[KMU-2024]
What will happen with the addition of salt to water?
A
Water potential will increase
B
Water potential will remain same
C
Osmotic potential will increase
D
Osmotic potential will remain same
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Pure water has a maximum water potential of zero. Adding solutes creates a negative potential.
Formula:$$ \Psi_{w} = \Psi_{s} + \Psi_{p} $$
Solution:- Adding salt (a solute) to water decreases the free kinetic energy of the water molecules.
- This causes the overall water potential (\( \Psi_{w} \)) to decrease (become more negative).
- Because the solute concentration has increased, the magnitude of the osmotic pull increases. This means the osmotic potential (which is technically a negative value, \( \Psi_{s} \)) increases in absolute magnitude (or simply, the potential for osmosis increases).
Note: In many older curricula, "osmotic potential" is used interchangeably with osmotic pressure, which increases. While technically \( \Psi_{s} \) becomes more negative, the "pulling power" increases.
Why other options are incorrect:- Water potential definitively decreases, making option A incorrect.
[NUMS-2024]
Plants growing in saline soil face the problem of dehydration due to:
A
Ψw of soil > Ψw of root
B
Ψw of soil < Ψw of root
D
Ψw of root = Ψw of soil
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:Water always moves passively via osmosis from an area of higher water potential to an area of lower water potential.
Formula:$$ \text{Flow: High } \Psi_w \rightarrow \text{ Low } \Psi_w $$
Solution:- Saline soil contains massive amounts of dissolved salt (solutes), which dramatically lowers the water potential (\( \Psi_{w} \)) of the soil.
- If the soil becomes saltier than the plant's own roots, then the water potential of the soil becomes lower than that of the root (\( \Psi_w \) of soil < \( \Psi_w \) of root).
- Consequently, water is drawn out of the roots and into the soil, causing lethal dehydration (exosmosis) in the plant.
Why other options are incorrect:- If \( \Psi_{w} \text{ soil} > \Psi_{w} \text{ root} \) (Option A), water would correctly flow into the plant, and it would not face dehydration. Note that Option B and C are mathematically the same statement, but based on the key, B is the direct phrasing describing the environmental cause.
[NUMS-2024]
Weakened papillary muscles of right ventricle would result in constant back flow of blood into:
View Answer & Propolis Autopsy
Correct Key: Option A
Diagnostic Explanation
Concept:Papillary muscles anchor the AV valves to prevent prolapse during ventricular systole.
Formula:None
Solution:- The papillary muscles of the right ventricle are attached to the tricuspid valve via chordae tendineae.
- If these muscles weaken or rupture, the intense pressure generated during right ventricular contraction will blow the tricuspid valve flaps backward (prolapse).
- This valve failure allows blood to continuously regurgitate (back flow) upwards into the chamber it just came from: the right atrium.
Why other options are incorrect:- The right ventricle is entirely isolated from the left side of the heart, so it would not affect the left atrium or left ventricle directly.
[NUMS-2024]
Which of the following set of characteristics are related to veins?
A. Present, Thick, \(7-9\mu m\)
B. Absent, Thick, \(40-50\mu m\)
C. Present, Thinner, \(40-50\mu m\)
D. Absent, Thinner, \(40-50\mu m\)
B
Absent, Thick, 40-50 μm
C
Present, Thinner, 40-50 μm
D
Absent, Thinner, 40-50 μm
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Veins are structurally adapted for low-pressure blood return to the heart.
Formula:None
Solution:- Valves: Veins must fight gravity under low pressure, so internal valves are universally present.
- Wall Thickness: Without high systolic pressure, veins do not need massive muscle layers, rendering their walls thinner than arteries.
- Diameter: To act as a blood reservoir, veins have large internal lumens, typically ranging from \(40-50\text{ }\mu m\) (or larger in macroscopic veins) compared to microscopic capillaries.
Why other options are incorrect:- Options claiming absent valves define arteries. Thick walls define arteries. \(7-9\text{ }\mu m\) perfectly describes the diameter of a single capillary.
[NUMS-2024]
The presence of which molecules distinguish blood from interstitial fluid?
A
Large proteins and electrolytes
C
Antibodies and electrolytes
D
RBCs and large proteins
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:Capillary walls act as biological sieves, allowing small molecules to exit into the tissues while retaining massive structures.
