1.
A fluid secreted into small intestine during digestion that contains cholesterol, emulsification agents and phospholipids is:
Correct Answer
A. Bile.
Explanation
Bile is a fluid secreted into the small intestine during digestion that contains cholesterol, emulsification agents, and phospholipids. Bile helps in the emulsification and digestion of fats by breaking them down into smaller droplets, increasing their surface area for better absorption. It also aids in the absorption of fat-soluble vitamins. Bile is produced by the liver and stored in the gallbladder before being released into the small intestine.
2.
Select the correct statement about the ureters.
Correct Answer
D. The ureters are capable of peristalsis like that of the gastrointestinal tract.
Explanation
The ureters are capable of peristalsis like that of the gastrointestinal tract. Peristalsis is a coordinated muscular contraction that helps propel urine from the kidneys to the bladder. This mechanism ensures the one-way flow of urine and prevents its back-flow. The presence of sphincters at the entrance to the bladder also helps in preventing the back-flow of urine, but this is not the only correct statement about the ureters. The ureters are not innervated by parasympathetic nerve endings only, and the epithelium of the ureters is not stratified squamous like the skin.
3.
The mechanism of water reabsorption by the renal tubules is:
Correct Answer
A. Osmosis.
Explanation
Water reabsorption by the renal tubules occurs through osmosis. Osmosis is the passive movement of water molecules across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. In the renal tubules, water is reabsorbed back into the bloodstream by moving from an area of lower solute concentration in the tubules to an area of higher solute concentration in the surrounding tissues and blood vessels. This process helps maintain the body's water balance and prevents excessive water loss.
4.
The lamina propria is composed of:
Correct Answer
C. Loose connective tissue.
Explanation
The lamina propria is a layer of connective tissue found beneath the epithelial lining of various organs, such as the gastrointestinal tract and respiratory system. It serves to support and nourish the epithelium. Loose connective tissue is the correct answer because it is the main component of the lamina propria, providing flexibility and allowing for movement and diffusion of substances. Reticular connective tissue forms the framework of organs, dense irregular connective tissue provides strength and support, and dense regular connective tissue is found in tendons and ligaments, which are not typically part of the lamina propria.
5.
The fluid in the glomerular (Bowman's ) capsule is similar to plasma except that it does not contain a significant amount:
Correct Answer
A. Plasma protein.
Explanation
The fluid in the glomerular (Bowman's) capsule is similar to plasma in terms of its composition, containing glucose, electrolytes, and hormones. However, it does not contain a significant amount of plasma protein. This is because plasma proteins are too large to be filtered through the glomerular filtration membrane, which allows smaller molecules like glucose and electrolytes to pass through. Therefore, plasma protein is not present in the fluid within the glomerular capsule.
6.
The fatty tissue surrounding the kidney is important because:
Correct Answer
A. It stabilizes the position of the kidneys by holding them in their normal position.
Explanation
The fatty tissue surrounding the kidney is important because it stabilizes the position of the kidneys by holding them in their normal position. This adipose tissue acts as a cushion and support for the kidneys, preventing them from moving or shifting out of place. Without this fatty tissue, the kidneys would be more susceptible to displacement or injury from physical activity or trauma.
7.
Select the correct statement about the physical factors influencing pulmonary ventilation.
Correct Answer
C. As alveolar surface tension increases, additional muscle action will be required.
Explanation
As alveolar surface tension increases, the forces that hold the alveoli open are reduced, making it more difficult for the lungs to expand during inhalation. This increased surface tension requires additional muscle action to overcome and expand the lungs, allowing for adequate ventilation.
8.
The enzymatic breakdown of any type of food molecule is called _____.
Correct Answer
D. Hydrolysis
Explanation
Hydrolysis is the correct answer because it refers to the enzymatic breakdown of any type of food molecule. Hydrolysis involves the addition of water molecules to break down complex molecules into simpler ones. This process is commonly observed in digestion, where enzymes break down food molecules into smaller components that can be easily absorbed and utilized by the body. Diffusion, active transport, and denaturation are not relevant to the enzymatic breakdown of food molecules.
9.
Which of the following is not reabsorbed by the proximal convoluted tubule?
Correct Answer
A. Creatinine
Explanation
Creatinine is not reabsorbed by the proximal convoluted tubule. The proximal convoluted tubule is responsible for reabsorbing important substances such as glucose, Na+, and K+ back into the bloodstream. However, creatinine, a waste product of muscle metabolism, is not reabsorbed and is instead excreted in the urine. This makes it a useful marker for kidney function, as its levels in the blood can indicate how well the kidneys are filtering waste products.
