pptx, 2.25 MB
pptx, 2.25 MB
docx, 16.2 KB
docx, 16.2 KB
docx, 15.57 KB
docx, 15.57 KB

This lesson describes how the loop of Henle acts as a countercurrent multiplier to increase the reabsorption of water. The PowerPoint and accompanying resources are part of the 2nd lesson in a series of 2 lessons which have been designed to cover point 7.20 of the Edexcel International A-level biology specification.

The lesson begins by challenging the students to recognise that the glomerular filtrate entering the loop will only contain water, ions and urea if the kidneys are functioning properly. Time is then taken to look at the structure of the loop of Henle, focusing on the descending and ascending limbs, and their differing permeabilities. Students will be reminded that this part of the nephron is located in the renal medulla, before a step-by-step guide is used to describe how the transfer of ions, particularly sodium ions, from the ascending limb to the descending limb, creates a very negative water potential in this region of the kidney. This allows water to move out of the descending limb to the tissue fluid and then into the capillaries.

The next task has been designed to challenge the students on their knowledge of the numbers associated with biology to reveal the key term, countercurrent. They will learn that the countercurrent flow principle involves fluids flowing in opposite directions past each other and an example in bony fish is used to increase the relevance, before they understand how this multiplier works in the loop to increase water reabsorption.

The next part of the lesson challenges students to consider the bigger picture as they learn that this decreasing water potential in the medulla allows water to be reabsorbed from the filtrate in the collecting duct too.

The remainder of the lesson uses the real-world examples of the hopping mouse and kangaroo rat to check student understanding, and there are also prior knowledge checks to encourage students to make links to relevant content from earlier topics. All answers are embedded into the PowerPoint.

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Topic 7: Respiration, Muscles and the Internal Environment (Edexcel Int. A-level Biology)

This bundle contains 20 lesson PowerPoints which are highly detailed to ensure that the topic 7 content is covered at the depth required for A-level Biology. The lessons have been intricately planned to contain a wide variety of tasks that will engage and motivate the students whilst covering the current material and to make links to other lessons in this topic as well as to the previous 6 topics. The tasks, which include exam-style questions with mark schemes, guided discussion time and quick quiz competitions, cover the following points in the respiration, muscles and the internal environment topic of the Edexcel International A-level Biology specification: * The overall reaction of aerobic respiration * The many steps of respiration are controlled and catalysed by a specific intracellular enzyme * The roles of glycolysis in aerobic and anaerobic respiration * The role of the link reaction and the Krebs cycle in the complete oxidation of glucose * The synthesis of ATP by oxidative phosphorylation * Know the way in which muscles, tendons, the skeleton and ligaments interact in movement * The structure of skeletal muscle fibre * The structural and physiological differences between fast and slow twitch muscle fibres * The contraction of skeletal muscle in terms of the sliding filament theory * The myogenic nature of cardiac muscle * The coordination of the heartbeat * The use of ECGs in the diagnosis of abnormal heart rhythms * The calculation of cardiac output * The control of heart rate and ventilation rate by the cardiovascular control centre and the ventilation centre in the medulle oblongata * The role of adrenaline in the fight or flight response * The principle of negative feedback in maintaining systems within narrow limits * The meaning of homeostasis and the maintenance of a dynamic equilibrium in exercise * The gross and microscopic structure of the mammalian kidney * Selective reabsorption in the proximal tubule * Water reabsorption in the loop of Henle * The control of mammalian plasma concentration * Switching genes on and off by DNA transcription factors and the roles of peptide and steroid hormones Due to the detail included in this lesson bundle, it is estimated that it will take in excess of 2 months of allocated A-level teaching time to cover the content If you would like to sample the quality of the lessons in the bundle, then download the skeletal muscle, coordination of the heartbeat, role of adrenaline and control of mammalian plasma concentration lessons as these have been uploaded for free The negative and positive feedback lesson is also uploaded on TES for free but hasn't been included in this bundle as the size limit has been reached

£31.50

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