Pearson Edexcel Level 3 GCE

Please check the examination details below before entering your candidate information Candidate surname Other names Centre Number Candidate Number Pearson Edexcel Level 3 GCE Wednesday 18 June 2025 reference 9BN0/03 Biology A (Salters Nuffield) Total Marks Instructions • Use black ink or ball-point pen. centre number and candidate number. • Show all your working out in calculations and include units where appropriate. – there may be more space than you need. Information • The total mark for this paper is 100. – use this as a guide as to how much time to spend on each question. In questions marked with an asterisk (*), marks will be awarded for your ability to structure your answer logically, showing how the points that you make are related or follow on from each other where appropriate. Advice • Read each question carefully before you start to answer it. • Check your answers if you have time at the end. Turn over P78659A ©2025 Pearson Education Ltd. Y:1/1/1/1/1/ Answer ALL questions. Write your answers in the spaces provided. 1 In 1980, a volcano erupted in Washington State, USA. Ash from the volcano covered surrounding vegetation, killing all the plants. Succession has been investigated on one of the sides of the volcano. (a) In one study, species richness on the side of the volcano was measured. The graph shows the change in mean species richness from 1983 to 2005. 25 20 Mean species richness 15 10 5 0 1980 1985 1990 1995 2000 2005 Year (i) State what is meant by the term succession. 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(ii) Calculate the rate of increase in the mean number of species from 1986 to 1995. Give your answer to two significant figures and include units. (2) Answer .............................................................. (iii) Following the eruption, one of the first plant species to be observed was Lupinus lepidus. Give the term used to describe the first species to appear at a location. (1) ............................................................................................................................... ............................................................................................................................... ...................... (b) Species of Lupinus have organs called root nodules that contain bacteria. Sugars and nutrients are exchanged between the plant and the bacteria in the root nodules. (i) State what is meant by the term organ. (1) ............................................................................................................................... ............................................................................................................................... ...................... ............................................................................................................................... ............................................................................................................................... ...................... ............................................................................................................................... ............................................................................................................................... ...................... (ii) Bacteria in root nodules are able to fix nitrogen gas (N2) into ammonium compounds that the plant can use. Name two organic molecules, containing nitrogen, needed to synthesise proteins. 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(Total for Question 1 = 8 marks) 2 Stentor coeruleus is a unicellular organism. The drawing shows the structure of a Stentor coeruleus. cilia multilobed nucleus holdfast vacuoles (a) This Stentor has a height of 1 mm and a diameter of 0.4 mm at the top. (i) Calculate the volume of this cone-shaped Stentor. Use the equation for the volume of a cone: V  πr2 h 3 Give your answer to three decimal places. (ii) Give the domain to which Stentor coeruleus belongs.