Aerobic respirationIB MYP Sciences: Subtopic test

1. 1
   A long-distance runner in Nairobi trains every morning. Her muscle cells release energy from glucose using oxygen that she breathes in and her blood carries to them. The reaction goes on all the time, but it speeds up a great deal during a run.

   (a)

   In which part of a muscle cell is most of the energy released from glucose during aerobic respiration?

   [1 mark]

   • ANucleus
   • BMitochondria
   • CCell membrane
   • DRibosomes

   (b)

   Which is the correct balanced symbol equation for aerobic respiration?

   [1 mark]

   • AC₆H₁₂O₆ + 6CO₂ → 6O₂ + 6H₂O
   • B6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
   • CC₆H₁₂O₆ + O₂ → CO₂ + H₂O
   • DC₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

   (c)

   Write the word equation for aerobic respiration.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A hummingbird hovers in front of a flower and drinks sugary nectar. Its flight muscles beat about 50 times each second and are packed with a very large number of tiny structures in their cells. The bird breathes quickly and its heart beats very fast while it hovers.

   (a)

   Which statement best explains why hummingbird flight muscle cells contain a very large number of mitochondria?

   [1 mark]

   • AMuscle cells need to release a great deal of energy quickly
   • BMitochondria store the nectar that the bird drinks
   • CMitochondria carry out photosynthesis to make glucose for the muscle
   • DMitochondria make the muscle cells contract by themselves

   (b)

   Which of these is a use of the energy released by respiration in the hummingbird?

   [1 mark]

   • AMaking the glucose in the nectar
   • BAbsorbing carbon dioxide from the air
   • CMaking the muscles contract so that the wings can beat
   • DMaking light for the bird's cells to use

   (c)

   Explain why the hummingbird's breathing rate and heart rate both increase while it hovers.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student in Dubai wants to show that living cells release energy. She fills two identical vacuum flasks, each with 100 g of dried peas that have been soaked in water. In flask A the peas are germinating. In flask B the peas have been boiled to kill them. Each flask is sealed with a cotton wool plug and a thermometer, and both start at 21.0 °C. After 24 hours the temperature in flask A is 26.5 °C and in flask B it is 21.3 °C.

   (a)

   Identify the independent variable, the dependent variable and one control variable in this investigation.

   [3 marks]

   (b)

   Process the data and evaluate what the investigation shows about respiration, suggesting one improvement to the method.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A school in Manila sells a sports drink in its canteen. Each bottle contains 30 g of glucose. Some students drink one before football matches. The school nurse is worried that other students drink one every day and then sit in lessons for the rest of the afternoon.

   (a)

   Explain how the glucose in the sports drink is used in a muscle cell to release energy, including where in the cell this happens and what the energy is used for.

   [6 marks]

   (b)

   Discuss and evaluate the school's decision to sell this sports drink to students.

   [6 marks]

   Total for question 4: 12 marks

End of questions