Cell Chemistry and Structure Know the elements present in proteins, carbohydrates and lipids. Know that proteins are composed of amino acids linked by peptide bonds to form polypeptides which are then folded into a 3 dimensional shape. Understand how properties of a protein depend on its amino acid content, sequence and shape. Know that proteins can be classed as fibrous or globular and know examples of each class. Understand the principles of chromatography as demonstrated by separation and identification of amino acids in a mixture. Know in simple terms how carbohydrates and lipids are built up from smaller units. Be able to name, on a diagram, the parts of a cell revealed by electron microscopy. Know the fluid mosaic model for membrane structure. Know and understand the properties of the plasma membrane, including active transport. Be able to identify cases of active transport from data on ion concentrations inside and outside cells. Understand the effect of changes in temperature on the plasma membrane. Know the structure and functions of the following organelles: mitochondrion, chloroplast, endoplasmic reticulum, ribosome, lysosome, nuclear membrane, nucleus, golgi body and vesicles, cell wall. Water in cells Understand the principles of diffusion and osmosis as learned at S grade. Understand the terms hypotonic, isotonic and hypertonic. Know and understand the effects of hypertonic, isotonic and hypotonic solutions on plant and animal cells. Nucleic Acids and Protein Synthesis Know the elements present in nucleic acids. Know that DNA consists of deoxyribose, phosphate, and four bases. Know the names of the bases. Know how phosphate, deoxyribose and a base link together to form a nucleotide. Know how nucleotides are linked together to form a chain. Know that two chains of nucleotides pair by weak hydrogen bonding between opposing bases. Know that only A - T and G - C pairings are possible. Know that the two strands are twisted into a double helix. Know that DNA is the material of which genes are made. Know that all cells in an organism contain the same amount of DNA, except gametes, which have half this amount. Know that DNA replication takes place at cell division, and understand why this is necessary. Understand all the events which take place during DNA replication. Know how the structure of RNA differs from that of DNA (ribose, uracil, single strand). Know that two types of RNA exist (mRNA and tRNA). Understand the term ‘semiconservative replication’. Know the events, which take place during the transcription of DNA into mRNA. Know that mRNA moves to a ribosome and becomes attached. Know that tRNA has an important base triplet - the anticodon. Know that each tRNA has a specific amino acid attached. Know the events, which take place when tRNA anticodons pair with mRNA codons at the ribosome, producing a chain of amino acids. Understand the relationship between the amino acid sequence in a protein and the DNA base sequence, which determines it. Understand the term ‘genetic code’. Be able to solve problems involving DNA and RNA base sequences, and amino acid sequences in protein. Cell Defences Know the general structure of a typical virus. Know the sequence of events, which takes place in a cell during attack by a virus. Know first line body defences, which prevent entry of invading organisms to the body. Know how phagocytes attack invading organisms by phagocytosis, and the role of lysosomes in this process. Know that foreign material has antigens, which stimulate an immune response. Know that lymphocytes produce specific antibodies against foreign antigens. Know that antibody and antigen combine at specific binding sites, making the antigen harmless. Understand how the various types of immunity are achieved. Know that the immune system is involved in rejection of transplanted tissues. Know how plants create barriers to invasion (lignin, callose, galls etc.) Know how plants respond to invasion by cyanogenesis and by producing a variety of other toxic chemicals such as tannins and nicotine. Photosynthesis Know the summary equation and conditions required for photosynthesis as learned at S-Grade. Know and understand the procedure for separating photosynthetic pigments by chromatography. Know the names of pigments separated and their positions on the chromatogram. Understand the information in an absorption spectrum. Know what an action spectrum is and how it relates to absorption spectra of photosynthetic pigments. Know that chlorophyll absorbs mainly red and blue light. Know that yellow and green light are reflected and transmitted by chlorophyll. Understand the importance of the secondary