B2 - Revision Topic 3- Common Systems Name: Lesson Topic B2.25 Fossils and Evolution B2.26 Growth B2.27 Blood B2.28 The Heart B2.29 The Circulatory System B2.30 The Digestive System B2.31 Breaking Down Food B2.32 Villi B2.33 Enzymes Concentration: PCA B2.34 Probiotics and Prebiotics Prior to revision - RAG Quick Check/ Revision? After Revision RAG
Term Key Terms Definition
B2.25 - Fossils and evolution What is a fossil? How are they formed? How does the fossil record suggest that organisms have evolved over time? The fossil record is incomplete and has many gaps. These gaps mean that scientists must interpret how organisms change over time from incomplete data. How might this lead some people to believe in divine intelligence and not evolution? What else may have caused these gaps?
B2.26 - Growth What is growth? How does growth differ in plants and animals? Use the table below to match up the key characteristics: Questions: 1. A balloon gets bigger when you blow it up but this isn t growth. Why not? 2. What is the difference between embryonic and adult stem cells? 3. Why is it relatively easy to grow an entire plant from a single meristem cell but impossible (so far) to grow a new adult animal from a single adult stem cell. animal cell division occurs at meristems - roots and tips only cells lose the ability to differentiate early - except for stem cells most cells never lose the ability to differentiate tend to grow to a maximum size plant often can grow continuously most growth is due to cell enlargement, not dividing (increase in cell size) cell divison occurs all over the body in most tissues growth is due to cell division (increasing the number of cells)
B2.27 - Blood Complete the table to show the main components of blood and their functions. Component Plasma Function Red blood cells White blood cells Platelets Describe 3 specialisations of a red blood: Draw a diagram to show how specific (lymphocytes) and non-specific (phagocytes) defend the body against pathogens.
B2.28 - The Heart Label the diagram of the heart: Colour the oxygenated components of the heart RED and the deoxygenated components BLUE. Describe the flow of blood around the body beginning with the VENA CAVA.
Questions: 1. Why is the muscular wall of the left ventricle thicker than the right ventricle? 2. Why is the heart sometimes called a double pump? 3. What is the function of the valves in the heart?
B2.29 - The Circulatory System Describe the features of the 3 main blood vessels in the body: Arteries Capillaries Veins What is their job? What is the structure of the wall? How does their structure help them do their job?
B2.30 & B2.31- The Digestive System & Breaking down food Label the components of the Digestive system: Describe the passage of food throughout the digestive system. Be sure to include information about the enzymes and how they are used to digest fats, proteins and starch.
Questions: 1. What is the role of the pancreas, liver and gall bladder in the digestive system? 2. What is peristalsis and why is it so important in the digestive system? 3. Describe two roles of bile in the digestive system. 4. What is the optimum ph for pepsin and how does the stomach provide this environment?
B2.32 - Villi Questions: 1. What adaptations does the small intestine have for absorption? 2. What effect does Coeliac disease have on the villi in the intestines? 3. How can this information be used as evidence for the importance of a large surface area in the absorption of digested food? Inside the Small Intestine 1. Digested food passes into blood by diffusion 2. Bigger surface areas = more diffusion 3. Finger-like folds called Villi increase surface area of small intestine 4. Features of a Villus to speed up diffusion 1. Good network of capillaries moving absorbed nutrients 2. Low concentration of food 3. Steep concentration gradient maintained 4. Wall is a single cell layer (shorter distance to diffuse)
B2.34 - Probiotics and Prebiotics Plant Stanol Esters Oily substances in plants Stop the small intestine absorbing cholesterol Lowers blood cholesterol Use in many foods like yogurt and spreads. Probiotics Live bacteria friendly or beneficial Bifidobacteria or Lactobacillus They produce lactic acid in your gut and companies claim they improve health NOT ENOUGH EVIDENCE to support the claims they are effective Prebiotics Substances the body cannot digest They act as food for the beneficial bacteria Oligosaccharides are a common form of prebiotic (contained in tomatoes, onions and asparagus) Also found in specially made dairy foods and sold as capsules Increasing evidence supports their positive effect on health