occurs passively before atrial systole.
Step 5: Approximately 30% of ventricular filling occurs due to atrial contraction.

Why other options are wrong:
- Option A: A-30; B-70 is incorrect because most filling is passive.
- Option C: A-40; B-60 is incorrect because most filling is passive.
- Option D: A-60; B-40 is incorrect because most filling is passive.

Key Concepts:
- Cardiac cycle
- Ventricular filling
- Atrial systole
- Diastole

Memory Aids:
- 70/30 rule for ventricular filling

Quick Tips:
- Understand the contribution of atrial contraction to ventricular filling.

83 Medium

83 of 157

Understanding +4 | -1

In complete double circulation :

View answer and explanation

Correct option: C

There are two separate circulatory pathways.

Option C (There are two separate circulatory pathways) is correct because complete double circulation involves separate pulmonary and systemic circuits, ensuring oxygenated and deoxygenated blood do not mix.

Solution approach

Correct Answer + Core Reason: There are two separate circulatory pathways. This is the defining characteristic of complete double circulation.

Step-by-Step Solution:

Step 1: Define complete double circulation. Complete double circulation means that blood passes through the heart twice in each complete circuit: once in the pulmonary circuit (to the lungs) and once in the systemic circuit (to the rest of the body).

Step 2: Consider the other options. In complete double circulation, the left and right ventricles pump out oxygenated and deoxygenated blood, respectively, but this is a consequence, not the definition. There is no mixing of blood in the ventricles. Blood passes through the heart twice, not once.

Step 3: Identify the correct option. The presence of two separate circulatory pathways is the defining characteristic of complete double circulation.

Why other options are wrong:
- Option A: While left and right ventricles pump out oxygenated and deoxygenated blood respectively, this is a result of double circulation, not the definition.
- Option B: Mixing of blood in ventricles occurs in incomplete circulation, not complete double circulation.
- Option D: Blood passes through the heart twice in complete double circulation, not once.

Key Concepts:
- Complete double circulation
- Pulmonary circuit
- Systemic circuit

Memory Aids:
- Double circulation = two circuits.

Quick Tips:
- Remember the definition of complete double circulation.

84 Medium

84 of 157

Application +4 | -1

If the stroke volume is 70 mL and heart rate is 72 per min. What is cardiac output?

View answer and explanation

Correct option: B

5040 \mathrm{~mL}

Option B (

5040 \mathrm{~mL}

) is correct because cardiac output is calculated by multiplying heart rate by stroke volume: 72 beats/min * 70 mL/beat = 5040 mL/min.

Solution approach

Correct Answer + Core Reason: $5040 \mathrm{~mL}$ . Cardiac output is calculated by multiplying heart rate and stroke volume.

Step-by-Step Solution:

Step 1: Identify the given information. Heart rate (HR) = 72 per min, Stroke volume (SV) = 70 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 = 72 x 70.

Step 4: Calculate the cardiac output. CO = 5040 mL.

Why other options are wrong:
- Option A: $500 \mathrm{~mL}$ is incorrect. It might be a calculation error.
- Option C: $3600 \mathrm{~mL}$ is incorrect. It might be a calculation error.
- Option D: $300 \mathrm{~mL}$ 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.

85 Medium

85 of 157

Application +4 | -1

Which parental phenotypes would produce offspring with blood group phenotypes in the expected ratio of 1 type A : 1 type B?

View answer and explanation

Correct option: D

Blood group of mother - AB; Blood group of father - O

Option D (Blood group of mother - AB; Blood group of father - O) is correct because the cross between AB (IAIB) and O (ii) parents yields offspring with genotypes IAi (type A) and IBi (type B) in a 1:1 ratio.

Solution approach

Correct Answer + Core Reason: Blood group of mother - AB; Blood group of father - O. This parental combination produces offspring with blood group phenotypes in a 1:1 ratio of type A to type B.

Step-by-Step Solution:\nStep 1: Understand the genotypes of ABO blood groups.\nStep 2: Recall that type A can be IAIA or IAi, type B can be IBIB or IBi, type AB is IAIB, and type O is ii.\nStep 3: Consider the cross between AB (IAIB) and O (ii) parents: IAIB x ii.\nStep 4: Determine the possible offspring genotypes: IAi (type A) and IBi (type B).\nStep 5: The ratio of type A to type B offspring is 1:1.

