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  • Question 1 - What is the conversion of pyruvate before it enters the Krebs cycle? ...

    Correct

    • What is the conversion of pyruvate before it enters the Krebs cycle?

      Your Answer: Acetyl-CoA

      Explanation:

      The Krebs cycle occurs in the mitochondrion and involves the conversion of acetyl-CoA to oxaloacetate. This cycle produces six NADH, two FADH, and two ATP for each molecule of glucose. Pyruvate is converted to acetyl-CoA before entering the Krebs cycle, and water and carbon dioxide are end products. Acetic acid itself has no role in the cycle, but its acetyl group is used to form acetyl-CoA. Some anaerobic bacteria can convert sugars to acetic acid directly.

    • This question is part of the following fields:

      • Basic Sciences
      8.6
      Seconds
  • Question 2 - A 29-year-old woman visits your clinic with concerns about a possible pregnancy.

    Can...

    Incorrect

    • A 29-year-old woman visits your clinic with concerns about a possible pregnancy.

      Can you explain the mechanism behind a urinary pregnancy test?

      Your Answer: PCR

      Correct Answer: ELISA

      Explanation:

      Techniques in Biochemistry

      Over-the-counter urine pregnancy tests use ELISA to detect beta-HCG in a woman’s urine. The test stick contains antibodies that react with beta-HCG, producing a color change that confirms pregnancy. The urinary pregnancy test is a solid-phase ELISA, where the antibody is immobilized on a specialized filter paper. The fluid travels laterally across the paper to bind with the antibody, and if beta-HCG is present, the line turns blue. Electrophoresis characterizes the electrical charge and size of substances, while PCR identifies specific sequences of DNA or RNA. Radioimmunoassay uses radioactivity to identify specific proteins. Enzymatic degradation breaks down large proteins into smaller subunits for which target antibodies may already exist. This method is used to characterize large proteins for which the structure has not yet been described.

    • This question is part of the following fields:

      • Basic Sciences
      14.3
      Seconds
  • Question 3 - What is the estimated percentage of oxygen in the blood that is attached...

    Incorrect

    • What is the estimated percentage of oxygen in the blood that is attached to haemoglobin?

      Your Answer: 60%

      Correct Answer: 100%

      Explanation:

      Calculation of Oxygen in Blood

      The majority of oxygen in the blood is bound to haemoglobin, with the exact amount varying based on the oxygen saturation and haemoglobin level. To calculate the amount of oxygen per litre of blood, the formula (13.9 × Hb × sats/100) + (PaO2 × 0.03) can be used. For example, an average man with an Hb of 14, saturations of 98% on room air, and a PaO2 of 12 would have 191 ml of oxygen per litre of blood. It is important to note that only 0.36 ml of this oxygen is dissolved in the blood.

    • This question is part of the following fields:

      • Basic Sciences
      7.5
      Seconds
  • Question 4 - What role does the nucleolus play in eukaryotic cells? ...

    Incorrect

    • What role does the nucleolus play in eukaryotic cells?

      Your Answer: To maintain the shape of the nucleus

      Correct Answer: To transcribe ribosomal RNA and assemble ribosomes

      Explanation:

      The Nucleolus: Structure and Function

      The nucleolus is a non-membrane-bound structure that takes up about a quarter of the nuclear volume. It is composed mainly of proteins and nucleic acids and is responsible for transcribing ribosomal RNA (rRNA) and assembling ribosomes in the cell. Nucleoli are formed in nucleolar organizing regions (NORs), which are also the regions of the genes for three of the four eukaryotic rRNAs.

      During ribosome assembly, ribosomal proteins enter the nucleolus from the cytoplasm and begin to assemble on an rRNA precursor. As the pre-rRNA is cleaved to produce 5.8S, 18S, and 28S rRNAs, additional ribosomal proteins and the 5S rRNA (which is synthesized elsewhere in the nucleus) assemble to form preribosomal subunits. These subunits then exit the nucleolus into the cytoplasm and combine to produce the final 40S and 60S ribosomal subunits.

      Overall, the nucleolus plays a crucial role in protein synthesis by producing the components necessary for ribosome assembly. Its unique structure and function make it an essential component of the cell’s machinery.

    • This question is part of the following fields:

      • Basic Sciences
      5.9
      Seconds
  • Question 5 - A 10-year-old patient presents with recurrent skin cancer and is diagnosed with xeroderma...

    Incorrect

    • A 10-year-old patient presents with recurrent skin cancer and is diagnosed with xeroderma pigmentosum. What is the defective biochemical mechanism in this disease?

