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Question 1
Correct
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What function does vitamin E serve in the body?
Your Answer: Antioxidant
Explanation:Vitamin E and its Functions
Several substances are classified as vitamin E, with alpha-tocopherol being the most common, accounting for 90% of human vitamin E. Alpha-tocopherol is composed of two carbon rings and a long saturated hydrocarbon chain, making it hydrophobic. It has an aromatic ring with an OH- group attached to it. Other substances with vitamin E activity include other tocopherols and tocotrienols, all of which act as antioxidants. Alpha-tocopherol is particularly important in cell membranes, preventing the peroxidation of unsaturated fatty acids by free radicals. It also has other functions, such as regulating gene transcription, inhibiting clotting formation, reducing proliferation of vascular smooth muscle, and playing a role in immunity.
Despite claims that taking vitamin E can reduce the risk of heart disease, cancer, and enhance sexual performance, there is currently no strong evidence to support these claims.
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This question is part of the following fields:
- Basic Sciences
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Question 2
Correct
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Which statement regarding microtubules is accurate in relation to Chédiak-Higashi syndrome?
Your 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.
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This question is part of the following fields:
- Basic Sciences
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Question 3
Incorrect
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What is the estimated percentage of oxygen in the blood that is attached to haemoglobin?
Your Answer: 80%
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.
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This question is part of the following fields:
- Basic Sciences
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Question 4
Incorrect
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At what stage of eukaryotic mitosis do the centromeres of chromosomes separate?
Your Answer: Prometaphase
Correct Answer: Anaphase
Explanation:Chromosome Division during Anaphase
Chromosomes are joined together in an X shape at the centromere. During anaphase, the centromeres break down and the chromosomes divide into two identical pairs called sister chromatids. These sister chromatids then move to opposite sides of the cell along a network of spindle fibres. When the cell divides during telophase, each daughter cell receives one sister chromatid from the parent cell. This ensures the accurate copying and propagation of genes. The process of chromosome division during anaphase is crucial for the proper distribution of genetic material in cells.
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This question is part of the following fields:
- Basic Sciences
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Question 5
Correct
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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: 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.
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This question is part of the following fields:
- Basic Sciences
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Question 6
Incorrect
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What are the clinical effects that can occur due to acute or chronic over-administration of multivitamins leading to Vitamin A toxicity?
Your Answer: Bone overgrowth with deformity
Correct Answer: Nausea, vomiting and headaches
Explanation:The Importance and Risks of Vitamin A
Vitamin A is an essential nutrient that plays a crucial role in various bodily functions such as growth and development, vision, enzyme signalling pathways, and the maintenance of epithelial membranes. However, excessive intake of vitamin A can lead to toxicity, which can cause several adverse effects. These include raised intracranial pressure resulting in headaches, nausea, vomiting, and visual loss, increased bone resorption leading to osteoporosis and hypercalcaemia, liver damage, hair loss, and skin changes. Moreover, there is a possible increased risk of malignancy, particularly among smokers. Pregnant women are also advised to avoid foods rich in vitamin A, such as liver and fish oils, due to the teratogenicity of vitamin A-derived drugs. Therefore, it is crucial to maintain a balanced intake of vitamin A to avoid the risks associated with its toxicity.
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This question is part of the following fields:
- Basic Sciences
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Question 7
Incorrect
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In which part of the cell are the electron transport chain carriers situated?
Your Answer: Mitochondrial redox compartment
Correct Answer: Mitochondrial cristae
Explanation:The Electron Transport Chain in Mitochondria
The electron transport chain (ETC) is a crucial process in cellular aerobic respiration that occurs in the mitochondrial cristae. These are folded membranes inside the organelle. During respiration, NADH and FADH produced from other parts of the process, such as glycolysis, transfer electrons from electron donors to electron acceptors through redox reactions. This electron transfer is coupled with proton transfer across the mitochondrial membrane, creating an electrochemical proton gradient. This gradient induces the production of ATP, which is used as an energy currency by the cell.
