Questions and Answers - BIOL121
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Added on 2021-06-18
Questions and Answers - BIOL121
Added on 2021-06-18
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BIOL121 WORKSHEETDue: 3am Tuesday 15th MaySubmit: via Turnitin link on BIOL121 LEO pageWeighting: 20% final gradeQUESTION 1Which type of immunity is expressed in the following scenarios? Choose between:Non-specific (first line defence)Specific (antibody-mediated) Specific (cell-mediated immunity)(0.5 mark each – total 2 marks)ScenarioType of immunityBacterial septicaemia (bacterial contamination in systemic circulation) Specific (cell-mediated immunity)The pH of hydrochloric acid in the stomach acts to destroy ingested bacteriaNon-specific (first line defence)A liver cell mutates and becomes cancerousSpecific (cell-mediated immunity)A virus multiplies inside the epithelial cells in your throat.Specific (antibody-mediated) QUESTION 2Describe how bone cells respond to the hormones involved in the homeostasis of blood calcium ion concentration. (3 marks)when the blood calcium is low, the parathyroid gland secretes parathyroid hormone which has several effects to various organs like kidneys and bones. In the bones, the parathyroid hormone increases bones breakdown in the bone cells (osteoblasts) to release calcium ions.
QUESTION 3Choose ONE of the below scenarios and highlight this row bold. State which general property of adaptive immunity the scenario illustrates in the second column. Select ONE phrase (from the list below) that BEST describes what is happening at a cellular level to result in this property of adaptive immunity. Write the letter corresponding to this phrase in the third column. An example is included in italics. (1 mark)ScenarioGeneral property of immunity ExplanationEven though your body contains a relatively small number of lymphocytes, your immune system is capable of mounting a response against almost any antigen it encounters.VersatilityAGenerally, after an initial infection, subsequent immune responses to that antigen are faster, stronger and more sustained.You can suffer from ‘the flu’ multiple times throughout your lifetime.Differentiation CYour immune system is capable of distinguishing between antigens on your own cells, and those of an invading pathogen.Possible phrases are listed below. Not all phrases will need to be used and only ONE phrase is required per row. If you record more than one, you will not be awarded any marks for your explanation. AThere are millions of different lymphocyte populations, each of which is sensitive to a different antigen. Lymphocytes proliferate when activated by their specific antigen.BThe immune response ignores self-antigens and targets non-self antigens.CB cells differentiate into T cells to create a long-lived immune response.DEach T and B cell can recognise many antigens and respond to a wide variety of possible threats.EEach T or B cell has receptors that respond to only one antigen and ignores all others.FPhagocytes have a reduced ability to destroy pathogens during subsequent infections.GT cells are versatile because they produce copious quantities of antibodies that can respond to a wide variety of threats.HActivated lymphocytes produce two groups of cells: one group that attacks the invader immediately, and another that remains inactive unless it is exposed to the same antigen at a later date2
QUESTION 4A.Using the patellar reflex as an example, explain the purpose of a neural reflex. (2 marks)The patellar reflex is a stretch reflex which tests the l2,3 and 4 regions of the spinal cord. The neuronal reflex therefore involves the alpha motor neuron which conducts efferent impulses back to the quadriceps femoris of the muscles., leading to a muscle contraction (Brussé et al., 2015). B.What happens to the patellar reflex when someone clasps their hands and squeezes them strongly? Why does this occur? (2 marks)During clapping, the patellar reflex is stricken in the patellar tendon using a reflex hammer bellow the patella. Then the muscle fibres on the hands stretches out to form a signal which travels beck to the spinal cord. QUESTION 5Using the diagram provided as a prompt, outline the four steps involved in the transmission of an electrical impulse from the presynaptic neurone to the post synaptic neurone. (4 marks)StepOutline1Voltage gated calcium ions are activated (Weingart & Rüdisüli, 2017)2Binding of neurotransmitters to postsynaptic end3Changes in electrical voltages of sodium and potassium ions 3
4Production of the electrical impulse to the postsynaptic endQUESTION 6Describe the series of events occurring at a neuromuscular junction required for muscular contraction. (3 marks)At the neuromuscular junction, a chemical synapse is formed when a contact is made between muscle fibres and motor neuron (Tintignac et al., 2015). This junction begins once an action potential reaches at the presynaptic end of a motor neuron. The voltage dependent calcium ion channels are activated allowing calcium ions to enter into the neuron. These ions bind to the synaptic end causing vesicle fusion on the cell membrane. And a release of the neurotransmitter from neurons into synaptic cleft (Rudolf et al., 2016). QUESTION 7Think about how the renin-angiotensin-aldosterone system acts to maintain normal blood pressure. Susan has sustained damage to her adrenal glands. Consequently, her circulating levels of aldosterone are abnormally low. A.Where are the target cells for aldosterone located in the body? (1 mark)Kidneys B.What do you expect the lack of aldosterone to do to Susan’s blood pressure? Explain your answer. (3 marks)Low blood pressure. This is due to lack of reabsorption of sodium, and the excretion of potassium from and into the renal tubes of the kidneys leading to loss blood pressure. 4
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