Topic 2: Cells2.1 Cell theory Assessment statement 2.1.1 Outline the cell theory. 2.1.2 Discuss the evidence for the cell theory. Example Questions Discuss possible exceptions to the cell theory. (4) Skeletal muscle fibres are larger / have many nuclei / are not typical cells; fungal hyphae are (sometimes) not divided up into individual cells; unicellular organisms can be considered acellular; because they are larger than a typical cell / carry out all life functions; some tissues / organs contain large amounts of extracellular material; eg vitreous humour of eye / mineral deposits in bone / xylem in trees / other example; statement of cell theory / all living things / most tissues are composed entirely of true cells; 2.1.3 State that unicellular organisms carry out all the functions of life. 2.1.4 Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles and cells, using the appropriate SI unit. What is the correct order of increasing size for the following biological structures? I. The width of a virus II. The width of a bacterium III. The thickness of a cell surface membrane IV. The diameter of a eukaryotic cell A. I III II IV B. I III IV II C. III I II IV D. III II I IV 2.1.5 Calculate the linear magnification of drawings and the actual size of specimens in images of known magnification. If a red blood cell has a diameter of 8 m and a student shows it with a diameter of 40 mm in a drawing, what is the magnification of the drawing? A. × 0.0002 B. × 0.2 C. ×5 D. × 5000 2.1.6 Explain the importance of the surface area to volume ratio as a factor limiting cell size. Explain the importance of the surface area to volume ratio as a factor limiting cell size. (2) the rate of material / heat exchange / diffusion is proportional to surface area; the rate of metabolism is proportional to mass / volume; as a cell grows, the volume increases faster than the surface area / as a cell grows, surface area to volume ratio decreases; (without cell division) material / heat cannot be exchanged fast enough to meet the needs of the cell; 2.1.7 State that multicellular organisms show emergent properties. 2.1.8 Explain that cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others. Outline the differentiation of cells in a multicellular organism. (4) differentiation is development in different / specific ways; cells carry out specialized functions / become specialized; example of a differentiated cell in a multicellular organism; 1 cells have all genes / could develop in any way; some genes are switched on / expressed but not others; position / hormones / cell to cell signals / chemicals determine how a cell develops; a group of differentiated cells is a tissue; 2.1.9 State that stem cells retain the capacity to divide and have the ability to differentiate along different pathways. 2.1.10 Outline one therapeutic use of stem cells. Outline one therapeutic use of stem cells (6) Award [4 max] for any of the following general statements: stem cells are cells that retain the capacity to divide and have the ability to differentiate along different paths into all types of cells / are pluripotent / totipotent; stem cells are derived from blastocysts / human embryos, left over from IVF / placenta / umbilical cord / some adult tissues; new techniques / technologies rely on replacing diseased / dysfunctional cells with healthy / functioning ones; need to identify desired type of stem cell and grow in culture / special solutions / controlled conditions; develop biochemical solution that will cause cells to differentiate into desired cell type; develop means of implanting / integrating cells into patient’s own tissues so that they function with the body’s natural cells; danger of rejection of cells therefore need to suppress immune system; must make sure new cells do not become overgrown / develop into cancerous tumours; Award [2 max] for a specific example ie: [1] for type of cells and [1] for proposed use: eg retinal cells; replace dead cells in retina to cure presently incurable diseases such as glaucoma and macular degeneration; eg graft new skin cells; to treat serious burn victims; eg nerve tissue; help repair catastrophic spinal injuries / help victims of paralysis regain movement; 2.2 Prokaryotic cells 2.2.1 Assessment statement Example Questions Draw and label a diagram of the ultrastructure of Escherichia coli (E. coli) as an example of a prokaryote. Draw and label a generalized prokaryotic cell as seen under the electron microscope (4) Award [1] for any of the following clearly drawn and correctly labelled. Award [2 max] if two or more eukaryotic structures are given and if a nucleus is included award [0]. cell wall / capsule / slime wall / layer; plasma / cell membrane; mesosome, cytoplasm; ribosomes; nucleoid / naked DNA; 2 4 The rough endoplasmic reticulum (rER) Mitochondria A nuclear membrane A plasmid State that prokaryotic cells divide by binary fission. 2. (4) of a liver cell as an example of an animal cell. rough endoplasmic recticulum: site of synthesis of proteins (to be secreted) / intracellular transport of polypeptides to Golgi Apparatus. B. 2. plasmid.2. State one function of each of the following organelles.2.1 with the functions of each named structure. 2. D. nucleus: controls cell activities / mitosis / replication of DNA / transcription of DNA (to RNA) / directs protein 3 . Award [1] for each structure clearly drawn and correctly labelled.3 Eukaryotic cells Assessment statement Example Questions 2. nucleus-smaller area than cytoplasm. small vesicles near ends of tubules / sacs.3.2. pili and a single circular chromosome are observed. In viewing an electron micrograph of a cell.1 in electron micrographs of E. (5) Lysosome Golgi apparatus Rough endoplasmic recticulum Nucleus Mitochondrion lysosome: hydrolysis / digestion / break down of materials (macromolecules).2. ribosomes both attached to rER and free ribosomes in cytoplasm drawn and labelled. pili. coli. lysosome / nucleolus / nuclear envelope / nuclear pore / plasma membrane.2 Annotate the diagram from 2.2 Annotate the diagram from 2.3.3. What other structure is likely to be present? A. surrounded by double membrane with pores. inner membrane has infoldings. mitochondrion-surrounded by double membrane.3 Identify structures from 2.2. 2. C.1 Draw and label a diagram of the ultrastructure Draw and label a diagram of the ultrastructure of a liver cell. 4 max Award [0] if a plant cell is drawn. ribosomes. rough endoplasmic reticulum-stacked tubules with dots / small circles on outer surfaces. Golgi apparatus-curved stacked tubules. 2. Golgi Apparatus: synthesis / sorting / transporting / secretion of cell products.flagella. size stated 1 to 10 μm.1 with the functions of each named structure. Award [3 max] if a plant cell structure (such as the cell wall) is present. mitochondrion: (aerobic) respiration / generates ATP. mitochondria present. have cholesterol in the cell membrane. no / very few membrane-bound organelles vs. Distinguish between the structure of plant and animal cells.4 Compare prokaryotic and eukaryotic cells.4 Membranes Assessment statement 2. membrane. (3) Award [1]for each of the following pairs. 2.3.4. store starch. have a large central vacuole.3.1 Example Questions Draw and label a diagram to show the structure Draw a labelled diagram of the fluid mosaic model of the plasma of membranes. a double layer of lipid / phospholipid molecules . animal cells do not. Compare prokaryotic and eukaryotic cells in regards to three different features. a peripheral protein . animal cells do not. an integral protein with a pore passing through its entire length / a glycoprotein with the carbohydrate components shown / cholesterol as 4 . naked DNA / no histones vs. 2.1 in electron micrographs of liver cells. flagella lack internal microtubules vs flagella have microtubules (9+2) 2. no mitosis / meiosis vs. have plasmodesomata. Golgi / ER present.with hydrophilic heads and hydrophobic tails.3. linear DNA.3 Identify structures from 2.passing completely through the lipid bilayer.shown on the surface and not penetrating the lipid bilayer. animal cells do not. have plastids / chloroplasts. animal cells store glycogen. no mitochondria vs. plant cells generally have a fixed shape / more regular whereas animal cells are more rounded. (5) Award [1] for each of the following clearly drawn and labelled correctly. (Practice identifying structures from real pictures of cells online or in the presentation) 2.synthesis.3.3. ribosomes larger / 80S. plant cells: have cell walls. no Golgi / no ER vs. animal cells do not. mitosis / meiosis.6 Outline two roles of extracellular components. an integral protein . prokaryotic cells eukaryotic cells nucleoid / no nucleus / nuclear membrane vs. plant cells do not. 2. circular DNA vs. nucleus / nuclear membrane. (6) Award [1] per difference. ribosomes smaller / 70S vs.5 State three differences between plant and animal cells. animal cells: have centrioles. plant cells do not.NA associated with protein / histone. membrane-bound organelles. 