Why other options are wrong:
- Option A: Blood group of mother - A; Blood group of father - B. This cross (IAIA or IAi x IBIB or IBi) will not always produce a 1:1 ratio of type A to type B.
- Option B: Blood group of mother - AB; Blood group of father - AB. This cross (IAIB x IAIB) will produce offspring with types A, B, and AB, but not in a 1:1 ratio of A to B.
- Option C: Blood group of mother - AB; Blood group of father - B. This cross (IAIB x IBIB or IBi) will not produce a 1:1 ratio of type A to type B.

Key Concepts:
- ABO blood group inheritance
- Genotypes and phenotypes
- Punnett squares

Memory Aids:
- IAIB x ii gives 1:1 ratio of A and B.

Quick Tips:
- Use Punnett squares to determine the possible offspring genotypes and phenotypes.

86 Medium

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Remembering +4 | -1

Which one of the following is necessary to start clotting of blood?

View answer and explanation

Correct option: C

Thromboplastin and

C{a^{2 + }}

Option C (Thromboplastin and

C{a^{2 + }}

) is correct because Thromboplastin initiates the clotting cascade, and Calcium ions (

C{a^{2 + }}

) are essential cofactors for many steps in the coagulation process.

Solution approach

Correct Answer + Core Reason: Thromboplastin and $C{a^{2 + }}$ . These are essential for initiating the clotting cascade.

Step-by-Step Solution:

Step 1: Understand the initial steps of blood clotting.

Step 2: Thromboplastin (tissue factor) initiates the extrinsic pathway of coagulation.

Step 3: Calcium ions ( $C{a^{2 + }}$ ) are required as cofactors for several steps in both the intrinsic and extrinsic pathways of coagulation.

Why other options are wrong:
- Option A: Heparin is an anticoagulant, which inhibits clotting.
- Option B: Serotonin is a vasoconstrictor, which reduces blood flow to the injured area, but it doesn't directly start clotting.
- Option D: Fibrinogen and prothrombin are involved later in the clotting cascade, but they don't initiate it.

Key Concepts:
- Blood coagulation cascade
- Role of thromboplastin and calcium

Memory Aids:
- Thromboplastin = Trigger; Calcium = Clotting

Quick Tips:
- Remember that thromboplastin and calcium are essential for initiating the clotting process.

87 Medium

87 of 157

Understanding +4 | -1

Which structures are directly involved in the “systemic circulation”?

View answer and explanation

Correct option: C

Left ventricle, aorta and inferior vena cava.

Option C (Left ventricle, aorta and inferior vena cava) is correct because the systemic circulation involves the left ventricle pumping blood into the aorta, which then circulates to the body and returns to the heart via the inferior vena cava.

Solution approach

Correct Answer + Core Reason: Left ventricle, aorta and inferior vena cava. These are the key structures involved in the systemic circulation.

Step-by-Step Solution:

Step 1: Define systemic circulation.

Step 2: Systemic circulation involves the flow of oxygenated blood from the left ventricle to the body and the return of deoxygenated blood to the right atrium.

Step 3: The left ventricle pumps blood into the aorta.

Step 4: The aorta branches into arteries that supply the body.

Step 5: Deoxygenated blood returns to the heart through the superior and inferior vena cava, with the inferior vena cava being a major vessel.

Why other options are wrong:
- Option A: Superior vena cava is part of the systemic circulation, but the right ventricle is part of the pulmonary circulation.
- Option B: Right ventricle and pulmonary arteries are part of the pulmonary circulation, and the left atrium receives oxygenated blood from the lungs.
- Option D: Right atrium is the receiving chamber for deoxygenated blood, pulmonary trunk is part of the pulmonary circulation, and the left ventricle pumps oxygenated blood into the systemic circulation.

Key Concepts:
- Systemic Circulation
- Pulmonary Circulation
- Heart Chambers
- Major Blood Vessels

Memory Aids:
- Think of "Systemic = Body", and trace the path of blood to and from the body.

Quick Tips:
- Visualize the flow of blood through the heart and the major vessels.

