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FOUNDATION – 2022
Questions from the 2022 Module + Annual Exam
Think about the concentration of salt that would “suck water out” of the red blood cells. What happens when the surrounding solution is saltier than the inside of the cell?
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Category: Foundation – Physiology
Which of the following solutions would cause red blood cells to shrink?
Red blood cells (RBCs) respond to the osmolarity of their surrounding solution:
A 1.0% NaCl solution is hypertonic compared to the intracellular fluid of RBCs, leading to water loss and cell shrinkage.
Think about the muscle that’s the “star player” in lifting the leg. What’s the term for the muscle that’s primarily responsible for a specific movement?
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Category: Foundation – Anatomy
A 16-year-old boy came to the hospital with the complaint of an inability to lift his leg. Muscle testing was performed and it revealed the weakening of his muscles. What is the weakened muscle called in this movement?
The prime mover (agonist) is the muscle primarily responsible for a specific movement. In the case of lifting the leg (hip flexion), the prime mover is the iliopsoas muscle. If this muscle is weakened, the patient would have difficulty performing the movement.
Other muscle roles include:
Think about the classic microscopic change in the liver caused by alcohol abuse, especially in someone who hasn’t yet developed severe symptoms. What’s the first thing that goes wrong when the liver starts struggling with alcohol metabolism?
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Category: Foundation – Pathology
A 48-year-old man who has a history of chronic alcohol abuse is capable of doing his work just fine. He has had no major illnesses and physical examination reveals no significant findings. Laboratory studies also do not show any significant dysfunction. Which of the following findings are likely to be seen in his liver under light microscope?
Chronic alcohol abuse is a common cause of fatty liver (steatosis), which is characterized by the accumulation of large lipid droplets within hepatocytes. This occurs due to impaired metabolism of fatty acids and increased synthesis of triglycerides in the liver. In the early stages, fatty liver may not cause significant symptoms or laboratory abnormalities, as described in this patient.
The other options are incorrect:
Think about the amino acid that acts as a “safe container” for ammonia in the body. What’s the end product of ammonia detoxification?
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Category: Foundation – Biochemistry
Ammonia is converted into which of the following non-toxic amino acids?
Ammonia (NH₃) is highly toxic to cells, especially in the brain. To safely transport and store ammonia, it is converted into glutamine via the enzyme glutamine synthetase. Key points:
Think about what happens after you pick something up with your thumb and fingers. What do you do next to “reset” your hand? The answer lies in reversing a very specific and useful hand movement.
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Which of the following statements best describes reposition?
Reposition is the movement that returns the thumb (and sometimes the fingers) to their original anatomical position after opposition. Opposition is the movement where the thumb touches the tips of the fingers, allowing for precision grip (e.g., picking up a pen). Reposition reverses this action, bringing the thumb back to its neutral position.
Think about the notorious bacterium that thrives when the gut’s natural defenses are wiped out by antibiotics. It’s a spore-forming, toxin-producing culprit that can turn the colon into a battlefield.
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Category: Foundation – Microbiology
The excessive use of antibiotics can have serious side effects on the body, especially the gastrointestinal tract (GIT). Which organism can lead to the formation of a pseudo-membrane in the GIT due to excessive antibiotic use?
Excessive use of antibiotics can disrupt the normal flora of the gut, creating an opportunity for pathogenic bacteria to overgrow. Clostridium difficile is a gram-positive, spore-forming bacterium that can cause pseudomembranous colitis, a severe inflammation of the colon characterized by the formation of a pseudo-membrane composed of necrotic tissue, fibrin, and inflammatory cells. This condition is often associated with antibiotic use, particularly broad-spectrum antibiotics like clindamycin, ampicillin, and cephalosporins.
The other organisms are incorrect:
Think of apoptosis as a controlled demolition of a cell. Do you want the wrecking crew (caspases) to be active or inactive for the demolition to happen? Which of these proteins are like the “trigger” for the demolition, and which pathway is initiated by signals from outside the cell?
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Which of the following statements is correct regarding apoptosis?
The correct statement is: BAX and BAK are pro-apoptotic proteins.
Here’s a breakdown of why:
Why the other statements are incorrect:
Apoptosis involves the activation of caspases, not their inactivation. Caspases are a family of proteases (enzymes that cut proteins) that play a central role in apoptosis. They are activated in a cascade, ultimately leading to the dismantling of the cell.
The intrinsic pathway is also known as the mitochondrial pathway, not the death receptor pathway. It’s triggered by internal cellular stress, such as DNA damage or growth factor deprivation, and involves the mitochondria.
Caspase 8 (and 9 in the intrinsic pathway) are initiator caspases, not caspase 3 and 6. Initiator caspases activate the executioner caspases, such as caspase 3 and 6, which then carry out the actual cell destruction.
The extrinsic pathway is also known as the death receptor pathway, not the mitochondrial pathway. It’s triggered by the binding of death ligands to death receptors on the cell surface.
Imagine you’re suddenly plunged into an ice bath. What’s your body’s immediate, instinctive reaction to warm itself up? Does it involve relaxing or tensing your muscles?
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A group of friends visited a cold hilly area during their winter vacations. Which of the following physiological responses is most likely to occur in their body?
The answer is Shivering of skeletal muscles.
Here’s why:
When exposed to cold temperatures, the body’s primary goal is to generate heat and conserve the heat it has. Shivering is a rapid, involuntary contraction of skeletal muscles. This muscle activity generates heat, helping to raise the body’s core temperature.
Why the other options are incorrect:
Increased sweating: Sweating is a mechanism for cooling the body, not warming it. It would be counterproductive in a cold environment.