5 . 2. Award [5 max] for a suitable diagram that is labeled correctly. hydrophilic / hydrophobic layers restrict entry / exit of substances. A suitable annotated diagram may incorporate all or many of the above points. the molecules are too large or too charged to diffuse directly through the membrane. channels for (passive) transport.4. List the functions of membrane proteins. small polar and non-polar molecules / gases. enzymes. fluidity / flexibility helps membranes to be (functionally) stable.component in bilayer. fluidity is important in breaking and remaking membranes (eg endocytosis / exocytosis). (pumps) for active transport. (4) hormone binding sites. heads face outside the membrane / tails face inside the membrane / hydrophobic interior / hydrophilic exterior of membrane. receptors for neurotransmitters. electron carriers. 4 max 2. tail made from two fatty acids. active transport requiring ATP. phospholipids layers are stabilized by interaction of hydrophilic heads and surrounding water. 2.4 Define diffusion and osmosis. phospholipids allow for membrane fluidity / flexibility. by the formation of vesicles. arrangement in membrane phospholipids form a bilayer. Explain the various methods cells use to transport materials across membranes. protein channels enable facilitated diffusion of molecules down concentration gradient.3 List the functions of membrane proteins. through exocytosis large particles are removed from cells. uses protein pumps. (8) through endocytosis large particles are brought into cells across membranes. head made from glycerol and phosphate. to move materials against concentration gradients.5 Explain passive transport across membranes by simple diffusion and facilitated diffusion. 2. from an area of high concentration to an area of low concentration / down the concentration gradient (until equilibrium is reached). phospholipids with short fatty acids / unsaturated fatty acids are more fluid.4.4. phospholipid structure hydrophobic tail / hydrophilic head. can diffuse directly through the membrane. cell to cell recognition.2 Explain how the hydrophobic and hydrophilic Explain how the structure and properties of phospholipids help to properties of phospholipids help to maintain the maintain the structure of cell membranes (9) structure of cell membranes. phospholipids can move about / move horizontally / “flip flop” to increase fluidity. phospholipids held together by hydrophobic interactions.4. saturated / unsaturated fatty acid (in tail). Golgi apparatus and plasma membrane. Describe how the fluidity of the membrane allows it to change shape. goes against concentration gradient / lower to higher concentration. called pinocytosis when solutions are taken in (vesicles are much smaller). organelle doubling.osmosis is the passive movement of water molecules. Describe the process of active transport. vesicles can be used to transport material around inside cells.5. requires a protein in the cell membrane / pump / carrier protein (reject channel).7 2. across a partially / selectively permeable membrane. proteins are transported in vesicles.4. from the Golgi apparatus to the plasma membrane. including the way in which they form and are reabsorbed.5 Cell division Assessment statement 2. vesicle is made by pinching off a piece of membrane.8 Explain how vesicles are used to transport materials within a cell between the rough endoplasmic reticulum. exocytosis is secretion of material using a vesicle. Example Questions State three activities that occur during part A of the cell cycle. including interphase (G1.4. S. 2.6 Explain the role of protein pumps and ATP in active transport across membranes. (4) uses / requires energy / ATP. 2. infolding of cell membrane. 2. involves a conformational change in the pump / protein / diagram to show this. hydrolysis of ATP / ATP ADP + phosphate.) the mechanism whereby cells take in solids and / or solutions. requires energy / active process. (8) (Annotated diagram illustrating the process may be used to gain some or all the marks. break and re-form during endocytosis and exocytosis. phagocytosis is called feeding in some unicellular organisms.1 Outline the stages in the cell cycle.4. mitosis and cytokinesis. called phagocytosis when solids / organisms are engulfed. from a region of lower solute concentration to a region of higher solute concentration. involves the formation of vesicles. from the rough endoplasmic reticulum to the Golgi apparatus. G2). Explain how vesicles are used in cells. named example of endocytosis or exocytosis. protein synthesis / translation DNA replication / chromosome replication. cell growth / increase in cell volume. fluidity of membrane allows this. Outline the process of endocytosis. may be receptor-mediated (eg HIV). formation of vesicle from plasma membrane allows material to be taken in. fusion of vesicle with plasma membrane allows material to be secreted / passed out. 6 . (3) Any three of the following [1] each. endocytosis / pinocytosis / phagocytosis / phagolysosome is absorption of material using a vesicle. Credit may be given for diagrams clearly illustrating these points. otherwise award [3 max].5. DNA B. tissue repair and asexual reproduction involve mitosis. transcription / mRNA production. during interphase DNA replicates / produces two copies of genetic material.5.6 State that growth. Chiasmata form 2. telophase showing cytokinesis occurring. prophase showing replicated chromosomes.5. 2. DNA replication replication and an increase in the number of C. prophase showing condensed chromatin. (8) identical nuclei.4 Describe the events that occur in the four phases of mitosis (prophase. move by contraction of microtubules. Centromeres split occur. (5) prophase showing spindle fibres. sister chromatids are separated during mitosis to form two genetically identical nuclei. anaphase and telophase). D. anaphase showing chromatids moving to opposite poles.5. chromosomes attach to spindle microtubules at centromeres. Accept first three answers only. chromosomes begin to move towards equator / centre of cell. The four diagrams must have the name of the phase. 7 . Nuclear membrane breaks down mitochondria and/or chloroplasts. during metaphase all chromosomes lined up at equator separately / not in homologous pairs. increase energy stores. in prophase chromosomes shorten / thicken / become visible as double-stranded chromosomes / joined sister chromatids. metaphase showing replicated chromosomes lining up at the equator. at start of anaphase centromeres divide separating sister chromatids. embryonic development. 2. including protein synthesis.2 State that tumours (cancers) are the result of uncontrolled cell division and that these can occur in any organ or tissue.3 State that interphase is an active period in the What is occurring in the cell cycle during interphase? life of a cell when many metabolic reactions A. respiration / glycolysis.5. 2. If correct number of chromosomes is not shown award [4 max]. sister chromatids are two identical DNA molecules held together by centromere. telophase showing nucleus reforming. nuclear envelope / membrane forms around each set of chromosomes. chromosomes condense by supercoiling.5 Explain how mitosis produces two genetically Explain how mitosis produces two genetically identical nuclei. (identical sets of) chromosomes pulled to opposite poles. Draw diagrams to show the four stages of mitosis in an animal cell with four chromosomes. separated sister chromatids known as (single stranded) chromosomes. 