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GCSE Science – Revision Guidance
Biology
Unit 2: Biology 2 – Revision Guidance
Summary of the Content What I should be able to do resources Reference to past questions that indicate successful understanding and web links for further study. Most human and animal cells have a nucleus, cytoplasm, membrane, mitochondria and ribosomes. Plant and algal cells also have a cell wall and often have chloroplasts and a permanent vacuole. Describe and label diagrams of animal and plant cells. Describe cell structure using a microscope. Explain how to prepare slides of plant and animal cells. Explain how cell organelles are related to their functions. Join the Biology community for more resources at national Stem Centre by registering with http://www.nationalstemcentre.org.uk BBC class clips plant and animal cells video http://www.bbc.co.uk/learningzone/clips/plant
- and-animal-cell-structures/4188.html Puzzles, quizzes and images can be found at www.cellsalive.com Useful information on cell structure can be found at www.biology4kids.com
Reference to past questions that indicate successful understanding and web links for further study. Assess using Powerpoint AQA B2.1 cells Bacterial cells have cytoplasm and a membrane surrounded by a cell wall; genes are not in a distinct nucleus. Yeast cells have a nucleus, cytoplasm and a membrane surrounded by a cell wall. Describe and label diagrams of bacterial and yeast cells. Recognise diagrams of cells as being from an animal, plant, bacterium or yeast. http://www.bbc.co.uk/learningzone/clips/unde rstanding-the-size-of-bacteria/2279.html Cells may be specialised to carry out a particular function. Make observations and describe different types of cells under a microscope. Relate their structure to their function. Explain how specialised cells are adapted for their function. A useful video clip on cells and their functions can be found on the BBC website at www.bbc.co.uk/learningzone/clips by searching for ‘1832’. Look at National Learning Network materials on National Stem Centre website for interactive resources Assess using Powerpoint AQA B2.1 cells Dissolved substances can move into and out of cells by
Reference to past questions that indicate successful understanding and web links for further study. Organs are made of tissues; tissues in stomach. A tissue is a group of cells with similar structure and function; muscular, glandular and epithelial tissues. Multicellular organisms develop systems for exchanging materials; during development cells differentiate to perform different functions. Recognise the main organs in the human body and state their functions. Describe the tissues in the stomach and explain what they do. Explain the terms tissue and organ. Explain why large organisms need different systems to survive. Explain what cell differentiation is. Describe organisation in large organisms. Plant organs include stems, roots and leaves. Examples of plant tissues – epidermal, mesophyll, xylem and phloem. Describe the main organs of a plant and describe their functions. Recognise different tissues in a leaf and describe their functions. Photosynthesis equation. Light energy is absorbed by chlorophyll in chloroplasts and used to convert carbon dioxide and water into glucose, oxygen is a by-product. Glucose may be converted into starch for storage. Explain the word equation for photosynthesis. Investigate how light, carbon dioxide and chlorophyll are needed to make glucose. Explain why plants should be destarched before photosynthesis experiments and describe how this is done. Describe experiments to show that plants produce oxygen in the light. Explain the steps involved in testing a leaf for starch. Explain why glucose is converted to starch for storage. Lots of ideas and info can be found at www- saps.plantsci.cam.ac.uk/pubphoto.htm and www.s-cool.co.uk , iodine solution and microscopes.
Reference to past questions that indicate successful understanding and web links for further study. Factors affecting the rate of photosynthesis – temperature, CO 2 concentration, light intensity. Limiting factors and the rate of photosynthesis. Interpret data showing how factors affect the rate of photosynthesis. Describe factors that affect the rate of photosynthesis. Explain how conditions in greenhouses can be controlled to optimise the growth of plants. Evaluate the benefits of artificially manipulating the environment in which plants are grown. Useful information can be found on the BBC GCSE Bitesize at www.bbc.co.uk/schools/gcsebitesize Further information can be found at www.s- cool.co.uk Tomato plants, pots, compost, fertiliser, sensors and balance. http://www.bbc.co.uk/gardening/design/ http://www.channel4.com/4homes/rooms/out doors Glucose can be stored as starch and used in respiration. Glucose is also used to produce fats and oils for storage, cellulose to strengthen cell walls and proteins. To produce proteins, plants also use nitrate ions that are absorbed from the soil. Recognise ways in which glucose is used by a plant. Describe functions of fats, oils, cellulose, starch and proteins in a plant. Explain how plants obtain nitrate ions and what they are needed for. Interpret data from the results of bicarbonate indicator Video clips on photosynthesis and plant growth can be found on the BBC website at www.bbc.co.uk/learningzone/clips by searching for clips ‘212’ and ‘213’. Indicator: Bicarbonate indicator solution, acid, alkali, straw, boiling tubes, bungs, black paper, Cabomba, small invertebrates, gauze and lamp.