pigments xanthophyll and carotene. Know that chlorophyll requires magnesium for its synthesis. Know that photosynthesis consists of a ‘light’ and a ‘dark’ stage. Know that in the light reaction water is split into hydrogen and oxygen and that this is called photolysis. Know that the oxygen from photolysis is released as a waste product. Know that the hydrogen from photolysis combines with the hydrogen carrier molecule NADP. Know that some energy trapped in the light reaction is used to make ATP from ADP and phosphate. Know that the light reactions take place in the grana of the chloroplast. Know that the dark reactions consist of the Calvin Cycle. Understand the purpose of the Calvin Cycle in ‘fixing’ CO2 and producing glucose. Know the names of the cycle intermediates and the number of carbon atoms they contain. Know the point in the cycle at which CO2 enters and combines with RuBP. Know the point at which ATP and NADPH2 from the light reaction enter the cycle. Know that the ATP provides energy for the cycle. Know that the Calvin Cycle takes place in the stroma of the chloroplast. Know that the glucose formed in the cycle may be converted to other carbohydrates e.g. starch and cellulose, and is also needed to make other important molecules (protein, fat, nucleic acid etc.) Know that enzymes catalyse all reactions in the cycle. Understand what is meant by limiting factors in photosynthesis. Be able to identify the limiting factors in graphs of experimental data on photosynthesis. Understand the importance of limiting factors to plants in their normal habitat. Know that leaf mosaic arrangement is an adaptation to cope with light as a limiting factor. Understand what is meant by compensation point. Know that shade plants have low compensation point and understand why this is advantageous to them. Understand how the different pigmentation of shade plants is a useful adaptation. (Unit2) Respiration Know the summary equation for aerobic respiration and understand the purpose of respiration as learned at Standard Grade. Understand the working of respirometers. Know that the breakdown of glucose involves a series of enzyme catalysed reactions. Know that some reactions release energy. Know that the energy releasing reactions are linked to the formation of ATP from ADP and phosphate. Know that ATP is an energy rich compound, which can break down to ADP and phosphate, releasing energy for use in energy requiring processes. Be able to give examples of energy requiring processes driven by ATP. Know that some reactions involve removal of hydrogen from compounds in the pathway. Know that hydrogen combines with NAD, forming NADH2. Know that the first stage in respiration is glycolysis. Know and understand the events taking place in glycolysis. Know that the end products of glycolysis are 2 molecules each of pyruvic acid, NADH2, and ATP. Know that glycolysis takes place in the cytoplasm. Know that in aerobic respiration, pyruvic acid from glycolysis is converted to acetyl Co-A with a loss of CO2 Know that the acetyl group enters the Krebs Cycle by combining with a 4carbon compound to form citric acid Understand the purpose of the Krebs Cycle in breaking down pyruvic acid to CO2, generating NADH2 at various points in the cycle. Know the number of carbon atoms in the Krebs Cycle compounds. Know that CO2 is released at reactions where the carbon number of one of the cycle compounds is reduced. Know that the Krebs Cycle takes place in the central matrix of the mitochondrion. Know that the NADH2 from the Krebs Cycle and glycolysis passes hydrogen to the cytochrome system. Know that at the end of the cytochrome system, hydrogen finally combines with oxygen to form water. Know that as hydrogen is being passed through the cytochrome system, ATP is formed from ADP and phosphate. Know that the cytochrome system is the principal ATP generating stage in respiration. Know that the cytochrome system is located on the folded inner membrane (cristae) of the mitochondrion. Know that aerobic respiration generates 38 molecules of ATP per molecule of glucose (including 2 ATP from glycolysis). Know that both aerobic and anaerobic respiration start with glycolysis. Know that under anaerobic conditions, pyruvic acid is converted to fermentation products. Know that under anaerobic conditions glycolysis is the only source of ATP (2ATP per molecule of glucose). Know that as a result, aerobic respiration yields 19 times more ATP than anaerobic respiration. Know the products of fermentation in yeast (ethanol & CO2), and muscle cells during exercise (lactic acid). Know that formation of these compounds takes place in the cytoplasm.