8 max Many of these points can be shown by correctly annotated diagrams. 2. The four stages must be included to receive [5]. metaphase.microtubule formation. 3 State one role for each of the elements mentioned in 3. D.1. cohesive and solvent properties of water. Nitrogen D. transparency – allows plants to photosynthesise in water / allows animals to see. nitrogen and sulphur are elements found in living cells. Covalent bonds between hydrogen and oxygen within water molecules 3. Carbon B. (6) Features and their significance may include: surface tension – allows some organisms (eg insects) to move on water’s surface.2 State that a variety of other elements are needed by living organisms. (excellent) thermal properties (high heat of vaporization) – excellent coolant. iron and sodium.1 State that the most frequently occurring chemical elements in living things are carbon. allowing life under the ice. It results in the thermal properties of water.1. Cohesion between water molecules and the container in which the water is boiled D. hydrogen.1.5 Outline the thermal. B.1 Chemical elements and water Assessment statement Example Questions 3. It is a bond within the water molecule. II. including sulfur. calcium. A. II and III only C. It forms part of the structure of ribose. habitat – place for aquatic organisms to live.1. 3. What is one role of the element phosphorus? A.1. It forms part of the structure of amino acids.6 Explain the relationship between the properties of water and its uses in living organisms as a coolant. Hydrogen bonds between water molecules B. Sulphur 3.1. Each feature or property must be related to living organisms in order to receive a mark. C.2. It forms part of the structure of nucleotides. It forms part of the structure of fatty acids. What causes water to have a relatively high boiling point? A. I and III only D. 8 . Which of the following features are correct for hydrogen bonding? I. Describe the significance of water to living organisms. structure – turgor in plant cells / hydrostatic skeleton. I. Carbon.Topic 3 – The Chemistry of Life 3. buoyancy – supports organisms. II and III 3. hydrogen. Hydrogen C. polarity / capillarity / adhesion – helps plants transport water. III. 3. It is involved in the cohesion of water. Hydrogen bonds between hydrogen and oxygen within water molecules C. Which is the least common? A.1. medium for metabolic reactions and transport medium. involved in chemical reactions in organisms. oxygen and nitrogen. ice floats – lakes / oceans do not freeze. I and II only B. (excellent) solvent – capable of dissolving substances for transport in organisms. phosphorus.4 Draw and label a diagram showing the structure of water molecules to show their polarity and hydrogen bond formation. Be able to identify molecules by sight.4 State one function of glucose. Lipids II. I only B. Glycogen C.2. and of fructose.2. 3.2 Identify amino acids. 3. long-term energy storage.2. II and III only C. 3. glucose.7 Compare the use of carbohydrates and lipids in Describe the use of carbohydrates and lipids for energy storage in energy storage.1 Distinguish between organic and inorganic compounds.2. condensation / dehydration synthesis: water produced (when two amino acids joined). lactose and glycogen in animals. sucrose and cellulose in plants. As components of the animal cell wall 3. more energy per gram than carbohydrates. Carbon dioxide A. more soluble in water for easier transport. Amylase D. carbohydrates: stored as glycogen (in liver).5 Outline the role of condensation and hydrolysis in the relationships between monosaccharides. hydrolysis: water needed to break bond. Glycerol 3. between fatty acids.(5) Answers must discuss both carbohydrates and lipids to receive full marks. ribose and fatty acids from diagrams showing their structure. and between amino acids and polypeptides. glycerol and triglycerides. (4) diagram of peptide bond drawn. lipids are insoluble in water less osmotic effect. Ribose B.condensation occurs.2. I and II only D. Which molecule is a monosaccharide? A. I. 9 . animals. disaccharides and polysaccharides. disaccharides and polysaccharides.2. dipeptide amino acids . amino acids dipeptide .6 State three functions of lipids. Outline the role of condensation and hydrolysis in the relationship between amino acids and dipeptides.3 List three examples each of monosaccharides. short-term energy storage. more easily digested than lipids so energy can be released more quickly. II and III 3.hydrolysis occurs.Water III. Which of the following substances are organic? I.3. lipids: stored as fat in animals.2 Carbohydrates. Lipids and Proteins Assessment statement Example Questions 3. As enzymes C. As channels for passive transport B. As energy storage D. What is a role of carbohydrates in animal cells? A.2. If only one nucleotide is drawn.3 Outline how DNA nucleotides are linked together by covalent bonds into a single strand.5 Draw and label a simple diagram of the molecular structure of DNA. B.1 Outline DNA nucleotide structure in terms of sugar (deoxyribose). What is the composition of the backbone of DNA? A.3 DNA Structure Assessment statement Example Questions 3. cytosine.3.4. A polysaccharide Draw a diagram showing the molecular structure of a section of the DNA molecule. Two glucose molecules in a disaccharide 3. sugar shown connected to base. covalent bonding between phosphate and sugar. Which substance is a base that is found in DNA? A. Cytokinin C. a nitrate and one of the bases: adenine. guanine or thymine B. cytosine. A base pair of a DNA molecule C. a phosphate and one of the bases: adenine. followed by 10 . sugar-phosphate backbone shown. 3. Deoxyribose. a phosphate and one of the bases: adenine. base and phosphate. cytosine.3. diagram shows complementary base pairing / A bonded to T. Award previous mark if bases (unlabelled) are shown in the diagram but the complementary base pairing is explained in the annotation.3. guanine or thymine 3. hydrogen bonding between bases shown. arranged in a double helix.4 Explain how a DNA double helix is formed Which of the following are connected by a hydrogen bond? using complementary base pairing and A. Adenosine B. Deoxyribose. Alternating sugar and phosphate molecules B. Explain how unwinding the double helix and separation DNA is replicated within the cells of living organisms. C with G.3.3. guanine or uracil C. Ribose. Two amino acid molecules of a dipeptide D. Ribose. a nitrate and one of the bases: adenine. 3.1 Example Questions Explain DNA replication in terms of Living organisms use DNA as their genetic material. Uracil 3. (8) of the strands by helicase. award [2 max] sugar identified as deoxyribose. Complementary base pairs C. cytosine. (5) two polymers shown.2 State the names of the four bases in DNA. Alternating sugar and base molecules D.3. Guanine D. What are the components of a DNA nucleotide? A.4 DNA Replication Assessment statement 3. The hydrogen and oxygen atoms of a water molecule hydrogen bonds. guanine or thymine D. DNA helicase and polymerase are complementary. each of the DNA molecules formed has one old and one new strand. helix is unwound. ACGUUGCAUGGCA 3. ACGTTGCATGGCA D. UGCAACGUACCGU B. A. DNA polymerase forms the new complementary strands.formation of the new complementary strands by DNA polymerase.2 Explain the significance of complementary What is responsible for the conservation of the base sequence during base pairing in the conservation of the DNA replication? base sequence of DNA. (3) RNA ribose (normally) single stranded DNA deoxyribose. Unpaired bases always attracting their complementary nucleotides. NB Histone proteins are only in eukaryotic DNA not prokaryotic. Both strands are identical to each other. two strands are separated. ACGTTGCATGGCA.5. 11 . be formation of an RNA strand complementary transcribed? to the DNA strand by RNA polymerase. (AUG is the) start codon.3 State that DNA replication is semiconservative. A to T and G to C.3 Describe the genetic code in terms of codons composed of triplets of bases.5. 