12Organs are made of tissues. The stomach is an organ that contains: ■ muscular tissue, to churn the contents■ glandular tissue, to produce digestive juices■ epithelial tissue, to cover the outside and the inside of the stomach.
14Examples of plant tissues include: epidermal tissues, which cover the plantmesophyll, which carries out photosynthesisxylem and phloem, which transport substances around the plant
15We know that plants make their own food from sunlight We know that plants make their own food from sunlight. They are the producers in the food chain. This is done in the green parts of the plant, e.g. upper surface of the leaves.FOOD (GLUCOSE)OXYGEN+WATERCARBON DIOXIDE+Made by photosynthesis and stored as starch in leaves, roots, stems, etc.Taken in through holes in the leaves as a gas in airwaste product exhaledTaken in through the roots from soilWith light andchlorophyllStudents to note the equation
20Paraffin lamps have traditionally been used in greenhouses Paraffin lamps have traditionally been used in greenhouses. Their use increases the rate of photosynthesis because as well as the light generated from the lamps, the burning paraffin produces heat and carbon dioxide tooThe use of artificial light allows photosynthesis to continue beyond daylight hours. Bright lights also provide a higher-than-normal light intensity.The use of artificial heating allows photosynthesis to continue at an increased rate.
21Glucose Converted into insoluble starch for storage Used in respirationGlucoseTo produce fats and oils for storageTo produce cellulose for cell wallsTo produce proteinsTo produce proteins, plants also use nitrate ions that are absorbed from the soil.
27Proteins act as:structural components of tissues such as muscleshormonesantibodiescatalystsCatalysts increase the rate of chemical reactions. Biological catalysts are called enzymes. Enzymes are proteins.
28Boardworks GCSE Additional Science: Biology Enzymes Enzymes are protein molecules, and so are made up of long chains of amino acids. Most enzymes contain between 100 and 1,000 amino acids.These long chains are folded to produce a unique 3D shape which enables other molecules to fit into the protein.
29The shape of an enzyme is vital for the enzyme’s function The shape of an enzyme is vital for the enzyme’s function. High temperatures change the shape. Different enzymes work best at different pH values.
31This is what happens at the active site Boardworks GCSE Additional Science: BiologyEnzymesThis is what happens at the active site++↔↔enzymereactant+enzyme-reactant complex↔products
32Boardworks GCSE Additional Science: Biology Enzymes If the temperature and pH changes sufficiently beyond an enzyme’s optimum, the shape of the enzyme irreversibly changes.This affects the shape of the active site and means that the enzyme will no longer work.When this happens the enzyme is denatured.denaturednormalheatpH
33Effect of pH…A change in the pH changes the shape of the protein molecule, the enzyme loses its active site and so can no longer act as a catalyst.
35QUIZ! What are biological catalysts called? What are enzymes made of? What is the place on the enzyme where the reactant molecule binds called?What does it mean when an enzyme is denatured?What two factors can affect enzyme action?
36Some enzymes work outside the body cells. The digestive enzymes are produced by specialised cells in glands and in the lining of the gut. The enzymes then pass out of the cells into the gut where they come into contact with food molecules.They catalyse the breakdown of large INSOLUBLE molecules into smaller SOLUBLE molecules.
37NameWhere it is madeThe nutrient it catalysesWhat it breaks down intoWhere the break down occurs in the bodyAmylaseSalivary glandsPancreasSmall IntestineStarch(carbohydrates)GlucoseMouthProteaseStomachProteinsAmino acidsLipaseLipids (fatsFatty acids and glycerol
38The stomach produces hydrochloric acid to create the optimum conditions for the protease enzymes in the stomach
39Bile neutralises the acid that was added to food in the stomach Bile neutralises the acid that was added to food in the stomach. This provides alkaline conditions in which enzymes in the small intestine work most effectively.
40QUIZ! Name the enzyme that breaks down fats? Name the enzyme that breaks down proteins?Name the enzyme that breaks down carbohydrates?What are fats broken down into?What are proteins broken down into?What are carbohydrates broken down into?Where is amylase made?Where is protease made?Where is lipase made?Where is bile produced?Where is it stored?What does it do?