Formula:None
Solution:- Interstitial fluid is formed when hydrostatic pressure pushes blood plasma out of the capillaries.
- Water, glucose, amino acids, and electrolytes easily pass through the endothelial clefts.
- However, formed cellular elements like Red Blood Cells (RBCs) and massive molecules like large plasma proteins (albumin, fibrinogen) are physically too large to escape. Thus, their presence strictly distinguishes whole blood from the fluid bathing the tissues.
Why other options are incorrect:- Electrolytes, glucose, and even some smaller antibodies easily cross into the interstitial fluid.
[NUMS-2024]
Which of the following would not be compromised in the absence of lymphatic system?
B
Oxygen carrying capacity of blood
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:The lymphatic system manages fluid homeostasis, lipid absorption, and immune defense, but has no role in respiratory gas transport.
Formula:None
Solution:- If the lymphatic system disappeared, leaked plasma could not return to the veins, destroying blood volume and blood pressure.
- Without lymph nodes, the adaptive defense mechanism would collapse.
- However, the oxygen-carrying capacity of blood is determined entirely by the mass of Red Blood Cells and hemoglobin molecules locked safely within the cardiovascular system. Since RBCs do not leave the blood vessels to enter lymph, their oxygen-carrying capacity remains mechanically unaffected.
Why other options are incorrect:- Blood composition would alter as proteins and fluid leak into tissues without returning.
[UHS-2023]
The ____ describes how water and dissolved chemicals are carried through the cell wall and intercellular gaps of plants.
View Answer & Propolis Autopsy
Correct Key: Option A
Diagnostic Explanation
Concept:Water travels through plant cortex tissues via interconnected non-living and living spaces.
Formula:None
Solution:- The apoplast pathway refers exclusively to the movement of water and solutes through the "dead" or non-living parts of the plant tissue.
- This includes the porous cellulose cell walls and the intercellular air spaces, bypassing the living cytoplasm entirely until reaching the Casparian strip.
Why other options are incorrect:- Symplast theory: Describes water moving strictly through the living cytoplasm and plasmodesmata.
[SZABMU-2023]
The pathways of water transport in which water moves through plasmodesmata is:
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:Plant cells are physically and chemically connected to allow efficient intracellular transport.
Formula:None
Solution:- Plasmodesmata are tiny, membrane-lined channels that traverse plant cell walls.
- They connect the cytoplasm of adjacent cells into one continuous network.
- Water moving through this living, cytoplasmic continuum utilizes the symplast pathway.
Why other options are incorrect:- Apoplast: Travels outside the cell membrane (through cell walls).
[UHS-2023]
The movement of water to lower solute concentration area through a semipermeable membrane is?
View Answer & Propolis Autopsy
Correct Key: Option A
Diagnostic Explanation
Concept:Water movement across biological membranes is dictated by free energy, driven by differences in solute concentrations.
Formula:$$ \Psi_{w} = \Psi_{s} + \Psi_{p} $$
Solution:- The tendency of water to move across a semi-permeable membrane into a region of differing solute concentration is defined by osmosis.
- The quantitative measure of this specific driving force, driven strictly by the presence of solutes, is referred to as osmotic potential (or solute potential).
- Water always moves from an area of higher water potential (lower solute concentration) to an area of lower water potential (higher solute concentration).
Why other options are incorrect:- Pressure potential: Relates to the physical turgor pressure exerted by the cell wall.
[UHS-2023]
Descending aorta is bifurcated into two vessels which on further division from (form) femoral artery that supply blood to high (Thigh) muscles of legs:
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:Systemic circulation branches sequentially to deliver oxygen to the lower extremities.
Formula:None
Solution:- The massive descending abdominal aorta travels down the spine and ends by bifurcating (splitting in two) at the lower abdomen.
- It splits into the right and left common iliac arteries.
- These iliac arteries travel into the pelvis and eventually become the femoral arteries as they enter the thighs to supply the leg muscles.
Why other options are incorrect:- Iliac vein: Returns deoxygenated blood; the question asks about arteries supplying blood.
- Temporal artery: Located in the head/skull.
[SZABMU-2023]
In human heart, the left atrium receives:
D
The four Pulmonary Veins
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:The left side of the heart is exclusively responsible for handling oxygenated blood returning from the lungs.