Vasodilation: Vasodilation is the widening of blood vessels. While it can increase blood flow to the skin, it also increases heat loss. In a cold environment, the body would primarily use vasoconstriction (narrowing of blood vessels) to conserve heat.
Relaxation of piloerector muscles: Piloerector muscles are the small muscles attached to hair follicles. Their contraction causes “goosebumps.” While this can trap a thin layer of air for slight insulation, it’s a minor effect compared to shivering. Relaxation of these muscles would have the opposite effect – making you colder.
Relaxation of skeletal muscles: Muscle relaxation would decrease heat production. This is the opposite of what the body needs in a cold environment.
Imagine a crowded bus where all the seats are taken. How would a new passenger (pathogen) find a place to sit? The normal flora are like the passengers already occupying the seats, leaving no room for newcomers.
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The normal flora inhibits pathogenic bacteria from binding to the mucosal surfaces of the body. Which of the following statements best describes the mechanism of colonization resistance?
Colonization resistance refers to the ability of normal flora to prevent pathogenic bacteria from establishing themselves in the body. One of the key mechanisms is competitive exclusion, where resident bacteria occupy binding sites on mucosal surfaces, leaving fewer available sites for pathogens to attach. This prevents pathogens from colonizing and causing infection.
The other options describe related concepts but do not explain colonization resistance:
Imagine building a Lego structure out of sugar bricks. What kind of “connector” would you use to join the bricks together? It wouldn’t be the same connector you’d use for metal or plastic, would it?
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Which of the following bonds exists between the two monomers of a disaccharide?
Glycosidic bonds are the specific type of covalent bond that links two monosaccharide (simple sugar) units together to form a disaccharide (like sucrose or lactose) or a polysaccharide (like starch or cellulose). Think of it as the “glue” that holds the sugar building blocks together.
Ionic bond: Ionic bonds involve the electrostatic attraction between oppositely charged ions. They are important in many biological molecules, but not the primary linkage between sugar monomers.
Ether bond: While glycosidic bonds are technically a type of ether bond, “glycosidic bond” is the more specific and correct term in this context. Using the general term “ether bond” wouldn’t be precise enough.
Ester bond: Ester bonds are formed between an alcohol and a carboxylic acid. They are important in lipids (fats and oils), but not in carbohydrates.
Peptide bond: Peptide bonds link amino acids together to form proteins.
They are not found in carbohydrates.
Imagine drug metabolism as a two-step process. Phase I is like preparing the drug for disposal, and Phase II is like packaging it up for removal. Which of these options sounds like it belongs in the “packaging” stage?
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Category: Foundation – Pharmacology
Which of the following is not a phase 1 reaction in the process of drug metabolism?
Phase I reactions in drug metabolism primarily involve oxidation, reduction, hydrolysis, and sometimes dehydrogenation. These reactions modify the drug molecule, often making it more polar. They prepare the drug for Phase II reactions.
Conjugation is a Phase II reaction. In Phase II, the products of Phase I reactions are conjugated (joined) with other molecules, such as glucuronic acid, sulfate, or glutathione. This usually makes the drug much more water-soluble and easier to excrete.
Focus on the structure and function of the periosteum, particularly its role in bone growth, repair, and blood supply.
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Category: Foundation – Histology
Which of the following statements is incorrect regarding the periosteum?
The periosteum is a dense layer of connective tissue that covers the outer surface of bones, except at joint surfaces. It has the following characteristics:
Thus, the statement claiming the periosteum is avascular is incorrect.
Consider the directionality of DNA polymerase and the differences between the leading and lagging strands during DNA replication.
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Okazaki fragments are formed on the ______ strands in the ______ direction.
During DNA replication, the two strands of the double helix are replicated differently due to the antiparallel nature of DNA and the 5′-3′ directionality of DNA polymerase:
The lagging strand is synthesized in the opposite direction of the replication fork movement, requiring the formation of Okazaki fragments.
Think about the relationship between pKa and the tendency of an acid to donate protons and proportionality of pKa with strength of an acid.
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A high pKa value refers to which of the following?
The pKa value is a measure of the strength of an acid in solution. It is the pH at which half of the acid molecules are dissociated. The relationship between pKa and acid strength is as follows:
The other options are unrelated to pKa:
Think about the chemical nature of hematoxylin and what it binds to. What cellular components are negatively charged and attract this blue dye?
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A tissue is stained with hematoxylin and eosin (H&E) and it is readily stained blue. What does this signify about the tissue?
H&E staining is a common histological technique where:
If the tissue appears blue, it indicates the presence of basophilic components, such as nucleic acids or acidic proteins.
The neural tube gives rise to most CNS neurons, while the neural crest gives rise to PNS components and other specialized structures.
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Category: Foundation – Embryology
Which of the following cells is not derived from the neural crest cells?
Neural crest cells give rise to a diverse set of structures in the body, including Schwann cells, melanocytes, and glial cells. However, neurons are not derived from neural crest cells, except for specific populations of peripheral neurons.
✅ Peripheral nervous system (PNS) components:
Thus, the correct answer is “Neurons,” as most neurons in the CNS arise from the neural tube, not neural crest cells.
Think about the direction of movement of the foot and the anatomical terms used to describe specific motions.
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Which term refers to the twisting of the foot in the inward direction?
Inversion is a movement of the foot that involves turning the sole of the foot inward (toward the midline of the body). This motion occurs primarily at the subtalar and transverse tarsal joints.
The other terms describe different movements:
Focus on the functional specialization of chorionic villi and their role in facilitating exchange between maternal and fetal circulations.
