AS Biology 9700 | May/June 2025 Paper 12 | Past Paper Solution | Part 1 | скачать в хорошем качестве

AS Biology 9700 | May/June 2025 Paper 12 | Past Paper Solution | Part 1 |

For Part 2    • AS Biology 9700 | May/June 2025 Paper 12 |...   In this video I am solving AS level biology pastpaper paper 1. AS LEVEL BIOLOGY PAPER 12 MAY JUNE 2025 0:00 - INTRO 0:40 - 1 Which row shows possible uses of an eyepiece graticule? 2:31 - 2 Which statement about a light microscope is correct? 7:40 - 3 The electron micrograph shows a cell. What is the actual maximum length of the cell? 11:02 - 4 The table compares some biochemical molecules of P, Q, R and S. 13:56 - 5 Which cell structures contain enzymes and are enclosed by a double membrane 15:54 - 6 What is the order of size of cell structures? 20:44 - 7 A sample of a solution of sucrose tested for reducing sugars remains blue, but when another sample of the same solution is tested for non-reducing sugars the solution turns red. What explains these results? 24:57 - 8 Which molecules contain at least two double bonds? 30:23 - 9 Amylose, amylopectin and glycogen are all polysaccharides. Enzyme X removes one maltose molecule at a time from the ends of a polysaccharide molecule by hydrolysis of-1,4-glycosidic bonds. 33:20 - 10 Which property of water enables sweating to be an efficient means of losing heat from the body? 35:50 - 11 Which bonds are found in the levels of structure of a protein molecule? 38:35 - 12 Prokaryotes and eukaryotes use extracellular enzymes. Extracellular digestive enzymes are found in the external environments of some prokaryotes. Some prokaryotes are digested by hydrolytic enzymes during phagocytosis by eukaryotic cells. Which row shows the locations where extracellular enzymes are produced? 40:14 - 13 Amylase breaks down starch molecules. Which substance will have the same number of molecules for the duration of this reaction? 43:06 - 14 Which graphs could show the effect of pH on the rate of enzyme-catalysed reactions? 46:06 - 15 After a heart attack, the enzyme lactate dehydrogenase leaks into the blood plasma from damaged heart muscle. What is required to measure the activity of lactate dehydrogenase activity in a sample of blood plasma? 49:02 - 16 Which graph correctly shows Km and Vmax? 51:15 - 17 Cell membranes become less fluid as the temperature decreases. Bacteria and yeast cannot regulate their cell temperatures. How do bacteria and yeast maintain the fluidity of their cell membranes when the temperature decreases? 54:06 - 18 Samples X, Y and Z are epidermal tissues cut from an onion. Each epidermal tissue was immersed in one of three different concentrations of a salt solution for 30 minutes. 57:42 - 19 The graph shows the results of an osmosis investigation using potato tissue. What is the concentration of sodium chloride solution that has the equivalent water potential to this potato tissue and what is correct about the movement of water at that point? 1:00:19 - 20 Some agar was coloured pink using a pH indicator. The pink agar was then used to make three agar cubes with different dimensions. The cubes were placed in a beaker and covered with 0.1 moldm–3 hydrochloric acid. The temperature of the experiment was standardised at 20 °C. Hydrochloric acid diffused into the agar cubes causing the cubes to become colourless. What is the surface area to volume ratio of the agar cube that became colourless in the least amount of time?