Reference to past questions that indicate successful understanding and web links for further study. act as structural components, hormones, antibodies and catalysts. Catalysts increase the rate of chemical reactions. Biological catalysts are called enzymes; these are proteins. living organisms. Define the terms ‘catalyst’ and ‘enzyme’. The shape of an enzyme is vital for the enzyme’s function. High temperatures change the shape Explain why enzymes are specific in their action. Explain why enzymes are denatured by high temperatures. Enzyme action video http://www.bbc.co.uk/learningzone/clips/enzy mes/13505.html Enzyme simulations can be found at http://mhhe.com/biosci/genbio/virtual_labs/B L_11/BL_11.html An enzyme animation can be found at www.youtube.com by searching for ‘CZD5xs OKres’. Different enzymes work best at different pH values . Describe and explain the effect of different pH values on the activity of different enzymes.
Reference to past questions that indicate successful understanding and web links for further study. Some enzymes work outside body cells, eg digestive enzymes catalyse the breakdown of large molecules into smaller ones in the gut. Amylase is produced in the salivary glands, pancreas and small intestine. It catalyses the breakdown of starch into sugars. Protease enzymes are produced by the stomach, pancreas and small intestine. They catalyse the breakdown of proteins into amino acids. Lipase enzymes are produced by the pancreas and small intestine. They catalyse the breakdown of lipids (fats and oils) into fatty acids and glycerol. The stomach produces hydrochloric acid to provide the right conditions for stomach enzymes to work effectively. The liver produces bile, which is stored in the gall bladder. Bile neutralises the acid added to food in the stomach and provides alkaline conditions in the small intestine for the enzymes there to work effectively. Explain why food molecules need to be digested. Recognise the names of digestive enzymes, and identify the organs which produce them, substrates they act on and products of digestion. Plot a line graph and interpret results of effect of temperature on amylase activity. The digestive system in www.science.jrank.org Microorganisms produce enzymes that pass out of cells. Explain that microorganisms produce enzymes that we use in the
Reference to past questions that indicate successful understanding and web links for further study. Most of the reactions in aerobic respiration take place inside mitochondria. Describe some uses of energy in animals and in plants. Explain why respiration has to occur continually in plant and animal cells. State the site of aerobic respiration and be able to give examples of cells that contain a lot of mitochondria. Describe the test for carbon dioxide. Word equation for aerobic respiration. (^) State that all animals and plants produce carbon dioxide all the time as a by-product of aerobic respiration. Describe the test for carbon dioxide. Demo: Two bell jars connected to two containers of limewater that air is passing through via tubes, first container fitted with thistle funnel containing soda lime, pump to draw air through system, small animal, plant and black paper. During exercise the heart rate, breathing rate and depth of breathing increase. (^) Explain why heart rate and breathing rate increase during exercise. Useful videos Screaming jellybaby http://www.bbc.co.uk/learningzone/clips/aero
Reference to past questions that indicate successful understanding and web links for further study. These changes increase blood flow to muscles and so increase the supply of sugar and oxygen and removal of carbon dioxide. Muscles store glucose as glycogen, which can be converted back to glucose for use during exercise. Interpret data relating to the effects of exercise on the body, eg spirometer tracings. Write equations and explain the conversion between glucose and glycogen in liver and muscle cells. bic-respiration/13518.html Respiration in humans http://www.bbc.co.uk/learningzone/clips/respi ration-in-humans/113.html During exercise, if insufficient oxygen is reaching the muscles they use anaerobic respiration to obtain energy. Anaerobic respiration is the incomplete breakdown of glucose and produces lactic acid. HT only Anaerobic respiration releases less energy than aerobic respiration; it results in an oxygen debt that is repaid in order to oxidise lactic acid to carbon dioxide and water. Muscles can become fatigued and stop contracting efficiently; lactic acid can build up which is removed by the blood. Write the equation for anaerobic respiration in animal cells. Explain the effect of lactic acid build up on muscle activity. HT only Explain why anaerobic respiration is less efficient than aerobic respiration. Define the term oxygen debt. Write the equation for the Breakdown of lactic acid into carbon dioxide and water. Timers, masses Force meters Be able to understand that the build up of lactic acid leads to oxygen debt. Powerpoint B2.6 Aerobic and anaerobic respiration
