IB Biology Quiz: Apply Integration Of Body Systems
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Apply Integration Of Body SystemsQuestion 1 of 20

A glucose molecule is absorbed from the lumen of the small intestine. Which sequence correctly describes the integration of the circulatory and digestive systems for its immediate transport to a hepatocyte (liver cell)?

Villus capillary → hepatic portal vein → liver sinusoid → hepatocyte
Villus lacteal → lymphatic system → subclavian vein → hepatocyte
Villus capillary → superior vena cava → aorta → hepatic artery → hepatocyte
Villus epithelium → hepatic artery → liver sinusoid → hepatocyte
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IB Biology Quiz

IB Biology Quiz: Apply Integration Of Body Systems

Practice Apply Integration Of Body Systems in IB Biology with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

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Question 1

A glucose molecule is absorbed from the lumen of the small intestine. Which sequence correctly describes the integration of the circulatory and digestive systems for its immediate transport to a hepatocyte (liver cell)?

  1. Villus capillary → hepatic portal vein → liver sinusoid → hepatocyte (correct answer)
  2. Villus lacteal → lymphatic system → subclavian vein → hepatocyte
  3. Villus capillary → superior vena cava → aorta → hepatic artery → hepatocyte
  4. Villus epithelium → hepatic artery → liver sinusoid → hepatocyte
Explanation: Water-soluble nutrients like glucose are absorbed into the blood capillaries within the intestinal villi. These capillaries converge to form venules and then veins, which lead to the hepatic portal vein. This vein carries nutrient-rich blood directly to the liver, where it enters specialized capillaries called sinusoids, allowing hepatocytes to process the absorbed nutrients before they enter general circulation. The other pathways are incorrect for initial glucose transport.

Question 2

A person with untreated type 1 diabetes mellitus cannot produce insulin. How does this disrupt the integration between the endocrine, digestive, and excretory systems after a carbohydrate-rich meal?

  1. Without insulin, digestive enzymes are not released, preventing carbohydrate breakdown and causing their excretion.
  2. Without insulin, the liver and muscles cannot take up glucose from the blood, leading to hyperglycemia that overwhelms the kidney's reabsorptive capacity. (correct answer)
  3. Without insulin, the kidneys are stimulated to reabsorb less water, leading to dehydration despite high blood glucose levels.
  4. Without insulin, the stomach empties more rapidly, flooding the small intestine with sugars that cannot be absorbed and are thus excreted.
Explanation: Insulin signals liver and muscle cells to take up glucose from the blood for storage as glycogen. Without insulin, glucose absorbed from the digested meal remains in the bloodstream, causing severe hyperglycemia. The glucose concentration in the glomerular filtrate becomes so high that the carrier proteins for glucose reabsorption in the proximal convoluted tubule become saturated. The excess glucose is therefore not reabsorbed and is excreted in the urine (glucosuria).

Question 3

A drug that blocks the release of ADH (antidiuretic hormone) is ingested. What is the resulting effect on the integration of the excretory and circulatory systems?

  1. The collecting ducts become less permeable to water, leading to a large volume of dilute urine and an increase in blood osmolarity. (correct answer)
  2. The glomerulus filtration rate increases, leading to a greater volume of urine and a decrease in blood pressure.
  3. The collecting ducts become more permeable to water, leading to a small volume of concentrated urine and a decrease in blood osmolarity.
  4. The reabsorption of sodium in the proximal tubule is inhibited, causing more water to be lost in the urine and blood volume to decrease.
Explanation: ADH increases the permeability of the collecting ducts and distal convoluted tubules to water. By blocking ADH release, these structures become less permeable. Consequently, less water is reabsorbed from the filtrate back into the blood. This results in the production of a large volume of dilute urine. The loss of water from the body without a proportional loss of solutes causes the remaining blood to become more concentrated, thus increasing its osmolarity.

Question 4

In individuals with celiac disease, the villi of the small intestine are damaged and flattened. What is the most significant systemic consequence of this condition?

