3 10.4.2 10.4.6 Read the article on oxygen in the atmosphere. For questions 1-5, choose the correct answers (A, B, C or D). Justify answers. your 1 Air that is mainly oxygen is A low in free radicals. B useful to the body. C dangerous to humans. D bad for evolution. 2 Oxygen is A 50% of the atmosphere. B necessary in order for life to exist. C the result of atmospheric chemistry. unnecessary for plants. D 3 According to the article, animals A couldn't have evolved without plants. B took a long time to get big in size. C were anaerobic at first. D needed large breathing systems in the past. 4 The dragonfly experiment suggests A large creatures need less oxygen. B insects develop more quickly in high- oxygen environments. C low levels of oxygen will result in large creatures. D insects fly more easily in high-oxygen environments. 5 Without sea algae A there would be no oxygen in the atmosphere. B animals would stop evolving. C all life in the oceans would die. D all life on Earth would be in danger. 1 2 W​