3.4. complementary base pairing.5. uracil thymine. 3. no double helix helix. DNA polymerase working on one strand at the same time. 3.4. the genetic code is universal. Distinguish between the structure of DNA and RNA. nucleotides added to form new strands.2 Outline DNA transcription in terms of the How would the following DNA sequence. D. A. meaning it is the same in almost all organisms. C.5 Transcription and Translation 3. by breaking hydrogen bonds between bases. each codes for the addition of an amino acid to a growing polypeptide chain. helicase (is the enzyme that unwinds the helix separating the two strands). new strands formed on each of the two single strands. Describe the genetic code. replication is semi-conservative. B. called codons. meaning more than one codon can code for a particular amino acid. 64 different codons. (6) composed of mRNA base triplets. 3. TGCAACGTACCGT C. double stranded .1 Assessment statement Example Questions Compare the structure of RNA and DNA. the genetic code is degenerate. some (nonsense) codons code for the end of translation. mRNA “read” in base triplets / codon. or within the active site. The sequence of amino acids responsible for the structure of an enzyme. altering pH can alter intermolecular interactions within the protein. (5) mRNA is used as a template / guide. The sequence of amino acids responsible for the catalytic activity of enzymes. (8) enzymes have an active site. Outline the process of translation. Outline enzyme-substrate specificity.3. that binds to a specific codon. each codon specifying addition of a particular amino acid to the growing polypeptide.5. chemical properties of substrate and enzyme attract / opposite charges. allows substrates of similar structure to bind with same enzyme.6. enzyme activity. (Remember.5 Explain the process of translation. The specific area responsible for the activity of all proteins. that fits the substrate precisely.6 Enzymes Assessment statement 3. What is an active site? A. shape of the active site and substrate fit / complement each other. pH and Explain the effects of temperature. may interfere with the binding of the substrate with the active site. 3.4 3. causes weakening of bonds in substrate to lower activation energy. 3.6. pH and substrate concentration on substrate concentration on enzyme activity. increase in temperature can increase molecular motion 12 . The part of an enzyme that binds only to the product molecules. up to TWO “quality of construction” marks per essay) Discuss the relationship between one gene and one polypeptide.5. D. changes in the chemical environment of the enzyme can lead to a shape / conformational change in the protein. tRNA has a complementary anti-codon. 3.2 Explain enzyme–substrate specificity. enzymes have an optimum pH. leading to polypeptide formation. C. stop codon causes release of polypeptide / termination. ribosomes bind to mRNA / initiation ribosomes move along mRNA facilitating addition of amino acids / elongation tRNA bring amino acids (to mRNA-ribosome complex). lock and key model. enzyme / active site is not rigid and substrate can induce slight changes in shape. B. leading to a change in the shape of the active site.3 Explain the effects of temperature. induced fit.1 Define enzyme and active site. (5) active site of enzyme binds to specific substrate.6. glucose in the cytoplasm is broken down by glycolysis into pyruvate. milk passed over immobilized lactase / lactase bound to inert substance.leading to disruption of intermolecular interactions. optimal temperature. (5) of lactose-free milk. to release energy for use in the cell? A.7. in cell respiration. 3. after a point.4 Explain that. with no further yield of ATP. during aerobic cell respiration.4 below What is the correct sequence of chemicals produced in the anaerobic respiration pathway? A. aerobic requires oxygen and anaerobic does not utilize oxygen.6.5 Explain the use of lactase in the production Outline one industrial use of lactose. the more substrate. Ethanol → pyruvate → glucose C.2 State that. or ethanol and carbon dioxide. Cytoplasm C. Lactate → pyruvate → ethanol B. Glucose → pyruvate → lactate 3. Chloroplast B. (8) mitochondrion into carbon dioxide and water with Answers must include both similarities and differences to a large yield of ATP. no need to add extra sugar in manufacture of flavoured milk drinks / frozen desserts. 13 . 3. additional substrate will not lead to a greater rate of product formation at this point. 3.acidophilus which has same effect on lactose as in yoghurt. Where in eukaryotic cells is glucose broken into pyruvate. with a small yield of ATP. can add (harmless) bacterium such as L. similarities: both can start with glucose. lactose intolerance high in some human populations / Asian / African / native American and Australian aboriginal populations.3 Explain that. Mitochondrion D. increases chance of enzyme substrate collisions so enzyme activity increases.7. Nucleus 3.7. pyruvate can be converted in the cytoplasm into lactate. Glucose → lactate → pyruvate D. lactase used to produce lactose-free / low-lactose milk.7 Cell respiration Assessment statement Example Questions 3. increase sweetness of milk. lactase breaks down lactose to glucose and galactose. receive full marks. 3.4 Define denaturation.6.1 Define cell respiration. Explain the similarities and differences in anaerobic and aerobic pyruvate can be broken down in the cellular respiration. the more product / more enzymesubstrate complex forms. all active sites are bound to substrate / all active sites occupied.7.7. moulds. See answer for 3. during anaerobic cell respiration. source of lactase is usually yeast / many sources such as bacteria. temperature changes / pH changes can denature the protein. 1. can use other compounds / lipids / amino acids for energy. Examples of specific enzymes: protease / trypsin / pepsin / chymotrypsin / other named protease digest proteins into polypeptides / dipeptides / amino acids / peptides. in preparation for absorption. by hydrolysis of bonds / to form monomers.1. (5) large food molecules must be broken down. occurs in cytoplasm of the cell.both use glycolysis. carbohydrates and lipids in humans. second enzyme example – name: Pancreatic Lipase. Describe the role of enzymes in the process of digestion of proteins. produce a larger amount of ATP (36–38 ATP) / anaerobic produces less ATP (2). 6. first enzyme example – names: amylase. Enzymes must match products. rate of reaction at body temperature too slow. substrate: starch and product: maltose. substrate.2 Explain the need for enzymes in digestion. Award [3 max] if no examples given. both produce pyruvate. both produce ATP / energy (heat). further oxidized to CO2 and water (in Krebs’ cycle). aerobic cellular respiration: pyruvate transported to mitochondria. (6) Award [1] per role.1. one protease and one lipase. substrate: Lipids and product: Glycerol. differences: anaerobic: (fermentation) produces lactic acid in humans. 14 . (both start with glycolysis) aerobic leads to Krebs’ cycle and anaerobicleads to fermentation.1 Explain why digestion of large food molecules is essential. lipase digest lipids into glycerol / fatty acids. products and optimum pH conditions for one amylase. Describe the role of enzymes in digestion with reference to two named examples. such as carbohydrates / proteins. etc.1 Digestion Assessment statement Example Questions 6. (fermentation) produces ethanol and CO2 in yeast. Topic 6: Human health and physiology 6. amylase digest polysaccharides into disaccharides / monosaccharides. recycles NADH (NAD+). carbon dioxide is produced. 6.3 State the source. enzymes increase the rate of breakdown / act as catalysts. (4) blood vessels.2. venule. valves and the route of blood through the heart.1. Draw a labelled diagram showing the structure of the digestive system. liver large. 