BIOD102/ BIOD 102 Essential Biology II Module 4 | Latest Updated Q&A 2026/ 2027 | Verified Answers | Grade A+ (Portage)

BIOD102/ BIOD 102 Essential Biology II Module 4 | Latest Updated Q&A 2026/ 2027 | Verified Answers | Grade A+ (Portage) Q: What is a consequence of blood calcium levels being dangerously elevated? Answer The crystallization of tissues Q: What is the set point for blood calcium levels? Answer 10 mg/mL Q: What are the four main parts of a negative feedback loop? And what would they be for calcium? Answer set point: 10/mg per ml stimulus: decreased calcium sensor: calcium sensing receptors response: PTH is released and causes more absorption Q: Describe the mechanisms of calcitonin and how blood calcium is increased: Answer Calcitonin is released and binds to osteoclasts to prevent breakdown, then binds to renal tubes to increase excretion. Q: What is the cause of hypercalcemia in adults? Answer excess PTH Q: Islets of Langerhans are composed of which cell types? What does each one do? Answer Alpha/Beta Alpha is responsible for glucagon release Beta is responsible for insulin release Q: True or False. Insulin is the main source of energy for almost all body Answer tissues. False Q: True or False. Beta cells not only secret insulin to lower blood glucose, but also serve as the sensor in monitoring blood glucose concentration. Answer True Q: Fill in the blank. Excess glucose is first stored as glycogen in the ______1_______and in skeletal muscle. Next, it will be stored within adipose tissue as______2_______ . Answer Liver Fat/triglycerides Q: The process of stored glycogen being converted to glucose and released into the blood is called: Answer Glycogenolysis Q: Fill in the blank. ______1_______attacking ______2_______results in Answer Type I diabetes. Antibodies Beta cells Q: (short answer) What are two major risk factors for Type II diabetes? Answer Obesity and sedentary lifestyle- mentioned in lecture but age, race, family history, high blood pressure, polycystic ovarian syndrome, and gestational diabetes are also risk factors. Q: Type I diabetes is controlled through blood glucose monitoring and: Answer insulin injections Q: Fill in the blank. As fats are converted to ketones a condition called ________________ may occur. Answer acidosis Q: Neurons of the hypothalamus serve as the ___________for the role of maintaining satiety feedback loops. Answer Sensor Q: Which of the following plays a role in eliciting a feeling of fullness (satiety) in the appetite feedback regulation system? (select all that apply): Answer Insulin PYY Leptin Q: Osmoreceptors monitoring blood osmolarity are located in the: Answer Hypothalamus Q: ADH released from the pituitary causes: Answer increased water absorption Q: (short answer) If ADH causes the reabsorption of water in the renal tubules, what is the consequence of urine output (i.e. what happens to urine? Answer It is excreted in a smaller volume and is more concentrated in terms of ions and metabolites Q: When excess fluid is lost but osmolarity remains unchanged, ___________ is released from the juxtaglomerular apparatus. Answer Renin Q: Each of the following are regulators in the RAAS pathway except: Answer ADH is not part of the RAAS Q: Fill in the blank. Aldosterone is released from the ________1_________ after being stimulated by _________2________ . Answer Adrenal cortex Angiostensin 2 Q: (short answer) Explain how targeting certain steps within the RAAS pathway can be an effective treatment for high blood pressure. Answer Targeting ACE prevents the conversion of angiotensin I to angiotensin II, and therefore arterioles aren't being stimulated to constrict. Blood vessels will remain dilated therefore lowering blood pressure. Intervening at that level also stops aldosterone from being released. Q: Baroreceptors are located in the: Answer Large arteries of the neck and chest Q: During baroreceptor regulation, the sensor is: Answer The baroreceptors Q: When blood pressure deceases, what is the secondary mechanism that is activated? Answer Adrenal medullary Q: True or False. Norepinephrine is released in response to signals from the medulla. Answer False Q: True or False. Chemoreceptors do not require input from the hypothalamus. Answer True Q: Stimulation of the SNS by chemoreceptors causes the following response: Answer Vasoconstriction Q: True or False. The hypothalamus only responds to changes in body temperature occurring from evaporation. Answer False Q: (short answer) Explain how heat stroke occurs. Answer When humidity is above 60% water (sweat) does not evaporate. Evaporative cooling is the body's most effective means of cooling, so one can rapidly overheat when it is impaired. Q: How does blood vessel dilation contribute to restoring the homeostatic set point for body temperature? Answer Blood is brought closer to the surface, and the skin won't absorb heat from the