Digital Private School MYP 3 Biology PDF

DIGITAL PRIVATE SCHOOL MYP 3 BIOLOGY MS. SARA TAWFIK Unit : How do different chemical environments support life? Global context : Scientific and technical innovation Key concepts : systems Related concepts : Balance – environment Statement of inquiry : If healthy lives...

DIGITAL PRIVATE SCHOOL MYP 3 BIOLOGY MS. SARA TAWFIK Unit : How do different chemical environments support life? Global context : Scientific and technical innovation Key concepts : systems Related concepts : Balance – environment Statement of inquiry : If healthy lives are to be enjoyed by all, we must understand the fine balance of chemical systems both inside our bodies and with our environment.  What should I eat ? Everything that we eat, and drink gets broken down into smaller molecules during the process of digestion then distributed to our cells through blood and lymph by the process of diffusion. The molecules that the cell use to perform different functions are called nutrients. Micronutrients are needed in a small quantities like iron, iodine and vitamin A. Macronutrients are needed in a relatively large quantities like proteins, carbohydrates and fats.  Carbohydrates They are mainly composed of carbon, hydrogen and oxygen They are divided into : - Simple sugars like glucose which produces energy in the form of ATP. - Complex sugars like starch which take longer time to be broken down which means the cell will produce ATP at a slower but more steady rate. Research shows that carbohydrates should make up 45-65% of the caloreies you are consuming daily Calory is the unit of energy.  Fats Fats are also known as lipids which should make up 20-35% of our daily calories Unsaturated fats - Good fats - Usually liquid in room temperature - Doctors recommend them as a source of fats - Ex.: oils from olives, avocado, nuts and salmon Saturated fats - Bad fats - Usually solid in room temperature - Doctors recommend that they make 10% only of your total fats - Ex. : butter, beef, the dark meet of chicken, bacon and processed meat like salami Trans fats - They are potentially harmful to your health - Used to fry fast food like chips, and to make commercially processed foods like cookies, cakes or microwaved popcorn.  Saturated and trans fats raise the level of another type of fat, called cholesterol - Low density cholesterol (LDL cholesterol) : it comes from our body and our food too. It’s necessary for building the cell membrane. However, it may cause narrowing and blockages in blood vessels, which may lead to heart attacks or strokes if happened in an artery that carries blood from heart to the rest of the body. - High density cholesterol (HDL cholesterol) : it’s produced naturally by our cells, it helps prevent the build up of LDL cholesterol in blood vessels and maintain a strong blood flow.  Proteins They are mainly made of carbon, hydrogen, oxygen and nitrogen. They are broken down into amino acids which can be divided into - Essential amino acids : cannot be synthesized by the body. - Nonessential amino acids : they can be produced by the body. - Proteins have main role in building our bodies and muscles. They are also part of enzymes which speed up the metabolic reactions in our body.  Nutrition in living organisms Autotrophs ( auto = does it on its own ) Heterotrophs ( hetero = different ) They can make their own food They get food from different resources to itself Green plants use the solar energy as a source of Mammals as heterotrophic organisms take the energy. They uptake water H2O from the soil, food in a process called ingestion to the carbon dioxide CO2 from the air and produce digestive system, where it’s digested chemically glucose sugar C6H12O6 in a process known as : and physically. photosynthesis Physical ( mechanical ) digestion : the 6CO2 + 6H2O C6H12O6 chewing action to break down food into smaller Photosynthesis happens in the chloroplasts. pieces. Chemical digestion : the effect of enzymes on food to break it down into simple molecules.  Digestive system Digestion : the process of breaking down food into simple nutrients Ingestion : taking of substances Egestion : the passing out of food that has not been digested or absorbed, as faeces, through the anus. Absorption : the movement of small food molecules through the walls of the intestine into the blood Assimilation : the movement of digested food molecules into the cells where they are used Enzymes : specialized proteins that speed up the biochemical reactions.  Structure of the digestive system https://www.youtube.com/watch?v=zr4onA2k_LY Mouth Mechanical digestions happens by the effect of teeth and tongue. Mouth contains saliva ( amylase enzyme ) which breaks down starch into maltose sugar Tongue helps mixing the food with saliva Esophagus : The tongue muscle pushes the food – called a bolus – to the back of your mouth and into the esophagus. Muscle in your esophagus squeeze the food down to the stomach Stomach : The stomach is a muscle-covered bag filled with acids and enzymes. When boules enters the stomach, it stretches and produce the gastric juice which contains : - Pepsin enzyme : breaks down protein into amino acids - Hydrochloric acid : makes the stomach acidic to activate the pepsin enzyme, and kill germs  What’s an acid ? Https://www.Youtube.Com/watch?V=eysnuahztbw Small intestine It’s small in diameter, but 7m long in adults. A thin muscular tube that bends itself back and forth in the lower portion of the abdominal cavity. In small intestine, food is squeezed and mixed with water, mucus, and enzymes, which breaks down food into its main nutrients that it was made of.  Secondary digestive organs : pancreas It produces some enzymes which continue to break down carbohydrates, proteins and begin the process of breaking down fats.  Secondary digestive organs : liver and gall bladder Liver produces bile juice which emulsify fats It also produces that break down toxic substances such as the components of alcohol, cigarettes and drugs Gall bladder stores the bule juice.  In the last section of the small intestine, the nutrients and some other substances from the digested food diffuse through the cells of the small intestine to the blood streamin a process called absorption. During absorption, blood will be distributed to all body parts by diffusion where it will be used for respiration or formation of proteins by the body cells in a process known as assimilation. Large intestine The unabsorbed food, which contains water and indigestible components of food, passes into the large intestine, which is much shorter but much wider that the small intestine. The function of the large intestine is to reabsorb and give ot back to the body. If the food waste moves through the large intestine too quickly, or if the cells of the large intestine are not able to absorb sufficient water, diarrhea occurs, which may lead to dehydration if it’s severe or frequent.  This whole process usually takes between 30 and 40 hours after eating. Our intestines (small and large) contain a wide variety of beneficial bacteria known as probiotics which help us break down food and support our immunity because they compete harmful bacteria that may have not been killed in the stomach. Fermented food like yoghurt, kimchi, and sauerkraut all contain probiotics.  Cellular respiration The process of burning food to release energy. Aerobic respiration Anaerobic respiration Happens in the presence of Oxygen Happens when there is no enough Oxygen The products are water, carbon dioxide and The products are : energy In yeast : ethyl alcohol and carbon dioxide C6H12O6 + 6O2 → 6CO2 + 6H2O In muscles : lactic acid (glucose + oxygen -> carbon dioxide + water)