Reference to past questions that indicate successful understanding and web links for further study. HT only During meiosis copies of the genetic information are made, then the cell divides twice to form four gametes, each with a single set of chromosomes. When gametes join at fertilisation, a single body cell with new pairs of chromosomes is formed. A new individual then develops by this cell repeatedly dividing by mitosis. Explain why sexual reproduction results in variety. HT only Draw diagrams to explain how gametes are formed in meiosis. Compare mitosis and meiosis. Note: Knowledge and understanding of the stages in meiosis are not required. Most 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. Stem cells from human embryos and adult bone marrow can be made to differentiate into many types of cells. Human stem cells can develop into any type of human cell. Treatment with stem cells may be able to help conditions such as paralysis. Identify the sources of stem cells in humans. Describe cell differentiation in plants and animals. Explain the function of stem cells. Explain how stem cells could be used to help treat some medical conditions. Make informed judgements about the social and ethical issues concerning the use of stem cells from embryos in medical Information on stem cells can be found at www.eurostemcell.org and www.stemcells.nih.gov Video clips on embryo stem cells and stem cell research can be found on the BBC website at www.bbc.co.uk/learningzone/clips by searching for clips ‘6581’ and ‘6013’. Useful information can be found at www.christopherreeve.org and www.ukscf.org
Reference to past questions that indicate successful understanding and web links for further study. research and treatments. Chromosomes are made up of large molecules of DNA which has a double helix structure. A gene is a small section of DNA. HT only Each gene codes for a particular combination of amino acids which makes a specific protein. Describe the structure of chromosomes and DNA. Explain that a gene is a small section of DNA. HT only State that each gene codes for a particular sequence of amino acids to make a specific protein. Note: The names of the four bases are not required. Further information on Watson and Crick can be found at www.bbc.co.uk by searching ‘historic figures Watson and Crick’. How to extract DNA from fruits can be found at www.funsci.com/fun3_en/dna/dna.htm A video clip on DNA and the Human Genome Project can be found on the BBC website at www.bbc.co.uk/learningzone/clip by searching for clip ‘6015’. Useful information on the DNA timeline can be found at www.timelineindex.com by searching ‘DNA’.
Summary of the Specification Content What I should be able to do (^) resources Reference to past questions that indicate successful understanding and web links for further study. I need to review and revise this section or present on only one of the chromosomes. A recessive allele controls the development of a characteristic only if the dominant allele is not present. Predict and explain the outcome of crosses using genetic diagrams based on Mendel’s experiments and using unfamiliar information. HT only Define the terms homozygous, heterozygous, phenotype and genotype. Each person, apart from identical twins, has unique DNA. This can be used to identify individuals using DNA fingerprinting. Define the term ‘DNA fingerprinting’.(techniques not required) Identify individuals from their DNA fingerprints. A video clip on DNA finger printing can be found at www.engineering.com by searching ‘DNA fingerprinting’. Crime scene, DNA fingerprints and DNA profile from crime scene. Some disorders are inherited. Polydactyly, having extra fingers or toes, is caused by a Explain what polydactyly is (extra fingers or toes). Draw/interpret genetic diagrams to show how polydactyly is inherited. Past BLY2 exam questions.
Summary of the Specification Content What I should be able to do (^) resources Reference to past questions that indicate successful understanding and web links for further study. I need to review and revise this section or dominant allele. Cystic fibrosis, a disorder of cell membranes, is caused by a recessive allele. Explain what cystic fibrosis is and why it can be inherited from two healthy parents. Draw/interpret genetic diagrams to show how cystic fibrosis is inherited. Embryos can be screened for the alleles that cause genetic disorders. Make informed judgements about the economic, social and ethical issues concerning embryo screening. Evidence for early forms of life comes from fossils. Fossils are the ‘remains’ of organisms from many years ago, which are found in rocks. They can be formed in various ways. Explain what a fossil is. Describe ways in which fossils are formed – from hard parts that do not decay easily; when conditions for decay are absent; when parts are replaced by other materials as they decay; as preserved imprints.
Summary of the Specification Content What I should be able to do (^) resources Reference to past questions that indicate successful understanding and web links for further study. I need to review and revise this section or New species arise as a result of isolation (HT only – genetic variation, natural selection and speciation). Define the term ‘species’. Explain how new species arise using the terms ‘isolation’ Genetic variation Natural selection speciation HT only Include, explain and use the terms ‘genetic variation’, ‘natural selection’ and ‘speciation’