10.
The propulsion of food down the gastrointestinal tract includes:
Correct Answer
A. The pharyngeal-esophageal phase, an involuntary process.
Explanation
The correct answer is the pharyngeal-esophageal phase, an involuntary process. This phase refers to the movement of food from the pharynx to the esophagus, which is controlled by involuntary muscle contractions. During this phase, the muscles in the throat and esophagus contract in a coordinated manner to propel the food downwards, allowing it to pass from the mouth to the stomach. This process is essential for the transportation of food through the gastrointestinal tract and is not under conscious control.
11.
Which of the following does not occur in the mitochondria?
Correct Answer
D. Glycolysis.
Explanation
Glycolysis is a metabolic pathway that occurs in the cytoplasm of cells, not in the mitochondria. It is the process by which glucose is broken down into pyruvate, producing a small amount of ATP and NADH. The Krebs cycle, also known as the citric acid cycle, occurs in the mitochondria and is the second stage of cellular respiration. Formation of malic acid from fumaric acid is a step in the Krebs cycle, and electron transport, which generates the majority of ATP, also takes place in the mitochondria. Therefore, the correct answer is Glycolysis.
12.
Factors that influence the rate and depth of breathing include:
Correct Answer
B. Voluntary cortical control.
Explanation
Voluntary cortical control refers to the ability of the brain's cortex to consciously regulate the rate and depth of breathing. This means that a person can intentionally increase or decrease their breathing rate and depth. Factors such as emotions, physical activity, and conscious effort can all influence the voluntary control of breathing. The other factors mentioned in the question, such as stretch receptors in the alveoli, thalamic control, and composition of alveolar gas, are also important in regulating breathing but do not involve conscious control.
13.
A Bowman's capsule does not contian:
Correct Answer
D. A vasa recta.
Explanation
The Bowman's capsule is a structure in the kidney that surrounds the glomerulus, which consists of a network of fenestrated capillaries. The podocytes, specialized cells in the Bowman's capsule, wrap around the capillaries to form filtration slits. The efferent arteriole is a blood vessel that carries blood away from the glomerulus. The vasa recta, on the other hand, are specialized capillaries that surround the loop of Henle in the kidney. Therefore, the correct answer is A vasa recta, as it is not a component of the Bowman's capsule.
14.
Since the lungs are filled with fluid during fetal life which of the following statements is true regarding respiratory exchange?
Correct Answer
D. Respiratory exchanges are made through the placenta.
Explanation
During fetal life, the lungs are filled with fluid and are not yet functional. Therefore, respiratory exchanges do not occur through the lungs. Instead, the exchange of oxygen and carbon dioxide takes place through the placenta. The placenta acts as a bridge between the mother and the fetus, allowing the exchange of gases and nutrients. This is essential for the fetus's survival and development until the lungs are fully developed and can take over the respiratory function after birth.
15.
You have just eaten french fries, buttered toast, ice cream and whole milk. Which of the following glands would be active in helping you to digest this food?
Correct Answer
A. The pancreas.
Explanation
The pancreas is responsible for producing digestive enzymes that help break down carbohydrates, proteins, and fats in the food we eat. It also produces insulin, which helps regulate blood sugar levels. In this scenario, the food consumed includes carbohydrates (french fries, toast), fats (buttered toast, ice cream), and proteins (milk). Therefore, the pancreas would be active in aiding the digestion of this food by releasing the necessary enzymes. The other options, such as the buccal glands (salivary glands in the mouth), parotid glands (a type of salivary gland), and the thyroid gland, do not play a significant role in the digestion of this specific food.
16.
The amount of ______ produced is probably the most important factor in determining BMR.
Correct Answer
D. Thyroxine
Explanation
Thyroxine is a hormone produced by the thyroid gland that regulates metabolism. It plays a crucial role in determining the basal metabolic rate (BMR), which is the amount of energy expended by the body at rest. The higher the level of thyroxine produced, the higher the BMR, as it increases the rate at which the body burns calories. Therefore, the amount of thyroxine produced is likely the most important factor in determining BMR.
17.
The functional and structural unit of the kidneys is:
Correct Answer
D. The nephron.
Explanation
The nephron is the functional and structural unit of the kidneys. It is responsible for the filtration, reabsorption, and secretion of substances to maintain the body's fluid balance and remove waste products. The nephron consists of various components, including the glomerulus, Bowman's capsule, proximal and distal tubules, and the loop of Henle. These structures work together to filter blood, reabsorb important substances, and excrete waste products, ultimately producing urine. Therefore, the nephron is the correct answer as it encompasses all the essential components involved in kidney function.