      Your Answer: DNA polymerisation

      Correct Answer: DNA excision repair

      Explanation:

      Xeroderma Pigmentosum and DNA Repair

      Deoxyribonucleic acid (DNA) found in the skin cells can absorb ultraviolet (UV) light, which can cause the formation of pyrimidine dimers. These dimers are removed through a process called excision repair, where the damaged DNA is cut out and replaced with new DNA. However, if this process fails, it can lead to mutations in genes that suppress tumors or promote their growth, potentially leading to cancer.

      Xeroderma pigmentosum is a genetic disorder that is inherited in an autosomal recessive pattern. This means that an individual must inherit two copies of the mutated gene, one from each parent, to develop the disorder. Generally, disorders that affect metabolism or DNA replication on a cellular or genetic level are inherited in an autosomal recessive pattern. On the other hand, genetic disorders that affect larger structural components are usually inherited in an autosomal dominant pattern. While there are exceptions to these rules, they can serve as a helpful guide for exam preparation.

    • This question is part of the following fields:

      • Basic Sciences
      10.6
      Seconds
  • Question 6 - The Krebs or TCA cycle is a series of metabolic processes beginning with...

    Correct

    • The Krebs or TCA cycle is a series of metabolic processes beginning with the synthesis of citrate from acetyl-CoA which results in a number of important metabolic products. Where in the cell does this cycle occur?

      Your Answer: Mitochondria

      Explanation:

      Cellular Processes and Organelles

      Metabolic processes in the cell occur in specific locations. Acetyl-CoA production and the Krebs cycle take place in the mitochondrium, while glycolysis occurs in the cytoplasm. The nucleus is the central structure of the cell that contains DNA and is double membrane-bound. The rough endoplasmic reticulum is responsible for packaging and transporting proteins, while the smooth endoplasmic reticulum performs a similar function but lacks ribosomes.

      It is important to understand where these processes occur in the cell to better understand their functions and how they contribute to the overall functioning of the cell. The mitochondrium is responsible for producing energy in the form of ATP, while the cytoplasm is where glucose is broken down during glycolysis. The nucleus is where genetic information is stored and replicated, and the endoplasmic reticulum is involved in protein synthesis and transport.

      In summary, the cell is a complex system with various organelles that perform specific functions. where these processes occur in the cell is crucial to how they contribute to the overall functioning of the cell.

    • This question is part of the following fields:

      • Basic Sciences
      8.4
      Seconds
  • Question 7 - What is the primary function of riboflavin in the B vitamin group? ...

    Incorrect

    • What is the primary function of riboflavin in the B vitamin group?

      Your Answer: Energy production via the Krebs cycle

      Correct Answer: Mopping up free radicals

      Explanation:

      The Role of Riboflavin in the Body

      Riboflavin, also known as vitamin B2, is a B-vitamin that plays a crucial role in the body. One of its functions is to act as an antioxidant, mopping up free radicals that can cause damage to cells. However, if the metabolites formed during this process are not excreted promptly, the free radicals can be generated again. Riboflavin is also involved in the production of blue-light sensitive pigments in the eye, which help establish the circadian rhythm. This function is not related to visual acuity.

      Riboflavin is found in a variety of foods, including milk and offal. Deficiency of this vitamin is rare, but when it does occur, it can cause non-specific effects on the skin and mucous membranes. There is no evidence of clear long-lasting damage from riboflavin deficiency. Overall, riboflavin is an important nutrient that plays a vital role in maintaining good health.

    • This question is part of the following fields:

      • Basic Sciences
      4.4
      Seconds
  • Question 8 - What is the statement of Henry's law? ...

    Incorrect

    • What is the statement of Henry's law?

      Your Answer: The rate of diffusion of a gas is in inverse proportion to its weight

      Correct Answer: The concentration of a gas when dissolved in liquid is proportional to its partial pressure

      Explanation:

      Gas Laws

      Gas laws are a set of scientific principles that describe the behavior of gases under different conditions. One of these laws is Avogadro’s law, which states that equal volumes of gases at a standardized temperature and pressure contain the same number of molecules. Another law is Boyle’s law, which explains that gases expand when the temperature is increased. Charles’ law, on the other hand, states that the pressure of a gas is inversely proportional to its volume at a standardized temperature. Lastly, Graham’s law explains that the rate of diffusion of a gas is in inverse proportion to its weight. The specific gas laws that you need to know may vary depending on your syllabus, but you should be able to recognize and apply them if given the formulae. It is unlikely that you will be expected to know the correct formula.

    • This question is part of the following fields:

      • Basic Sciences
      2.9
      Seconds
  • Question 9 - What significance do linoleic and alpha-linolenic acids hold? ...

    Incorrect

    • What significance do linoleic and alpha-linolenic acids hold?