ATP is produced through a mechanism called chemiosmotic phosphorylation. The structure of the mitochondrion is essential for this process to occur. The cristae provide a large surface area for the ETC to take place, and the mitochondrial membrane is impermeable to protons, allowing for the creation of the proton gradient. The inner membrane also contains ATP synthase, the enzyme responsible for producing ATP through chemiosmotic phosphorylation.
In summary, the electron transport chain in mitochondria is a complex process that involves the transfer of electrons and protons across the mitochondrial membrane to create a proton gradient. This gradient is then used to produce ATP through chemiosmotic phosphorylation. The structure of the mitochondrion is crucial for this process to occur efficiently.
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This question is part of the following fields:
- Basic Sciences
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Question 8
Correct
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A couple in their late 20s comes to your clinic seeking advice regarding the possibility of their children inheriting cystic fibrosis. The husband has a confirmed diagnosis of the condition, but the carrier status of the wife is unknown.
What is the likelihood of any of their offspring being affected by cystic fibrosis?Your Answer: 2.50%
Explanation:Cystic Fibrosis Inheritance
Cystic fibrosis (CF) is a genetic disorder that affects the chloride ion channels, leading to the thickening of respiratory and other secretions. It is an autosomal recessive condition, which means that a person must inherit two copies of the defective gene, one from each parent, to develop the disease. The most common defective allele is carried by approximately 1 in 20 people.
If a man with CF has children with a woman who does not carry the recessive gene, then none of their children will be affected by the disease. However, they will all be carriers of the CF gene. On the other hand, if the woman is a carrier of the CF gene, there is a 50% chance that each child will inherit one copy of the defective gene from each parent and be affected by the disease. The remaining 50% of the children will inherit one copy of the defective gene and one normal gene, making them carriers of the CF gene but not affected by the disease.
In summary, the probability of any child being affected by CF is 2.5% if one parent has the defective gene and the other does not. It is important for individuals who are carriers of the CF gene to be aware of their status and seek genetic counseling before planning to have children.
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This question is part of the following fields:
- Basic Sciences
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Question 9
Correct
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What occurs in eukaryotic prometaphase?
Your Answer: The nuclear membrane and the nucleoli disintegrate and kinetochores appear
Explanation:The Significance of Prometaphase in Cell Division
Prometaphase is a crucial phase in cell division that marks the transition from prophase to metaphase. Although it is often considered as a part of these two phases, it has distinct events that make it an individual phase. During prometaphase, the nuclear membrane disintegrates, and the nucleoli are no longer visible. Additionally, each chromosome forms two kinetochores near the centromere, which serve as attachment points for spindle fibers. These fibers connect to the opposite poles of the cell, forming travelling lines that will separate the sister chromatids during anaphase.
Prophase is characterized by chromatin condensation, while DNA and centrosome duplication occur during interphase. Chromosome alignment takes place during metaphase, and the sister chromatids separate during anaphase. Prometaphase, therefore, plays a crucial role in preparing the chromosomes for separation during anaphase. Its distinct events make it an essential phase in cell division, and its proper execution is necessary for successful cell division.
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This question is part of the following fields:
- Basic Sciences
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Question 10
Correct
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What significance do leucine, lysine, and phenylalanine hold?
Your Answer: They are essential amino acids
Explanation:Essential Amino Acids and their Importance in the Diet
There are approximately 20 essential amino acids that are crucial for human health. These amino acids are considered essential because the body cannot produce them on its own and they must be obtained through the diet. While some of these essential amino acids can be used to create other non-essential amino acids, they are still necessary for overall health and wellbeing.
Some examples of essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. However, the amount of these essential amino acids can vary depending on the type of dietary protein consumed. Additionally, cooking or preserving proteins can alter the amino acid composition, making them less effective for the body.
In summary, essential amino acids play a vital role in maintaining human health and must be obtained through the diet. the importance of these amino acids and their sources can help individuals make informed decisions about their dietary choices.
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This question is part of the following fields:
- Basic Sciences
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Question 11
Incorrect
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What are the clinical consequences of a lack of vitamin A?