  1. Reduced water reabsorption leads to chronic dehydration and electrolyte imbalances.
  2. Increased peristalsis causes rapid transit, preventing proper nutrient processing.
  3. Malabsorption of nutrients due to reduced surface area leads to malnutrition. (correct answer)
  4. Pancreatic overstimulation leads to excess digestive enzymes in the bloodstream.
Explanation: The villi and microvilli of the small intestine vastly increase the surface area available for nutrient absorption. In celiac disease, damage to these structures severely reduces this surface area. As a result, the body cannot efficiently absorb nutrients (vitamins, minerals, carbohydrates, fats, proteins) from digested food. This malabsorption leads to systemic effects like malnutrition, weight loss, and various deficiency-related disorders, demonstrating how a disruption in the digestive system's structure affects the entire organism.

Question 5

A sudden, severe drop in systemic blood pressure occurs. How does this event affect the integration of the circulatory and excretory systems at the level of the nephron?

  1. It increases the glomerular filtration rate (GFR) because the afferent arteriole dilates to compensate.
  2. It decreases the GFR because the hydrostatic pressure driving filtration is reduced. (correct answer)
  3. It has no effect on GFR because of hormonal regulation by ADH and aldosterone.
  4. It causes the glomerular capillaries to become more permeable, increasing the amount of protein in the filtrate.
Explanation: Glomerular filtration is driven by the hydrostatic pressure of the blood in the glomerular capillaries, which is a direct result of systemic blood pressure. A severe drop in blood pressure will significantly reduce this filtration pressure. While some autoregulation occurs, a large drop will overcome these mechanisms, leading to a decreased GFR. This demonstrates the direct dependence of the kidney's primary function (filtration) on the state of the circulatory system.

Question 6

The arrival of acidic chyme into the duodenum stimulates the release of the hormone secretin. How does secretin integrate the function of the small intestine and the pancreas?

  1. Secretin travels via the blood to the pancreas, stimulating it to release bicarbonate-rich fluid to neutralize the acid. (correct answer)
  2. Secretin stimulates the stomach to increase acid production, aiding further digestion in the duodenum.
  3. Secretin directly activates pancreatic amylase and lipase within the lumen of the small intestine.
  4. Secretin stimulates the liver to release bile, which then activates pancreatic enzymes.
Explanation: This is an example of hormonal integration. The duodenum (part of the digestive system) detects the low pH of chyme from the stomach. In response, its cells release secretin into the bloodstream (integrating with the circulatory/endocrine system). Secretin travels to the pancreas, another digestive organ, and stimulates duct cells to secrete a fluid rich in bicarbonate. This fluid neutralizes the stomach acid in the duodenum, creating an optimal pH for pancreatic digestive enzymes to function.

Question 7

A toxin selectively and completely inhibits all active transport pumps in the membranes of the epithelial cells of the proximal convoluted tubule (PCT). What is the most immediate consequence for the composition of urine?

  1. The urine will become highly concentrated with urea but will lack glucose and sodium ions.
  2. The urine will have an abnormally high volume and contain significant amounts of glucose, amino acids, and mineral salts. (correct answer)
  3. The urine will have a significantly reduced volume as water is retained in the body to compensate for the loss of active transport.
  4. The urine will become highly acidic due to the inability to reabsorb bicarbonate ions, but its volume will remain normal.
Explanation: The PCT is responsible for reabsorbing most of the glucose, amino acids, mineral salts, and water from the glomerular filtrate. This reabsorption relies on active transport (e.g., Na+/K+ pumps). If these pumps are inhibited, these solutes will not be reabsorbed. As a result, the filtrate remains solute-rich, preventing the osmotic reabsorption of water. This leads to a large volume of urine containing substances that should have been reabsorbed.

Question 8

A patient with severe liver disease develops edema, which is the swelling of tissues due to excess fluid. What is the most direct explanation for this symptom, considering the liver's role in integrating with the circulatory system?