      Your Answer: They are essential amino acids

      Correct Answer: They are essential fatty acids

      Explanation:

      The Importance of Essential Fatty Acids in the Diet

      Essential fatty acids, such as linoleic and alpha-linolenic acids, are crucial components of a healthy diet. Although they are only required in small amounts, they play several important roles in the body. These fatty acids are necessary for the synthesis of phospholipids, which are essential components of cell membranes. They also help regulate cholesterol transport and synthesis, and serve as precursors for omega-3 fatty acids and arachidonic acid. Additionally, essential fatty acids are important for the synthesis of prostaglandins, leukotrienes, and thromboxanes.

      A lack of adequate essential fatty acids in the diet can have negative consequences, particularly for brain growth in infancy. It can also lead to alopecia, dermatitis, and fatty liver. Therefore, it is important to ensure that the diet includes sources of these essential fatty acids, such as certain types of fish, nuts, and seeds. By doing so, individuals can support their overall health and well-being.

    • This question is part of the following fields:

      • Basic Sciences
      4.4
      Seconds
  • Question 10 - What is a primary function of vitamin A? ...

    Correct

    • What is a primary function of vitamin A?

      Your Answer: Vision

      Explanation:

      Vitamin A: Forms, Sources, and Functions

      Vitamin A is a crucial nutrient that exists in various forms in nature. The primary dietary form of vitamin A is retinol, also known as pre-formed vitamin A, which is stored in animal liver tissue as retinyl esters. The body can also produce its own vitamin A from carotenoids, with beta-carotene being the most common precursor molecule.

      The richest sources of vitamin A include liver and fish liver oils, dark green leafy vegetables, carrots, and mangoes. Vitamin A can also be added to certain foods like cereals and margarines.

      Vitamin A plays several essential roles in the body, including supporting vision by being a component of rhodopsin, a pigment required by the rod cells of the retina. It also contributes to the growth and development of various types of tissue, regulates gene transcription, and aids in the synthesis of hydrophobic glycoproteins and parts of the protein kinase enzyme pathways.

      In summary, the different forms and sources of vitamin A and its vital functions in the body is crucial for maintaining optimal health.

    • This question is part of the following fields:

      • Basic Sciences
      4.4
      Seconds
  • Question 11 - What stage of cellular respiration is responsible for the production of pyruvic acid?...

    Incorrect

    • What stage of cellular respiration is responsible for the production of pyruvic acid?

      Your Answer: Electron transport chain

      Correct Answer: Glycolysis

      Explanation:

      The Versatility of Pyruvic Acid in Cellular Metabolism

      Pyruvic acid is a simple alpha-keto acid that plays a crucial role in several metabolic pathways within the cell. It serves as a central intersection where different pathways converge and diverge. One of the primary ways pyruvic acid is produced is through glycolysis, where glucose is broken down into pyruvic acid. Depending on the cell’s needs, pyruvic acid can be converted back into glucose through gluconeogenesis or used to synthesize fatty acids through the acetyl-CoA pathway. Additionally, pyruvic acid can be used to produce the amino acid alanine.

      Pyruvic acid is also involved in respiration, where it enters the Krebs cycle under aerobic conditions. This cycle produces energy in the form of ATP, which is used by the cell for various functions. Under anaerobic conditions, pyruvic acid can ferment into lactic acid, which is used by some organisms as a source of energy.

      In summary, pyruvic acid is a versatile molecule that plays a critical role in cellular metabolism. Its ability to be converted into different molecules depending on the cell’s needs makes it an essential component of many metabolic pathways.

    • This question is part of the following fields:

      • Basic Sciences
      5.4
      Seconds
  • Question 12 - At what stage of meiosis does the process of homologous recombination occur? ...

    Correct

    • At what stage of meiosis does the process of homologous recombination occur?

      Your Answer: Prophase I

      Explanation:

      Homologous Recombination: A Mechanism for DNA Repair and Genetic Variation

      Homologous recombination is a process that allows for the exchange of nucleotide sequences between two similar or identical DNA molecules. This occurs during meiosis, specifically during the second phase of prophase I, where sister chromatids swap sequences. The primary purpose of homologous recombination is to accurately repair harmful double-strand DNA breaks. This process results in new combinations of DNA sequences that provide genetic variation in daughter cells and, ultimately, the organism’s offspring.

      In prokaryotic organisms such as bacteria and viruses, homologous recombination occurs during horizontal gene transfer. This process involves the exchange of genetic material between different strains and species. Homologous recombination plays a crucial role in the evolution of these organisms by allowing for the acquisition of new traits and adaptations.

      Overall, homologous recombination is a vital mechanism for DNA repair and genetic variation. It ensures the accuracy of DNA replication and contributes to the diversity of life on Earth.

    • This question is part of the following fields:

      • Basic Sciences
      4.1
      Seconds
  • Question 13 - Which of the following would not increase the rate of diffusion of a...

    Incorrect

    • Which of the following would not increase the rate of diffusion of a substance across a lipid membrane such as the cell wall?

