Bio 212 Exam 5

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Quizzes Created: 1 | Total Attempts: 79

Questions: 50 | Attempts: 79 | Updated: Sep 8, 2023

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Questions and Answers

1.

Consider a neuron with a resting potential of -60mV. The intracellular sodium ion concentration is much lower than the extracellular sodium concentration. Conversely, the intracellular potassium ion concentration is higher inside the cell, relative to the extracellular space. If the potassium channels open, what will happen to the intracellular [Na+] and [K+]?
- A.
  
  The intracellular [Na+] will not change, and the intracellular [K+] will decrease
- B.
  
  The intracellular [Na+] will not change, and the intracellular [K+] will increase.
- C.
  
  The intracellular [Na+] will decrease, and the intracellular [K+] will not change.
- D.
  
  The intracellular [Na+] will increase, and the intracellular [K+] will decrease.
- E.
  
  The intracellular [Na+] will increase, and the intracellular [K+] will not change
Correct Answer
A. The intracellular [Na+] will not change, and the intracellular [K+] will decrease

Explanation
When the potassium channels open, potassium ions will move out of the cell down their concentration gradient. This will cause a decrease in the intracellular potassium ion concentration. However, the movement of potassium ions out of the cell does not directly affect the intracellular sodium ion concentration. Therefore, the intracellular sodium ion concentration will remain unchanged.

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2.

As an action potential moves along an axon, the membrane potential changes. Which of the following best describes the molecular mechanisms that cause these changes in membrane potential?
- A.
  
  As an electron moves along the length of the axon, it transiently heats the membrane, and this changes the membrane potential.
- B.
  
  Action potentials are mediated by voltage-gated sodium and potassium channels, and diffusion of ions across the membrane cause the changes in membrane potential.
- C.
  
  Action potentials are mediated by calcium-mediated exocytosis of neurotransmitters. When the vesicles fuse with the membrane, this changes the membrane potential.
- D.
  
  Sodium and potassium ions speed along the length of the axonal cytoplasm, and this changes the local membrane potential as the action potential passes through..
Correct Answer
B. Action potentials are mediated by voltage-gated sodium and potassium channels, and diffusion of ions across the membrane cause the changes in membrane potential.
3.

Basal metabolic rate (BMR) is a measure of the resting metabolism of
- A.
  
  Ectotherms
- B.
  
  Endotherms
- C.
  
  All animals
- D.
  
  Only humans
- E.
  
  Only females
Correct Answer
B. Endotherms

Explanation
Endotherms are organisms that can regulate their body temperature internally, regardless of the temperature of their environment. This ability requires a higher metabolic rate compared to ectotherms, which rely on external sources of heat to regulate their body temperature. Basal metabolic rate (BMR) is a measure of the minimum amount of energy required to sustain basic bodily functions while at rest. Since endotherms have a higher metabolic rate, they would have a higher BMR compared to ectotherms. Therefore, the correct answer is endotherms.

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4.

What is NOT a type of animal tissue?
- A.
  
  Muscle
- B.
  
  Connective
- C.
  
  Alimentary
- D.
  
  Nervous
- E.
  
  Epithelial
Correct Answer
C. Alimentary

Explanation
The alimentary system refers to the organs involved in the digestion and absorption of food, such as the stomach and intestines. It is not a type of animal tissue, but rather a system or set of organs. Animal tissues include muscle tissue, connective tissue, nervous tissue, and epithelial tissue.

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5.

The typical negative feedback regulation of the hypothalamus-anterior pituitary axis occurs by
- A.
  
  The nontropic hormone stimulating pituitary tropic hormone release
- B.
  
  The nontropic hormone stimulating hypothalamus tropic hormone release.
- C.
  
  The nontropic hormone inhibiting pituitary nontropic hormone release.
- D.
  
  The nontropic hormone inhibiting pituitary tropic hormone release.
- E.
  
  The tropic hormone inhibiting hypothalamus nontropic hormone release.
Correct Answer
D. The nontropic hormone inhibiting pituitary tropic hormone release.

Explanation
The negative feedback regulation of the hypothalamus-anterior pituitary axis typically occurs when a nontropic hormone inhibits the release of pituitary tropic hormones. This feedback mechanism helps to maintain homeostasis by preventing excessive secretion of tropic hormones.

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6.

What anatomical structure enhances nutrient absorption in the jejunum?
- A.
  
  Brush border
- B.
  
  Smooth epithelium
- C.
  
  Gap junctions
- D.
  
  Lacteal organization
- E.
  
  Countercurrent exchange
Correct Answer
A. Brush border

Explanation
The brush border is a microvilli-covered surface on the epithelial cells lining the jejunum. These microvilli greatly increase the surface area available for nutrient absorption. They contain various enzymes and transport proteins that facilitate the breakdown and absorption of nutrients such as carbohydrates, proteins, and fats. Therefore, the brush border plays a crucial role in enhancing nutrient absorption in the jejunum.

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7.

The double circulation system of mammals and birds consists of separate
- A.
  
  Arterial and veinal flows
- B.
  
  Systemic and pulmonary circuits
- C.
  
  Systolic and diastolic phases
- D.
  
  Myogenic and neurogenic controls
- E.
  
