Biology Paper 1 2020

Materials For this paper you must have: • a ruler • a scientific calculator. Instructions • Use black ink or black ball-point pen. • Pencil should only be used for drawing. • Fill in the boxes at the top of this page. • Answer all questions in the spaces provided. • If you need extra space for your answer(s), use the lined pages at the end of this book. Write the question number against your answer(s). • Do all rough work in this book. Cross through any work you do not want to be marked. • In all calculations, show clearly how you work out your answer. Information • The maximum mark for this paper is 100. • The marks for questions are shown in brackets. • You are expected to use a calculator where appropriate. • You are reminded of the need for good English and clear presentation in your answers. *jun20 4611H01* IB/M/Jun20/E23 8461/1H Answer all questions in the spaces provided. box This question is about photosynthesis. . Complete the word equation for photosynthesis. [2 marks] + → + oxygen . Describe how energy for the photosynthesis reaction is gained by plants. [2 marks] Students investigated the effect of temperature on the rate of photosynthesis. The students shone light from a lamp onto pondweed and measured the volume of oxygen produced per hour. Table 1 shows the results. Table 1 Temperature in °C Rate of photosynthesis in cm3/hour Test 1 Test 2 Test 3 Mean 20 18.5 19.3 19.5 X 25 32.6 34.1 32.9 33.2 30 41.9 45.2 44.9 44.0 35 38.6 39.8 44.0 40.8 40 23.1 20.5 22.4 22.0 45 1.9 14.2 2.2 2.1 . Calculate mean value X. [2 marks] box X = cm3/hour The students identified one anomalous result in Table 1. . Draw a ring around the anomalous result in Table 1. [1 mark] . Suggest one possible cause of the anomalous result. [1 mark] . How did the students deal with the anomalous result? [1 mark] . Give one factor the students should have kept constant in this investigation. [1 mark] Turn over ► Table 1 is repeated below. box Table 1 Temperature in °C Rate of photosynthesis in cm3/hour Test 1 Test 2 Test 3 Mean 20 18.5 19.3 19.5 X 25 32.6 34.1 32.9 33.2 30 41.9 45.2 44.9 44.0 35 38.6 39.8 44.0 40.8 40 23.1 20.5 22.4 22.0 45 1.9 14.2 2.2 2.1 . Why did the rate of photosynthesis decrease from 35 °C to 45 °C?