environment. Q: If shivering burns calories, why don't people just cool themselves instead of dieting to lose weight? Answer Because it's physically taxing. Long periods of shivering do indeed burn calories, but glycogen stores are depleted in the process, and an individual is likely to feel tired and weak. Q: True or False. The hypothalamus has the capability to temporarily reprogram the homeostatic set point, such as during exercise. Answer False Q: How is a positive feedback loop different from a negative feedback loop? Answer There is no return to baseline Q: Fill in the blank. During the onset of parturition, ________1________ is turned "off" making it possible for _________2_________ to stimulate contractions of the uterus. Answer Progesterone Estrogen Q: True or False. The hypothalamus does not play a role in the positive feedback response of parturition. Answer False Q: Describe the step (s) in which positive feedback is observed within the blood clotting cascade. Answer There is a positive feedback amplification loop once prothrombin is converted to thrombin. Thrombin increased the amount of activated clotting factors which in turn activates more thrombin. This amplification continues until a fibrin clot is formed. Irreversible hypovolemic shock occurs from: Answer negative feedback regulated through amplification What part of the nervous system controls fight or flight? Answer sympathetic nervous system ( SNS How does epinephrine work? Answer Epinephrine is a hormone that targets the heart, blood vessels, liver, and adipose tissue. Binding to heart cells increases heart rate and stroke volume, thereby increasing blood pressure. The smooth muscle of the blood vessel walls is stimulated to constrict, which also contributes to an increase in blood pressure What are chemoreceptors? Answer Chemoreceptors are sensors located in the large arteries near the heart that sense changes in blood oxygen and carbon dioxide concentrations and changes in blood pH what is the functional unit of the kidney? Answer The functional unit of a kidney is the nephron What is the healthy osmolarity range for humans? Answer A healthy osmolarity range for humans is 285-295 mOsm/L (milliosmole per liter) What organ/gland is responsible for monitoring osmolarity? Answer The hypothalamus Which glad secretes ADH? Answer posterior pituitary What is the function of ADH? Answer stimulates retention of water by the kidneys What is another name for ADH? Answer also known as vasopressin What are aquaporin channels and how do they work? Aquaporin channels increase the amount of water in the blood by reabsorption, which causes a lower volume of water to be excreted in the urine. Water reabsorption increases water volume in the blood, thereby decreasing blood osmolarity What is the order of operations for blood osmolarity Homeostatic regulation of osmolarity. Blood osmolarity increases as salts become more concentrated when water is lost through sweating. Osmoreceptors in the hypothalamus cause two responses. (1) Secretion of ADH from the posterior pituitary is triggered. ADH binds to membrane-bound receptors of the kidney tubule system, which increases water reabsorption, and a lower volume is therefore excreted. (2) This then stimulates satiety neurons to generate thirst. Thirst is quenched by drinking, and the volume of fluid that is ingested decreases osmolarity. Both mechanisms contribute to a return to normal osmolarity levels. how is the renin-angiotensin-aldosterone system ( RAAS) triggered? Major fluid or blood loss that causes a decrease in blood pressure. What is the order of operations of the RAAS complex? Homeostatic regulation of blood pressure and volume. Blood pressure drops as blood volume is decreased due to severe dehydration or blood loss. Changes are detected by sensors in the juxtaglomerular apparatus (JGA) and trigger the release of renin. Renin cleaves angiotensinogen (secreted from the liver) into angiotensin I. ACE then converts angiotensin I into angiotensin II, which stimulates the adrenal gland to secrete aldosterone. Aldosterone causes constriction of arterioles and promotes the reabsorption of sodium and water from the tubules of the kidney. When the cells of the JGA sense an increase in blood volume, renin is no longer released What is the function of aldosterone? aldosterone, which is a steroid hormone that targets cells of the distal tubules and collecting ducts to increase reabsorption of sodium and water how do ace inhibitors work? ACE inhibitors prevent the conversion of angiotensin I to angiotensin II, thereby promoting vasodilation of the arteries and reducing pressure within the vessels What is homeostasis? Homeostasis is the tendency to maintain an equilibrium, or setpoint, among interdependent physiological processes despite environmental changes What is homeostasis regulated by? Homeostasis is regulated by feedback loops, namely, both negative feedback and positive feedback loops. The most common feedback loop used for mammalian regulation is negative feedback, which involves a stimulus being reduced or removed. What is the normal body temp range? 