  Open and closed systems
Correct Answer
B. Systemic and pulmonary circuits

Explanation
The correct answer is systemic and pulmonary circuits. Mammals and birds have a double circulation system, which means that blood flows through two separate circuits. The systemic circuit carries oxygenated blood from the heart to the rest of the body, supplying oxygen and nutrients to the tissues. The pulmonary circuit carries deoxygenated blood from the heart to the lungs, where it picks up oxygen and gets rid of carbon dioxide. This ensures that oxygen-rich blood is delivered to the body's tissues and oxygen-poor blood is sent to the lungs for oxygenation.

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8.

Genome Instability can lead to…
- A.
  
  Activation of an oncogene due to gene duplication
- B.
  
  Inactivation of a tumor suppressor due to disruption of coding regions
- C.
  
  Activation of an oncogene due to translocation to another part of the genome
- D.
  
  1 and 2 above
- E.
  
  All of the above
Correct Answer
E. All of the above

Explanation
Genome instability refers to the occurrence of genetic alterations or abnormalities within the DNA sequence. This can lead to various consequences, including the activation of oncogenes due to gene duplication, the inactivation of tumor suppressor genes due to disruption of coding regions, and the activation of oncogenes due to translocation to another part of the genome. Therefore, all of the options provided (1, 2, and 3) are potential outcomes of genome instability.

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9.

Homeostatic regulation of glucose level in the blood occurs when ____________ is released in response to a ______________ in glucose.
- A.
  
  Insulin; rise
- B.
  
  Insulin; fall
- C.
  
  Glucagon; rise
- D.
  
  Glycogen; fall
- E.
  
  CCK; rise
Correct Answer
A. Insulin; rise

Explanation
Insulin is released in response to a rise in glucose levels in the blood. This is because insulin helps to lower blood glucose levels by promoting the uptake of glucose into cells and the storage of excess glucose as glycogen in the liver and muscles. Therefore, when there is an increase in glucose, the body releases insulin to regulate and maintain the balance of glucose in the blood.

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10.

The principal source of endocrine regulation of digestion is the
- A.
  
  Mouth
- B.
  
  Stomach
- C.
  
  Duodenum
- D.
  
  Jejunum
- E.
  
  Rectum
Correct Answer
C. Duodenum

Explanation
The duodenum is the correct answer because it plays a crucial role in the regulation of digestion. It receives partially digested food from the stomach and releases hormones such as secretin and cholecystokinin (CCK) in response to the presence of food. These hormones stimulate the release of digestive enzymes from the pancreas and bile from the gallbladder, which aid in the breakdown and absorption of nutrients. The duodenum also regulates the rate of gastric emptying to ensure that the stomach doesn't release too much food at once, allowing for efficient digestion and absorption.

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11.

Actin-myosin interaction during skeletal muscle contraction
- A.
  
  Does not require elevated Ca2+.
- B.
  
  requires displacement of tropomyosin.
- C.
  
  Requires t-tubule hyperpolarization.
- D.
  
  Does not require ATP hydrolysis.
- E.
  
  Requires intrinsic actin ATPase activity.
Correct Answer
B. requires displacement of tropomyosin.

Explanation
During skeletal muscle contraction, the actin-myosin interaction requires the displacement of tropomyosin. Tropomyosin is a protein that covers the myosin binding sites on actin in a relaxed muscle. When a muscle is stimulated to contract, calcium ions are released, which bind to troponin, causing a conformational change that moves tropomyosin away from the myosin binding sites on actin. This exposes the binding sites and allows myosin heads to attach to actin, leading to the sliding of actin filaments and muscle contraction. Therefore, the correct answer is that actin-myosin interaction during skeletal muscle contraction requires the displacement of tropomyosin.

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12.

A typical cell plasma membrane can be hyperpolarized by
- A.
  
  An increase in K+ permeability.
- B.
  
  An increase in Na+ permeability
- C.
  
  A decrease in Cl- permeability
- D.
  
  A decrease in K+ permeability
- E.
  
  All of these choices
Correct Answer
A. An increase in K+ permeability.

Explanation
When the K+ permeability of a cell plasma membrane increases, it means that more K+ ions are able to pass through the membrane. This leads to an increase in the concentration of positive ions outside the cell compared to the inside, causing the membrane potential to become more negative. This is known as hyperpolarization. Therefore, an increase in K+ permeability is the correct answer.

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13.

Which endocrine gland secretes both tropic and nontropic hormones?
- A.
  
  Pancreas
- B.
  
  Thyroid
- C.
  
  Gonad
- D.
  
  Pituitary
- E.
  
  Adrenal
Correct Answer
D. Pituitary

Explanation
The pituitary gland secretes both tropic and nontropic hormones. Tropic hormones are responsible for stimulating other endocrine glands to release their hormones, while nontropic hormones act directly on target tissues. The pituitary gland is often referred to as the "master gland" because it plays a crucial role in regulating various bodily functions by releasing a wide range of hormones.

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14.

What is TRUE of an OPEN circulatory system, but NOT of a CLOSE circulatory system?
- A.
  
  Has higher blood pressure
- B.
  
  Has more rapid blood flow
- C.
  
  Has no distinction between blood and interstitial fluid
- D.
  
  Has no heart to power circulation, but uses body movements
- E.
  
  Has circulatory fluid and a set of vessels
- F.
  