Your Answer: Bleeding gums
Correct Answer: Dry conjunctiva
Explanation:The Devastating Effects of Vitamin A Deficiency
Vitamin A deficiency is a serious health concern that can lead to a range of devastating effects. One of the most common consequences is blindness, particularly in children. Poor night vision is often an early sign of this deficiency, which can progress to complete blindness if left untreated.
In addition to blindness, vitamin A deficiency can also cause dry conjunctiva, a condition known as conjunctival xerosis. This occurs when the normally moist and fine conjunctiva becomes thickened and dysfunctional, leading to the formation of white plaques known as Bitot’s spots. Corneal ulceration can also occur as a result of this condition.
The respiratory and gastrointestinal epithelia can also be affected by vitamin A deficiency, leading to reduced resistance to infection. This deficiency is a major public health issue in some parts of the world and is the single most common preventable cause of blindness. It is crucial to address this issue through education and access to vitamin A-rich foods and supplements.
Overall, the devastating effects of vitamin A deficiency highlight the importance of proper nutrition and access to essential vitamins and minerals. By addressing this issue, we can help prevent blindness and improve overall health outcomes for individuals and communities around the world.
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This question is part of the following fields:
- Basic Sciences
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Question 12
Incorrect
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A 70-year-old male smoker complains of calf pain.
The GP performs a clinical test by raising the patient's legs and observing for the angle at which there is blanching. After one minute, the legs are lowered over the side of the couch so that they are fully dependent with feet on the floor. Reactive hyperaemia is observed.
Which clinical test does this describe?Your Answer: McMurray's test
Correct Answer: Buerger's test
Explanation:Tests for Assessing Arterial and Venous Circulation, Hip Dysfunction, and Meniscal Tear
Buerger’s test is a method used to evaluate the arterial circulation of the lower limb. The test involves observing the angle at which blanching occurs, with a lower angle indicating a higher likelihood of arterial insufficiency. Additionally, the degree of reactive hyperaemia on dependency of the limb after one minute is another positive sign of arterial insufficiency during the test.
Another test used to assess circulation is the Ankle-Brachial Pressure Index (ABPI), which involves using blood pressure cuffs to determine the degree of claudication. McMurray’s test, on the other hand, is used to evaluate for a meniscal tear within the knee joint.
Perthe’s test is a method used to assess the patency of the deep femoral vein prior to varicose vein surgery. Lastly, Trendelenburg’s test is used to evaluate hip dysfunction. These tests are important in diagnosing and treating various conditions related to circulation and joint function.
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This question is part of the following fields:
- Basic Sciences
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Question 13
Incorrect
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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: Thymine
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.
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This question is part of the following fields:
- Basic Sciences
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Question 14
Correct
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You are evaluating a geriatric patient in the emergency department who has fallen and needs a venous cannula for fluid resuscitation. To ensure maximum flow into the vein, you plan to apply the Hagen-Poiseuille equation to select an appropriate cannula size. Which of the following statements is true according to this law?
Your Answer: Flow will be faster through a shorter cannula
Explanation:Poiseuille’s Equation and Fluid Flow in Cylinders
Poiseuille’s equation is used to describe the flow of non-pulsatile laminar fluids through a cylinder. The equation states that the flow rate is directly proportional to the pressure driving the fluid and the fourth power of the radius. Additionally, it is inversely proportional to the viscosity of the fluid and the length of the tube. This means that a short, wide cannula with pressure on the bag will deliver fluids more rapidly than a long, narrow one.
It is important to note that even small changes in the radius of a tube can greatly affect the flow rate. This is because the fourth power of the radius is used in the equation. Therefore, any changes in the radius will have a significant impact on the flow rate. Poiseuille’s equation is crucial in determining the optimal conditions for fluid delivery in medical settings.
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This question is part of the following fields:
- Basic Sciences
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Question 15
Incorrect
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What is the cause of the symptoms of weakness, dermatitis, diarrhoea and dementia in pellagra?