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Which type of chorionic villi is involved in the exchange of nutrients and wastes between maternal and fetal blood?
Explanation: Chorionic villi are finger-like projections of the placenta that play a crucial role in fetal-maternal exchange. They develop in stages:
The other types of villi serve different functions:
This iron-storage pigment accumulates in macrophages and gives a yellow-brown color to resolving bruises.
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While working in a warehouse a 45-year-old man is struck on the leg by a falling pallet rack. It strikes him on his left leg in the region of his thigh. The skin is not broken. Within 2 days there is a 5 x 7 cm purple color bruise at the site of injury. Which of the following substances has most likely accumulated at the site of injury to produce a yellow-brown color at the site of injury 16 days later?
A bruise (contusion) results from trauma causing rupture of blood vessels, leading to extravasation of blood into tissues. The color changes seen in a bruise occur due to the breakdown of hemoglobin in RBCs over time.
✅ Hemosiderin is an iron-containing pigment that accumulates in macrophages after RBC breakdown. ✅ It is responsible for the yellow-brown color of resolving bruises seen 16 days after injury. ✅ Seen in chronic hemorrhage sites and conditions like hemosiderosis and hemochromatosis.
Thus, the correct answer is “Hemosiderin,” as it is the pigment responsible for the yellow-brown color seen in bruises during the later stages of healing.
Think about a toothbrush. The bristles are all clustered together at one end, right? Now imagine a bacterium with a similar “bristle-like” cluster of flagella at one pole. What would you call this arrangement?
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The presence of a cluster of flagella on a single pole of a bacterial cell is termed?
Bacterial flagella arrangements are classified based on their number and distribution:
The term lophotrichous specifically describes the arrangement where multiple flagella are grouped together at one end of the bacterium, resembling a tuft.
This energy storage form consists of three fatty acid chains attached to glycerol and is stored in adipose tissue.
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Fat is stored in the body in what form?
Fat is primarily stored in the body as triglycerides (triacylglycerols) within adipose tissue. Triglycerides serve as the main energy reserve for the body and are broken down into fatty acids and glycerol when energy is needed.
✅ Composed of one glycerol molecule and three fatty acid chains. ✅ Stored in adipocytes (fat cells) in adipose tissue. ✅ Most energy-dense macronutrient, providing 9 kcal per gram. ✅ Broken down by lipase enzymes during fasting or energy demand.
Thus, the correct answer is “Triglycerides,” as they are the primary form of stored fat in the body.
Think about how amino acids can have both acidic and basic groups. Is there a sweet spot where these charges balance each other out? What would you call that point?
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Which of the following terms is described as the point at which the net charge on an amino acid is neutral?
The isoelectric point (pI) of an amino acid (or protein) is the pH at which it has a net charge of zero. At this pH, the number of positive charges on the molecule equals the number of negative charges. The amino acid exists as a zwitterion, a molecule with both positive and negative charges, but the overall net charge is zero.
Why the other options aren’t the correct term:
Dissociation point: This is a more general term referring to the point at which a molecule dissociates into ions in solution. While related to the concept of charge, it’s not specific to the point of zero net charge for an amino acid.
Solubility point: This refers to the concentration of a solute at which it will dissolve in a given solvent at a specific temperature. It’s not related to the charge of an amino acid.
Ionization point: Similar to dissociation point, this is a general term for when a molecule gains or loses electrons and becomes ionized. It’s not specific to the zero net charge condition.
Neutral point: While it sounds close, “isoelectric point” is the established scientific term for the pH at which an amino acid has a net charge of zero.
Think about the structure that establishes the head-to-tail axis during early embryonic development.
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While performing an ultrasound, the physician cannot distinguish the embryo craniocaudally. This is most possibly due to the absence of which of the following events?
The primitive streak is a critical structure in early embryonic development that establishes the craniocaudal (head-to-tail) axis of the embryo. It forms during the third week of development and is essential for:
Without the primitive streak, the embryo lacks a clear craniocaudal axis, making it difficult to distinguish orientation during imaging.
Consider the electrolyte composition of gastric secretions and the body’s compensatory mechanisms in response to fluid and electrolyte loss.
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What does vomiting lead to?
Vomiting causes the loss of gastric contents, which are rich in hydrochloric acid (HCl). This leads to:
This phospholipid is the main component of surfactant, essential for reducing alveolar surface tension in newborns.
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The deficiency of which of the following lipids can result in respiratory distress syndrome in pre-term infants?
Dipalmitoyl lecithin (Diplamitoylphosphatidylcholine, DPPC) is a major component of pulmonary surfactant, which reduces alveolar surface tension and prevents lung collapse.
✅ Produced by type II alveolar cells in the lungs. ✅ Surfactant production begins around week 24 of gestation but reaches sufficient levels only after week 35. ✅ Deficiency in preterm infants leads to neonatal respiratory distress syndrome (NRDS) → alveoli collapse due to increased surface tension, leading to hypoxia and respiratory failure. ✅ Treatment → Exogenous surfactant therapy & corticosteroids (betamethasone) to stimulate fetal lung maturity.
Thus, the correct answer is “Dipalmitoyl lecithin,” as it is the primary lipid responsible for surfactant function, preventing neonatal respiratory distress syndrome (NRDS) in preterm infants.
Think about the muscle type that’s under your conscious control and has a striped appearance under the microscope. What’s its defining feature?
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Which of the following is the appropriate property of skeletal muscles?
Skeletal muscles are characterized by the following properties:
Other properties listed are incorrect:
Think about the electrolyte that makes salty fluids salty. Which cation is responsible for the high osmolarity of blood plasma and other extracellular fluids?