  Circulation of hormones
Correct Answer
C. Has no distinction between blood and interstitial fluid

Explanation
An open circulatory system does not have a distinction between blood and interstitial fluid, while a closed circulatory system does. In an open circulatory system, the circulatory fluid, called hemolymph, directly bathes the organs and tissues, allowing for exchange of nutrients and waste products. In contrast, a closed circulatory system has blood contained within vessels, separate from the interstitial fluid, which allows for more efficient transport of oxygen, nutrients, and waste products.

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15.

Homeostatic regulation of glucose level in the blood occurs by negative feedback control with _________ and ________ to lower and raise glucose level, respectively.
- A.
  
  Insulin, glycogen
- B.
  
  Glucose, glycogen
- C.
  
  Glucagon, insulin
- D.
  
  Insulin, glucagon
- E.
  
  CCK, gastrin
Correct Answer
D. Insulin, glucagon

Explanation
Insulin and glucagon are both hormones involved in the regulation of glucose levels in the blood. Insulin is released by the pancreas when blood glucose levels are high, and it helps to lower glucose levels by promoting the uptake of glucose into cells and the storage of excess glucose as glycogen. On the other hand, glucagon is released by the pancreas when blood glucose levels are low, and it helps to raise glucose levels by stimulating the breakdown of glycogen into glucose and the release of glucose into the bloodstream. Together, insulin and glucagon work in a negative feedback loop to maintain the homeostasis of glucose levels in the blood.

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16.

The body's automatic tendency to maintain a constant internal environment is termed
- A.
  
  Balanced equilibrium.
- B.
  
  Physiological chance.
- C.
  
  Homeostasis.
- D.
  
  Estivation.
- E.
  
  Static equilibrium.
Correct Answer
C. Homeostasis.

Explanation
Homeostasis refers to the body's ability to maintain a stable internal environment despite external changes. It involves various physiological processes that work together to regulate temperature, pH levels, blood sugar, and other vital parameters within a narrow range. This ensures optimal functioning of cells, tissues, and organs. The term "balanced equilibrium" does not accurately describe this concept, while "physiological chance" and "estivation" are unrelated. "Static equilibrium" refers to the balance of forces acting on an object, which is not applicable here. Therefore, the correct answer is homeostasis.

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17.

Mutations of both oncogenes and tumor suppressors can lead to cancer. Gain of function mutations in oncogenes can result in overexpression of the gene or expression in abnormal cell types. Which of the following is most likely to be an oncogene?
- A.
  
  Gene important for repairing DNA damage
- B.
  
  A gene which codes a fluorescent protein
- C.
  
  A gene required for one of the cell cycle checkpoints
- D.
  
  A gene which promotes programmed cell death
- E.
  
  A gene that increases cell proliferation
Correct Answer
E. A gene that increases cell proliferation

Explanation
A gene that increases cell proliferation is most likely to be an oncogene. Oncogenes are genes that have the potential to cause cancer when mutated. They can promote cell growth and division, leading to uncontrolled cell proliferation, which is a hallmark of cancer. Therefore, a gene that increases cell proliferation is more likely to be an oncogene compared to the other options mentioned.

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18.

In many neurons, action potentials activate voltage gated calcium channels in the plasma membrane of the synaptic ending. Calcium diffuses down the gradient, and the resulting increase in intracellular calcium triggers exocytosis of vesicles containing neurotransmitters. What is the likely effect of removing calcium from the extracellular fluid?
- A.
  
  This would prevent action potentials.
- B.
  
  The cell would release neurotransmitter in the absence of an change in membrane potential.
- C.
  
  The calcium channels would open, but there would not be an intracellular rise in calcium levels, and neurotransmitter would not be released.
- D.
  
  The calcium channels would not open, and this would inhibit neurotransmitter release.
Correct Answer
C. The calcium channels would open, but there would not be an intracellular rise in calcium levels, and neurotransmitter would not be released.

Explanation
Removing calcium from the extracellular fluid would prevent an increase in intracellular calcium levels, which is necessary for triggering exocytosis of vesicles containing neurotransmitters. Therefore, neurotransmitter release would be inhibited even though the calcium channels would still open.

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19.

What is TRUE about regulation of the vertebrate heart rate?
- A.
  
  The vertebrate heart is neurogenic.
- B.
  
  There is about 0.1 sec delay at the AV node.
- C.
  
  Special Purkinje cells act as the pacemaker.
- D.
  
  Conduction of the electrical signal occurs through tight junctions.
- E.
  
  Only depolarization, but not repolarization of the heart muscle is seen in an EKG.
Correct Answer
B. There is about 0.1 sec delay at the AV node.

Explanation
The statement "There is about 0.1 sec delay at the AV node" is true. The AV node, located between the atria and ventricles, acts as a delay to allow the atria to fully contract and fill the ventricles before ventricular contraction begins. This delay ensures efficient blood flow and coordination between the atria and ventricles.

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20.

Ectotherm is to endotherm as _____________ is to ______________.
- A.
  
  Single cell, multicellular
- B.
  
  Negative feedback, positive feedback
- C.
  
  Invertebrate, vertebrate
- D.
  
  Conformer, regulator
- E.
  
  Basal metabolic rate, standard metabolic rate
Correct Answer
D. Conformer, regulator

Explanation
The analogy between ectotherm and endotherm can be understood by comparing their ability to regulate body temperature. An ectotherm relies on external sources of heat to regulate its body temperature, while an endotherm can generate and regulate its own body heat internally. Similarly, a conformer is an organism that allows its internal conditions to vary with the external environment, while a regulator maintains a relatively constant internal environment regardless of external conditions. Therefore, the analogy between ectotherm and endotherm can be extended to conformer and regulator.

