Anaerobic respirationIB MYP Biology: Mind map

Exam questions on Anaerobic respiration

1. In a 400 m final in Kingston, Jamaica, an athlete sprints so hard that her muscles cannot be supplied with oxygen as fast as they need it. After she crosses the line she keeps breathing very deeply and quickly for several minutes.
   Explain why the athlete's muscle cells respire anaerobically during the sprint.2 marks
2. A baker in Istanbul mixes yeast, flour, sugar and warm water into a dough and leaves it covered in a bowl. After an hour the dough has doubled in size and is full of small holes.
   Explain why the dough rises.2 marks
3. A student investigates whether the amount of sugar affects how fast yeast ferments. She makes four mixtures, each with 5 g of yeast in 50 cm³ of sugar solution, with sugar concentrations of 0%, 2%, 5% and 10%. She covers each mixture with a thin layer of oil and passes the gas it gives off through a tube into water, counting the bubbles during 5 minutes. She records 0 bubbles for 0%, 14 bubbles for 2%, 31 bubbles for 5% and 52 bubbles for 10%.
   State a hypothesis for this investigation with a scientific reason, and name one control variable.3 marks