Formula:None
Solution:- The pulmonary circulation carries blood to the lungs to pick up oxygen.
- Once oxygenated, the blood travels back to the heart.
- It enters the left atrium via two right and two left pulmonary veins (four in total).
Why other options are incorrect:- The Superior Vena Cava, Inferior Vena Cava, and Coronary Sinus all drain oxygen-poor blood exclusively into the right atrium.
[NUMS-2023]
The heart chamber from where Aorta originates:
View Answer & Propolis Autopsy
Correct Key: Option A
Diagnostic Explanation
Concept:The aorta is the main trunk of the systemic arterial system.
Formula:None
Solution:- The systemic circuit requires immense pressure to push blood through the entire body.
- The left ventricle has the thickest muscular wall in order to generate this high pressure.
- When the left ventricle contracts, it ejects oxygenated blood upward through the aortic semilunar valve directly into the aorta.
Why other options are incorrect:- Right ventricle: Pumps blood into the pulmonary trunk (to the lungs).
- Atria: Receiving chambers only; they do not pump into major arterial trunks.
[SZABMU-2023]
Choose the correct pathway for the flow of blood:
A
Arterioles --- metarterioles thoroughfare channel capillaries
B
Capillaries through fare channel metarterioles arterioles
C
Throughfare channel metarterioles capillaries arterioles
D
Metarterioles arterioles throughfare channels capillaries
View Answer & Propolis Autopsy
Correct Key: Option A
Diagnostic Explanation
Concept:Blood flows sequentially from high pressure macroscopic vessels to low pressure microscopic vessels.
Formula:None
Solution:- Blood exits the arteries into smaller arterioles.
- Arterioles branch into terminal extensions called metarterioles.
- Metarterioles act as a vascular shunt, passing directly through the capillary bed as a thoroughfare channel, which then supplies the true capillaries branching off it.
Why other options are incorrect:- Options B, C, and D present the sequence backward or scrambled, violating the pressure gradient from arteries to capillaries.
[NUMS-2023]
Mesenteric veins drains the blood from:
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:The portal venous system collects blood from specific gastrointestinal organs to send to the liver.
Formula:None
Solution:- The mesenteric veins (specifically the Superior and Inferior Mesenteric veins) are named for their location in the mesentery.
- They are primarily responsible for draining nutrient-rich, deoxygenated blood from the small intestine and the large intestine (colon).
- They eventually merge with the splenic vein to form the hepatic portal vein.
Why other options are incorrect:- Stomach: Drained mostly by gastric veins.
- Liver: Drained by the hepatic vein.
[SZABMU-2023]
Regarding structure of the human heart, Chordae tendineae are present in:
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Chordae tendineae are the physical tension cords that anchor the atrioventricular (AV) valves during systolic contraction.
Formula:None
Solution:- During ventricular contraction, pressure spikes rapidly, threatening to blow the AV valves backward into the atria.
- Chordae tendineae connect the valve flaps to papillary muscles that sprout from the inner walls of the ventricles.
- Therefore, these structures are anatomically housed entirely within the left and right ventricles.
Why other options are incorrect:- Atria: Have smooth or pectinate muscle, but no chordae tendineae.
- Aortic/Pulmonary valves: Are semilunar valves and do not require chordae tendineae to function.
[ETEA-2023]
In human heart right atrium communicates with right ventricle through:
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Atrioventricular valves guard the openings between the upper and lower chambers of the heart.
Formula:None
Solution:- Deoxygenated blood arriving in the right atrium must flow down into the right ventricle to be pumped to the lungs.
- The portal between the right atrium and right ventricle is guarded by a one-way valve with three cusps.
- This is definitively known as the tricuspid valve.
Why other options are incorrect:- Bicuspid (Mitral) valve: Located on the left side of the heart.
- Septums: These are solid muscular walls that prevent communication (mixing) between the left and right sides of the heart.
[ETEA-2023]
The Purkinje fibers are the specialized fibers found in:
View Answer & Propolis Autopsy
Correct Key: Option A
Diagnostic Explanation
Concept:The rapid, synchronized contraction of the massive ventricular muscle requires a specialized, high-speed electrical conduction system.