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21.

Cells of a transport epithelium form an intercellular barrier by being joined with
- A.
  
  Bands of tight junctions.
- B.
  
  Bands of gap junctions.
- C.
  
  Bands of desmosomes.
- D.
  
  Bands of Casparian strip
- E.
  
  Bands of plasmodesmata.
Correct Answer
A. Bands of tight junctions.

Explanation
Cells of a transport epithelium form an intercellular barrier by being joined with bands of tight junctions. Tight junctions are specialized protein complexes that form a seal between adjacent cells, preventing the passage of molecules and ions between them. This helps to maintain the integrity of the epithelial layer and control the movement of substances across it. Gap junctions, desmosomes, Casparian strip, and plasmodesmata are all different types of intercellular junctions, but they do not play a role in forming a barrier for transport epithelium.

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22.

Which of the following might be present in a loss-of-function for a tumor suppressor gene?
- A.
  
  Uncontrolled cell division
- B.
  
  Abnormal numbers of chromosomes
- C.
  
  Cells that are resistant to death
- D.
  
  All of the above
- E.
  
  None of the above
Correct Answer
D. All of the above

Explanation
Loss-of-function for a tumor suppressor gene can result in uncontrolled cell division, abnormal numbers of chromosomes, and cells that are resistant to death. This is because tumor suppressor genes play a crucial role in regulating cell growth and preventing the formation of tumors. When these genes are not functioning properly, it can lead to the accumulation of genetic mutations and the development of cancerous cells. Uncontrolled cell division, abnormal numbers of chromosomes, and resistance to cell death are all characteristics commonly observed in cancer cells.

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23.

What pair of hormones is necessary for calcium homeostasis?
- A.
  
  Insulin-glucagon
- B.
  
  TRH-TSH
- C.
  
  Calcitonin-PTH
- D.
  
  FSH-LH
- E.
  
  ADH-epinephrine
Correct Answer
C. Calcitonin-PTH

Explanation
Calcitonin and PTH (parathyroid hormone) are the pair of hormones necessary for calcium homeostasis. Calcitonin helps to decrease blood calcium levels by inhibiting the release of calcium from bones and promoting its excretion by the kidneys. On the other hand, PTH increases blood calcium levels by stimulating the release of calcium from bones and promoting its reabsorption by the kidneys. These hormones work together to maintain a balance of calcium in the body, ensuring proper functioning of muscles, nerves, and bones.

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24.

Gas exchange at alveolar or cellular surfaces is driven by
- A.
  
  Osmotic pressure differences.
- B.
  
  ATP hydrolysis.
- C.
  
  Water potential differences.
- D.
  
  Partial pressure differences.
- E.
  
  Na+ dependent co-transport.
Correct Answer
D. Partial pressure differences.

Explanation
Gas exchange at alveolar or cellular surfaces is driven by partial pressure differences. This means that gases move from an area of higher partial pressure to an area of lower partial pressure. In the case of gas exchange in the lungs, oxygen moves from the alveoli (where its partial pressure is higher) to the blood (where its partial pressure is lower), while carbon dioxide moves from the blood (where its partial pressure is higher) to the alveoli (where its partial pressure is lower). This process allows for the exchange of gases necessary for respiration to occur efficiently.

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25.

The symbiotic E. coli that produce vitamins, including biotin, folic acid, vitamin K and several B vitamins live in the
- A.
  
  Large intestine
- B.
  
  Duodenum
- C.
  
  Ileum
- D.
  
  Stomach
- E.
  
  Jejunum
Correct Answer
A. Large intestine

Explanation
The correct answer is the large intestine. This is because the large intestine is home to a diverse population of bacteria, including E. coli, that play a crucial role in producing vitamins. These symbiotic E. coli bacteria produce essential vitamins such as biotin, folic acid, vitamin K, and several B vitamins. Therefore, the large intestine is the correct location where these E. coli bacteria reside and produce these vitamins.

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26.

Activation of digestive enzymes occurs by
- A.
  
  Negative feedback
- B.
  
  Positive feedback
- C.
  
  ATP hydrolysis
- D.
  
  Increase in pH
- E.
  
  Ca2+ binding
Correct Answer
B. Positive feedback

Explanation
Positive feedback is a mechanism that amplifies or increases a process or response. In the context of activation of digestive enzymes, positive feedback would mean that the activation of one enzyme leads to the activation of more enzymes, creating a cascade effect. This can enhance the efficiency of digestion by rapidly increasing the production of enzymes. In contrast, negative feedback would inhibit or decrease the activation of enzymes, ATP hydrolysis and Ca2+ binding are not directly related to the activation of digestive enzymes, and an increase in pH is more likely to inhibit enzyme activity rather than activate it.

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27.

What is true about human cardiac muscle cells?
- A.
  
  Cardiac cell are connected by tight junctions.
- B.
  
  Cardiac cells lack an orderly arrangement of thick and thin filaments.
- C.
  
  Cardiac muscle cell contraction does not require ATP hydrolysis.
- D.
  
  Cardiac muscle cell contraction is not regulated by Ca2+ level in the cell.
- E.
  
  Cardiac muscle cells can stimulate its own muscle contractions (myogenic).
Correct Answer
E. Cardiac muscle cells can stimulate its own muscle contractions (myogenic).