Your Answer: Deficiency of vitamin B12
Correct Answer: Deficiency of the vitamin niacin
Explanation:Niacin Deficiency and Other Genetic Diseases
Niacin, a vitamin present in two forms – nicotinamide and nicotinic acid, is found in a variety of plant and animal foodstuffs. However, in some cases, the form of the vitamin is not easily absorbed by the human body, leading to deficiency. This deficiency is common in areas where maize is the primary dietary carbohydrate. Additionally, niacin can be produced by the body from the amino acid tryptophan. Diseases that affect the availability of tryptophan, such as Hartnup disease and carcinoid syndrome, can also result in niacin deficiency.
Pellagra is a condition that arises from niacin deficiency. It initially presents with non-specific symptoms such as nausea, fatigue, and reduced appetite, followed by pigmented dermatitis in sun-exposed areas, gastrointestinal disturbance, mood disturbance, and dementia in severe cases.
Apart from niacin deficiency, genetic diseases affecting collagen synthesis, such as Ehlers Danlos, present with symptoms of fragile stretchy skin and joint hypermobility. Genetic diseases affecting haemoglobin, such as sickle cell anaemia, present with symptoms of pain, hepatosplenomegaly, shortness of breath, and anaemia. Deficiencies in B12 and folate can also lead to macrocytic anaemia, paresthesia, and lethargy.
In conclusion, the causes and symptoms of niacin deficiency and other genetic diseases is crucial for early diagnosis and effective treatment. A balanced diet and regular medical check-ups can help prevent and manage these conditions.
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This question is part of the following fields:
- Basic Sciences
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Question 16
Incorrect
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What is the primary reason for malnutrition?
Your Answer: Inadequate intake of multiple vitamins
Correct 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.
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This question is part of the following fields:
- Basic Sciences
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Question 17
Correct
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What are the defining features of an amino acid?
Your Answer: It has the formula H2N - CHR - COOH where R is the variable group
Explanation:The Versatility of Amino Acids and its Applications in Electrophoresis
Amino acids are the building blocks of proteins and are composed of a basic structure of H2N – CHR – COOH, where R represents the variable group that distinguishes one amino acid from another. The simplest amino acid is glycine, where the R group is just H. Amino acids are capable of forming complex and useful molecules due to their dipolar or amphoteric nature, which makes them simultaneously acidic and basic. In solution, they form zwitterions, which can act as either an acid or a base depending on the pH of the solution. This versatility of amino acids is what allows for the process of electrophoresis, which separates proteins based on their charge in a solution. By using solutions of different pH, different proteins can be assessed, making it a useful tool in the diagnosis of bone marrow malignancies like myeloma.
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This question is part of the following fields:
- Basic Sciences
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Question 18
Correct
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A 50-year-old female patient with varicose veins presents to the vascular clinic for evaluation.
During the assessment, a test is conducted to determine the location of incompetence. The patient is instructed to lie down, and the veins are emptied by elevating her legs off the couch. The examiner then identifies the site of the sapheno-femoral junction and applies pressure with their fingers. The patient is then asked to stand up to evaluate vein filling.
What is the name of this test?Your Answer: Trendelenburg's test
Explanation:Assessing Varicose Vein Site of Incompetence
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 site, while in the tourniquet test, a tourniquet is placed just below the junction level.
If the veins fill quickly upon standing, it indicates that the sapheno-femoral junction is not the source of the incompetence. These tests are essential in determining the location of the varicose vein site of incompetence, which is crucial in planning the appropriate treatment. By identifying the site of incompetence, physicians can perform targeted interventions to improve venous function and alleviate symptoms. Therefore, the Trendelenburg and tourniquet tests are valuable tools in the diagnosis and management of varicose veins.
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This question is part of the following fields:
- Basic Sciences
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Question 19
Incorrect
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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.
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This question is part of the following fields:
- Basic Sciences
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Question 20
Correct
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What occurs in eukaryotic prophase?
