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Anaerobic respiration in muscles

Science · Organisms & Life Processes · ages 12-14

Name ______________________ Date ____________

The muscle pathway called anaerobic respiration needs oxygen as a reactant.
Circle one: True False
In the school word equation for anaerobic respiration in muscles, what is made from glucose as some energy is released?
- Lactic acid
- Carbon dioxide
- Water
Which statement about tired muscles during hard exercise is supported by the lesson?
- Lactate alone explains muscle fatigue.
- Several changes contribute to fatigue.
- Fatigue means no glucose remains.
An invented classroom model gives 24 energy units for aerobic respiration and 2 for the muscle pathway without oxygen, using equal glucose amounts. How many times as much energy is 24 as 2?
Answer: ______________
Which releases more energy from the same amount of glucose: aerobic respiration or the pathway called anaerobic respiration in muscles?
- Anaerobic respiration
- Both pathways equally
- Aerobic respiration
After a hard sprint, breathing may stay fast. What does the extra oxygen help the body do?
- Use lactate as fuel and restore body stores.
- Stop aerobic respiration during recovery.
- Make oxygen from glucose and restore stores.
Two people used the same amount of glucose during different activities. Can that fact alone tell you who needs more extra oxygen during recovery?
- Equal glucose use means equal recovery needs.
- Exercise oxygen use alone decides recovery needs.
- Glucose use alone cannot rank recovery needs.
During a hard run, a muscle forms lactate while also using oxygen to release energy. Jamal says these observations contradict each other. Which explanation fits both observations?
- One pathway must stop before the other can start.
- Both pathways can contribute during the same activity.
- Lactate formation shows that the oxygen reading is false.

Answer key

For grown-ups. Fold this page away before handing over the rest.

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False · False. This pathway releases some energy from glucose without using oxygen as a reactant.
Lactic acid · The school equation is glucose → lactic acid, with some energy released. In the body, the product is mainly lactate.
Several changes contribute to fatigue. · Fatigue has several contributing causes. Lactate alone does not explain it and is not the cause of next-day muscle soreness.
12 · 24 ÷ 2 = 12, so the model gives 12 times as much energy. The invented values are not exact biological yields.
Aerobic respiration · Aerobic respiration breaks glucose down completely. Partial breakdown in the muscle pathway without oxygen leaves usable energy in lactate.
Use lactate as fuel and restore body stores. · Extra oxygen supports several recovery tasks, including using lactate as fuel and restoring energy and oxygen stores.
Glucose use alone cannot rank recovery needs. · Recovery includes several tasks. Equal glucose use alone cannot tell you how much extra oxygen each person needs or who needs more. You need more information about the activities and recovery.
Both pathways can contribute during the same activity. · The observations can coexist. The oxygen-independent muscle pathway forms lactate while aerobic respiration continues using oxygen. A hard run does not require the muscle to use only one pathway.