Explanation
Cardiac muscle cells have the unique ability to generate their own electrical impulses, which allows them to initiate and regulate their own contractions. This property is known as myogenicity. Unlike skeletal muscle cells, which require external stimulation from motor neurons to contract, cardiac muscle cells are able to independently generate action potentials that trigger contraction. This self-stimulation ensures the coordinated and rhythmic contraction of the heart, enabling it to pump blood effectively throughout the body.

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28.

Which of the following enzyme works most effectively at a very low pH?
- A.
  
  Salivary amylase
- B.
  
  trypsin
- C.
  
  Pepsin
- D.
  
  Pancreatic amylase
- E.
  
  Pancreatic lipase
Correct Answer
C. Pepsin

Explanation
Pepsin is the correct answer because it is an enzyme that works most effectively at a very low pH, specifically in the acidic environment of the stomach. Pepsin is secreted by the gastric glands and plays a crucial role in the digestion of proteins by breaking them down into smaller peptides. This acidic environment is necessary for the activation of pepsin and for its optimal functioning.

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29.

What happens to the cell membrane potential if the membrane became more Na⁺ permeable?
- A.
  
  The membrane potential would become more positive.
- B.
  
  The membrane potential would remain unchanged.
- C.
  
  The membrane potential would become more negative.
- D.
  
  More K+ would flow into the cell.
- E.
  
  More Na+ would flow out of the cell
Correct Answer
A. The membrane potential would become more positive.

Explanation
If the membrane becomes more permeable to Na+, it means that more Na+ ions will be able to pass through the membrane. Since Na+ ions have a positive charge, an increase in their permeability would result in an influx of positive ions into the cell. This influx of positive ions would cause the cell membrane potential to become more positive.

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30.

What is not true about hormonal control of digestion?
- A.
  
  The duodenum exerts an inhibitory regulation on the stomach.
- B.
  
  The duodenum stimulates bicarbonate release from the pancreas.
- C.
  
  The duodenum stimulates release of pancreatic enzymes.
- D.
  
  The duodenum stimulates bile release from the gallbladder.
- E.
  
  The stomach autoinhibits through release of gastrin.
Correct Answer
E. The stomach autoinhibits through release of gastrin.

Explanation
The correct answer is that the stomach autoinhibits through the release of gastrin. Gastrin is actually a hormone that stimulates the secretion of gastric acid in the stomach, rather than inhibiting it. The duodenum, on the other hand, plays a role in inhibiting the stomach through the release of hormones like somatostatin, which inhibits gastric acid secretion. So, the statement that the stomach autoinhibits through the release of gastrin is not true.

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31.

What is TRUE about the organization of skeletal muscles?
- A.
  
  Sarcomeres are arranged in a longitudinal array.
- B.
  
  Thick filaments consist of actin molecules.
- C.
  
  Thin filaments consist of myosin molecules.
- D.
  
  A muscle fiber contains a single myofibril.
- E.
  
  Each muscle fiber is innervated by several motor neurons.
Correct Answer
A. Sarcomeres are arranged in a longitudinal array.

Explanation
Sarcomeres are the basic contractile units of skeletal muscles. They are arranged in a longitudinal array, meaning they are aligned end to end along the length of the muscle fiber. This arrangement allows for the coordinated contraction of the muscle as the sarcomeres shorten. The statement that sarcomeres are arranged in a longitudinal array is true and accurately describes the organization of skeletal muscles.

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32.

Stimulation of a taste receptor cell always causes
- A.
  
  Hyperpolarization.
- B.
  
  Depolarization.
- C.
  
  Na+ entry.
- D.
  
  CAMP production.
- E.
  
  H+ release.
Correct Answer
B. Depolarization.

Explanation
When a taste receptor cell is stimulated, it causes depolarization. Depolarization refers to a change in the electrical charge of the cell membrane, making it less negative. This change in charge triggers an action potential, which allows the cell to transmit signals to the brain. In the context of taste, depolarization of the taste receptor cell is a crucial step in the process of detecting and transmitting taste signals. It initiates a cascade of events that eventually lead to the perception of taste.

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33.

What is NOT evidence for sliding filament model of muscle contraction?
- A.
  
  Disappearance of H zone during contraction
- B.
  
  Shortening of the A band during contraction
- C.
  
  Shortening of the distance between Z lines during contraction
- D.
  
  Disappearance of I band
- E.
  
  Increase in overlap between thick and thin filaments during contraction
Correct Answer
B. Shortening of the A band during contraction

Explanation
The shortening of the A band during contraction is not evidence for the sliding filament model of muscle contraction. The sliding filament model proposes that muscle contraction occurs when the thin filaments slide over the thick filaments, causing the sarcomere to shorten. The A band, which represents the length of the thick filaments, does not change during contraction. Therefore, the shortening of the A band is not consistent with the sliding filament model and cannot be considered evidence for it.

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34.

What is an advantage of saltatory conduction?
- A.
  
  Slower conduction velocity
- B.
  
  More ion load for the Na+, K+ pump
- C.
  
  More ATP consumption by the neuron
- D.
  
  None of these choices
- E.
  