      Your Answer: Area of the membrane

      Correct Answer: Thickness of the membrane

      Explanation:

      Diffusion and Fick’s Law

      Diffusion is a natural process that occurs when molecules move from an area of high concentration to an area of low concentration. This process is passive and random, meaning that it does not require any external energy input. Fick’s Law states that diffusion occurs more quickly across a large, permeable, and thin membrane. For example, in lung disease, the thickening of the alveolar epithelial barrier can lead to a poor carbon monoxide transfer coefficient because the thicker membrane slows down the diffusion process. the principles of diffusion and Fick’s Law can help us better understand how molecules move and interact in various biological and chemical processes. By optimizing the conditions for diffusion, we can improve the efficiency of many natural and artificial systems.

    • This question is part of the following fields:

      • Basic Sciences
      6
      Seconds
  • Question 14 - A man in his forties comes in with chest pain resembling a heart...

    Incorrect

    • A man in his forties comes in with chest pain resembling a heart attack and is diagnosed with a myocardial infarction. During his hospitalization, it is discovered that he has familial hypercholesterolemia but his triglyceride levels are normal. What is the underlying biochemical abnormality?

      Your Answer: Defective apolipoprotein E

      Correct Answer: Defective LDL receptors

      Explanation:

      Lipid Metabolism and Transport in the Body

      The breakdown of triglycerides in the small intestine is facilitated by pancreatic lipase. These triglycerides are then transported to the liver and other parts of the body through chylomicrons.

      Very low-density lipoprotein (VLDL) is responsible for carrying triglycerides from the liver to peripheral tissues. When there is an overproduction of VLDL in the liver, it can lead to high levels of triglycerides in the body.

      Pure hypercholesterolaemia is a condition that arises due to a defect in the process of cholesterol uptake into cells. This process relies on apolipoprotein B-100 binding to LDL receptors and facilitating endocytosis. When this process is disrupted, it can lead to high levels of cholesterol in the body.

    • This question is part of the following fields:

      • Basic Sciences
      6.9
      Seconds
  • Question 15 - What are the typical clinical manifestations of a deficiency in vitamin B6 (pyridoxine)?...

    Correct

    • What are the typical clinical manifestations of a deficiency in vitamin B6 (pyridoxine)?

      Your Answer: Sensory neuropathy

      Explanation:

      The Importance of Pyridoxine in the Body

      Pyridoxine is a group of B-vitamins that are crucial in various bodily functions. They act as essential cofactors in many reactions, particularly in the metabolism of amino acids and neurotransmitters. Pyridoxine also plays a role in regulating gene transcription and controlling steroid hormones.

      The body can produce pyridoxine through bacterial flora in the gut, and it is also present in many dietary sources. However, overheating certain foods can destroy pyridoxine, and some medications can alter its metabolism. Pyridoxine is also used therapeutically to prevent neuropathy in the treatment of tuberculosis.

      Deficiency in pyridoxine can lead to sensory neuropathy, skin changes, and damage to mucous membranes. On the other hand, deficiency in vitamin C can cause gingivitis and increased bleeding, while vitamin K deficiency can also lead to bleeding. Sleep disturbance is rarely attributed to vitamin B3 (niacin) deficiency.

      In summary, pyridoxine is a vital nutrient that plays a crucial role in various bodily functions. Its deficiency can lead to various health problems, highlighting the importance of maintaining adequate levels of this vitamin in the body.

    • This question is part of the following fields:

      • Basic Sciences
      8.4
      Seconds
  • Question 16 - What RNA base pairs with adenine when synthesizing a complementary RNA strand from...

    Incorrect

    • What RNA base pairs with adenine when synthesizing a complementary RNA strand from DNA, using RNA polymerase to split the helix at specific points?

      Your Answer: Guanine

      Correct Answer: Uracil

      Explanation:

      Differences between DNA and RNA

      DNA and RNA differ in several ways. The primary sugar in DNA is deoxyribose, while in RNA it is ribose. Additionally, DNA is double stranded, while RNA is single stranded. This single stranded structure with un-paired bases allows for transcription to occur when the DNA bases are freed. Each base has a specific pairing, with guanine always binding to cytosine and adenine always binding to thymine in the DNA strand. During transcription, the same complementary RNA bases assemble with the DNA bases, except for thymine, which is not an RNA base. Instead, uracil serves as the RNA pyrimidine base equivalent of thymine. Finally, lysine is an amino acid coded for by the RNA base triplet AAA, where A represents adenine.

    • This question is part of the following fields:

      • Basic Sciences
      9.2
      Seconds
  • Question 17 - What is the fundamental meaning of carbohydrate? ...

    Incorrect

    • What is the fundamental meaning of carbohydrate?