18.
The ______ contains lobules with sinusoids (lined with macrophages) that lead to a central venous structure.
Correct Answer
A. Liver
Explanation
The liver contains lobules with sinusoids that are lined with macrophages. These sinusoids allow blood to flow through the liver and are connected to a central venous structure. This structure is responsible for draining the blood from the liver and returning it to circulation.
19.
The mechanical and chemical receptors that control digestive activity are located:
Correct Answer
D. In the walls of the tract organ.
Explanation
The correct answer is "In the walls of the tract organ." The walls of the digestive tract contain both mechanical and chemical receptors that are responsible for controlling digestive activity. These receptors detect factors such as the presence of food, the stretching of the organ walls, and the chemical composition of the food. They then send signals to the brain and other parts of the digestive system to regulate the release of digestive enzymes, hormones, and muscle contractions, ensuring proper digestion and absorption of nutrients.
20.
Hydrochloric acid is secreted by which of the secretory cells of the stomach?
Correct Answer
B. Parietal cells
Explanation
Parietal cells are responsible for secreting hydrochloric acid in the stomach. These cells are found in the gastric glands and produce both hydrochloric acid and intrinsic factor. Hydrochloric acid helps in the digestion of food and also creates an acidic environment in the stomach, which is necessary for the activation of various digestive enzymes. Therefore, parietal cells play a crucial role in the digestive process.
21.
The most powerful respiratory stimulus for breathing in a healthy person is:
Correct Answer
D. Increase of carbon dioxide.
Explanation
Increase of carbon dioxide is the most powerful respiratory stimulus for breathing in a healthy person. When carbon dioxide levels in the body increase, it triggers a response in the brain to increase the rate and depth of breathing. This is known as the respiratory drive. The increase in carbon dioxide is detected by chemoreceptors in the brain, which send signals to the respiratory muscles to increase ventilation and remove the excess carbon dioxide. This mechanism helps to maintain the balance of gases in the body and ensure adequate oxygen supply to the tissues.
22.
The dental formula for an adult is 2-1-2-3. What does 1 stand for?
Correct Answer
B. Canine tooth
Explanation
The dental formula 2-1-2-3 represents the number and types of teeth in one half of the upper and lower jaws. The number "1" in the formula represents the canine tooth. Canine teeth are sharp, pointed teeth located on either side of the incisors. They are used for tearing and grasping food.
23.
The kidneys are stimulated to produce renin:
Correct Answer
C. By a decrease in the blood pressure
Explanation
The correct answer is "By a decrease in the blood pressure." When the blood pressure drops, the kidneys are stimulated to produce renin. Renin is an enzyme that helps regulate blood pressure by initiating a cascade of reactions that ultimately lead to the production of angiotensin II, a hormone that causes vasoconstriction and stimulates the release of aldosterone. Aldosterone then acts on the kidneys to increase sodium reabsorption, which helps increase blood pressure. Therefore, a decrease in blood pressure triggers the kidneys to produce renin to restore and regulate blood pressure levels.
24.
An increase in the permeability of the cells of the collecting tubule to water is due to:
Correct Answer
D. An increase in the production of ADH.
Explanation
An increase in the production of ADH (antidiuretic hormone) causes an increase in the permeability of the cells of the collecting tubule to water. ADH acts on the cells of the collecting tubule to insert aquaporin channels into their membranes, allowing water to be reabsorbed back into the bloodstream. This leads to increased water reabsorption and decreased urine output.
25.
The larynx contains:
Correct Answer
B. The thyroid cartilage.
Explanation
The correct answer is the thyroid cartilage. The question asks what the larynx contains, and out of the options given, the thyroid cartilage is the only one mentioned. The larynx is a part of the respiratory system located in the throat, and it houses the vocal cords. The thyroid cartilage is the largest cartilage in the larynx and forms the front wall of the larynx, protecting the vocal cords. The other options mentioned, such as the cricoid cartilage, true vocal folds, and false vocal folds, are also parts of the larynx, but they are not mentioned as options in the question.
26.
Which of the following mechanisms yields the most energy that is captured in ATP bonds during cellular respiration?