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Which of the following is the major cation present in extra-cellular fluid (ECF)?
Sodium is the most abundant cation in the extracellular fluid and plays a critical role in maintaining osmotic pressure, fluid balance, and nerve impulse transmission. The concentration of sodium in ECF is approximately 135-145 mEq/L, which is much higher than its concentration inside cells.
The other cations are either less abundant or primarily located intracellularly:
Think about the “energy savings account” of animals—what carbohydrate is stored in the liver and muscles for quick access?
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Which of the following carbohydrates serves as a stored form of energy in animals?
Glycogen is a polysaccharide that functions as the primary storage form of glucose in animals. Key features include:
Other carbohydrates:
Think about what happens to your food in your gut. Which of these carbohydrates might create a “sticky” environment that could trap fats? Which ones just get broken down and absorbed quickly?
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Which of the following carbohydrates modifies lipid absorption from the intestine?
Beta-glucans are a type of soluble dietary fiber. They form a viscous gel in the intestines. This gel can interfere with the absorption of fats and cholesterol, leading to reduced lipid absorption. This is one of the reasons beta-glucans are associated with heart health benefits.
Why the other options are less directly involved in modifying lipid absorption in the way beta-glucans do:
Alpha glucan: This is a general term for polysaccharides made of glucose linked by alpha glycosidic bonds. Starch is a prominent example. While starches are a source of energy, they don’t have the same viscous gel-forming properties as beta-glucans and don’t affect lipid absorption in the same way.
Glucose: Glucose is a simple sugar. It’s absorbed directly into the bloodstream and doesn’t directly modify the absorption of other lipids.
Starch: As mentioned above, starch is a polysaccharide made of glucose. It is a source of energy, but does not have a significant impact on lipid absorption.
Cellulose: Cellulose is another type of dietary fiber, but it’s insoluble fiber. It adds bulk to the stool and aids in digestion, but it doesn’t form a viscous gel like beta-glucan and therefore doesn’t have the same effect on lipid absorption.
Think about the lipoprotein that’s the “delivery truck” for dietary fats. Which one is packed with the most triacylglycerol?
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Which of the following has the highest concentration of triacylglycerol (TAG)?
Lipoproteins are particles that transport lipids (including TAG, cholesterol, and phospholipids) in the bloodstream. Their composition varies:
Think about the word “colonization” itself. What does it imply about the relationship between the bacteria and the host? Are they just passing through, or are they here to stay?
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Bacteria that are permanent residents in various parts of the body are known as normal flora. Which of the following statements best describes the colonization of the bacteria?
Normal flora, or microbiota, refers to the community of microorganisms (bacteria, fungi, and viruses) that permanently reside on or within the human body. These organisms establish a stable relationship with the host and are typically harmless or even beneficial. Colonization refers to the establishment and persistence of these microorganisms in specific body sites, such as the skin, mouth, colon, and vagina.
The other options describe aspects of normal flora but do not specifically define colonization:
Think about the structure of tendons and how they handle force. What type of tissue is built like a tightly wound rope, designed to pull but not stretch?
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Tendons are classified as what type of connective tissue?
Tendons are composed of densely packed collagen fibers that are arranged in parallel to provide high tensile strength and resistance to unidirectional forces. This organization is characteristic of dense regular connective tissue, which is specialized for transmitting mechanical forces, such as those generated by muscle contraction.
Think about the role of cell junctions in creating barriers. Which one acts like a “zipper” to seal the gaps between cells?
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Which of the following types of cell junctions does not allow passage of extracellular fluid via the paracellular route?
Zonula occludens, or tight junctions, are specialized cell junctions that form a nearly impermeable barrier between adjacent cells. They prevent the passage of extracellular fluid and molecules through the paracellular route (between cells). Tight junctions are commonly found in epithelial tissues, such as the lining of the intestines or blood-brain barrier, where control over substance movement is critical.
The other options allow some form of communication or structural connection:
Focus on the standardized position used in anatomy, particularly the orientation of the face, arms, and palms.
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The teacher asks the student to stand in an anatomical position. Which of the following correctly defines his position?
The anatomical position is a standardized reference position used in anatomy and medicine to describe the location and orientation of body structures. It is defined as follows:
This position ensures consistency in anatomical descriptions and allows for clear communication about the body’s structures.
This structure connects muscles to bones, allowing force transmission for movement.
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A dense connective tissue containing bundles of collagen fibers that run parallel to each other and have only fibroblast cells with flattened nuclei in between them. This tissue is present in which of the following?
The described dense connective tissue is dense regular connective tissue, which consists of:
✅ Bundles of collagen fibers running parallel → Provides high tensile strength in one direction. ✅ Fibroblast cells with flattened nuclei in between → These produce and maintain collagen fibers. ✅ Minimal ground substance → Helps maintain a compact and strong structure.
Tendons exclusively consist of dense regular connective tissue, designed for high tensile strength to endure the pulling forces generated by muscle contractions.
Thus, the correct answer is “Tendon,” as it consists of parallel collagen bundles with fibroblasts in between.
Think about the primary roles of the sodium-potassium pump, particularly its role in maintaining ion gradients and cellular homeostasis.
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Which of the following is a function of the sodium-potassium pump in the cell membrane?
The sodium-potassium pump (Na⁺/K⁺-ATPase) is an essential membrane protein that maintains cellular homeostasis by performing the following functions:
Think about the plane that allows for “forward and backward” movements. What’s the plane where extension and flexion happen?
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A 10-year-old boy presents to the emergency department after an injury to his leg. Upon examination, it is observed that he is unable to extend his leg. The affected movement occurs in which of the following planes?