6. (1) absorption is taking up of a substance by the skin / mucous membranes / digestive tract / cell membranes / layers of cells / the bloodstream. pancreas leaf-shaped. enzymes are specific. Award [1] for any two of the following clearly drawn and correctly labelled.7 Explain how the structure of the villus is related to its role in absorption and transport of the products of digestion.4 Draw and label a diagram of the digestive system. associated associated blood vessels. Draw a diagram of a villus in vertical section.6 Distinguish between absorption and assimilation. 6. attached to small intestine. (5) (Award [1] for each of the following structures clearly drawn and labelled correctly. in u-shaped region of small intestine with small duct connected to small intestine. 6. (4) Award [1] for each structure correctly drawn and labelled. right ventricle. require optimum pH.2 The transport system Assessment statement 6. anus at end of large intestine but narrower in diameter.1. (central) lacteal. microvilli. arteriole. to left of stomach.1. capillary network.1. small intestine and large intestine.speed up / catalyze reactions / increased efficiency. right atrium. 15 . triangular. digestive enzymes carry out hydrolytic processes.5 Outline the function of the stomach.1 Example Questions Draw and label a diagram of the heart Draw a diagram of the heart showing the chambers. Define the term absorption. esophagus attached to both mouth and stomach. valves and showing the four chambers. 6. epithelial layer / lining / epithelium. left atrium.) lymph vessel. stomach j-shaped sac attached to esophagus and u-shaped portion of small intestine. 6. lower the (activation) energy required for digestive reactions to occur. large intestine wider diameter than small intestine. gall bladder small sac drawn on top of liver with tube connected to small intestine at same region as duct from pancreas. occurs at body temperature. semilunar valves. goblet cells. left ventricle. ([3 max] for information on veins) lumen always large in relation to diameter. closed atrio-ventricular valves prevent backflow to the atria. nerve from brain can cause heart rate to slow down. artificial pacemakers can control the heartbeat. (6) of myogenic muscle contraction. fibres / electrical impulses cause chambers to contract. Explain the relationship between the structure and function of arteries. thin wall / more collagen and fewer elastic fibres (than arteries) since pressure low(er). blood is pumped from the atria to the ventricles. lumen small compared to wall thickness to maintain high pressure. pacemaker (SAN) initiates each heartbeat. allows the pressure to be altered (vasoconstriction and vasodilation). blood is pumped out from the ventricles to the arteries. Outline the events that occur within the heart. coordination of heartbeat is under the control of pacemaker. the role of the pacemaker. layers of (smooth) muscle to allow arteries to contract / elastic recoil. 6. outer fibrous coat prevents artery from rupturing under the high pressures.2. nerve from brain can cause heart rate to speed up.atrioventricular valves. 6. 6. (8) ([3 max] for information on arteries) thick wall / elastic fibres to help withstand the high(er) pressure. brain and epinephrine (adrenaline). located in the muscle / walls. capillaries and veins. which cause blood to move around the body. adrenalin (carried by blood) speeds up heart rate.4 Outline the control of the heartbeat in terms Outline the control of the heartbeat. pumping blood.2. valves in aorta and pulmonary artery to prevent back flow into ventricles in diastole. 6. except lumen large near the heart to conduct a large volume of blood. very little muscle since not needed for constriction. (6) blood is collected in the atria. vena cava (inferior / superior). veins and capillaries. pulmonary artery. pulmonary vein.3 Explain the action of the heart in terms of collecting blood. pressure generated by the heart causes blood to move around the body. atria contract followed by ventricular contraction. aorta. nerves. 16 . open semi-lunar valves allow flow from ventricles to arteries. closed semi-lunar valves prevent backflow from the arteries to the ventricles. sends out signal for contraction of heart muscle. 60-80 times a minute (at rest). chordinae tendinae / chords and septum. the medulla of the the heart is myogenic / beats on its own accord.2. opened atrio-ventricular valves allow flow from the atria to the ventricles.2 State that the coronary arteries supply heart muscle with oxygen and nutrients. and opening and closing of valves. relative wall thickness accurately drawn.5 Explain the relationship between the structure and function of arteries.2. lymphocytes and platelets D. (host cell) pathways are not affected by antibiotics. small diameter leads to exchange. hormones.2. State the difference between an antigen and an antibody. Which of the following best describes the composition of human blood? A.3. viruses reproduce using the host cell metabolic pathways. viruses do not have metabolic pathways. (1) 17 . 6. Erythrocytes. Erythrocytes. phagocytes and platelets C. contain macrophages / phagocytes. leucocytes and platelets B. 6. some fenestration / pores to allow rapid diffusion. fatty acids / waxes antimicrobial. Erythrocytes.3. erythrocytes. pathogens.3. ([3 max] for information on capillaries) no muscle / elastic tissue since pressure very low. no valves since pressure very low. bacteria but not against viruses. (4) To receive full marks. 6. antibodies. skin: lower pH / acid to keep bacteria from growing / chemical barrier.5 Distinguish between antigens and antibodies.3 Defence against infectious disease Assessment statement Example Questions 6.3. 6. oxygen. antimicrobial / lysozyme in sweat and saliva (mucous membrane) to keep bacterial growth in check.4 Outline how phagocytic leucocytes ingest pathogens in the blood and in body tissues. 6.2 Explain why antibiotics are effective against Explain why antibiotics are effective against bacteria but not viruses. urea and heat. mucous traps bacteria / sticky / mucus slightly acidic ie vagina. 6. (3) antibiotics block specific metabolic pathways / cell wall production in bacteria. cilia sweep mucous up to be swallowed to kill bacteria. physical barrier to prevent entry / dry skin inhibits bacterial growths. Erythrocytes.2. carbon dioxide.1 Define pathogen. endothelial layer one cell thick to allow permeability / diffusion of chemicals / tissue fluid.7 State that the following are transported by the blood: nutrients.3. responses must have two answers for each.6 State that blood is composed of plasma.3 Outline the role of skin and mucous Describe how human skin and mucous membranes act as barriers to membranes in defence against pathogens. bacteria on skin / mucous membranes prevent other bacteria from growing. antigens and platelets 6.valves to prevent back flow between pulses. leucocytes (phagocytes and lymphocytes) and platelets. early death reduces number of adults / reduces workforce / reduces family income. Responses must include reference to cause. blood transfusions. use of dirty needles. including The structure of the DNA double helix was described by Watson and the antiparallel strands. many orphaned children. transmission and social implications of AIDS.6 Explain antibody production. (3) antigen causes an immune response to produce antibodies specific for that antigen. breast milk / saliva and other body fluids. antibodies produced in B-lymphocytes. 6. drug treatment expensive. can be transmitted from man to woman / man to man contact / woman to man / mother to fetus. retrovirus / RNA to DNA. (8) subunits are nucleotides. together. antigen is a substance / molecule that causes antibody formation.3. carried in blood.Must have both for [1]. greater chance for opportunistic infections. transmission and social Explain the cause. description / diagram showing base linked to deoxyribose C1 and phosphate to C5. one base.1 DNA Structure Assessment statement 7. 3’–5’ linkages and Crick in 1953. 