  All of these choices
Correct Answer
D. None of these choices

Explanation
Saltatory conduction is the process by which nerve impulses jump from one node of Ranvier to another, increasing the conduction velocity of the impulse. This allows for faster transmission of signals along the axon. Additionally, saltatory conduction reduces the ion load for the Na+, K+ pump, as the ions only need to be transported across the membrane at the nodes of Ranvier instead of along the entire length of the axon. This results in less ATP consumption by the neuron. Therefore, the correct answer is "none of these choices" as none of the options listed in the question accurately describe an advantage of saltatory conduction.

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35.

What best describes the body representations on the cortical surfaces in the primary motor and primary somatosensory cortices?
- A.
  
  The cortical surface area devoted to each body part is related to number of neurons innervating that part.
- B.
  
  Neurons are randomly distributed.
- C.
  
  The cortical surface area devoted to each body part is related to size.
- D.
  
  Representation of the trunk is nearly as extensive as that of the face.
- E.
  
  Ensory and motor representations of the same body part are not in corresponding regions of the cortices.
Correct Answer
A. The cortical surface area devoted to each body part is related to number of neurons innervating that part.

Explanation
The cortical surface area devoted to each body part is related to the number of neurons innervating that part. This means that body parts with more sensory or motor neurons will have a larger representation on the cortical surface. This is known as somatotopic organization, where different body parts are represented in specific areas of the primary motor and primary somatosensory cortices. This organization allows for precise control and perception of different body parts.

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36.

Which sensory system begins information processing outside the brain?
- A.
  
  Hearing
- B.
  
  Equilibrium
- C.
  
  Taste
- D.
  
  Smell
- E.
  
  Vision
Correct Answer
E. Vision

Explanation
Vision is the correct answer because the sensory system of vision begins information processing outside the brain. The eyes receive visual stimuli from the environment and transmit this information to the brain for further processing and interpretation. The initial processing of visual information occurs in the retina, which is located in the eye, before being sent to the brain for higher-level processing and perception. This is different from other sensory systems like hearing, equilibrium, taste, and smell, which begin processing within the brain itself.

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37.

Which division of the ANS would most likely be activated if you arrived in class to learn that there will be a pop quiz?
- A.
  
  Somatic nervous system
- B.
  
  Sympathetic
- C.
  
  Parasympathetic
- D.
  
  Enteric
- E.
  
  Central nervous system
Correct Answer
B. Sympathetic

Explanation
The sympathetic division of the autonomic nervous system would most likely be activated if you arrived in class to learn that there will be a pop quiz. This division is responsible for the body's fight-or-flight response, which prepares the body for intense physical activity or stressful situations. In this case, the pop quiz would likely trigger a stress response, leading to increased heart rate, dilated pupils, and heightened alertness, all of which are characteristic of the sympathetic division's activation.

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38.

What happens when the neuron's membrane depolarize?
- A.
  
  The inside of the cell becomes more negative relative to the outside.
- B.
  
  There is a net diffusion of K+ out of the cell.
- C.
  
  There is an increase in membrane K+ permeability.
- D.
  
  There is a net diffusion of Na+ out of the cell.
- E.
  
  The inside of the cell becomes more positive relative to the outside.
Correct Answer
E. The inside of the cell becomes more positive relative to the outside.

Explanation
When the neuron's membrane depolarizes, the inside of the cell becomes more positive relative to the outside. This occurs because depolarization involves a change in the electrical charge across the membrane, causing a shift towards a more positive charge inside the cell. This change in charge is typically caused by the influx of positively charged ions, such as sodium (Na+), into the cell.

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39.

Why are action potentials conducted in only one direction along an axon?
- A.
  
  The node of Ranvier can conduct potentials in only one direction.
- B.
  
  The inactivation of the voltage-gated Na+ channels prevent immediate reopening.
- C.
  
  The cell body has a higher membrane potential than the terminals of the axon.
- D.
  
  Ions can only flow along the axon in only one direction.
- E.
  
  Voltage-gated channels for both K+ and Na+ open in only one direction.
Correct Answer
B. The inactivation of the voltage-gated Na+ channels prevent immediate reopening.

Explanation
The inactivation of the voltage-gated Na+ channels prevents immediate reopening, which is why action potentials are conducted in only one direction along an axon. When an action potential occurs, the voltage-gated Na+ channels open, allowing Na+ ions to enter the axon and depolarize the membrane. However, after a short period of time, these channels become inactivated, preventing them from reopening immediately. This ensures that the action potential can only propagate in one direction, as the inactivated channels cannot be reopened in the region that has just undergone depolarization.

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40.

What is NOT a sensory perception of the human inner ear?
- A.
  
  Sound volume
- B.
  
  Sound pitch
- C.
  
  Electromagnetic field lines
- D.
  
  Head position
- E.
  
  Body position
Correct Answer
C. Electromagnetic field lines

Explanation
The human inner ear is responsible for sensory perceptions related to sound and balance. Sound volume and sound pitch are both sensory perceptions related to sound. Head position and body position are sensory perceptions related to balance. However, the human inner ear does not have the ability to perceive electromagnetic field lines.

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41.

What is NOT part of the brainstem?
- A.
  
  Cerebellum
- B.
  
  Midbrain
- C.
  
  Pons
- D.
  
  Medulla oblongata
- E.
  
  None of these choices
Correct Answer
A. Cerebellum

Explanation
The cerebellum is not part of the brainstem. The brainstem consists of the midbrain, pons, and medulla oblongata, which are responsible for various vital functions such as controlling breathing, heart rate, and consciousness. The cerebellum, on the other hand, is located at the back of the brain and is involved in coordinating movement, balance, and posture. While it is closely connected to the brainstem, it is considered a separate structure.

