pptx, 2.54 MB
pptx, 2.54 MB

This lesson describes how the structure of the mammalian lung is adapted for rapid gaseous exchange. The engaging PowerPoint has been designed to cover point 2.1 (iii) of the Edexcel International A-level Biology specification and focuses on the essential features of the alveolar epithelium as well as the mechanism of ventilation to maintain a steep concentration gradient for the simple diffusion of oxygen and carbon dioxide.

Gas exchange at the alveoli is a topic that was covered at GCSE and considered during the previous lessons in topic 2.1 so this lesson has been written to challenge the recall of that knowledge and to build on it. The main focus of the first half of the lesson is the type of epithelium found lining the alveoli and students will discover that a single layer of flattened cells known as simple, squamous epithelium acts to reduce the diffusion distance.

The following features of the alveolar epithelium are also covered:

  • Surface area
  • Moist lining
  • Production of surfactant

The maintenance of a steep concentration gradient is the role of the respiratory system and the next part of the lesson focuses on the diaphragm and intercostal muscles. As the mechanism of inhalation is a cascade of events, the details of this process are covered in a step by step format using bullet points. At each step, time is taken to discuss the key details which includes an introduction to Boyle’s law that reveals the inverse relationship between volume and pressure. It is crucial that students are able to describe how the actions of the diaphragm, external intercostal muscles and ribcage result in an increased volume of the thoracic cavity and a subsequent decrease in the pressure, which is below the pressure outside of the body. At this point, their recall of the structures of the mammalian gas exchange system is tested, to ensure that they can describe the pathway the air takes on moving into the lungs.

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Edexcel Int. A-level Biology Topic 2: Membranes, Proteins, DNA and Gene expression

Hours and hours of planning have gone into each and every lesson that's included in this bundle to ensure that the students are engaged and motivated whilst the detailed content of topic 2 of the Edexcel International A-level Biology specification is covered. Membranes, proteins, DNA and gene expression represent some of the most important structures, molecules and processes involved in this subject and a deep understanding of their role in living organisms is important for a student's success. The 20 lesson PowerPoints and accompanying resources contain a wide range of activities which cover the following topic 2 specification points: * Know the properties of gas exchange surfaces in living organisms * Understand how the rate of diffusion can be calculated using Fick's Law of Diffusion * Understand how the structure of the mammalian lung is adapted for rapid gas exchange * The structure and properties of cell membranes * The movement of free water molecules by osmosis * The movement across membranes by passive and active transport * The role of channel and carrier proteins in membrane transport * The basic structure of an amino acid * The formation of polypeptides and proteins * The structure of proteins * The mechanism of action and specificity of enzymes * Enzymes are biological catalysts * Intracellular and extracellular enzymes * The basic structure of mononucleotides * The structure of DNA and RNA * The process of DNA replication * The nature of the genetic code * A gene as a sequence of bases on DNA that codes for a sequence of amino acids * The process of transcription and translation * Errors in DNA replication give rise to mutations * Mutations give rise to disorders but many mutations have no observable effect * The meaning of key genetic terms * Understanding the pattern of monohybrid inheritance * Sex linkage on the X chromosome * Understand how the expression of a gene mutation in people with cystic fibrosis impairs the functioning of the gaseous exchange, digestive and reproductive systems * The uses and implications of genetic screening and prenatal testing Due to the detail included in all of these lessons, it is estimated that it will take in excess of 2 months of allocated A-level teaching time to complete the teaching of the bundle If you would like to sample the quality of these lessons, then download the rapid gas exchange, osmosis, DNA & RNA, genetic code, genetic terms and cystic fibrosis lessons as these have been uploaded for free.

£28.00

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