OCR 2023 GCSE Biology B Twenty First Century Science J257/03: Breadth in Biology (Higher Tier) Question Paper & Mark Scheme (Merged

2 © OCR 2023 1 (a) (i) Complete the table to compare cellular aerobic and anaerobic respiration in humans. Tick () the correct boxes in each row. [3] (ii) Which statement about respiration is correct? Tick () one box. Aerobic respiration produces more ATP than anaerobic respiration. Anaerobic respiration produces more ATP than aerobic respiration. Both aerobic and anaerobic respiration produce the same amount of ATP. Neither aerobic or anaerobic respiration produces ATP. [1] (b) Heart muscle contains approximately 5000 mitochondria in every cell. (i) Suggest why heart muscle cells need so many mitochondria. ........................................................................................................................................... ........................................................................................................................................... . ..................................................................................................................................[2] (ii) The image shows the mitochondria in a section of heart muscle. The mitochondria are different sizes. One of the mitochondria is labelled. A mitochondria Estimate the number of mitochondria in this image. Number of mitochondria =...........................................................[1] Process It requires glucose It requires oxygen It produces carbon dioxide It produces water It produces lactic acid Aerobic respiration Anaerobic respiration 3 © OCR 2023 Turn over 2 The table shows the percentage of land covered in rainforest in a country. Year Percentage of land covered in rainforest (%