Formula:None
Solution:- The electrical signal travels from the AV node, down the Bundle of His, and splits into the bundle branches.
- At the apex of the heart, these branches curve upward and disperse into a network of highly specialized conducting cells called Purkinje fibers.
- These fibers distribute the electrical impulse uniformly throughout the ventricular walls of the human heart.
Why other options are incorrect:- Lungs, stomach, and brain rely on the autonomic nervous system, not the intrinsic Purkinje conduction network.
#18 of 50
ETEA-2023 Retake
[ETEA-2023 Retake]
Which of the following is known as the vessels of the vessels?
View Answer & Propolis Autopsy
Correct Key: Option A
Diagnostic Explanation
Concept:Large blood vessels are so thick that the cells in their outer layers cannot receive oxygen and nutrients by simple diffusion from the blood flowing inside them.
Formula:None
Solution:- Large arteries and veins (like the aorta and vena cava) require their own dedicated microscopic blood supply.
- This network of tiny blood vessels embedded in the tunica externa of large vessels is termed the vasa vasorum.
- The direct translation of "vasa vasorum" from Latin is "the vessels of the vessels."
Why other options are incorrect:- Tunica media/externa/interna: These are the tissue layers of the blood vessel wall, not the micro-vessels feeding them.
#19 of 50
ETEA-2023 Retake
[ETEA-2023 Retake]
The sinoatrial node is located in the ____ wall of the right atrium.
C
On the interatrial septum
D
Near the coronary sinus
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:The anatomical placement of the SA node ensures that the electrical signal sweeps downwards across the atria.
Formula:None
Solution:- The Sinoatrial (SA) node is a cluster of specialized pacemaker cells.
- It is situated in the upper dorsal (superior-posterior) wall of the right atrium, precisely near the opening of the superior vena cava.
- This high position allows the depolarization wave to efficiently travel downward toward the AV node.
Why other options are incorrect:- Near the coronary sinus / lower dorsal: This is the location of the Atrioventricular (AV) node, not the SA node.
[UHS-2023]
The final destination of lymph is:
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:The lymphatic system is an open, one-way system designed to capture leaked interstitial fluid and return it to the blood.
Formula:None
Solution:- Lymph fluid travels from microscopic capillaries, through nodes, into larger lymphatic trunks, and finally into two main ducts (the Right Lymphatic Duct and the Thoracic Duct).
- Both of these massive ducts ultimately empty their fluid contents directly into the right and left subclavian veins, officially returning the fluid to the cardiovascular system.
Why other options are incorrect:- Lymph nodes/organs: These are checkpoints along the journey, not the final destination.
[ETEA-2023]
The largest body of lymphoid tissue in the human body is:
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Secondary lymphoid organs are macroscopic structures that house high densities of lymphocytes for immune surveillance.
Formula:None
Solution:- Located in the upper left quadrant of the abdomen, the spleen is an organ roughly the size of a fist.
- It contains vast amounts of white pulp (lymphoid tissue) and red pulp. By sheer mass and volume, it is the largest single collection of lymphoid tissue in the human body.
Why other options are incorrect:- Thymus/Tonsils: These are much smaller lymphoid structures.
- Pancreas: An endocrine/exocrine digestive organ, not a lymphoid organ.
[UHS-2022]
Digested food from intestine is carried to the liver by:
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:The portal venous system directs blood from parts of the gastrointestinal tract to the liver.
Formula:None
Solution:- The hepatic portal vein is responsible for carrying nutrient-rich, deoxygenated blood from the small intestine directly to the liver.
- This allows the liver to process nutrients before the blood enters the general systemic circulation.
Why other options are incorrect:- Hepatic artery: Carries oxygenated blood to the liver.
- Hepatic vein: Carries deoxygenated blood away from the liver to the vena cava.
[SZABMU-2022]
The pathway of water transport in which water moves through plasmodesmata is:
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:Water and solutes can move through plant tissues via different pathways: the apoplast (non-living spaces) and symplast (living contents).
Formula:None
Solution:- The symplast pathway involves water moving from cell to cell through the cytoplasm.
- The cells are connected by microscopic channels called plasmodesmata, which facilitate this direct cytoplasmic transport.
Why other options are incorrect:- Apoplast: Movement through cell walls and intercellular spaces, not plasmodesmata.
