This did not cause the cells to burst but moved the chromosomes further apart in order to reduce the overlapping of the chromosomes when observed with an optical microscope. Examine large number of fields of view / many. Centre number Candidate number . (The alveolar epithelium) is one cell thick; The Crohn's disease symptom of swelling of the lining of the intestines could be triggered by pathogenic bacteria in the intestines. Suggest how the siRNA produced these results. Add 1 part (bacteria) culture to 9 parts (sterile), The student looked at cells in the 1 in 10 dilution during his preliminary work. Start studying A-Level Biology Past Papers (2018). These gland cells have adaptations that include many mitochondria and many Golgi vesicles. The mass flow hypothesis is used to explain the movement of substances through phloem. Past papers and mark schemes for the Edexcel A Level Biology course. Mutation changes the tertiary structure / amino. Anaerobic respiration produces carbon dioxide; Explain why a log scale is used to record the number of cells. The scientists tested their null hypothesis using the chi-squared statistical test. Monday 11 June 2018 Afternoon Time allowed: 2 hours ... • The maximum mark for this paper is 91. Binding of insulin leads to an increase in the rate of respiration in cells such as osteoblasts. If most of the mitochondria in a cell are faulty, this prevents many important enzyme-catalysed reactions taking place or slows them down. 1. 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Click on the links below to go to the relevant subject's past papers, they are free to download. Describe how a peptide bond is formed between two amino acids to form a dipeptide. Water moves into the cells/cytoplasm by. When counting, cells that touch top or left lines are counted but cells that touch right or bottom lines are not counted. English Literature. The milk, 1. If you are not sure which exam board you are studying ask your teacher. Drama and Theatre Studies. Business Studies. Learn vocabulary, terms, and more with flashcards, games, and other study tools. 1. Please write clearly in block capitals. Suggest and explain one reason why bacteria resistant to tetracycline are more common than bacteria resistant to streptomycin in these farm animals. Use all of the information to suggest how the mutation of NOTCH1 led to the difference in the percentage of B cells destroyed by Rituximab. Rubisco activity increases with temperature. 1. B cells specific to the venom reproduce by. 1. Use your knowledge of transport across membranes to explain the shape of the curve in Figure 1 for uptake of monosaccharides between concentrations: Figure 1 is evidence for monoglycerides being lipid-soluble molecules. Use your knowledge of water potential to suggest why lactulose can be used to help people suffering from constipation. A change from Glu to Lys at amino acid 300 had no effect on the rate of reaction catalysed by the enzyme. 1. Endocellulase create more ends / increases. 1. People with complete achromatopsia have difficulty in seeing detail. 1. 1. (Less/no) carbon dioxide (reacts) with RuBP; The scientists concluded that heat stress reduces the activity of rubisco in plant leaves by affecting rubisco activase. 1. Give two structural differences between a molecule of messenger RNA (mRNA) and a molecule of transfer RNA (tRNA). All the volunteers were given the same food for 3 days. Art and Design. (Presence of) antigen of the (pathogenic), Suggest the meaning of 'a genetic tendency to Crohn's disease'. Using evidence from Figure 6, what can you conclude about the net primary productivity (NPP) in the sand dunes that are older than 1000 years? Describe how lactose is formed and where in the cell it would be attached to a polypeptide to form a glycoprotein. When preparing the cells for observation the scientist placed them in a solution that had a slightly higher (less negative) water potential than the cytoplasm. Method of randomly determining position (of. Cambridge International AS and A Level Biology builds on the skills acquired at Cambridge IGCSE (or equivalent) level. He decided not to use this dilution to determine the number of cells in the undiluted liquid, 1. (Binding) alters the tertiary structure. Two proteins have the same number and type of amino acids but different tertiary structures. History. Named structures - trachea, bronchi, bronchioles, alveoli; Compare and contrast the structure and properties of triglycerides and phospholipids, 1. 1. Antivenom is injected as treatment. Green sensitive pigment/cones non-functional. 1. Endocellulases and exocellulases act at different places on cellulose molecules. Describe the roles of two named types of enzymes used to insert DNA fragments into box plasmids. When a person is bitten by a venomous snake, the snake injects a toxin into the person. Where dividing cells are found / mitosis occurs; Describe and explain what the student should have done when counting cells to make sure that the mitotic index he obtained for this root tip was accurate. This mutation does not occur in the gene coding for lactase. The scientist used the same concentration of endocellulase and exocellulase in the mixtures. (Movement) down a gradient / from high. (DNA) helicase causes breaking of hydrogen/H, Describe the gross structure of the human gas exchange system and how we breathe. 1. Lactase persistence is caused by a mutation in DNA. State and explain the property of water that can help to buffer changes in temperature. Describe how you would test a liquid sample for the presence of lipid box and how you would recognise a positive result. Large range/difference/increase in numbers; Many yeast cells die during the death phase. (Inside of postsynaptic) neurone becomes more. 1. siRNA binds to / destroys mRNA for CENP-W; Suggest one suitable method for sterilising the bottles and explain why it was necessary to sterilise them. The acidic pH conditions created by osteoclasts cause the inactive form of the protein osteocalcin to change into the active form of osteocalcin. (a monomer is a smaller / repeating) unit /. Over 22,000 learners have used our materials to pass their exams. (So) the animal does not suffer from the. Biology. (Both) negatively charged to positively charged. Condensation (reaction) / loss of water; The secondary structure of a polypeptide is produced by bonds between amino acids. Biology A (Salters Nuffield) June 2018 – Edexcel Past Papers (8BN0 & 9BN0) AS-Level Biology A: Paper 1 – Lifestyle, Transport, Genes and Health (8BN0/01) Download Paper - Download Marking Scheme. 1. Name the blood vessels that carry blood to the heart muscle. (The water content of the leaves was) not. Describe the role of two named enzymes in the process of semi-conservative replication of DNA. A decrease in the activity of the enzyme rubisco would limit the rate of photosynthesis. Maths. Weak / easily broken hydrogen bonds between, Name the process by which prokaryotic cells divide. Explain why the antibody binds to the transcription factor. Use the information provided to explain why the number of people showing LP would rapidly increase once selection for this condition had been established.

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