Your Answer: Chromatin condenses into chromosomes
Explanation:The Stages of Prophase in Eukaryotic Mitosis
Prophase is the first stage of eukaryotic mitosis, except for plant cells which have a preprophase stage. During prophase, the cell’s chromatin, which is made up of DNA and associated proteins, condenses into double rod-shaped structures called chromosomes. This process is facilitated by the condensin protein I and/or II complexes. As the chromosomes form, the nuclear membrane and nucleoli disintegrate and disappear, making the chromatin visible.
Before prophase, the cell’s DNA is replicated during interphase, resulting in identical pairs of chromosomes called chromatids. These chromatids attach to each other at a DNA element called the centromere. DNA and centrosome duplication occur during interphase, while chromosome alignment takes place during metaphase. The nuclear membrane and nucleoli re-form during telophase, and the sister chromatids separate during anaphase.
In summary, prophase is the initial stage of eukaryotic mitosis where chromatin condenses into chromosomes, and the nuclear membrane and nucleoli disappear. Chromosome alignment, DNA and centrosome duplication, and re-formation of the nuclear membrane and nucleoli occur in subsequent stages.
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This question is part of the following fields:
- Basic Sciences
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Question 21
Correct
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A couple in their early 30s come to your clinic seeking advice. The husband has a history of haemophilia B and they are worried about the possibility of passing it on to their children. Can you determine which of their offspring will be affected by the disease?
Your Answer: All daughters will be carriers; no sons will be affected
Explanation:The inheritance of Haemophilia A and B is crucial in identifying individuals who are at risk of developing the condition. Haemophilia A and B are genetic disorders that are inherited in an X-linked recessive manner. Haemophilia A is caused by a deficiency in clotting factor VIII, while haemophilia B is caused by a deficiency in clotting factor IX.
On the other hand, haemophilia C, which is caused by a deficiency in clotting factor XI, is primarily inherited in an autosomal recessive manner. In X-linked recessive conditions like haemophilia B, males are more likely to be affected than females. This is because males only need one abnormal copy of the gene, which is carried on the X chromosome, to be affected.
Females, on the other hand, can be carriers of the condition if they carry one normal and one abnormal copy of the gene. While carriers can have clotting abnormalities, these are usually milder than those seen in affected individuals. Men cannot pass the condition to their sons, but they will pass on the abnormal X chromosome to all their daughters, who will be carriers.
Female carriers can pass on the condition to around half their sons, and half their daughters will be carriers. Females can only be affected if they are the offspring of an affected male and a carrier female. In summary, the inheritance of haemophilia A and B is crucial in identifying individuals who are at risk of developing the condition. It also helps in providing appropriate genetic counseling and management for affected individuals and their families.
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This question is part of the following fields:
- Basic Sciences
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Question 22
Correct
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A 32-year-old snowboarder presents to the Emergency department complaining of pain and swelling around the first metacarpophalangeal joint (MCP joint) following a fall during practice.
Upon examination, there is significant swelling and bruising on the ulnar side of the joint.
What is the most probable injury that the patient has sustained?Your Answer: Ulnar collateral ligament
Explanation:Skier’s Thumb: A Common Injury in Winter Sports
Skier’s thumb, also known as gamekeeper’s thumb, is a common injury that occurs in winter sports. It is caused by damage or rupture of the ulnar collateral ligament, which is located at the base of the thumb. This injury can result in acute swelling and gross instability of the thumb. In severe cases where a complete tear of the ligament is suspected, an MRI may be necessary to confirm the diagnosis, and surgical repair may be required.
Once the acute swelling has subsided, treatment for skier’s thumb typically involves immobilization in a thumb spica. This is the standard therapy for cases of partial rupture.
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This question is part of the following fields:
- Basic Sciences
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Question 23
Incorrect
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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 fourth power 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, causing them to collapse first. This phenomenon is similar to what happens when two balloons of different sizes are attached together, with the smaller balloon emptying into the larger one.
In the lungs, this collapse of smaller alveoli can lead to atelectasis and collapse if 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. this relationship between alveolar size and surface tension is crucial in respiratory physiology, as it helps explain the importance of surfactant in maintaining proper lung function.