- Vacuolar: Movement across vacuoles, which involves crossing tonoplast membranes.
[ETEA-2022]
____ is the attractive force between a water molecule and container.
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:Water molecules exhibit unique attractive forces that assist in transport mechanisms within the xylem.
Formula:None
Solution:- Adhesion is the attractive force between water molecules and unlike surfaces, such as the walls of the xylem vessels (or a container).
- This property prevents water columns from collapsing under gravity.
Why other options are incorrect:- Cohesion: The attractive force between water molecules themselves.
- Tension: The pulling force exerted on the water column by transpiration.
[SZABMU-2022]
Select the duration of cardiac cycle:
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:The cardiac cycle comprises one complete sequence of filling and pumping of the heart.
Formula:$$ \text{Duration} = \frac{60 \text{ seconds}}{\text{Heart Rate (beats/min)}} $$
Solution:- At a normal resting heart rate of roughly \(72\text{ to }75\text{ beats per minute}\):
- \( \text{Duration} = \frac{60}{75} = 0.8 \text{ seconds} \).
- This \(0.8\text{ sec}\) cycle includes atrial systole (\(0.1\text{s}\)), ventricular systole (\(0.3\text{s}\)), and complete cardiac diastole (\(0.4\text{s}\)).
Why other options are incorrect:- Values like \(0.4\text{ sec}\) describe only specific phases (e.g., joint diastole), not the entire cycle.
[SZABMU-2022]
In human heart, the left atrium receives:
D
The four pulmonary veins
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:The left side of the heart is dedicated to systemic circulation and receives freshly oxygenated blood.
Formula:None
Solution:- The left atrium acts as the receiving chamber for blood returning from the pulmonary circuit.
- It receives this oxygenated blood through four distinct pulmonary veins.
Why other options are incorrect:- Vena Cavae and Coronary Sinus: All three of these vessels return deoxygenated blood exclusively to the right atrium.
[NUMS-2022]
Heart beat is normally regulated by:
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Heart rate regulation is intrinsically controlled by autorhythmic cells.
Formula:None
Solution:- The Sinoatrial (SA) node possesses the fastest intrinsic rate of spontaneous depolarization.
- It functions as the heart's natural pacemaker, initiating the action potential and thus regulating the normal heartbeat.
Why other options are incorrect:- While the AV-bundle, Purkinje fibers, and Bundle of His conduct the impulse, they do not establish the primary rhythm under normal physiological conditions.
[UHS-2022]
Flow of blood in the capillaries is adjusted by:
B
Pre-capillary sphincters
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:Microcirculation must be finely tuned to match the metabolic demands of specific tissues at any given moment.
Formula:None
Solution:- At the junction between metarterioles and true capillaries, there are rings of smooth muscle known as pre-capillary sphincters.
- By contracting or relaxing, these sphincters act as valves to restrict or permit blood flow into the capillary beds based on local chemical signals.
Why other options are incorrect:- The heart provides systemic pressure but cannot dictate localized flow to individual capillary beds. Vein valves only prevent backflow.
[BUMHS-2022]
Histamine causes blood vessels to:
View Answer & Propolis Autopsy
Correct Key: Option A
Diagnostic Explanation
Concept:Histamine is a primary chemical mediator in the inflammatory response and allergic reactions.
Formula:None
Solution:- When released by mast cells or basophils, histamine acts on the smooth muscle of local blood vessels.
- It causes aggressive vasodilation (widening of the vessels) and increases capillary permeability.
- This allows more blood, immune cells, and fluid to reach the site of infection or injury, causing classic redness and swelling.
Why other options are incorrect:- Constrict: Histamine does the exact opposite; vasoconstriction is typically caused by epinephrine or angiotensin.
[UHS-2022]
The lymphatic vessels of the body empty the lymph into blood stream at:
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Lymph must be returned to the cardiovascular system to maintain total blood volume and fluid homeostasis.
Formula:None
Solution:- The two major lymphatic ducts (the Right Lymphatic Duct and the Thoracic Duct) gather all the body's lymph.
- They both connect to the circulatory system at the right and left subclavian veins, respectively, situated just under the collarbones.
Why other options are incorrect:- The jugular vein merges nearby but is not the direct entry point. Bile duct is part of the digestive system.