      Your Answer: A compound containing carbon, hydrogen and oxygen in any proportion.

      Correct Answer: A compound following the formula Cx(H2O)y

      Explanation:

      Carbohydrates: Building Blocks of Energy and Storage

      Carbohydrates are organic compounds made up of carbon, hydrogen, and oxygen, with a general formula of Cx(H2O)y. They can be classified as either aldehydes or ketones and contain multiple hydroxyl groups. Monosaccharides are the simplest form of carbohydrates, consisting of a single unit. They are categorized based on the number of carbon atoms they contain, with trioses having three, pentoses having five, and hexoses having six carbon atoms. These monosaccharides are essential for energy production and building larger carbohydrate structures.

      Disaccharides are formed when two monosaccharides are joined together through a condensation reaction, releasing a water molecule. The most common disaccharides are lactose, maltose, and sucrose. Polysaccharides, on the other hand, are long, branched polymers made up of multiple single units. They serve as convenient storage molecules for energy reserves, such as glycogen in humans and starch in plants.

      In summary, carbohydrates are vital building blocks for energy production and storage in living organisms. Monosaccharides, disaccharides, and polysaccharides all play important roles in maintaining the body’s energy balance and overall health.

    • This question is part of the following fields:

      • Basic Sciences
      8.3
      Seconds
  • Question 18 - As part of your general practice placement, you have been tasked with conducting...

    Incorrect

    • As part of your general practice placement, you have been tasked with conducting an audit on the duration of solid food introduction in the practice population. You review the data for the last six infants born within the practice:
      6 months, 7 months, 8 months, 9 months, 10 months, 11 months.

      What is the variance value for the duration of solid food introduction in the practice population?

      Your Answer: 30.3

      Correct Answer: 74.9

      Explanation:

      Variance and Standard Deviation in Breast Feeding Duration

      Variance is a statistical measure that indicates how spread out a set of data is. In the case of breast feeding duration, variance can help us understand how much the duration varies from the mean. The formula for variance involves squaring the difference between each data point and the mean, then dividing the sum by n-1, where n is the total number of data points. In a sample population, n-1 is a better estimate of variance than n because it accounts for the variability within the sample.

      For example, if the variance of breast feeding duration is 74.9 months, this indicates that the duration is widely distributed from the mean of 17.6 months. A smaller variance, such as 4.5 months, would indicate that the duration varies less and is closer to the mean. The standard deviation, which is the square root of the variance, is also important in the spread of data. In a normal distribution, 95% of observations will fall within two standard deviations of the mean.

      In the case of breast feeding duration, the mean is 17.6 months, indicating that babies are breast fed for an average of 15 and a half months. The median, which is the middle number in the data set, is 15 months, meaning that half of the babies were breast fed for 15 months. variance and standard deviation can help us better understand the distribution of breast feeding duration and other medical measurements.

    • This question is part of the following fields:

      • Basic Sciences
      2.3
      Seconds
  • Question 19 - What is the final product of glycolysis besides ATP? ...

    Incorrect

    • What is the final product of glycolysis besides ATP?

      Your Answer: NADH+

      Correct Answer: Pyruvate

      Explanation:

      Glycolysis: The Energy-Producing Reaction

      Glycolysis is a crucial energy-producing reaction that converts glucose into pyruvate while releasing energy to create ATP and NADH+. It is one of the three major carbohydrate reactions, along with the citric acid cycle and the electron transport chain. The reaction involves ten enzymatic steps that provide entry points to glycolysis, allowing for a variety of starting points. The most common starting point is glucose or glycogen, which produces glucose-6-phosphate.

      Glycolysis occurs in two phases: the preparatory (or investment) phase and the pay-off phase. In the preparatory phase, ATP is consumed to start the reaction, while in the pay-off phase, ATP is produced. Glycolysis can be either aerobic or anaerobic, but it does not require nor consume oxygen.

      Although other molecules are involved in glycolysis at some stage, none of them form its end product. Lactic acid is associated with anaerobic glycolysis. glycolysis is essential for how the body produces energy from carbohydrates.

    • This question is part of the following fields:

      • Basic Sciences
      6.4
      Seconds
  • Question 20 - What is the primary reason for malnutrition? ...

    Correct

    • What is the primary reason for malnutrition?

      Your Answer: Inadequate intake of calories in any form

      Explanation:

      Malnutrition

      Malnutrition refers to a state where the dietary intake is insufficient to maintain a healthy state and stable weight. It can be caused by over- or under-nutrition, but it is commonly used to describe under-nutrition. Malnutrition can be defined as a state of nutrition where a deficiency, excess, or imbalance of energy, protein, and other nutrients causes measurable adverse effects on tissue, function, and clinical outcome. Protein malnutrition is the most severe form of malnutrition, causing significant mortality and clinical effects such as kwashiorkor. Carbohydrate malnutrition is less common as carbohydrate sources are widely grown and cheap. Fat malnutrition rarely results in problems if there is adequate dietary protein and carbohydrate. Deficiencies of fat-soluble vitamins can result in various clinical effects. Body size can give some indication of nutritional status, but many obese patients may have nutritional deficiencies due to their faddy diets.