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42.

A series of sound waves caused vibrations of the basilar membrane that moves from the base to the apex. How would your brain interpret this series?
- A.
  
  High to low volume
- B.
  
  Low to high volume
- C.
  
  High to low pitch
- D.
  
  Low to high pitch
- E.
  
  None of these choices
Correct Answer
C. High to low pitch

Explanation
The basilar membrane is a part of the inner ear that plays a crucial role in hearing. When sound waves enter the ear, they cause vibrations in the basilar membrane. These vibrations travel from the base of the membrane to the apex. The brain interprets these vibrations as different pitches of sound. Since the vibrations move from the base to the apex, the brain would interpret this series of sound waves as high to low pitch.

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43.

What is NOT a taste perception?
- A.
  
  Foul
- B.
  
  Sweet
- C.
  
  Umami
- D.
  
  Bitter
- E.
  
  Salty
Correct Answer
A. Foul

Explanation
Foul is not a taste perception because taste perceptions refer to the basic tastes that can be detected by the taste buds on our tongue. These basic tastes include sweet, umami, bitter, and salty. Foul, on the other hand, is not a distinct taste but rather a description of something that is unpleasant or offensive in taste or smell. Therefore, it does not fall under the category of taste perceptions.

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44.

Which statement about smooth muscles is NOT TRUE?
- A.
  
  Smooth muscle filaments are well organized.
- B.
  
  Smooth muscles lack troponin.
- C.
  
  Smooth muscle contraction is Ca2+ regulated.
- D.
  
  Smooth muscle contraction is typically slow and extended.
- E.
  
  Smooth muscle contraction requires myosin and actin.
Correct Answer
A. Smooth muscle filaments are well organized.

Explanation
Smooth muscle filaments are not well organized. Unlike skeletal and cardiac muscles, smooth muscles lack the organized sarcomere structure with distinct bands of actin and myosin filaments. Instead, smooth muscle filaments are arranged in a more random pattern, making them appear non-striated under a microscope. This lack of organization allows smooth muscles to stretch and contract more easily, giving them the ability to perform slow and sustained contractions.

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45.

Region of a neuron involved with integration of stimuli is
- A.
  
  The axon.
- B.
  
  The dendrites.
- C.
  
  The synapse.
- D.
  
  The nucleus.
- E.
  
  The axon hillock.
Correct Answer
B. The dendrites.

Explanation
The dendrites of a neuron are responsible for receiving stimuli from other neurons or sensory receptors. They are covered in specialized structures called dendritic spines, which increase the surface area available for receiving signals. The dendrites integrate these incoming signals and transmit them to the cell body, where further processing occurs. Therefore, the region of a neuron involved with the integration of stimuli is the dendrites.

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46.

Region of the brain involved with sensory-motor coordination
- A.
  
  Cerebrum
- B.
  
  Brainstem
- C.
  
  Hypothalamus
- D.
  
  Cerebellum
- E.
  
  Thalamus
Correct Answer
D. Cerebellum

Explanation
The cerebellum is the region of the brain involved with sensory-motor coordination. It plays a crucial role in coordinating voluntary movements, maintaining balance, and controlling muscle tone. It receives sensory information from various parts of the body and integrates it with motor signals from the cerebrum to ensure smooth and coordinated movements. The cerebellum also helps in learning and fine-tuning motor skills.

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47.

What factor does NOT contribute to graded muscle contraction?
- A.
  
  Varying the rate of muscle fiber stimulation.
- B.
  
  Multiple motor neuron innervations of each muscle fiber
- C.
  
  Multiple muscle fiber innervations by each motor neuron
- D.
  
  Varying the number of stimulated motor units
- E.
  
  Varying the number of stimulated muscle fibers
Correct Answer
B. Multiple motor neuron innervations of each muscle fiber

Explanation
Graded muscle contraction refers to the ability of muscles to contract with varying degrees of force. This is achieved through several factors, such as varying the rate of muscle fiber stimulation, varying the number of stimulated motor units, and varying the number of stimulated muscle fibers. However, multiple motor neuron innervations of each muscle fiber does not contribute to graded muscle contraction. In fact, each muscle fiber is typically innervated by only one motor neuron, ensuring precise control over muscle contraction.

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48.

Which of these cellular activities is NOT allosteric modulation?
- A.
  
  Na+ diffusion during conduction of an action potential
- B.
  
  Ca2+ binding and release of troponin complex during muscle contraction
- C.
  
  GTP-GDP exchange of G protein during G protein-linked receptor signaling
- D.
  
  Phosphorylation cascade by enzyme kinases during signal transduction
- E.
  
  Photon binding by phytochrome during de-etiolation response
Correct Answer
A. Na+ diffusion during conduction of an action potential

Explanation
Allosteric modulation refers to the regulation of enzyme activity or protein function through the binding of a molecule at a site other than the active site. Na+ diffusion during conduction of an action potential does not involve the regulation of enzyme activity or protein function through allosteric modulation. Instead, it is a passive process that occurs due to the concentration gradient of Na+ ions across the cell membrane.

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49.

During contraction of a vertebrate skeletal muscle fiber, Ca²⁺ ions
- A.
  
  Break myosin-actin cross-bridges.
- B.
  