Correct Answer
D. Oxidative phosphorylation
Explanation
Oxidative phosphorylation is the mechanism that yields the most energy captured in ATP bonds during cellular respiration. This process occurs in the mitochondria and involves the transfer of electrons from NADH and FADH2 to the electron transport chain. As the electrons move through the chain, energy is released and used to pump protons across the inner mitochondrial membrane. The buildup of protons creates a gradient, which drives the production of ATP through ATP synthase. Overall, oxidative phosphorylation produces a large amount of ATP compared to other mechanisms such as substrate-level phosphorylation or oxidation-reduction reactions.
27.
The renal corpuscle is made up of:
Correct Answer
D. Bowman's capsule and glomerulus.
Explanation
The renal corpuscle is the functional unit of the kidney responsible for filtration. It consists of two main components: Bowman's capsule and the glomerulus. Bowman's capsule is a cup-shaped structure that surrounds the glomerulus and collects the filtrate. The glomerulus is a network of capillaries where filtration occurs. Together, these structures play a crucial role in the initial filtration of blood in the kidney.
28.
From the esophagus to the anal canal the walls of every organ of the alimentary canal are made up of the same four basic layers. Arrange them in order from the lumen.
Correct Answer
C. Mucosa, submucosa, muscularis externa and serosa
Explanation
The correct answer is "mucosa, submucosa, muscularis externa, and serosa." This is the correct order of the layers from the lumen of the alimentary canal. The mucosa is the innermost layer that lines the lumen and helps with absorption and secretion. The submucosa is the layer that provides support and contains blood vessels and nerves. The muscularis externa is responsible for the movement and contraction of the organ. Finally, the serosa is the outermost layer that provides protection and helps attach the organ to surrounding structures.
29.
What cartilages of the larynx anchor the vocal cords and open and close them?
Correct Answer
D. Arytenoid
Explanation
The arytenoid cartilages are responsible for anchoring the vocal cords and controlling their movement. These cartilages are located at the back of the larynx and play a crucial role in the production of sound. They are responsible for opening and closing the vocal cords, allowing for the control of airflow and the production of different pitches and tones. The thyroid, epiglottis, and cricoid cartilages also play important roles in the larynx, but they do not directly anchor and control the vocal cords like the arytenoid cartilages do.
30.
________ is locally regulated in the blood by the active form of vitamin D which acts a cofactor.
Correct Answer
C. Calcium
Explanation
Calcium is locally regulated in the blood by the active form of vitamin D, which acts as a cofactor. Vitamin D helps in the absorption of calcium from the intestines and promotes its reabsorption in the kidneys, thereby maintaining calcium levels in the blood. This regulation is important for various physiological processes, including bone health, nerve function, and muscle contraction.
31.
Which of the following is not a stimulus fro breathing?
Correct Answer
A. Rising blood pressure
Explanation
Rising blood pressure is not a stimulus for breathing because the respiratory system is primarily regulated by the levels of carbon dioxide and oxygen in the blood, as well as the pH of the blood. When carbon dioxide levels rise or the pH becomes too acidic, it triggers an increase in breathing rate to remove excess carbon dioxide and restore balance. However, rising blood pressure does not directly affect the respiratory system and therefore does not stimulate breathing.
32.
The most abundant dietary lipids are:
Correct Answer
A. Neutral fats.
Explanation
Neutral fats, also known as triglycerides, are the most abundant dietary lipids. They are composed of three fatty acid molecules attached to a glycerol molecule. Neutral fats are the main storage form of energy in the body and are found in foods such as oils, butter, and animal fats. Cholesterol is a type of lipid found in animal products and is important for various functions in the body, but it is not as abundant in the diet as neutral fats. Fatty acids and phospholipids are also dietary lipids, but they are not as abundant as neutral fats.
33.
The plicae circulares and intestinal villi are found in which of the four layers of the alimentary tube wall?
Correct Answer
A. Mucosa
Explanation
The plicae circulares and intestinal villi are found in the mucosa layer of the alimentary tube wall. The mucosa is the innermost layer of the tube and is responsible for absorption and secretion. The plicae circulares are circular folds in the mucosa that increase the surface area for absorption, while the intestinal villi are small finger-like projections that further increase the surface area. This arrangement allows for efficient absorption of nutrients in the digestive process.
34.
The process of breaking triglycerides down into glycerol and fatty acids is known as:
Correct Answer
A. Lipolysis.
Explanation
Lipolysis is the correct answer because it refers to the process of breaking down triglycerides into glycerol and fatty acids. This process occurs when the body needs to use stored fat as an energy source. Lipolysis is an essential step in metabolism and weight loss, as it allows the body to access and utilize fat stores for energy production. Lypogenesis, on the other hand, is the process of synthesizing new fat molecules, while fat utilization and gluconeogenesis are not directly related to the breakdown of triglycerides.