88 Medium

88 of 157

Understanding +4 | -1

The ‘ventricular systole’ increases the ‘intra ventricular pressure’. It results in the closure of

View answer and explanation

Correct option: B

Tricuspid and bicuspid valves

Option B (Tricuspid and bicuspid valves) is correct because the increase in intraventricular pressure during ventricular systole causes the atrioventricular valves (tricuspid and bicuspid) to close, preventing backflow of blood into the atria.

Solution approach

Correct Answer + Core Reason: Tricuspid and bicuspid valves. The increase in intraventricular pressure causes these valves to close.

Step-by-Step Solution:

Step 1: During ventricular systole, the ventricles contract, increasing the pressure inside them.

Step 2: This increased pressure forces the tricuspid and bicuspid (mitral) valves to close, preventing backflow of blood into the atria.

Step 3: The semilunar valves (aortic and pulmonary) open to allow blood to flow out of the ventricles.

Why other options are wrong:
- Option A: Semilunar valves open during ventricular systole, not close.
- Option C: Aortic valves open during ventricular systole, not close.
- Option D: Pulmonary and aortic valves open during ventricular systole, not close.

Key Concepts:
- Ventricular systole
- Heart valves
- Pressure changes

Memory Aids:
- Ventricular Systole: AV valves close, Semilunar valves open

Quick Tips:
- Understand the relationship between pressure changes and valve function.

89 Medium

89 of 157

Application +4 | -1

What would be the heart rate of a person if the cardiac output is 5 L, blood volume in the ventricles at the end of diastole is 100 mL and at the end of ventricular systole is 50 mL?

View answer and explanation

Correct option: C

100 beats per minute

Option C (100 beats per minute) is correct because stroke volume is the difference between end-diastolic and end-systolic volumes (100 mL - 50 mL = 50 mL). Cardiac output is stroke volume multiplied by heart rate, so heart rate = cardiac output / stroke volume = 5000 mL / 50 mL = 100 beats per minute.

Solution approach

Correct Answer + Core Reason: 100 beats per minute. Heart rate is calculated by dividing cardiac output by stroke volume.

Step-by-Step Solution:

Step 1: Identify the given information. Cardiac output (CO) = 5 L = 5000 mL, End-diastolic volume (EDV) = 100 mL, End-systolic volume (ESV) = 50 mL.

Step 2: Calculate the stroke volume (SV). SV = EDV - ESV = 100 mL - 50 mL = 50 mL.

Step 3: Recall the formula for cardiac output. CO = HR x SV.

Step 4: Rearrange the formula to solve for heart rate (HR). HR = CO / SV.

Step 5: Substitute the given values into the formula. HR = 5000 mL / 50 mL.

Step 6: Calculate the heart rate. HR = 100 beats/min.

Why other options are wrong:
- Option A: 50 beats per minute is incorrect. It might be a calculation error.
- Option B: 75 beats per minute is incorrect. It might be a calculation error.
- Option D: 125 beats per minute 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 heart rate.

90 Medium

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Remembering +4 | -1

Viper venom affects

View answer and explanation

Correct option: A

Circulatory system

Option A (Circulatory system) is correct because viper venom primarily affects the circulatory system, causing issues like blood clotting and hemorrhaging.

Solution approach

Correct Answer + Core Reason: Circulatory system. Viper venom contains hemotoxins that affect the blood and blood vessels.

Step-by-Step Solution:

Step 1: Understand the effects of different types of venom.

Step 2: Viper venom is primarily hemotoxic, meaning it affects the blood and circulatory system.

Step 3: The venom can cause blood clotting, hemorrhaging, and damage to blood vessels.

Step 4: Therefore, viper venom affects the circulatory system.

Why other options are wrong:
- Option B: Nervous system is incorrect because while some snake venoms are neurotoxic, viper venom is primarily hemotoxic.
- Option C: Respiratory system is incorrect because while respiratory distress can occur as a secondary effect, the primary target is the circulatory system.
- Option D: None of these is incorrect because viper venom does affect a specific system, which is the circulatory system.

Key Concepts:
- Viper venom
- Hemotoxins
- Circulatory system

Memory Aids:
- Remember that vipers are known for their hemotoxic venom.

Quick Tips:
- Differentiate between hemotoxic and neurotoxic venoms.

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Body fluids and circulation practice · Medium

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