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This question is part of the following fields:
- Basic Sciences
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Question 24
Correct
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What is the fundamental meaning of carbohydrate?
Your 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.
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This question is part of the following fields:
- Basic Sciences
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Question 25
Correct
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What is the end result of meiosis in a cell?
Your Answer: 4 haploid cells
Explanation:Meiosis
Meiosis is a crucial process that occurs in the genetic cells of eukaryotic organisms. Its primary purpose is to recombine genes, which results in genetic variation while also ensuring genetic preservation. Although meiosis shares some similarities with mitosis, it is restricted to genetic cells, also known as gametes, of eukaryotic organisms.
During meiosis, a gamete duplicates each of its chromosomes and divides into two diploid cells. These cells then divide into four haploid cells by the end of the second stage of meiosis (telophase II and cytokinesis). These haploid cells are either sperm cells (male) or eggs (female) in mammals. When these haploid cells fuse together, they produce a diploid zygote that contains two copies of parental genes.
In summary, meiosis is a crucial process that ensures genetic variation and preservation in eukaryotic organisms. It involves the duplication and division of genetic cells into haploid cells, which can then fuse together to produce a diploid zygote.
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This question is part of the following fields:
- Basic Sciences
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Question 26
Correct
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During which phase of aerobic respiration is FADH2 generated?
Your Answer: Krebs cycle
Explanation:The Krebs Cycle and the Role of FADH2
The Krebs cycle is a crucial part of aerobic respiration in cells. It involves a series of reactions that convert acetate, derived from carbohydrates, fats, and proteins, into carbon dioxide and energy in the form of ATP. Additionally, the Krebs cycle produces precursors for some amino acids and reducing agents like NADH and FADH2 that are involved in other metabolic pathways.
FAD is a redox cofactor that plays a vital role in the Krebs cycle. It receives two electrons from the sixth reaction of the cycle, where succinate dehydrogenase converts succinate into fumarate by removing two hydrogen atoms and attaching them onto FAD. This process results in FAD gaining two electrons and reducing into FADH2.
FADH2 then donates the electrons to the electron transport chain, which is another part of cellular respiration. This mechanism helps compensate for the relatively low amount of ATP produced by the Krebs cycle (2.5 molecules of ATP per turn) compared to the electron transport chain (26-28 molecules of ATP). Overall, the Krebs cycle and the role of FADH2 are essential for generating energy in cells.
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This question is part of the following fields:
- Basic Sciences
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Question 27
Correct
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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.
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This question is part of the following fields:
- Basic Sciences
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Question 28
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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.
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This question is part of the following fields:
- Basic Sciences
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Question 29
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What stage of cellular respiration is responsible for the production of pyruvic acid?
Your 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.
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This question is part of the following fields:
- Basic Sciences
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Question 30
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What type of molecule does haemoglobin belong to?
Your Answer: Quaternary protein structure
Explanation:The Structure and Functions of Proteins
Proteins are complex molecules that can vary in structure from single amino acids to large, folded molecules. Amino acids are joined together by peptide bonds to form dipeptides and polypeptides. More complex molecules can also have disulphide bonds and ionic bonds. The primary structure of a protein is a simple amino acid chain, while the secondary structure is a specific shape such as a helix or pleated sheet. The tertiary structure is a more globular shape, arranged by ionic, hydrogen, and disulphide bonds, and hydrophobic interactions. The quaternary structure is a complex protein containing several polypeptide chains held together by interactions.
Proteins have multiple roles within the human body, including as hormones, food substrates, enzymes, receptor molecules, muscles, cell membrane constituents, carrier molecules in blood, and determinants of oncotic/osmotic pressures. However, proteins can be easily damaged by denaturation, which is the loss of the specific three-dimensional shape of a molecule. Denaturation can be caused by heat, salts, heavy metals, solvents, detergents, and extremes of pH.
In summary, proteins are essential molecules with a diverse range of structures and functions within the human body. their structure and potential for denaturation is crucial for maintaining their proper function.
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This question is part of the following fields:
- Basic Sciences
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