[SZABMU-2022]
Lymphatic system contains all of the following organs/structures except:
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:The lymphatic system is composed of an interconnected network of vessels, nodes, and specialized organs that house immune cells.
Formula:None
Solution:- Primary and secondary lymphoid organs include the bone marrow, thymus, spleen, lymph nodes, and tonsils.
- The lungs are primarily organs of the respiratory system dedicated to gas exchange.
- While lungs contain lymphatic drainage (like all tissues), the organ itself is not classified as a structure of the lymphatic system.
Why other options are incorrect:- Spleen: The largest secondary lymphoid organ in the body.
[BUMHS-2022]
Which of the following act as lymphatic organ?
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Lymphatic organs are specialized tissues where lymphocytes develop, mature, or execute their immune functions.
Formula:None
Solution:- The spleen is fundamentally a massive lymph node that filters blood instead of lymph.
- It contains white pulp (packed with lymphocytes for immune surveillance) and red pulp (for destroying old RBCs), firmly classifying it as a secondary lymphatic organ.
Why other options are incorrect:- Stomach, kidney, and liver are primarily digestive, excretory, and metabolic organs, respectively.
[PMC-2020]
Regarding structure of human heart chordae tendineae are present in:
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:Chordae tendineae are the mechanical anchors for the atrioventricular valves.
Formula:None
Solution:- These tendinous cords extend from the inferior edges of the AV valve cusps downwards.
- They attach to the papillary muscles, which are specialized extensions of the ventricular walls. Therefore, they are physically located within the ventricles.
Why other options are incorrect:- Atria: Receive blood; do not contain chordae tendineae.
- Pulmonary valve: A semilunar valve, which relies on its cup-like shape to close, lacking chordae tendineae entirely.
[PMC-2020]
In human heart the left atrium receives:
D
The four pulmonary veins
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:The left atrium serves as the collection chamber for oxygen-rich blood returning from the pulmonary circuit.
Formula:None
Solution:- After gas exchange in the lungs, oxygenated blood travels back to the heart.
- It enters the left atrium specifically via the four pulmonary veins (two from each lung).
Why other options are incorrect:- Vena Cava & Coronary Sinus: These vessels deliver deoxygenated blood from the body and heart muscle specifically to the right atrium.
[PMC-2020]
The only vein in the human body carrying oxygenated blood is:
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Anatomically, arteries carry blood away from the heart and veins carry blood toward the heart, regardless of oxygenation status.
Formula:None
Solution:- In the systemic circuit, veins carry deoxygenated blood.
- However, in the pulmonary circuit, the pulmonary vein returns blood from the lungs back to the left atrium of the heart.
- Because this blood has just undergone gas exchange in the alveoli, it is highly oxygenated, making the pulmonary vein the major exception to the rule.
Why other options are incorrect:- Femoral, Renal, and Iliac veins all carry deoxygenated systemic blood back to the vena cava.
[PMC-2020]
Which of the following blood vessels have the highest pressure of blood?
View Answer & Propolis Autopsy
Correct Key: Option A
Diagnostic Explanation
Concept:Blood pressure is directly proportional to the force of ventricular contraction and is highest closest to the pump.
Formula:None
Solution:- The left ventricle is the most powerful chamber, generating immense force to push blood through the massive systemic circuit.
- The aorta is the immediate vessel exiting the left ventricle.
- Because it receives the full, undissipated force of left ventricular systole, the aorta experiences the highest blood pressure in the body (typically \(120\text{ mmHg}\)).
Why other options are incorrect:- Vena cava: Has the lowest pressure as blood returns to the right atrium.
- Pulmonary arteries: Driven by the weaker right ventricle (usually around \(25\text{ mmHg}\)).
[MDCAT-2019]
Four plants are present in different environmental conditions. Plant A is present in warm climate with continuous rainfall, plant B is present in a cool forest, plant C is present in warm climate with little breeze while plant D is present in warm climate high wind speed. Which one of the above plants will have highest rate of transpiration?
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:The rate of transpiration depends heavily on external environmental factors like temperature, wind, and humidity.
Formula:None
Solution:- High temperatures increase the rate of evaporation of water from the mesophyll cells.