    • This question is part of the following fields:

      • Basic Sciences
      3.8
      Seconds
  • Question 21 - What is the primary means of transportation for vitamin D in the human...

    Correct

    • What is the primary means of transportation for vitamin D in the human body?

      Your Answer: In blood, bound to the group specific component

      Explanation:

      The Role of UV Light and Vitamin D in Calcium and Phosphate Regulation

      In order for the body to produce Vitamin D3, UV light at a specific wavelength is required to convert cholesterol in the skin. Vitamin D2 and D3 are then transported in the bloodstream bound to the Vitamin-D Binding Protein and undergo further modifications in the liver and kidney to become the active form, 1,25 (OH)2Vitamin D. This active form plays a crucial role in regulating calcium and phosphate concentrations in the body.

      1,25 (OH)2Vitamin D increases calcium absorption in the duodenum and inhibits the secretion and synthesis of PTH, which helps to maintain calcium concentrations. It also increases phosphate absorption in the jejunum and ileum, which is important for maintaining phosphate concentrations. Additionally, 1,25 (OH)2Vitamin D promotes bone turnover by stimulating both osteoblast and osteoclast activity.

      Overall, the production and activation of Vitamin D through UV light and dietary sources is essential for proper calcium and phosphate regulation in the body.

    • This question is part of the following fields:

      • Basic Sciences
      2.6
      Seconds
  • Question 22 - What is a good dietary source of vitamin A? ...

    Incorrect

    • What is a good dietary source of vitamin A?

      Your Answer: Citrus fruit

      Correct Answer: Liver

      Explanation:

      The Importance of Vitamin A in Our Body

      Vitamin A is an essential nutrient that can be found in various sources such as liver, fish liver oils, dark green leafy vegetables, carrots, and mangoes. It can also be added to certain foods like cereals and margarines. This nutrient plays a crucial role in our body as it is required for vision, growth and development of tissues, regulation of gene transcription, and synthesis of hydrophobic glycoproteins and parts of the protein kinase enzyme pathways.

      One of the primary functions of vitamin A is to support our vision. It is a component of rhodopsin, a pigment that is necessary for the rod cells of the retina. Without vitamin A, our eyesight can be compromised, leading to various eye problems. Additionally, vitamin A is also essential for the growth and development of many types of tissues in our body. It helps in maintaining healthy skin, teeth, and bones.

      Moreover, vitamin A is involved in regulating gene transcription, which is the process of converting DNA into RNA. This nutrient also plays a role in the synthesis of hydrophobic glycoproteins and parts of the protein kinase enzyme pathways. These processes are essential for the proper functioning of our body.

      In conclusion, vitamin A is a vital nutrient that our body needs to function correctly. It is essential for our vision, growth and development of tissues, regulation of gene transcription, and synthesis of hydrophobic glycoproteins and parts of the protein kinase enzyme pathways. Therefore, it is crucial to include vitamin A-rich foods in our diet or take supplements if necessary.

    • This question is part of the following fields:

      • Basic Sciences
      11
      Seconds
  • Question 23 - A 50-year-old female patient presents to the vascular clinic for evaluation of varicose...

    Incorrect

    • A 50-year-old female patient presents to the vascular clinic for evaluation of varicose veins. During the assessment, a test is conducted to determine the site of incompetence. The patient is instructed to lie down, and her legs are raised to empty the veins. A constricting band is then placed below the sapheno-femoral junction, and the patient is asked to stand up to observe for varicose vein filling. What is the name of this test?

      Your Answer: Trendelenburg's test

      Correct Answer: Tourniquet test

      Explanation:

      Tests for Varicose Veins and Arterial Insufficiency

      The Trendelenburg and tourniquet tests are both used to evaluate the site of incompetence in varicose veins at the sapheno-femoral junction. During the Trendelenburg test, the examiner applies pressure with their fingers over the junction, while in the tourniquet test, a tourniquet is placed just below the junction. If the veins fill rapidly upon standing, it suggests that the sapheno-femoral junction is not the source of the incompetence.

      Buerger’s test is used to assess the arterial circulation of the lower limb. The lower the angle at which blanching occurs, the more likely there is arterial insufficiency. This test is important in diagnosing peripheral artery disease.

      The ankle-brachial pressure index (ABPI) is another test used to assess arterial insufficiency. Blood pressure cuffs are used to measure the systolic blood pressure in the ankle and arm. The ratio of the two pressures is calculated, and a lower ratio indicates a higher degree of claudication.