6. reduces promiscuity / encourages use of condoms. enters T-helper cells.3. one deoxyribose and one phosphate in each nucleotide.7 Outline the effects of HIV on the immune system. hydrogen bonding between purines and including its subunits and the way in which they are bonded pyrimidines. impact / costs on health systems of treating people. antibody is a (globular) protein / molecule that recognizes an antigen. B-lymphocytes produced in bone marrow.1 Example Questions Describe the structure of DNA. antigen presenting cell / helper T cell present antigen to B cell. Explain antibody production. Explain the structure of the DNA double helix. transmission and social implications to receive full marks.3. social stigma / discrimination. 6. immune system becomes disabled / weakened.8 Discuss the cause. (8) implications of AIDS. 18 . sexually transmitted.1. Topic 7: Nucleic Acids and Proteins 7. problems obtaining employment / life insurance. human immunodeficiency virus / HIV / HIV 1 and HIV 2. DNA polymerase / DNA polymerase III.2. 19 . (6) Award [1] for any two of the following up to [2 max].four different bases – adenine.1.2 Outline the structure of nucleosomes. helicase: splits / breaks hydrogen bonds / uncoils DNA / unwinds DNA. State a role for each of four different named enzymes in DNA replication. including the role of enzymes (helicase. base to base. 7. Okazaki fragments and deoxynucleoside triphosphates. A chain of ribosomes D. D. (RNA) primase: synthesizes a short RNA primer (which is later removed) on DNA. Accept any of the points above if clearly explained in a diagram 7. helicase. 7.2. RNA primase. DNA polymerase I. (DNA) polymerase III: adds nucleotides (in 5' to 3' direction) / proofreads DNA.4 Distinguish between unique or single-copy genes and highly repetitive sequences in nuclear DNA. The 3 B. covalent / phosphodiester bonds. The material within the nuclear membrane What is an intron? 5 A. (DNA) ligase: joins Okazaki fragments / fragments on lagging strand / makes sugar-phosphate bonds between fragments. two strands (of nucleotides) linked together.1. C.2 Explain the process of DNA replication in prokaryotes.3 State that DNA replication is initiated at many points in eukaryotic chromosomes.5 State that eukaryotic genes can contain exons and introns. The protein core of a chromosome B. cytosine. hydrogen bonds between bases. A to T and G to C. DNA polymerase. antiparallel strands. 7. RNA primase and DNA ligase). Histone proteins and DNA C.1. (DNA) polymerase I: replaces RNA primer with DNA. double helix drawn or described. 7. guanine and thymine. Award [1] for one function for each of the named enzymes.1 State that DNA replication occurs in a direction. (DNA) ligase.1.2.2 DNA Replication Assessment statement Example Questions 7. nucleotides linked up with sugar-phosphate bonds. The 5 3 strand of a DNA double helix A section of mRNA removed before translation A tRNA with a start anticodon strand of a DNA double helix 7. 7.3 State that nucleosomes help to supercoil chromosomes and help to regulate transcription. What is a nucleosome? A. tRNA needed for translation but not transcription. DNA. DNA is transcribed and mRNA is translated. Any two of the following: A / C / G / U.1 Assessment statement Example Questions Explain that each tRNA molecule is recognized by a tRNA-activating enzyme that binds a specific amino acid to the tRNA. RNA primers B. nucleoside both in 5' to 3' direction. RNA polymerase for transcription and ribosomes for translation / ribosomes in translation only.3.4 State that eukaryotic RNA needs the removal What is removed to form mature eukaryotic mRNA? of introns to form mature mRNA. Outline the structure of tRNA.3 Transcription Assessment statement Example Questions 7. but not to the antisense strand.3 Explain the process of transcription in Compare DNA transcription with translation. tRNA has a position / end / site attaching an amino acid. transcription factors. 7. nucleoside / ribonucleoside triphosphates.3. transcription produces RNA and translation produces polypeptides / protein.3. C. Exons C. B. transcription in the nucleus (of eukaryotes) and translation in the cytoplasm / at ER. RNA polymerases D.4 Translation 7. Nucleotides are linked to the antisense strand by hydrogen bonding during transcription.3. DNA? A. 20 . 7.1 State that transcription is carried out in a direction. Introns 7. The antisense strand has the same base sequence as mRNA but the sense strand does not. but not to the sense strand. but the antisense strand does not. A. 7. The sense strand has the same base sequence as tRNA. RNA polymerase.4.7. using ATP for energy. Nucleotides are linked to the sense strand by hydrogen bonding during transcription. (5) tRNA is composed of one chain of (RNA) nucleotides.2 Distinguish between the sense and antisense What is a difference between the sense and antisense strands of strands of DNA.) at the 3' terminal / consisting of CCA / ACC. including the role of the promoter region. D. RNA polymerase. apart from mRNA. triphosphates and the terminator. (ribose) nucleotides / ribonucleotides / RNA nucleotides. Ex# 2 List three of the other molecules. required for transcription. (4) prokaryotes. The process of translation involves the use of transfer RNA (tRNA) and amino acids. both require ATP. (Reject tRNA contains an amino acid. 7 State that free ribosomes synthesize proteins for use primarily within the cell.3 State that translation consists of initiation. indicating the significance of each level.4.5 Proteins Assessment statement 7.1 Explain the four levels of protein structure. (activated) tRNA has an anticodon and the corresponding amino acid attached. including the types of bonding within each and the significance of each level. mRNA translated in a 5' to 3' direction. Example Questions Outline the first three levels of protein structure. Accept any of the points above if clearly explained using a suitably labelled diagram. (1) free ribosomes synthesize proteins for use within the cell / cytoplasm and attached ribosomes produce proteins for export / use within lysosomes / membranes 7. including Explain the process of translation. 7.6 Explain the process of translation. second tRNA binds to ribosome. polysomes. first / initiator tRNA binds to start codon / to small subunit of ribosome. 7. binding of ribosome to mRNA. including protein and RNA composition. 7.tRNA has an anticodon.4. amino acid / polypeptide on first tRNA is transferred / bonded to amino acid on second tRNA.5. start codons and consists of initiation. anticodon of three bases which are not base paired / single stranded / forming part of a loop. 7. AUG is the start codon.4. requires GTP. peptide bonds between amino acids / peptidyl transferase. elongation. translocation and termination. and that bound ribosomes synthesize proteins primarily for secretion or for lysosomes.4 State that translation occurs in a direction. small sub-unit then large. movement of ribosome / small subunit of ribosome down the mRNA. (9) ribosomes. reach a stop codon / termination.5 Draw and label a diagram showing the structure of a peptide bond between two amino acids. tRNA has (three) loops (sometimes with an extra small loop).4. 7. State one difference between the proteins produced by free ribosomes and those produced by ribosomes attached to the endoplasmic reticulum. tRNA activating enzymes link correct amino acid to each tRNA. tRNA has a distinctive three dimensional / clover leaf shape.4.4. large subunit moves down mRNA after a second tRNA binds. three tRNA binding sites and mRNA binding sites. stop codons. loss of tRNA and new tRNA binds. (5) 21 . elongation and termination. tRNA has double stranded sections formed by base pairing. large and small subunits. double stranded sections can be helical.2 Outline the structure of ribosomes. 7. polypeptide released. 5. To receive full marks the candidate must mention each of the three levels. fibroin / elastin / silk protein in insects and spiders. held through hydrogen bonding. with reference to two examples of each protein type. giving a named List four functions of proteins. linked by peptide bonds. hemoglobin / myoglobin. hormones – insulin / growth hormone / TSH / FSH / LH. Award [1 max] for example of fibrous proteins. On the other hand. (4) example of each. giving one example of each. Creating hydrophilic channels through membranes: Polar amino acids are found inside membrane proteins and create a channel through which hydrophilic molecules can pass through.4 State four functions of proteins. 