- High wind speed continuously removes the saturated air around the leaf, maintaining a steep water vapor concentration gradient.
- Plant D experiences both conditions, maximizing transpiration.
Why other options are incorrect:- Continuous rainfall: Creates high humidity, minimizing the concentration gradient.
- Cool forest: Lower temperatures reduce evaporation rates.
[MDCAT-2019]
Which of the following blood vessels contain semilunar valves?
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Blood pressure in the venous system is incredibly low, necessitating mechanical assistance to return blood against gravity.
Formula:None
Solution:- To prevent the backflow of blood, especially in the extremities, veins are equipped with internal semilunar (pocket) valves.
- These valves work in tandem with the skeletal muscle pump to push blood unidirectionally toward the heart.
Why other options are incorrect:- Arteries: High pressure from the heart prevents backflow, so no valves are needed (except at the exit of the heart itself).
- Capillaries/Arterioles: Too microscopic and under sufficient pressure gradient to require valves.
[MDCAT-2018]
Which statement is correct about atrial systole?
A
Atria relax and ventricles contract
B
Atria contract and ventricle also contract
C
Atria and ventricles are relaxed
D
Ventricles remain relax while atria contract
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:The cardiac cycle is meticulously timed to ensure sequential filling and pumping.
Formula:None
Solution:- "Systole" refers to contraction. During atrial systole, the atria actively contract to top off the ventricles with blood.
- For this filling to occur efficiently, the ventricles must be in a state of relaxation (diastole). Thus, ventricles remain relaxed while atria contract.
Why other options are incorrect:- If both contracted simultaneously (Option B), blood could not flow forward efficiently. Option A describes ventricular systole.
[MDCAT-2018]
Which one of the following act as a pacemaker in heart?
C
Atria ventricular bundles of fibers
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:The natural pacemaker of the heart determines the baseline heart rate.
Formula:None
Solution:- The Sino-atrial (SA) node spontaneously generates electrical impulses at a rate of \(70-80\) times per minute.
- Because its intrinsic rate is the highest, it overrides other potential pacemakers and sets the rhythm for the entire heart.
Why other options are incorrect:- The AV node and Bundle of His can act as backup pacemakers if the SA node fails, but they operate at a much slower, secondary rate (\(40-60\) bpm).
#41 of 50
MDCAT-2017, ETEA-2018
[MDCAT-2017, ETEA-2018]
In ECG, QRS complex represent:
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:An electrocardiogram (ECG) traces the electrical depolarization and repolarization waves across the heart muscle.
Formula:None
Solution:- The P-wave represents atrial depolarization.
- The QRS complex represents the rapid depolarization of the large ventricular muscle mass.
- This ventricular depolarization immediately triggers ventricular contraction, clinically known as ventricle systole.
Why other options are incorrect:- Atrial repolarization (diastole) is masked by the massive QRS complex.
- Ventricle diastole corresponds to the T-wave (ventricular repolarization).
[MDCAT-2017]
Thoracic lymph duct of the lymphatic system opens into ____.
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:The lymphatic system acts as a one-way drainage network that eventually returns interstitial fluid back into the venous circulation.
Formula:None
Solution:- The thoracic duct is the largest lymphatic vessel in the body, draining lymph from the lower body and the left side of the upper body.
- It empties this massive volume of lymph directly into the venous system at the junction of the left internal jugular vein and the left subclavian vein.
Why other options are incorrect:- Emptying directly into the high-flow Vena Cavae could cause turbulence; the subclavian veins offer a safer, low-pressure venous return point.
[MDCAT-2016]
In human the closed sac which surrounds the heart is:
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:The heart is enclosed in protective layers that reduce friction during contraction.
Formula:None
Solution:- The pericardium is a double-walled sac containing the heart and the roots of the great vessels.
- It provides lubrication via pericardial fluid, protecting the heart from friction and external shock.
Why other options are incorrect:- Myocardium: The muscular layer of the heart wall.
- Endocardium: The inner lining of the heart chambers.
[MDCAT-2016]
Chordae tendineae are the fibrous cords attached with:
A
Cardiac end of stomach valve
B
Pyloric sphincter of stomach
C
Tricuspid valve of heart
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:Valvular prolapse in the heart is prevented by tension cables.