      Finally, Perthe’s test is used to assess the patency of the deep femoral vein before varicose vein surgery. This test involves compressing the vein and observing the filling of the superficial veins. If the superficial veins fill quickly, it suggests that the deep femoral vein is patent and can be used for surgery.

      In summary, these tests are important in diagnosing and evaluating varicose veins and arterial insufficiency. They help healthcare professionals determine the best course of treatment for their patients.

    • This question is part of the following fields:

      • Basic Sciences
      2.5
      Seconds
  • Question 24 - A premature baby is born and the anaesthetists are struggling to ventilate the...

    Incorrect

    • A premature baby is born and the anaesthetists are struggling to ventilate the lungs because of insufficient surfactant. How does Laplace's law explain the force pushing inwards on the walls of the alveolus caused by surface tension between two static fluids, such as air and water in the alveolus?

      Your Answer: Proportional to the square root of the radius of the alveolus

      Correct Answer: Inversely proportional to the radius of the alveolus

      Explanation:

      The Relationship between Alveolar Size and Surface Tension in Respiratory Physiology

      In respiratory physiology, the alveolus is often represented as a perfect sphere to apply Laplace’s law. According to this law, there is an inverse relationship between the size of the alveolus and the surface tension. This means that smaller alveoli experience greater force than larger alveoli for a given surface tension, and they will collapse first. This phenomenon explains why, when two balloons are attached together by their ends, the smaller balloon will empty into the bigger balloon.

      In the lungs, this same principle applies to lung units, causing atelectasis and collapse when surfactant is not present. Surfactant is a substance that reduces surface tension, making it easier to expand the alveoli and preventing smaller alveoli from collapsing. Therefore, surfactant plays a crucial role in maintaining the proper functioning of the lungs and preventing respiratory distress. the relationship between alveolar size and surface tension is essential in respiratory physiology and can help in the development of treatments for lung diseases.

    • This question is part of the following fields:

      • Basic Sciences
      3.6
      Seconds
  • Question 25 - The arrangement of amphipathic phospholipids in the mammalian cell membrane, what is it...

    Incorrect

    • The arrangement of amphipathic phospholipids in the mammalian cell membrane, what is it like?

      Your Answer: A lipid bilayer structured within the cell wall

      Correct Answer: A lipid bilayer with hydrophilic heads facing out and hydrophobic tails facing in

      Explanation:

      The Function and Structure of the Mammalian Cell Membrane

      The mammalian cell membrane serves as a protective barrier that separates the cytoplasm from the extracellular environment. It also acts as a filter for molecules that move across it. Unlike plant and prokaryotic cells, mammalian cells do not have a cell wall. The main component of the cell membrane is a bilayer of amphipathic lipids, which have a hydrophilic head and a hydrophobic tail. The phospholipids in the bilayer are oriented with their hydrophilic heads facing outward and their hydrophobic tails facing inward. This arrangement allows for the separation of the watery extracellular environment from the watery intracellular compartment.

      It is important to note that the cell membrane is not a monolayer and the phospholipids are not linked head-to-tail. This is in contrast to DNA, which has a helical chain formation. Overall, the structure and function of the mammalian cell membrane are crucial for maintaining the integrity and proper functioning of the cell.

    • This question is part of the following fields:

      • Basic Sciences
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  • Question 26 - What role does vitamin K play in the body? ...

    Correct

    • What role does vitamin K play in the body?

      Your Answer: Activation of clotting factors II, VII, IX, X

      Explanation:

      The Roles of Vitamin K in the Body

      Vitamin K plays several important roles in the body. One of its main functions is to modify clotting factors II, VII, IX, and X through a process called carboxylation. This modification allows calcium to bind to the factors, which is necessary for them to participate in the clotting pathway. This principle is used in full blood counts to prevent clotting by adding EDTA, which chelates the calcium. Vitamin K also modifies osteocalcin and matrix proteins in bone, as well as nephrocalcin in the kidney, in a similar way.

      In addition to its role in blood clotting and bone health, vitamin K is also important for nervous tissue development and growth. However, vitamin K antagonists such as warfarin are sometimes used as anticoagulants to prevent blood clots. It is important to follow guidelines and instructions carefully when using these medications. Overall, vitamin K plays a crucial role in maintaining the health and function of various systems in the body.

    • This question is part of the following fields:

      • Basic Sciences
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  • Question 27 - What is the term for the process described below in laboratory testing?

    Enzymes...

    Incorrect

    • What is the term for the process described below in laboratory testing?

      Enzymes are immobilised on a solid surface, such as a bead or well, and allowed to come into contact with the sample. After washing, another enzyme is added with a label allowing quantitation of the analyte.