  1. Failure to detoxify ammonia causes blood vessels to become more permeable, allowing plasma to leak into tissues.
  2. Reduced synthesis of the plasma protein albumin lowers the solute potential of the blood, hindering the return of fluid from tissues to capillaries. (correct answer)
  3. Impaired glycogenolysis leads to low blood sugar, which causes water to move out of the blood and into the more concentrated tissue fluid.
  4. Failure to produce bile prevents fat absorption, leading to a deficiency of phospholipids needed to maintain capillary wall integrity.
Explanation: The liver synthesizes most plasma proteins, including albumin, which is the main contributor to the colloid osmotic pressure (oncotic pressure) of the blood. This pressure is essential for drawing fluid from the interstitial space back into the capillaries. In severe liver disease, albumin synthesis is reduced, lowering blood oncotic pressure. Consequently, less fluid returns to the capillaries, and it accumulates in the tissues, causing edema.

Question 9

Jaundice can result from a blockage of the bile duct. This condition demonstrates a breakdown in the integration between which three systems?

  1. Circulatory, excretory, and nervous systems
  2. Digestive, lymphatic, and endocrine systems
  3. Circulatory, digestive, and integumentary systems (correct answer)
  4. Excretory, endocrine, and digestive systems
Explanation: The breakdown of old red blood cells (circulatory system) in the liver produces bilirubin. The liver excretes bilirubin into the bile, which flows into the small intestine (digestive system). If the bile duct is blocked, bilirubin cannot be excreted and builds up in the blood. This excess bilirubin is deposited in the skin and eyes (integumentary system), causing the characteristic yellowing of jaundice. This illustrates the integration of these three systems.

Question 10

During a prolonged period of fasting, how does the liver integrate its function with the needs of other body systems, particularly the nervous system?

  1. By increasing the rate of deamination to provide amino acids as a primary fuel source for brain cells.
  2. By breaking down stored glycogen (glycogenolysis) to release glucose into the blood, maintaining a supply for cellular respiration in the brain. (correct answer)
  3. By synthesizing ketone bodies from amino acids, which are then used by the muscles to spare glucose for the brain.
  4. By stimulating the pancreas to release insulin, which enhances the uptake of any available glucose by neurons.
Explanation: The brain relies almost exclusively on glucose for energy but cannot store it. During fasting, blood glucose levels drop. The liver maintains blood glucose homeostasis by breaking down its glycogen stores into glucose and releasing it into the bloodstream. This ensures a steady supply of glucose for the brain and other tissues. This is a critical integration of the liver's metabolic role with the circulatory system to meet the constant energy demands of the nervous system. Ketone body production from fats (not amino acids) occurs later in starvation.

Question 11

Severe liver failure can lead to hepatic encephalopathy, a condition with neurological symptoms like confusion and coma. This is a direct consequence of the failure of which integrated function?

  1. The liver's inability to regulate blood glucose, depriving the brain of its primary energy source.
  2. The liver's failure to synthesize clotting factors, leading to micro-hemorrhages in the brain tissue.
  3. The liver's inability to produce cholesterol, which is essential for the structure of neuron plasma membranes.
  4. The liver's failure to convert neurotoxic ammonia, a byproduct of amino acid metabolism, into urea for excretion. (correct answer)
Explanation: A key detoxification function of the liver is to take ammonia, produced from the deamination of amino acids in the liver and by bacteria in the gut, and convert it into the less toxic compound urea via the urea cycle. This urea is then safely transported in the blood to the kidneys for excretion. If the liver fails, ammonia levels in the blood rise. Ammonia is highly toxic to the central nervous system and can cross the blood-brain barrier, causing the neurological symptoms of hepatic encephalopathy.

Question 12

An athlete consumes a large amount of glucose an hour before a competition. How does the liver's function of nutrient interconversion help manage this glucose surplus?

  1. The liver converts the excess glucose into amino acids through deamination to be used for muscle repair.
  2. The liver immediately converts all excess glucose into ketone bodies for a more efficient energy source.
  3. The liver first stores excess glucose as glycogen and, once stores are full, converts further excess into fatty acids and triglycerides. (correct answer)
  4. The liver signals the kidneys to excrete the excess glucose to prevent hyperglycemia.
Explanation: The liver is the central organ for metabolic interconversion. After a large glucose intake, insulin stimulates the liver to take up glucose. Its first priority is to store it as glycogen (glycogenesis). Liver glycogen stores are limited. Once these stores are replenished, the liver converts any remaining excess glucose into fatty acids and glycerol, which are then assembled into triglycerides. These triglycerides are exported from the liver in very-low-density lipoproteins (VLDLs) to be stored in adipose tissue.