7. 7. 7. otherwise award [4 max]. (must give at least two bonds) determines overall shape / a named example eg: active sites on enzymes.5. Specificity of active site in enzymes: If the amino acids in the active site of an enzyme are non-polar then it makes this active site specific to a nonpolar substance. giving an example of each. if the active site is made up of polar amino acids then the active site is specific to a polar substance. secondary structure / level: regular folding / beta-pleated sheets / spiralling / alpha-helices. support / structural functions metabolic / other functions. Name of function and named protein must both be correct for the mark.5. transport – hemoglobin / lipoproteins (in blood). disulfide bonds / bridges and hydrophobic bonds. Reject fibrinogen. (mostly) insoluble in water (mostly) soluble in water.primary structure / level: order / sequence of amino acids. collagen. tertiary structure / level: 3-dimensional conformation of a polypeptide / protein. determines the type / function of protein / 2º and 3º structures. myosin. (5) Award [1] for each of the following pairs up to [3 max]. held with ionic bonds. Controlling the position of proteins in membranes: The non-polar amino acids cause proteins to be embedded in membranes while polar amino acids cause portions of the proteins to protrude from the membrane. long and narrow / long strands rounded / spherical / ball shaped. catalyses / other named enzyme. hydrogen bonds. 22 . Distinguish between fibrous and globular proteins. Award [1 max] for example of globular proteins. ()–keratin. insulin / other peptide hormone.2 Outline the difference between fibrous and globular proteins. fibrous repetitive amino-acid sequences irregular amino acid sequences. immunoglobulin / other globular protein. Reject examples of fibrous and globular proteins apart from the first named examples.3 Explain the significance of polar and non-polar amino acids. storage – zeatin (in corn seeds) / casein (in milk). 4 Explain the difference between competitive and non-competitive inhibition. substrate cannot bind / reaction not catalyzed / decreased enzyme activity. (8) Characteristic inhibitor: Competitive inhibition structurally / chemically very similar to substrate site of binding: active site effect: blocks active site effect: competes with substrate / prevents substrate binding example: 23 Butanedioic acid (succinate) dehydrogenase by propanedioic (malonate) acid in the Krebs cycle / any valid Non-competitive different from substrate. facilitated diffusion – sodium channels / aquaporins. movement – actin / myosin.6 Enzymes Assessment statement 7. There is an exact fit between a specific substrate and a specific enzyme. changes 3° structure of enzyme / conformational change of active site. Using a table. compare competitive and non-competitive inhibition and give one named example of each. with reference to one example of each. 7. Allow other named examples. C. structure – collagen / keratin / tubulin / fibroin. 7. 7. Example Questions What occurs in the induced fit model for enzyme catalysed reactions? A.3 Explain that enzymes lower the activation energy of the chemical reactions that they catalyse. defence – antibodies / immunoglobin. 7. The enzyme can change shape to accommodate the substrate.6.6.receptors – hormone receptor / neurotransmitter receptor / receptor in chemoreceptor cell. D. binds to different site / not active site / allosteric site. B. Mark first four functions only. + metal ions / Hg / +/ 2+ Ag Cu / – CN inhibit enzymes (cytocrome oxidase) by breaking .6. The substrate can change its shape to fit a number of enzymes.1 State that metabolic pathways consist of chains and cycles of enzyme-catalysed reactions.6. electron carriers – cytochromes. enzymes – catalase / RuBP carboxylase. pigments – opsin active transport – sodium pumps / calcium pumps.2 Describe the induced-fit model. Other substrates can bind away from the active site. ferns. each step of the pathway is unique / different substrate at each step. up to [4 max].(2) of allosteric sites. The leaves of plants are adapted to absorb light and use it in photosynthesis.) stem / stems. (5) name of dicotyledonous plant. finer control of metabolic pathways.1. Individual cells are not needed but do not penalize if they are shown. spongy layer / mesophyll. enzymes are specific for their substrate / lock and key model / energy requirements for reactions with substrates vary. Topic 9: Plant science 9. Draw a labelled diagram to show the arrangement of tissues in a leaf. can be reduced by increasing substrate concentration disulfide linkages / any valid example. Example Questions Draw a labelled diagram to show the external parts of a named dicotyledonous plant. Explain the control of metabolic pathways State why each step in a biochemical pathway often requires a by end-product inhibition.6. xylem (in a major or minor vein). Do not accept tree. (Shown forming a branching network joined to the stem. (6) Award [1] for each of the following structures. 9. lower epidermis. 9. leaf / leaves. axillary bud drawn in leaf axil. guard cells.5 example eg Folic acid synthesis in bacteria by sulfonamide Prontosil. collenchyma (in the midrib). conifers. palisade layer / mesophyll. pondweed. any monocots.effect of substrate concentration: 7. shown in the correct relative position and labelled. phloem (in a major or minor vein).3 Explain the relationship between the distribution of tissues in the leaf and the functions of these tissues. increasing substrate concentration does not reduce effect of inhibitor.1 Plant structure and growth Assessment statement .2 Outline three differences between the structures of dicotyledonous and monocotyledonous plants. root / roots. flower / inflorescence / named part of flower. terminal bud drawn at tip of stem. (do not accept stoma / stomata only) 24 .1 Draw and label plan diagrams to show the distribution of tissues in the stem and leaf of a dicotyledonous plant. including the role separate enzyme. upper epidermis. Award [1] for each of the following structures clearly drawn and correctly labelled.1. II and III 25 . 9.4 Identify modifications of roots. cohesion between water molecules.6 Explain how water is carried by the Describe how water is transported in a plant.9. including the structure transported in xylem (vessels). stems and leaves for different functions: bulbs.2. water is absorbed by osmosis.1. cortex cell walls (increase the surface area). transpiration pull. Explain how roots absorb water and then transport it to the xylem. Turgor pressure III. solute concentration inside the root is higher than in the soil / outside. apoplastic route is through the cell walls (and intercellular spaces).2. 9.1 Assessment statement Example Questions Outline how the root system provides a large surface area for mineral ion and water uptake by means of branching and root hairs.2. due to active transport of ions into the root.4 State that terrestrial plants support themselves by means of thickened cellulose. branching / lateral roots (increases the surface area). water has to pass through cytoplasm of endodermis / Casparian strip blocks walls. storage roots and tendrils.5 State that dicotyledonous plants have apical and lateral meristems. II and III only D.1. apoplastic and symplastic transport across the root.2 Transport in Angiospermophytes 9. Which of the following help(s) in supporting a terrestrial woody plant? I. stem tubers.2. noting any special adaptations that help these processes to occur. I and II only C.2. I only B.5 Define transpiration. 9.1. 9.2. Phloem tissue A. 9. (9) roots have a large / increased surface area (in relation to their volume). symplastic route is through the cytoplasm (and plasmodesmata). 9. 