41ENZYMES IN INDUSTRY From microorganisms More effective at low temperatures than other washing powdersIsomerase – converts glucose into fructose
42In industry, enzymes are used to bring about reactions at normal temperatures and pressures that would otherwise require expensive, energy-demanding equipment.However, most enzymes are denatured at high temperatures and many are costly to produce.
43QUIZ!What type of organisms produce enzymes that are used in industry?What enzymes are found in washing powders?What enzyme converts glucose into fructose?Why is fructose used in slimming foods rather than glucose?
45AEROBIC Respiration is the process that the body uses to release energy from digested food (glucose):energyglucoseoxygencarbondioxidewaterfrom the digestive systemfrom the breathing systemuseful!waste product exhaledHappens in all cells all the time in plants & animals inside mitochondria
46Which cells contain more mitochondria? Why? Muscles, liver and kidneysThey require more energyThey use energy at a higher rate, especially during exerciseThe folded layers produce a large surface area for the chemical reactionsThe large surface area means more enzymes can attach to the substrates to catalyse the reactions
47REASONSRespiration releases energy from the food we eat so body cells can use itBuilds large molecules up from smaller ones to make new cell material (synthesis reactions) – example – sugars and nitrates are built into amino acids which are then used to make proteinsMakes your muscles contract – whether aware of or not – e.g. sleeping – heart beats, breathe, gut churns!On cold days we use energy to keep warm and on hot days use energy to sweat and keep cool – WARM BLOODED
48QUIZ! Write the equation for aerobic respiration Where does respiration occur?Which cells contain more mitochondria?Give two reasons for respiration
50What do these changes mean? Increase the blood flow to the muscles and so increase the supply of glucose and oxygen and increase the rate of removal of carbon dioxide.
51If insufficient oxygen is available during exercise what type of respirationhappens?
52Anaerobic respiration is the incomplete breakdown of glucose and produces lactic acid
53HIGHER LEVEL!As the breakdown of glucose is incomplete, much less energy is released than during aerobic respiration.Anaerobic respiration results in an oxygen debt that has to be repaid in order to oxidise lactic acid to carbon dioxide and water.
54EXTRA!If muscles are subjected to long periods of vigorous activity they become fatigued, i.e. they stop contracting efficiently.One cause of muscle fatigue is the build-up of lactic acid in the muscles. Blood flowing through the muscles removes the lactic acid.
55QUIZ! What does anaerobic mean? What is produced in anaerobic respiration?Why is more energy produced with aerobic than anaerobic respiration?What is the ‘oxygen debt’?What is one cause of muscle fatigue?
57In body cells the chromosomes are normally found in pairs In body cells the chromosomes are normally found in pairs. Body cells divide by mitosis. The chromosomes contain the genetic information
58MITOSIS MEIOSIS Occurs during growth or to replace body cells Produces gametesOccurs in every cell in bodyOccurs only in ovaries/testesCell divides onceCell divides twiceProduces 2 daughter cellsProduces 4 daughter cellsAsexualSexual2 sets of chromosomes (46)One set of chromosomes (23)Produces genetically identical copiesProduces variation
59When a cell divides to form gametes: copies of the genetic information are madethen the cell divides twice to form four gametes, each with a single set of chromosomes.
62QUIZ! How do body cells divide? Where are the chromosomes found? How many daughter cells does mitosis produce?How many daughter cells does meiosis produce?Where does meiosis occur?What does meiosis produce?
63Most types of animal cells differentiate at an early stage whereas many plant cells retain the ability to differentiate throughout life.In mature animals, cell division is mainly restricted to repair and replacement
64STEM CELLSCells from human embryos and adult bone marrow, called stem cells, can be made to differentiate into many different types of cells, e.g. nerve cells.Human stem cells have the ability to develop into any kind of human cell.Treatment with stem cells may be able to help conditions such as paralysis.
65Sexual reproduction gives rise to variation because, when gametes fuse, one of each pair of alleles comes from each parent