  Bind troponin complex, causing tropomyosin movement
- C.
  
  Cause neurotransmitter release.
- D.
  
  Are sequestered into the sarcoplasmic reticulum.
- E.
  
  Spread the action potential through T tubules.
Correct Answer
B. Bind troponin complex, causing tropomyosin movement

Explanation
During the contraction of a vertebrate skeletal muscle fiber, Ca2+ ions bind to the troponin complex. This binding causes a conformational change in the troponin-tropomyosin complex, which moves tropomyosin away from the myosin binding sites on the actin filament. This movement exposes the binding sites and allows the myosin heads to bind to actin, forming cross-bridges and initiating muscle contraction. Therefore, the correct answer is "bind troponin complex, causing tropomyosin movement."

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50.

What is NOT true about skeletal muscle myosin protein?
- A.
  
  Myosin can act as an ATPase.
- B.
  
  Myosin can bind to actin.
- C.
  
  Myosin is directly regulated by Ca2+ ions.
- D.
  
  Myosin has four different allosteric states during one cycle of myosin-actin binding.
- E.
  
  Myosin is regulated by allosteric binding of ATP, ADP + Pi and ADP.
Correct Answer
C. Myosin is directly regulated by Ca2+ ions.

Explanation
Myosin is not directly regulated by Ca2+ ions. While Ca2+ ions play a crucial role in muscle contraction, they do not directly regulate myosin. Instead, Ca2+ ions bind to the protein troponin, which causes a conformational change in tropomyosin, uncovering the binding sites on actin for myosin. This allows myosin to bind to actin and initiate the sliding of the filaments, leading to muscle contraction. Myosin itself is regulated by the allosteric binding of ATP, ADP + Pi, and ADP, which affect its affinity for actin and its ability to hydrolyze ATP.

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Bio 212 Exam 5

As an action potential moves along an axon, the membrane potential changes. Which of the following best describes the molecular mechanisms that cause these changes in membrane potential?

Basal metabolic rate (BMR) is a measure of the resting metabolism of

What is NOT a type of animal tissue?

The typical negative feedback regulation of the hypothalamus-anterior pituitary axis occurs by

What anatomical structure enhances nutrient absorption in the jejunum?

The double circulation system of mammals and birds consists of separate

Genome Instability can lead to…

Homeostatic regulation of glucose level in the blood occurs when ____________ is released in response to a ______________ in glucose.

The principal source of endocrine regulation of digestion is the

Actin-myosin interaction during skeletal muscle contraction

A typical cell plasma membrane can be hyperpolarized by

Which endocrine gland secretes both tropic and nontropic hormones?

What is TRUE of an OPEN circulatory system, but NOT of a CLOSE circulatory system?

Homeostatic regulation of glucose level in the blood occurs by negative feedback control with _________ and ________ to lower and raise glucose level, respectively.

The body's automatic tendency to maintain a constant internal environment is termed

Mutations of both oncogenes and tumor suppressors can lead to cancer. Gain of function mutations in oncogenes can result in overexpression of the gene or expression in abnormal cell types. Which of the following is most likely to be an oncogene?

What is TRUE about regulation of the vertebrate heart rate?

Ectotherm is to endotherm as _____________ is to ______________.

Cells of a transport epithelium form an intercellular barrier by being joined with

Which of the following might be present in a loss-of-function for a tumor suppressor gene?

What pair of hormones is necessary for calcium homeostasis?

Gas exchange at alveolar or cellular surfaces is driven by

The symbiotic E. coli that produce vitamins, including biotin, folic acid, vitamin K and several B vitamins live in the

Activation of digestive enzymes occurs by

What is true about human cardiac muscle cells?

Which of the following enzyme works most effectively at a very low pH?

What happens to the cell membrane potential if the membrane became more Na+ permeable?

What is not true about hormonal control of digestion?

What is TRUE about the organization of skeletal muscles?

Stimulation of a taste receptor cell always causes

What is NOT evidence for sliding filament model of muscle contraction?

What is an advantage of saltatory conduction?

What best describes the body representations on the cortical surfaces in the primary motor and primary somatosensory cortices?

Which sensory system begins information processing outside the brain?

Which division of the ANS would most likely be activated if you arrived in class to learn that there will be a pop quiz?

What happens when the neuron's membrane depolarize?

Why are action potentials conducted in only one direction along an axon?

What is NOT a sensory perception of the human inner ear?

What is NOT part of the brainstem?

A series of sound waves caused vibrations of the basilar membrane that moves from the base to the apex. How would your brain interpret this series?

What is NOT a taste perception?

Which statement about smooth muscles is NOT TRUE?

Region of a neuron involved with integration of stimuli is

Region of the brain involved with sensory-motor coordination

What factor does NOT contribute to graded muscle contraction?

Which of these cellular activities is NOT allosteric modulation?

During contraction of a vertebrate skeletal muscle fiber, Ca2+ ions

What is NOT true about skeletal muscle myosin protein?

Homeostatic regulation of glucose level in the blood occurs when is released in response to a __ in glucose.

Homeostatic regulation of glucose level in the blood occurs by negative feedback control with _ and to lower and raise glucose level, respectively.

Ectotherm is to endotherm as _ is to __.

What happens to the cell membrane potential if the membrane became more Na⁺ permeable?

During contraction of a vertebrate skeletal muscle fiber, Ca²⁺ ions