9. root hairs increase the surface area. water movement in xylem due to pulling force / transpiration pull. (4) transpiration stream. cell turgor and lignified xylem. of xylem vessels.3 Explain the process of mineral ion absorption from the soil into roots by active transport. I. 9.1.6 Compare growth due to apical and lateral meristems in dicotyledonous plants.2 List ways in which mineral ions in the soil move to the root.7 Explain the role of auxin in phototropism as an example of the control of plant growth. Xylem tissue II. 9. (8) rate of transpiration in a typical terrestrial less transpiration as (atmospheric) humidity rises.2.1 Assessment statement Example Questions Draw and label a diagram showing the structure of a dicotyledonous animalpollinated flower. composed of companion cells / sieve tube members.3 Reproduction in Angiospermophytes 9. source / leaves to sink / fruits / roots / storage organs / named storage organ.7 State that guard cells can regulate transpiration by opening and closing stomata. adhesion and evaporation. Draw the structure of a dicotyledenous animal-pollinated flower. plant. faster evaporation (due to more latent heat available). faster diffusion / more kinetic energy (of water molecules).8 State that the plant hormone abscisic acid causes the closing of stomata. 9. apoplastic pathway is through cell walls.9 Explain how the abiotic factors light. sucrose / amino acids / assimilate / products of photosynthesis transported.10 Outline four adaptations of xerophytes that Which would be an adaptation of xerophytes? help to reduce transpiration. due to light causing stomata to open. more transpiration as temperature rises. A.2. transpiration stream / continuous column of water from roots to leaves. passive / no energy used by plants.cohesion. increasing the concentration gradient (of water vapour).2. water molecules are cohesive (so transmit the pull) / hydrogen bonding. Hairs on the leaves D. evaporation / transpiration causes low pressure / suction / pull. Reduced roots 9. Large numbers of stomata C.11 Outline the role of phloem in active translocation of sugars (sucrose) and amino acids from source (photosynthetic tissue and storage organs) to sink (fruits. roots). affect the plant. (6) Award [1] for each of the following structures clearly drawn and labelled correctly 26 . smaller concentration gradient (of water vapour). Explain how abiotic factors affect the rate of transpiration in a terrestrial temperature. narrower stomata with high carbon dioxide concentration hence less transpiration. seeds. wider opening with brighter light hence more transpiration. 9. wind and humidity.2. Large air spaces B. companion cells involved in ATP production. root pressure can move water up the plant.3. (5) living tissue. 9. more transpiration as wind (speed) increases. pressure flow hypothesis / movement of water into phloem causes transport. bi-directional transport.2. more transpiration in the light. CAM plants opposite. 9. 9. humid air / water vapour blown away from the leaf. Outline the role of the phloem in the active translocation of biochemicals. III I II 11. (5) 9.3. fertilization Fertilization.6 absorption of water. mobilize to tissues / transport of foods / nutrients to embryo.2 Distinguish between pollination. Which is the correct sequence of events when skin is cut and bleeding occurs? I. some plants grown in greenhouses with controlled light conditions.3 Draw and label a diagram showing the external and internal structure of a named dicotyledonous seed. (stimulates) production of amylase. which of the following helps seed dispersal? A.1.3.1 Describe the process of blood clotting. digestion of starch to smaller sugars / maltose. 9. long-day plants artificially lit during the night. others are long-day plants.Explain how manipulation of day length is used in the production of day and short-day plants. Pollination fertilization seed dispersal D.4 Explain the conditions needed for the germination of a typical seed. (6) of phytochrome. Describe the metabolic events of germination in a starchy seed. Thrombin is produced II. (embryo) secretes GA to (aleurone layer). using an appropriate wavelength / far-red light / 730 nm. some flowering plants are short-day plants. Germination 9. controlled by the plant’s biological clock. In what sequence do these processes occur? A.9. important variable is length of darkness / photoperiod. possible to expose only for brief periods to keep costs down but long enough to interrupt the dark period.1 Defence against infectious disease Assessment statement Example Questions 11. In flowering plants. III II I D. I II III B. Topic 11: Human health and physiology 11. Pollen C. including the role flowers. (embryo) increases respiration. pollination and seed dispersal all occur during the and seed dispersal. Platelets release clotting factors A.3.3. Seed dispersal pollination fertilization B.3. Bees B.2 Outline the principle of challenge and 27 . Mammals D. Fibrinogen is converted into fibrin III. involves interaction of phytochromes with metabolic reactions.1. Explain how flowering is controlled in long. short-day plants kept in the dark during daylight hours. Seed dispersal fertilization pollination 9. I III II C.5 Outline the metabolic processes during germination of a starchy seed. Fertilization pollination seed dispersal C. reproduction of a flowering plant. antigen is engulfed by macrophages. plasma cells produce specific antibodies to the antigen. antibodies are made in response to antigens / vaccine. (4) active immunity – production of antibodies by the organism itself. 11. testing for (different strains of) malaria. (6) vaccine is used (to induce immunity artificially). passive. treatment of rabies / Ebola / lymphoma destroying T-cells to reduce rejection of transplants. natural and artificial immunity. Explain the production of antibodies. (8) 28 . vaccine is injected / ingested. antibodies are produced in response to specific antigens. active immunity is when the body makes the antibodies itself. helper T-cells are activated. helper T-cells activate B-cells. immunity to a disease is due to presence of the appropriate antibodies / cells that can make them.7 Discuss the benefits and dangers of vaccination. memory cells for long-term immunity. artificial immunity – due to inoculation with vaccine / antibodies / vaccination. natural immunity is caused by exposure to a disease / pathogen / bacterium / virus.1. treatment: targeting cancer cells with attached drugs. booster shot may be needed. a faster / stronger response later. 11. natural immunity – immunity due to infection / acquisition from mother. detection of cardiac enzyme in suspected heart attacks.response.3 Define active and passive immunity. helper T-cells bind to antigen (on macrophage). passive immunity – acquisition of antibodies from another organism / from elsewhere. 11. ELISA test.1. Outline the process of immunization. Discuss the benefits and dangers of immunization against bacterial and viral infections. vaccine contains dead / weakened / attenuated forms of the pathogen / bacterium / virus. B-cells clone. into plasma cells and memory cells. 11. immunity due to vaccination / immunisation lasts for life / a long period. memory cells are made in response to antigens / vaccine.5 Describe the production of monoclonal State one use of monoclonal antibodies in diagnosis and one use in antibodies and their use in diagnosis and in treatment. (8) antigens stimulate an immune response. clonal selection and memory cells as the basis of immunity.1. detection of tissue / blood type. detection of HCG / pregnancy test kits. antigen is presented on macrophage membrane. antibodies are made by B-cells / lymphocytes / plasma cells. Define the terms active. (2) treatment.4 Explain antibody production. 11. Award [1 max] for use in diagnosis and [1 max] for use in treatment.1.6 Explain the principle of vaccination.1. diagnosis: detection of (antibodies to) HIV. reduce medical costs.benefits: prevent disease. weakened virus becomes virulent / get disease. prevent epidemics. eradicate diseases / smallpox entirely. disease free cattle / more food. autoimmune response. vaccine with side-effects eg salk vaccine / whooping cough vaccine / MMR vaccine. less job absenteeism. 29 . allergic reactions. danger of side-effects / example of side-effects. healthier society. speed up the body’s response to a disease. prevent harm / disabilities due to diseases.
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