36.1 - 37.2⁰ C What is normal blood PH range? 7.35 - 7.45 What is normal blood glucose range? 70 - 100 mg/dL What would happen if calcium blood levels dropped too sharply? Calcium (Ca2+) set points must be carefully regulated. If calcium levels drop sharply, skeletal muscle and cardiac muscle will experience strong, uncontrolled contractions that can be fatal What are the parathyroid glands and where are they located? The parathyroid glands are four tiny structures nestled within the posterior (back) surface of the thyroid gland. These glands are equipped with specialized calcium-sensing receptors (CaSRs) that monitor and detect changes in calcium levels in the blood. How does PTH function? Directly, PTH binds to receptors of bone and kidney tissue. In bone, PTH stimulates certain bone cells called osteoclasts to begin the process of breaking down bone matrix and releasing calcium ions into the bloodstream. In the kidneys, PTH binds to renal tubules to increase the reabsorption of calcium so that less is excreted in urine, and the ions are returned to the blood What is an indirect method of calcium absorption? The kidneys are stimulated to create active vitamin D which is then transported to the small intestine and facilitates he absorption of more calcium from food. What is the order of operations for calcium uptake? The parathyroid releases PTH to increase blood calcium levels. (top) Blood calcium levels are at a normal level of 10 mg/mL. Blood calcium levels fall, and the change is detected by CaSRs in the parathyroid glands. PTH is released into the blood. Directly, the osteoclasts of bone remodel bone matrix and release calcium into the blood. Directly, PTH binds to kidney tubules, increasing the reabsorption of calcium. Indirectly, the kidneys are also stimulated to facilitate the conversion of vitamin D from its precursor form. Active vitamin D binds to cells of the small intestine to increase calcium absorption. These direct and indirect mechanisms raise blood calcium levels. Not shown: PTH is inhibited by a negative feedback loop as the CaSRs detect a rise in blood calcium to the set point. How does calcitonin function? Opposite of PTH Prevents the osteoclasts from dumping calcium and tells the kidneys not to excrete calcium ions What are treatments for hypercalcemia? treatments for chronic hypercalcemia may include artificial calcitonin, drugs called calcimimetics that block PTH, and diuretics to increase urine output and calcium excretion. Where is insulin synthesized and stored ? Insulin is a peptide hormone synthesized and stored within specialized cells of the pancreas called the islets of Langerhans How much mass of the pancreas do the islets comprise? Altogether, the islet cells comprise 1-2% of the mass of the pancreas, with the remaining tissue being designated for digestive functions. In addition to the pancreas, the liver also plays a role in blood glucose homeostasis What organ can absorb glucose without insulin? The brain Where is most glucose absorbed and stored after a meal? Absorbed by the hepatic portal vein and stored in the liver as glycogen. What is glycogenolysis? Glycogenolysis is the catabolic process of glycogen being broken into smaller amino acids and glucose, which is released into the bloodstream and taken up by cells How does metformin work? Metformin decreases hepatic (liver) glucose synthesis, decreases glucose absorption in the small intestine, and increases the insulin sensitivity of target cells. Order of operations for glucose regulation Homeostatic regulation of blood glucose concentration. Top: Blood glucose is controlled by both insulin and glucagon. After eating, there is a spike in blood glucose that is detected by the pancreatic islets. Insulin is released, and body tissues take up glucose from the blood. Excess glucose is stored as glycogen in the liver and skeletal muscle. This mechanism allows for the set point to be maintained. Bottom: Blood glucose falls after fasting, and the pancreatic islets detect this change. Alphacells release glucagon, which facilitates the conversion of stored glycogen to be broken down into glucose and released into the bloodstream. Blood glucose levels rise, and as the set point is reached, glucagon secretion stops. What is grehlin? Ghrelin is a hormone secreted by cells of the stomach that stimulates the neurons of the hypothalamus to stimulate feelings of hunger What is PYY? The counter to grehlin order of operations for appetite Homeostatic regulation of appetite. The neurons that compose the satiety center of the brain are located within the hypothalamus. Ghrelin is a hormone secreted from the stomach that stimulates the satiety center to initiate hunger and encourage eating behavior. After a meal is ingested, inhibitory hormones are released, namely, leptin from adipose tissue, PPY from the small intestine, and insulin from the pancreas. The counterbalance among these hormones regulates the feelings of hunger and satiety. What is a consequence of blood calcium levels being dangerously elevated? The crystallization of tissues What is the set point for blood calcium levels? 