The sagittal plane divides the body into left and right halves. Movements in this plane include:
Other planes:
Think about the type of muscle that works silently in the background, controlling the flow of blood without you even noticing. Which muscle type is always “on duty” in your blood vessels? And that’s not rough but?
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Which of the following types of muscles is responsible for the dilation and constriction of blood vessels?
Smooth muscle is found in the walls of blood vessels (among other structures like the digestive tract and airways). It is responsible for vasodilation (widening of blood vessels) and vasoconstriction (narrowing of blood vessels), which regulate blood flow and pressure. Smooth muscle is involuntary and controlled by the autonomic nervous system.
This is a unique type of joint that connects a tooth to the alveolar bone via the periodontal ligament.
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A 23-year-old man presents with pain in his tooth. Upon inspection it is found that pain is in the joint between the tooth and its root. Which joint is this?
The joint between a tooth and its root in the alveolar socket is called a gomphosis, which is a type of fibrous joint.
✅ A specialized type of fibrous joint that connects the tooth root to the alveolar bone. ✅ The periodontal ligament (PDL) anchors the tooth in place. ✅ Allows very minimal movement, mainly for shock absorption during chewing. ✅ Unique because it is the only joint that does not connect bone to bone but rather bone to a structure (tooth).
Thus, the correct answer is “Fibrous,” as gomphosis is a type of fibrous joint anchoring the tooth to the jawbone.
Focus on the type of cartilage present at the epiphyseal plate and its role in bone growth.
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A radiologist observes no line separating the epiphysis and diaphysis on an X-ray because of the complete fusion of bones. What is this joint at the epiphyseal plate called?
The epiphyseal plate (growth plate) is a hyaline cartilage structure located between the epiphysis and diaphysis of long bones in children and adolescents. It allows for longitudinal bone growth. Once growth is complete, the epiphyseal plate ossifies, and the epiphysis fuses with the diaphysis. This type of joint is classified as a primary cartilaginous joint (synchondrosis), where bones are joined by hyaline cartilage.
These biomolecules are the primary source of energy in living organisms and include sugars and starches.
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Which of the following biomolecules contain a polyhydroxy aldehyde or a polyhydroxy ketone in its structure?
Carbohydrates are organic molecules that contain a polyhydroxy aldehyde (-CHO) or a polyhydroxy ketone (C=O) functional group in their structure.
✅ Classified based on their functional group:
Thus, the correct answer is “Carbohydrates,” as they contain either a polyhydroxy aldehyde or ketone group in their structure.
Think about the “molecular mimicry” strategy—what type of inhibition involves an inhibitor that looks like the substrate and competes for the same spot?
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The structure of the inhibitor is similar to the structure of the substrate in which of the following types of enzyme inhibition?
In competitive inhibition:
Other types of inhibition:
Imagine a tiny, single-celled organism trying to move through water. What structure would it use to “swim” toward food or away from danger? Think about the most dynamic and active part of the bacterial cell.
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What is the function of flagella in bacteria?
Flagella are long, whip-like appendages that protrude from the surface of bacterial cells. Their primary function is to enable movement (locomotion) by rotating like propellers, allowing bacteria to swim through liquid environments. This movement is crucial for bacteria to seek nutrients, escape harmful substances, or reach favorable environments.
The other options describe functions of other bacterial structures:
Think about the process that removes water from the tissue to prepare it for the next steps. What’s the critical step after fixation?
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When preparing a tissue for routine light microscopic study, which procedure is carried out once the tissue proteins are fixed in a solution of fixatives and cross-linking compounds?
The steps in preparing a tissue for light microscopy are as follows:
After fixation, the next step is dehydration, which prepares the tissue for embedding.
Think about the core mission of the WHO and its focus on health promotion and disease prevention in city settings.
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Category: Foundation – Community Medicine
The World Health Organization (WHO) has given the concept of a healthy city. What is the primary objective of this action plan?
The WHO’s Healthy Cities initiative is a global movement aimed at promoting health and well-being in urban environments. Its primary objectives include:
While the other options (income generation, economic development, social support networks, and community partnerships) may be components of the initiative, the overarching goal is to improve the health and quality of life of urban populations.
Think about the tissue where transparency and hydration are critical for function, and the specific GAG that contributes to these properties.
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Which of the following structures contains keratin sulfate in abundance?
Keratan sulfate is a type of glycosaminoglycan (GAG) found in various tissues. It is particularly abundant in the cornea, where it plays a critical role in maintaining transparency and hydration. Keratan sulfate is also present in cartilage but in lower amounts compared to other GAGs like chondroitin sulfate.
Focus on the mechanism by which ACE inhibitors reduce enzyme activity and how this affects Vmax and Km.
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A hypertensive patient is given an angiotensin-converting enzyme (ACE) inhibitor that works by lowering Vmax. What type of inhibition is most likely to be involved in this case?
ACE inhibitors, such as captopril or enalapril, typically work by binding to the angiotensin-converting enzyme at a site other than the active site, reducing its activity. This is characteristic of non-competitive inhibition, where:
Focus and recall the definition of the molecule and their relationship to chirality and mirror-image configurations.
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Monosaccharides that are mirror images of each other are known as?
Enantiomers are a type of stereoisomer that are non-superimposable mirror images of each other. They have the same chemical formula and sequence of bonded atoms but differ in their three-dimensional orientation. Key points about enantiomers:
The other terms describe different types of isomers:
Think about the anatomical terms for movements at the ankle joint and focus on the direction of the foot relative to the leg.
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A person raises their foot towards their knee with toes pointing upwards. What is this movement of the foot termed?