Question 13

The breakdown of hemoglobin from old erythrocytes occurs in the liver and spleen, releasing iron. How is this process integrated with the circulatory system to conserve this essential mineral?

  1. The iron is bound to bile salts and excreted into the intestine for reabsorption.
  2. The iron is immediately filtered by the kidneys and stored in the renal medulla.
  3. The iron is attached to the plasma protein transferrin and transported in the blood to the bone marrow for new hemoglobin synthesis. (correct answer)
  4. The iron is stored permanently in the liver as ferritin and is not re-utilized by the body.
Explanation: This shows integration for resource conservation. When hemoglobin is broken down, the iron atom is recycled, not excreted. It is released into the bloodstream where it binds to a specific transport protein called transferrin. This protein safely transports the iron through the blood (circulatory system) to the red bone marrow, where it is used by developing erythrocytes (hematopoiesis) to synthesize new hemoglobin. This efficient recycling loop minimizes the need for dietary iron.

Question 14

Some kidney diseases increase the permeability of the glomerular filtration barrier. What would be a direct consequence seen in a urinalysis?

  1. Absence of urea, as it is fully reabsorbed to compensate for protein loss.
  2. High levels of glucose, as the transport proteins in the PCT become saturated.
  3. Presence of erythrocytes, because the entire filtration barrier has been compromised.
  4. Presence of albumin, as this large plasma protein can now pass through the barrier into the filtrate. (correct answer)
Explanation: The healthy glomerular filtration barrier, consisting of the fenestrated endothelium, basement membrane, and podocytes, prevents large molecules like plasma proteins (e.g., albumin) and blood cells from entering the filtrate. If the barrier's permeability increases, albumin can leak through. Since there is no mechanism for reabsorbing proteins in the tubule, it will appear in the urine (proteinuria). Erythrocytes are much larger and would only appear with more severe damage.

Question 15

If the efferent arteriole of a glomerulus is constricted while the afferent arteriole remains unchanged, what is the integrated effect on glomerular filtration and systemic blood volume?

  1. Glomerular filtration rate (GFR) increases and systemic blood volume decreases. (correct answer)
  2. Glomerular filtration rate (GFR) decreases and systemic blood volume increases.
  3. Glomerular filtration rate (GFR) decreases and systemic blood volume is unchanged.
  4. Glomerular filtration rate (GFR) increases and systemic blood volume increases.
Explanation: Constricting the efferent arteriole (the exit) increases resistance to blood flow out of the glomerulus. This 'dams up' the blood within the glomerulus, increasing the hydrostatic pressure inside the glomerular capillaries. This higher pressure drives more fluid out into the Bowman's capsule, thus increasing the GFR. An increased GFR means more fluid is being removed from the blood to become filtrate. If this fluid is subsequently excreted as urine, it will lead to a decrease in the total systemic blood volume.

Question 16

When comparing the composition of blood in the renal artery with blood in the renal vein of a healthy person, which of the following is expected?

  1. The renal vein has a higher concentration of glucose because the kidney produces it for energy.
  2. The renal vein has a lower partial pressure of carbon dioxide as it is excreted into the urine.
  3. The renal vein has a higher concentration of plasma proteins because water has been removed from the blood.
  4. The renal vein has a lower concentration of urea because it has been filtered from the blood and not reabsorbed. (correct answer)
Explanation: The primary function of the kidney is to filter waste products from the blood. Blood enters the kidney via the renal artery. In the nephrons, urea is filtered from the blood at the glomerulus and is not significantly reabsorbed. Therefore, the blood leaving the kidney via the renal vein has a much lower concentration of urea. Glucose is normally fully reabsorbed, CO2 is produced by kidney cell respiration (so it's higher in the renal vein), and while some water is removed, the relative change in urea is the most significant and defining difference.

Question 17

An individual with a healthy liver and kidneys adopts a diet extremely high in protein. Which statement correctly describes the integrated response of the liver and kidneys to this dietary change?