      Your Answer:

      Correct Answer: Enzyme-linked immunosorbent assay

      Explanation:

      ELISA: A Common Immunoassay in Medical Diagnostic Testing

      An enzyme-linked immunosorbent assay (ELISA) is a type of immunoassay that is widely used in medical diagnostic testing. This method uses antibodies to identify and/or quantify the analyte being tested. The ELISA process involves several steps, including coating a plate with the antigen, adding the patient’s sample, washing the plate to remove any unbound material, adding an enzyme-linked antibody, washing the plate again, and adding a substrate to produce a measurable signal.

      Over time, many modifications have been made to the ELISA, making it a versatile tool in the laboratory for measuring various analytes. Some of the substances that can be measured using immunoassays include thyroid hormone, testosterone, oestrogen, troponin, and vitamin D. The ELISA has been around for a long time and is still widely used today due to its accuracy, sensitivity, and specificity.

    • This question is part of the following fields:

      • Basic Sciences
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  • Question 28 - A 65-year-old patient with suspected spinal cord compression has been admitted to the...

    Incorrect

    • A 65-year-old patient with suspected spinal cord compression has been admitted to the neurosurgical team for an urgent MRI of the spine. Which particle's magnetic properties does magnetic resonance imaging rely predominantly upon?

      Your Answer:

      Correct Answer: Hydrogen ion (proton)

      Explanation:

      How MRI Scanners Use Hydrogen Ions to Create Images

      MRI scanners use the magnetic properties of hydrogen ions, also known as protons, to create images of the human body. These protons have nuclear spin, which means they have magnetic vectors that can be aligned in an electromagnet. The scanner bombards the protons with radiofrequency radiation, causing them to release energy when they return to their resting state. This energy release is recorded and used to construct the MRI image.

      While other nuclei, such as carbon 13, also have nuclear spin and could be used in MRI imaging, hydrogen ions are much more abundant in human tissues. This makes them the preferred choice for creating images of the body. The process of aligning the magnetic vectors of the protons and then recording their energy release is repeated many times to create a detailed image of the body’s internal structures.

      Overall, MRI scanners use the magnetic properties of hydrogen ions to create detailed images of the human body. This non-invasive imaging technique has revolutionized medical diagnosis and treatment, allowing doctors to see inside the body without the need for surgery.

    • This question is part of the following fields:

      • Basic Sciences
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  • Question 29 - During which stage of the cell cycle does the replication of DNA occur?...

    Incorrect

    • During which stage of the cell cycle does the replication of DNA occur?

      Your Answer:

      Correct Answer: S phase

      Explanation:

      The Five Phases of the Cell Cycle

      The cell cycle is a complex process that is divided into five main phases, each with its unique cellular events. The first phase is the G0 phase, which is a resting phase where the cell has stopped dividing and is out of the cell cycle. The second phase is the G1 phase, also known as interphase Gap 1, where cells increase in size, and a checkpoint control mechanism prepares the cell for DNA synthesis.

      The third phase is the S phase, where DNA replication occurs. The fourth phase is the G2 phase, also known as Gap 2, which is a gap between DNA synthesis and the onset of mitosis. During this phase, the cell continues to grow until it is ready to enter mitosis. Finally, the fifth phase is the M phase, also known as mitosis, where cell growth stops, and the cell focuses its energy to divide into two daughter cells.

      A checkpoint in the middle of mitosis, known as the metaphase checkpoint, ensures that the cell is prepared to complete division. the five phases of the cell cycle is crucial in how cells divide and grow.

    • This question is part of the following fields:

      • Basic Sciences
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  • Question 30 - Which statement regarding microtubules is accurate in relation to Chédiak-Higashi syndrome? ...

    Incorrect

    • Which statement regarding microtubules is accurate in relation to Chédiak-Higashi syndrome?

      Your Answer:

      Correct Answer: They are arranged in a 9+2 formation in cilia

      Explanation:

      Microtubules and Chédiak-Higashi Syndrome

      Microtubules are made up of alpha and beta tubulin dimers that are arranged in a helix and can be added or removed to change the length. They are found in structures such as flagella, mitotic spindles, and cilia, where they have a 9+2 arrangement. These structures are important for cell movement and division. Chemotherapy agents, such as taxanes, target microtubules and are used in breast cancer treatment.

      Chédiak-Higashi syndrome is a rare inherited immunodeficiency disorder caused by mutations in the LYST gene. This condition is characterized by neutrophil inclusions, albinism, recurrent infections, and peripheral neuropathy. The neutrophil inclusions are thought to be caused by abnormal microtubule function, which affects the immune system’s ability to fight infections. While there is no cure for Chédiak-Higashi syndrome, treatment focuses on managing symptoms and preventing infections.

    • This question is part of the following fields:

      • Basic Sciences
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