Dorsiflexion refers to the movement at the ankle joint where the foot is pulled upwards towards the shin (tibia). This action decreases the angle between the dorsum (top) of the foot and the leg. It is the opposite of plantarflexion, where the foot points downward (e.g., standing on tiptoes).
Focus on the bacterial structures involved in immune evasion and their potential for variation.
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Which of the following parts of the bacterial cell shows the most antigenic variability?
The bacterial capsule is a polysaccharide or polypeptide layer outside the cell wall that serves as a virulence factor by protecting the bacterium from phagocytosis and immune recognition. Capsules exhibit significant antigenic variability due to differences in their chemical composition and structure among bacterial species and even strains. This variability allows bacteria to evade the host immune system.
The other options are less variable:
Focus on the maturation stages of the oocyte and the components present in a fully developed Graafian follicle.
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Which of the following is not a component of the Graafian follicle?
The Graafian follicle is a mature ovarian follicle that is ready for ovulation. It contains the following components:
The primary oocyte is present in earlier stages of follicular development (primordial and primary follicles) but undergoes meiosis I to become a secondary oocyte in the Graafian follicle.
Think about the brain’s unique response to injury. What type of necrosis results in a soft, liquefied area due to the brain’s high enzyme content?
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A 65-year-old man fainted and is brought to the emergency room. When he regains consciousness, he is unable to speak and has paralysis. The doctors diagnose him with cerebral artery occlusion resulting in ischemia of the left cerebral hemisphere. What type of necrosis has occurred in this patient?
Liquefactive necrosis typically occurs in the brain due to ischemic injury or bacterial infection. Key features include:
Other types of necrosis:
Focus on the classification of amino acids as essential or non-essential. Remember that essential amino acids cannot be synthesized by the body.
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Which of the following amino acids is not produced in the body and is therefore needed in our diet?
Amino acids are classified as either essential or non-essential:
Phenylalanine is an essential amino acid, meaning it must be consumed through dietary sources. The other options (glutamine, glycine, alanine, and arginine) are non-essential and can be synthesized by the body.
Think about the molecule that blurs the line between a genetic material and a catalyst. It’s the “enzyme” of the RNA world, and its discovery turned molecular biology upside down. What could it be?
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Which of the following types of RNA exhibits catalytic property?
Ribozymes are RNA molecules that can catalyze specific biochemical reactions, similar to how protein enzymes function. They are unique because they combine the genetic information-carrying capability of RNA with the catalytic activity typically associated with proteins. Examples of ribozymes include the peptidyl transferase activity of the ribosome (during protein synthesis) and self-splicing introns.
These complex sphingolipids are most abundant in the membranes of brain cells, particularly in nerve synapses.
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Gangliosides are complex sphingolipids mostly found in which of the following cells of the body?
Gangliosides are a type of glycosphingolipid that are predominantly found in the neuronal cell membranes of the central nervous system (CNS). They play an essential role in cell signaling, neurodevelopment, and synaptic transmission.
✅ Mainly located in the outer leaflet of neuronal plasma membranes. ✅ Involved in synaptic transmission and signal transduction. ✅ Rich in sialic acid residues, which contribute to electrical conductivity and intercellular communication. ✅ Abnormal metabolism of gangliosides leads to lysosomal storage disorders, such as Tay-Sachs disease and Sandhoff disease.
Thus, the correct answer is “Neurons,” as gangliosides are highly concentrated in neuronal membranes, especially in the CNS.
Focus on the total number of somites formed during development and their role in embryonic and fetal development.
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Which of the following statements regarding somites is incorrect?
Somites are blocks of paraxial mesoderm that form during embryonic development and give rise to important structures such as the axial skeleton, skeletal muscles, and dermis of the skin. Key facts about somites include:
Thus, the statement claiming 44-47 pairs of somites is incorrect.
Imagine you have a bunch of pipe cleaners and you can bend and connect them. Could you make different shapes that all use the same number of pipe cleaners? Now, if you could also twist those shapes in 3D space, that’s where you start to get into optical isomers.
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What is the class of isomers that differ in structure because of the different arrangement of functional groups around the carbon atoms called?
Structural isomers, also known as constitutional isomers, have the same molecular formula but differ in the way their atoms are connected. This leads to different arrangements of functional groups and the carbon skeleton itself. Think of it like having the same Lego bricks but building completely different structures with them.
Here’s why the other options aren’t the best fit:
Optical isomers (Enantiomers): These are stereoisomers (same connectivity, different spatial arrangement) that are non-superimposable mirror images of each other, like your left and right hands. They arise due to chirality, often around a carbon atom bonded to four different groups. While they are isomers, the question specifically asks about differences due to functional group arrangement, not just spatial arrangement.
Chain isomers: These are a specific type of structural isomer where the difference is in the branching of the carbon chain. While they are structural isomers, the question is asking about the broader category.
Epimers: These are stereoisomers that differ in the configuration at only one chiral center. Again, while they are isomers, they are a more specific type of stereoisomer, and the question asks about functional group arrangement, not just spatial arrangement.
Think about the defining feature of synovial joints—what makes them unique compared to other joint types? Hint: It’s all about movement.
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A patient is diagnosed with the dislocation of a synovial joint in the upper limb. Which of the following is an inappropriate statement regarding the synovial type of joints?
Synovial joints are characterized by the following features:
The statement that synovial joints are “immobile” is incorrect because synovial joints are specifically designed for movement.
These organisms cannot neutralize harmful oxygen byproducts because they lack protective enzymes.
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Which of the following best explains why obligate anaerobes cannot grow in the presence of oxygen?