10 mg/mL What is a consequence of blood calcium levels being dangerously elevated? The crystallization of tissues What is the set point for blood calcium levels? What is homeostasis? How is it regulated? Homeostasis is the tendency to maintain an equilibrium, or setpoint, among interdependent physiological processes despite environmental changes. Homeostasis is regulated by feedback loops. The most common feedback loop used for mammalian regulation is negative feedback, which involves a stimulus being reduced or removed. Conversely, positive feedback amplifies a stimulus. (See section 4.1 in the module) Explain how PTH and Calcitonin work to maintain blood calcium levels. When blood calcium levels are low, PTH is stimulated to help increase/restore levels to their set point. When blood calcium levels are high, calcitonin is released to help decrease/restore levels to their set point. (See section 4.1 in the module) Compare and contrast Type 1 and Type 2 Diabetes Type 1 is characterized by too little or no secretion of insulin from the islet cells. This type is considered insulin-dependent. Type 2 is non-insulin-dependent. Insulin is produced, but cells are resistant to insulin. What are the roles of Ghrelin and Leptin in satiety Ghrelin is a hormone secreted by cells of the stomach that stimulates the neurons of the hypothalamus to stimulate feelings of hunger. Leptin is released from adipose tissue to inhibit neurons of the hypothalamus producing the sensation of satiety. (See section What is osmolarity? What conditions can change its set point? Osmolarity is the measure of solute concentration in a liter of solution that contributes to the osmotic pressure of a solution. Specifically, it is the number of moles of a given solute per one liter of solution. The osmolarity set point can be changed by excessive sweating, large increases in salty food consumption, or dehydration due to illness. Explain how Angiotensinogen is converted to angiotensin II. Angiotensinogen is a blood protein synthesized and excreted by the liver. Once released, renin targets angiotensinogen and converts it to angiotensin I. Angiotensin-converting enzyme (ACE) is secreted by the cells of the lungs and kidneys and targets angiotensin I, thereby converting it to angiotensin I What role do baroreceptors play in the regulation of blood pressure? Baroreceptors are sensors that are located along the large arteries of the neck and chest that monitor blood pressure minute-to-minute. Baroreceptors permit a person to change position from laying to standing without any indication of the changes in blood pressure due to position and gravity. These receptors respond to the degree of “stretch” that occurs within the arteries. Increased stretching serves as an alert that blood pressure is too high and that there is a greater amount of resistance in the vessels. What role do chemoreceptors play in the regulation of blood pressure? Chemoreceptors are sensors located in the large arteries near the heart that sense changes in blood oxygen and carbon dioxide concentrations and changes in blood pH. Like baroreceptors, chemoreceptors restore homeostasis through negative feedback but are reflexive and do not communicate with the hypothalamus. Chemoreceptors that only monitor carbon dioxide concentration and pH of the blood are also found in the medulla oblongata. These receptors can be thought of as emergency-type regulators. Ordinarily, these receptors do not play a major role in blood pressure regulation but when there is a rapid decrease in oxygen concentration or a rapid increase in carbon dioxide concentration, they become active. The gain or loss of infrared energy between two objects that are not in direct contact with each other best describes which of the following Radiation Sweating is an example of what type of heat exchange? Evaporation Thrombin is an ________ that converts _______ to fibrin enzyme, fibrinogen Explain the positive feedback loop mechanism using parturition as an example starting with the initiation of uterine contractions. Action potentials are propagated from the mother’s uterus to sensory neurons of the mother’s hypothalamus. The hypothalamus stimulates the mother’s posterior pituitary to secrete oxytocin into the bloodstream. Oxytocin then reaches the uterus, where it binds to receptors causing the smooth muscle to contract. As the cervix (situated below the uterus) is stretched, it sends sensory signals to the