35.
The function of the hepatic portal circulation is to:
Correct Answer
C. Collect absorbed nutrients for metabolic processing or storage.
Explanation
The hepatic portal circulation is responsible for collecting absorbed nutrients from the gastrointestinal tract and delivering them to the liver for metabolic processing or storage. This allows the liver to regulate nutrient levels in the blood and ensure that nutrients are properly utilized by the body. The other options mentioned in the question, such as returning glucose to the general circulation, distributing hormones, and carrying toxins to the venous system, are not the primary functions of the hepatic portal circulation.
36.
With the Bohr effect more oxygen is released because:
Correct Answer
C. A decrease in pH acidosis weakens the hemoglobin-oxygen bond.
Explanation
The Bohr effect refers to the phenomenon where a decrease in pH (acidosis) weakens the hemoglobin-oxygen bond, causing more oxygen to be released from hemoglobin. This occurs because in an acidic environment, such as during exercise or in tissues with high metabolic activity, there is an increase in carbon dioxide and a subsequent increase in hydrogen ions (H+). These hydrogen ions bind to hemoglobin, causing a conformational change that weakens the bond between hemoglobin and oxygen, leading to the release of oxygen to the surrounding tissues. Therefore, the correct answer is that a decrease in pH (acidosis) weakens the hemoglobin-oxygen bond.
37.
The respiratory membrane is a combination of:
Correct Answer
D. Respiratory bronchioles and alveolar sacs.
Explanation
The respiratory membrane is the site of gas exchange in the lungs. It consists of the thin walls of the respiratory bronchioles and alveolar sacs. These structures are lined with a single layer of epithelial cells, which are surrounded by a network of capillaries. Oxygen from the inhaled air diffuses across the respiratory membrane into the capillaries, while carbon dioxide from the blood diffuses in the opposite direction to be exhaled. This exchange of gases occurs due to the close proximity and thinness of the walls of the respiratory bronchioles and alveolar sacs.
38.
Most electrolyte reabsorption by the renal tubules:
Correct Answer
C. Is hormonally controlled in distal tubule segments.
Explanation
Electrolyte reabsorption in the renal tubules is a complex process that occurs throughout different segments of the tubules. The correct answer states that most electrolyte reabsorption is hormonally controlled in distal tubule segments. This means that the reabsorption of electrolytes such as sodium, potassium, and chloride is regulated by hormones in the distal parts of the tubules, specifically the distal convoluted tubules. These hormones, such as aldosterone, play a crucial role in controlling the reabsorption of electrolytes to maintain electrolyte balance and regulate blood pressure.
39.
Glycolysis is best defined as the:
Correct Answer
A. Conversion of glucose into two molecules of pyruvic acid.
Explanation
Glycolysis is a metabolic pathway that occurs in the cytoplasm of cells and involves the breakdown of glucose into two molecules of pyruvic acid. This process does not involve the formation of sugar or the conversion of pyruvic acid into carbon dioxide and water. Therefore, the correct answer is the conversion of glucose into two molecules of pyruvic acid.
40.
Paneth cells:
Correct Answer
B. Secrete enzymes that kill bacteria.
Explanation
Paneth cells are specialized cells found in the small intestine, particularly in the crypts of Lieberkühn. They are more common in the ileum than in the jejunum. These cells secrete various antimicrobial peptides and enzymes, such as lysozyme and defensins, that help kill bacteria and protect the intestinal lining from infection. Their role in the immune defense of the gut makes them an important component of the intestinal barrier.
41.
The terminal portion of the small intestine is known as the:
Correct Answer
A. Ileum.
Explanation
The terminal portion of the small intestine is known as the ileum. The ileum is the last section of the small intestine, located between the jejunum and the large intestine. It is responsible for the absorption of nutrients, such as vitamins, minerals, and bile salts. The ileum also plays a role in the immune system, as it contains lymphoid tissue that helps to protect the body against pathogens. Therefore, the correct answer is ileum.
42.
Which of the following provide the greatest surface area for gas exchange?
Correct Answer
B. Alveoli.
Explanation
Alveoli provide the greatest surface area for gas exchange. Alveoli are tiny air sacs located at the end of the respiratory bronchioles in the lungs. They are surrounded by a network of capillaries, which allows for the exchange of oxygen and carbon dioxide between the air in the alveoli and the bloodstream. The large number and small size of alveoli greatly increase the surface area available for gas exchange, making them the most efficient structures for this process.