Obligate anaerobes cannot survive in the presence of oxygen because they lack the enzymes necessary to neutralize toxic reactive oxygen species (ROS).
✅ Oxygen generates toxic byproducts, such as superoxide radicals (O₂⁻) and hydrogen peroxide (H₂O₂), which can damage cellular components. ✅ Obligate anaerobes lack key detoxifying enzymes:
Thus, the correct answer is “They lack superoxide dismutase and catalase,” as this explains why oxygen is toxic to obligate anaerobes.
Think about the modifications that protect mRNA and help it survive longer in the cell. What structure is added to the “tail end” of the mRNA molecule?
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During the posttranscriptional modification of mRNA which of the following is added at the 3′ end?
Posttranscriptional modification of mRNA includes several key steps:
This standard reference position ensures consistent descriptions of body structures in anatomy.
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Which of the following descriptions of the anatomical position is correct?
The anatomical position is the standard reference position for describing the human body. It ensures consistency in anatomical terminology.
✅ Body standing upright (erect posture). ✅ Face forward (eyes looking straight ahead). ✅ Arms by the side with palms facing forward (supinated). ✅ Feet together, pointing forward.
This standardized position allows for consistent reference when describing anatomical structures and movements.
Thus, the correct answer is “Standing straight, both arms by the side, and both feet together,” as this is the universally accepted anatomical position.
Think about the ion that’s constantly being pumped out of the cell to create an electrical gradient. What’s the key player in maintaining the cell’s “battery”?
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Which of the following minerals is required to maintain the membrane potential?
Membrane potential is the difference in electrical charge across a cell membrane, primarily maintained by the sodium-potassium pump (Na⁺/K⁺-ATPase). This pump actively transports:
This creates an electrochemical gradient, with sodium playing a key role in depolarization and action potentials. Other minerals like calcium, magnesium, and chlorine are important for cellular functions but are not directly responsible for maintaining the membrane potential.
Think about the structure of chromatin and the role of the proteins. What biomolecule is tightly wrapped around histone proteins to form chromosomes?
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A chromosome has a protein conjugated with which of the following biomolecules?
Chromosomes are composed of chromatin, which is a complex of DNA and proteins. The primary proteins associated with DNA in chromosomes are histones. DNA wraps around histone proteins to form nucleosomes, which are the fundamental units of chromatin. This structure allows for the efficient packaging of DNA within the nucleus.
This type of burn is painful, red, and forms blisters, but does not destroy the entire dermis.
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A patient suffers some burns. The skin looks red with painful blisters. Which of the following layers of the skin are most likely to be affected?
The clinical description of red skin with painful blisters suggests a second-degree (partial-thickness) burn, which affects both the epidermis and the superficial part of the dermis.
✅ Involves both the epidermis and superficial dermis. ✅ Blister formation due to fluid accumulation between the damaged epidermis and dermis. ✅ Painful because nerve endings are still intact. ✅ Redness, swelling, and moist appearance due to inflammation and capillary damage.
Thus, the correct answer is “Epidermis and superficial dermis,” as second-degree burns affect these layers and cause blisters, redness, and pain.
Where should microbes not be found in a healthy body? Think about what a doctor looks for in a blood test. Is the presence of any bacteria in the blood a good thing?
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In which of the following regions of the body the normal flora is absent?
Normal flora, also known as commensal microbiota, are microorganisms (mostly bacteria) that live in or on the human body without normally causing disease. They colonize various sites, including the skin, throat, small intestine, and large intestine. These areas provide a suitable environment for these microorganisms to thrive.
However, blood is normally sterile. The presence of microorganisms in the bloodstream indicates a serious infection (bacteremia or septicemia), not normal flora. The body has robust defense mechanisms to prevent microbial growth in the blood.
Focus on the structural changes in the control center that signify irreversible damage and cell death.
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What is the hallmark of irreversible injury?
Irreversible injury, also known as cell death, is characterized by specific morphological changes. The most definitive hallmark is the loss of the nucleus, which can occur through:
Other features of irreversible injury include:
Focus on the key feature of the semi-conservative model: the preservation of one parental strand in each daughter DNA molecule.
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Which of the following correctly describes the semi-conservative model of DNA replication?
The semi-conservative model of DNA replication, proposed by Watson and Crick and experimentally proven by Meselson and Stahl, describes the process as follows:
This ensures genetic continuity while allowing for replication and repair. The other options describe incorrect or alternative models of DNA replication:
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An athlete was doing his third set of push-ups. What is his anatomical position in this situation?
The term prone refers to a body position where the individual is lying face down. During push-ups, the athlete’s chest and abdomen face the ground, which aligns with the definition of the prone position.
Other anatomical positions include:
Think about the “base” of the implanted embryo. What part of the decidua would logically support the growing embryo and form the maternal side of the placenta? The answer lies in the name itself.
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The part of decidua which lies underneath the implanted embryo is termed as?
The decidua is the specialized endometrium of the uterus during pregnancy. It is divided into three regions based on its relationship to the implanted embryo:
The decidua basalis is critical for placental development and maternal-fetal exchange. The other options are incorrect because:
Think about the amino acid that’s the “starting point” for stress hormones and thyroid function. What’s the common precursor that ties these powerful molecules together?
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The hormones epinephrine, norepinephrine, and thyroxine are derivatives of which of the following amino acids?
Tyrosine is an amino acid that serves as the precursor for the synthesis of several important hormones:
The other amino acids listed are not involved in the synthesis of these hormones:
Think about the group of vitamins that are the “helpers” in metabolic reactions. Which ones are directly involved in enzyme function?