Formula:None
Solution:- Chordae tendineae (heart strings) are tough, tendinous cords in the heart.
- They connect the papillary muscles to the tricuspid valve (and bicuspid valve) to prevent them from inverting during ventricular systole.
Why other options are incorrect:- Options A, B, and D describe structures completely unrelated to cardiovascular anatomy.
[MDCAT-2016]
Bicuspid valve controls the flow of blood from:
A
Right atrium to right ventricle
B
Left ventricle to aorta
C
Right atrium to left atrium
D
Left atrium to left ventricle
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:The unidirectional flow of oxygenated blood on the left side of the heart is regulated by the mitral valve.
Formula:None
Solution:- The bicuspid valve, also known as the mitral valve, is situated between the left atrium and the left ventricle.
- It ensures that blood passes downwards into the ventricle and does not regurgitate back into the atrium during contraction.
Why other options are incorrect:- Right atrium to right ventricle: Controlled by the tricuspid valve.
- Left ventricle to aorta: Controlled by the aortic semilunar valve.
[MDCAT-2015]
Right atrium is separated from right ventricle by:
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:Atrioventricular (AV) valves prevent the backflow of blood from the ventricles into the atria during systolic contraction.
Formula:None
Solution:- The valve located between the right atrium and the right ventricle consists of three cusps or flaps.
- It is anatomically named the tricuspid valve.
Why other options are incorrect:- Bicuspid (Mitral) Valve: Separates the left atrium and left ventricle.
- Semilunar Valves: Guard the exits of the ventricles (pulmonary trunk and aorta).
[MDCAT-2015]
The flaps of tricuspid valves are attached to muscular extensions of right ventricle known as:
View Answer & Propolis Autopsy
Correct Key: Option C
Diagnostic Explanation
Concept:The structural integrity of AV valves during ventricular contraction is maintained by an anchoring system.
Formula:None
Solution:- The flaps (cusps) of the AV valves are anchored by fibrous cords called chordae tendineae.
- These cords are tethered to cone-shaped muscular pillars projecting from the inner walls of the ventricles, called papillary muscles.
Why other options are incorrect:- Smooth/Skeletal Muscles: The heart is composed of specialized cardiac muscle, not general smooth or skeletal muscle.
- Intercostal Muscles: Located between the ribs to assist in breathing.
[MDCAT-2015]
The heart beat cycle starts when electric impulses are generated from:
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:The rhythmic contraction of the heart is autorhythmic, driven by specialized pacemaking tissue.
Formula:None
Solution:- The Sinoatrial (SA) node, located in the upper wall of the right atrium, naturally depolarizes faster than any other cardiac tissue.
- It initiates the electrical impulse that spreads across the atria, officially starting each heartbeat cycle.
Why other options are incorrect:- AV node: Delays and relays the impulse to the ventricles, but does not normally originate it.
- SV/PQ node: These are fictitious terms not used in standard cardiac electrophysiology.
[MDCAT-2015]
The lymph vessel of villi is called:
View Answer & Propolis Autopsy
Correct Key: Option D
Diagnostic Explanation
Concept:Dietary fats are too large and hydrophobic to directly enter the microscopic blood capillaries of the digestive tract.
Formula:None
Solution:- Within the center of each intestinal villus lies a specialized, blind-ended lymphatic capillary.
- This vessel is called a lacteal.
- Lacteals absorb packaged dietary fats (chylomicrons) to transport them through the lymphatic system before they are dumped into the bloodstream.
Why other options are incorrect:- Epithelium: The cellular lining of the villi.
- Afferent lymph vessel: Carries lymph towards a lymph node, not the specific fat-absorbing vessel in a villus.
[MDCAT-2014]
The oxygenated blood from lungs to heart is transported by the:
View Answer & Propolis Autopsy
Correct Key: Option B
Diagnostic Explanation
Concept:The pulmonary circulation operates oppositely to the systemic circulation in terms of oxygen content within vessels.
Formula:None
Solution:- Veins generally carry blood toward the heart.
- The pulmonary veins carry newly oxygenated blood from the capillary beds of the lungs back to the left atrium of the heart.
Why other options are incorrect:- Pulmonary artery: Carries deoxygenated blood away from the heart to the lungs.
- Coronary artery: Supplies oxygenated blood to the heart muscle itself.
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