43.
Oxidation-reduction reactions are catalyzed by which of the following enzymes?
Correct Answer
A. Dehydrogenases and oxidases.
Explanation
Dehydrogenases and oxidases are enzymes that catalyze oxidation-reduction reactions. Dehydrogenases remove hydrogen atoms from substrates, while oxidases transfer electrons to molecular oxygen. These enzymes play a crucial role in various metabolic pathways, such as cellular respiration and the breakdown of fatty acids. By facilitating the transfer of electrons, dehydrogenases and oxidases help generate energy and maintain cellular redox balance.
44.
Oxygen and carbon dioxide are exchanged in the lungs and through all cell membranes by:
Correct Answer
C. Diffusion.
Explanation
Oxygen and carbon dioxide are exchanged in the lungs and through all cell membranes by diffusion. Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration, down their concentration gradient. In the lungs, oxygen moves from the air sacs (alveoli) into the bloodstream, while carbon dioxide moves from the bloodstream into the alveoli to be exhaled. Similarly, in cells, oxygen moves from the bloodstream into the cells, while carbon dioxide moves out of the cells into the bloodstream. This exchange occurs passively, without the need for energy or a membrane transport protein, making diffusion the correct answer.
45.
The loudness of a person's voice depends on:
Correct Answer
C. The force with which air rushes across the vocal folds.
Explanation
The correct answer is the force with which air rushes across the vocal folds. This is because the loudness of a person's voice is determined by the amount of air passing through the vocal folds. When more forceful air rushes across the vocal folds, it causes them to vibrate more vigorously, resulting in a louder voice. The strength of the intrinsic laryngeal muscles, the length of the vocal folds, and the thickness of vestibular folds may affect the quality or pitch of the voice, but they do not directly determine the loudness.
46.
Which of the following statements best describes complete protein?
Correct Answer
A. Must meet all the body's amino acid requirements for maintenance and growth.
Explanation
Complete proteins are those that contain all the essential amino acids in the right proportions that the body needs for maintenance and growth. This means that they provide all the necessary building blocks for the body to synthesize proteins and carry out various functions. The other options, such as meeting the minimum daily requirements or being derived from specific sources, do not encompass the concept of complete proteins.
47.
When ketone bodies are present in the blood and urine in large amounts, it indicated increased metabolism of:
Correct Answer
B. Fatty acids.
Explanation
When ketone bodies are present in large amounts in the blood and urine, it indicates increased metabolism of fatty acids. Ketone bodies are produced when the body breaks down fatty acids for energy in the absence of glucose. This suggests that the body is utilizing fatty acids as a primary source of fuel, which can occur during periods of prolonged fasting, low carbohydrate intake, or certain metabolic disorders. Increased metabolism of glycogen, lactic acid, or amino acids would not result in the production of ketone bodies.
48.
Air and food are routed into the proper channels by the:
Correct Answer
A. Larynx.
Explanation
The larynx is responsible for routing both air and food into the proper channels. It contains the vocal cords and is located at the top of the trachea. When we breathe, the larynx opens up to allow air to pass through the trachea and into the lungs. When we swallow, the larynx closes off the trachea to prevent food from entering the airway and directs it into the esophagus instead. Therefore, the larynx plays a crucial role in ensuring that air and food are directed to the correct pathways.
49.
The molecule hat serves as the major source of readily available body fuel is:
Correct Answer
D. Glucose.
Explanation
Glucose is the correct answer because it is a simple sugar that is easily broken down by the body to provide energy. It is the primary source of fuel for the brain and muscles. Acetyl CoA is a molecule involved in the metabolism of glucose and fats, but it is not the major source of readily available body fuel. Fat and cellulose are not as easily and quickly converted into energy as glucose.
50.
The mucosa of the developing alimentary tube comes from :
Correct Answer
A. Endoderm.
Explanation
The mucosa of the developing alimentary tube comes from the endoderm. During embryonic development, the endoderm germ layer gives rise to the epithelial lining of the digestive tract, including the mucosa. The endoderm also gives rise to other internal organs such as the liver, pancreas, and lungs. The ectoderm gives rise to the skin and nervous system, while the mesoderm gives rise to the muscles, connective tissues, and some internal organs. Pachyderm, on the other hand, refers to a group of large mammals with thick skin, such as elephants, and is not related to the development of the alimentary tube.