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Which of the following vitamins acts as a coenzyme?
The B-complex vitamins (e.g., B1, B2, B3, B5, B6, B7, B9, and B12) are essential coenzymes in various metabolic pathways. Examples include:
Other vitamins:
Think about conditions where both water and electrolytes are lost in equal proportions, leading to a decrease in extracellular fluid volume without altering osmolarity.
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In which of the following conditions does isosmotic volume contraction occur?
Isosmotic volume contraction refers to a loss of fluid from the body that is isotonic (same osmolarity as plasma), leading to a decrease in extracellular fluid volume without a change in osmolarity. This occurs in conditions where both water and electrolytes are lost in equal proportions.
Focus on the components of glycosphingolipids and the role of ceramide as an intermediate.
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Cerebrosides are composed of which of the following?
Cerebrosides are a type of glycosphingolipid, which are lipids containing a sphingosine backbone. Their structure includes:
Thus, cerebrosides are composed of sphingosine, a fatty acid, and a sugar (galactose or glucose), forming ceramide as an intermediate.
Think about the fatty acids that your body can’t make on its own—what must you get from your diet? Focus on the omega-3 and omega-6 families.
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Which of the following are essential fatty acids?
Essential fatty acids (EFAs) are those that cannot be synthesized by the body and must be obtained from the diet. They include:
Think about the differences between cartilaginous and synovial joints. Which feature is unique to synovial joints and not found in symphyses?
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A woman presents with an injury to the pubic symphysis after a motorbike accident. The pubic symphysis is a secondary cartilaginous joint. Which of the following is not a characteristic of secondary cartilaginous joints?
Secondary cartilaginous joints, also called symphyses, are characterized by:
However, they are not covered by a synovial membrane, which is a feature of synovial joints (e.g., knee, shoulder). Synovial membranes produce synovial fluid to lubricate the joint, but secondary cartilaginous joints lack this structure.
This small RNA molecule does not encode proteins but instead modifies mRNA function by silencing genes.
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Which of the following takes part in the regulation of gene expression?
MicroRNAs (miRNAs) are small, non-coding RNA molecules that play a crucial role in the regulation of gene expression by binding to messenger RNA (mRNA) and either blocking translation or inducing degradation.
✅ Binds to complementary sequences on mRNA (usually in the 3’ UTR region). ✅ Inhibits translation by preventing ribosome attachment. ✅ Leads to mRNA degradation if the binding is highly complementary. ✅ Regulates numerous biological processes, including cell differentiation, proliferation, and apoptosis. ✅ Dysregulation of miRNA is linked to diseases, such as cancer and neurodegenerative disorders.
Thus, the correct answer is “miRNA,” as it directly regulates gene expression by targeting mRNA.
Think of the nucleus as a high-security vault. What’s the “file organizer” that keeps DNA tightly packed yet accessible for action? It’s not just a storage unit—it’s the master regulator of genetic expression. What’s this DNA-protein complex called?
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Which of the following parts of the nucleus is composed of histone proteins and DNA?
Chromatin is the complex of DNA and histone proteins that make up the genetic material within the nucleus. It exists in two forms:
The other parts of the nucleus have different functions:
Think about the type of epithelium that forms the outer layer of your skin. What kind of tissue is tough and dry enough to protect you from scrapes and cuts?
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A boy fell down while cycling, injured his elbow, and started bleeding. Which of the following types of epithelium is damaged in this case?
The skin over the elbow is covered by stratified squamous keratinized epithelium, which provides protection against mechanical stress, dehydration, and pathogens. However, the inner lining of the mouth, esophagus, and other moist surfaces is covered by stratified squamous non-keratinized epithelium. Since the question specifies bleeding from an injury (likely involving the skin), the damaged epithelium is stratified squamous keratinized.
This forensic technique is widely used in law enforcement and forensic investigations because no two individuals share the same pattern.
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What is the advantage of fingerprinting?
Fingerprinting is one of the most reliable methods of personal identification because fingerprints are unique to each individual and remain unchanged throughout life.
✅ Absolute Identification → No two people have the same fingerprints, making it the gold standard for forensic and legal identification. ✅ Permanent and Stable → Fingerprint patterns do not change with age or external conditions. ✅ Used in Law Enforcement → Helps in criminal investigations, border security, and forensic science.
Thus, the correct answer is “It enables absolute identification of an individual,” as fingerprinting provides a unique and reliable method for personal identification.
Think about the structural “scaffold” of the skin—what fibers determine its strength and the direction of tension?
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Cleavage lines of the skin indicate the direction of orientation of which of the following fibers?
Cleavage lines (also known as Langer’s lines) are natural orientation patterns of collagen fibers in the dermis. These lines are clinically significant because:
Other fibers in the skin:
Think about the molecule that stores and transfers energy in cells. Which anion is a key player in cellular energy and structure?
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Which of the following is the most abundant anion in the intra-cellular fluid?
Phosphate is the primary intracellular anion and plays a crucial role in energy metabolism (e.g., ATP), buffering, and nucleic acid synthesis. Its concentration is much higher inside cells than in extracellular fluid.
The other anions are either less abundant or primarily located extracellularly:
Think about the adaptive response of cells to increased workload or stress, particularly in the context of the cardiovascular system.
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Which type of cell change occurs due to long-standing hypertension?
Hypertrophy refers to an increase in the size of cells, leading to an increase in the size of the affected organ. In long-standing hypertension, the heart (particularly the left ventricle) undergoes hypertrophy to compensate for the increased workload required to pump blood against elevated pressure. This is known as left ventricular hypertrophy (LVH).
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