hypothalamus, which in turn stimulates the pituitary, causing more oxytocin to be released. As labor progresses, the action potentials increase in frequency, causing spurts of oxytocin to be released that continue to stimulate the smooth muscle of the uterus. The amplification of oxytocin causes the uterine smooth muscle to stretch, and the stretching stimulates oxytocin in a continuous loop. It is this positive feedback loop that facilities the cervical dilation and uterine contractions that cause expulsion of the fetus. (See section What is radiation? Radiation involves the gain or loss of infrared energy between two objects that are not in direct contact with each other. Examples of radiation energy include absorption of heat from the hot sun or the cooling effect found by walking next to the cool ocean What is conduction? Conduction is the exchange of heat between two objects that are in direct contact. Walking barefoot outside on the cold pavement or strolling along the warm sand of the beach are examples of conduction heat exchange What is convection? Convection is the transfer of energy (heat) between the body and air or water. For example, a cool wind blowing over you on a chilly Fall evening is an example of convection. What is evaporation? Evaporation occurs when a liquid is converted to a gas. For example, during exercise, you may sweat, and the liquid evaporates from your skin, which produces a cooling effect. What is the temp range for a human? 36-38⁰ C Can the hypothalamus reprogram the temperature set point during illness? Yes What is parturition? Parturition refers to the birthing process, better known as labor and delivery. The fetal hypothalamus secretes a releasing hormone that stimulates the release of adrenocorticotropic hormone (ACTH) from the pituitary. ACTH, in turn, binds to the fetal adrenal glands, stimulating the secretion of various adrenal steroid hormones. The steroid hormones travel through the umbilical cord into the placenta. order of operations for clotting Positive feedback mechanism of blood clotting. (1) Clotting begins when the connective tissue of the vessel is exposed. Platelets adhere to the exposed connective tissue and begin sticking to one another. Clotting factors are released from the platelets, damaged tissue, and proteins in the blood plasma. An enzymatic cascade of clotting factors causes the conversion of prothrombin to thrombin. Thrombin amplifies the cascade to increase the number of activated clotting factors, which, in turn, activate more thrombin. Thrombin is the key clotting factor that converts inactive fibrinogen to active fibrin. (2) The platelet aggregation forms a plug to seal the tear in the vessel. (3) The amplification of activated fibrin facilitates the formation of a fibrin clot. Bacteria and archaea differ fundamentally in these areas Gene expression Cell walls Plasma membranes DNA replication What is the main method of prokaryotic reproduction? Binary fission Bioremediation includes __________. the use of prokaryotes to clean up pollutants The presence of a membrane-enclosed nucleus is a characteristic of _______. eukaryotic cells Bacterial cell walls contain which compound that helps strengthen the structure? Peptidoglycan In the video called "Flu Attack! How a Virus Invades Your Body", receptors on the surface of the host cell bind to virus capsid proteins or virus envelope glycoproteins. To help remember the limitations, the virus proteins were called __[a]___ and the receptors on the host cell's surface were called __[b]___. (Hint: think about houses and cars. How do these inanimated objects make sure no one random can enter?) a. Key b. Lock Viroids are known to infect all types of cells (plant and animal) because they lack a protein coat. False Which of the following is not associated with prions? Nucleic acids All bacteria are harmful for humans. False Prokaryotes divide by binary fission and do not reproduce sexually. Therefore, genetic variation is not important. False Viruses have to enter eukaryotic cells by endocytosis or, if enveloped, by fusion with the cell's membrane. Virus DNA is too unstable to enter a cell naked. False Vaccines _______________. stimulate an immune response Prokaryotes stain as Gram-positive or Gram-negative because of differences in the cell ______. wall In general, extremophiles belong to which domain of life? Archaea Prokaryotic metabolism allows for the acquisition of carbon. There are two main forms of acquisition strategies. __[a]__ get the carbon from inorganic CO2 and __[b]__ get the carbon from organic molecules. a. autotroph b. heterotroph How did viruses evolve? It is still unclear Which statement is true? Viruses are acellular. Symbiosis refers to the ecological relationship between different species that live in direct contact with each other. Some example(s) of these relationships include... Mutualism Commensalism Parasitism