  1. The liver increases the rate of transamination to synthesize non-essential amino acids, while the kidneys increase the secretion of ammonia to balance blood pH.
  2. The liver increases the rate of deamination of excess amino acids, leading to a higher concentration of urea in blood arriving at the kidneys for filtration. (correct answer)
  3. The liver increases its synthesis of plasma proteins from the excess dietary amino acids, causing an increase in glomerular filtration rate due to higher blood pressure.
  4. The liver converts excess amino acids into glucose via gluconeogenesis, which subsequently increases the amount of glucose reabsorbed in the proximal convoluted tubules.
Explanation: A high-protein diet provides more amino acids than needed for protein synthesis. The excess amino acids are processed in the liver via deamination, which removes the amino group, forming ammonia. The liver rapidly converts toxic ammonia into less toxic urea. This urea enters the bloodstream, increasing its concentration, and is then filtered out by the kidneys for excretion in urine. This demonstrates the integration of the liver's metabolic function with the kidney's excretory function.

Question 18

Following digestion, the absorption of triglycerides differs from that of monosaccharides. How does this difference reflect an integration with different transport systems?

  1. Triglycerides are absorbed into the hepatic portal vein, while monosaccharides are absorbed into the lacteals of the lymphatic system.
  2. Monosaccharides are absorbed into capillaries, while reformed triglycerides enter the lacteals and are transported via the lymphatic system. (correct answer)
  3. Both are absorbed into blood capillaries, but triglycerides are packaged into lipoproteins while monosaccharides travel dissolved in plasma.
  4. Both are absorbed into the lacteals, but monosaccharides are immediately transferred to blood capillaries while triglycerides remain in the lymph.
Explanation: This question highlights the integration of the digestive system with two different circulatory systems. Water-soluble monosaccharides are absorbed directly into the blood capillaries of the villi, which lead to the hepatic portal vein. In contrast, fatty acids and monoglycerides are absorbed and re-formed into triglycerides within the epithelial cells, then packaged into chylomicrons. These are too large to enter capillaries and instead enter the lacteals, which are part of the lymphatic system. They eventually enter the bloodstream via the thoracic duct.

Question 19

Which statement best describes the integration of organ systems in the processing of dietary fat, from the small intestine to its use by an adipose cell?

  1. Bile emulsifies fats, which are absorbed into the hepatic portal vein and stored directly in the liver before being sent to adipose tissue.
  2. Bile digests fats into fatty acids, which are transported by plasma proteins directly to adipose cells for immediate use as energy.
  3. Stomach acid denatures fats, which are absorbed into capillaries, processed by the kidneys, and then transported to adipose cells.
  4. Pancreatic lipase digests fats, which are absorbed into lacteals, transported via the lymphatic system to the blood, and then stored in adipose tissue. (correct answer)
Explanation: This process involves multiple systems. The liver produces bile (stored in the gallbladder) and the pancreas produces lipase, both acting in the small intestine (digestive system). Digested fats are absorbed and reformed, then enter the lacteals (lymphatic system). The lymphatic system transports them as chylomicrons, which eventually enter the bloodstream (circulatory system). Lipoprotein lipase on capillary walls releases fatty acids from the chylomicrons, which are then absorbed by adipose cells for storage.

Question 20

During a state of metabolic acidosis, the blood pH drops. How do the kidneys integrate their function to help restore blood pH homeostasis?

  1. By decreasing the filtration rate at the glomerulus to retain more bicarbonate ions in the blood.
  2. By increasing the secretion of hydrogen ions (H+) into the filtrate and increasing the reabsorption of bicarbonate ions (HCO3-). (correct answer)
  3. By increasing the reabsorption of urea to create an osmotic gradient that helps excrete excess acid.
  4. By decreasing the secretion of potassium ions to allow for more exchange with hydrogen ions across the tubule membrane.
Explanation: The kidneys play a crucial role in long-term pH regulation. During acidosis (excess H+), the tubule cells of the nephrons increase their secretion of H+ into the filtrate, which is then excreted in urine. Simultaneously, they increase the reabsorption of bicarbonate ions (HCO3-), a key blood buffer, from the filtrate back into the blood. This dual action removes acid from the body and replenishes the blood's buffering capacity, directly integrating excretory function with the maintenance of blood chemistry.