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Olympiad (Class 7) Respiration in organisms — practice questions

Explore 49 free Respiration in organisms questions in Olympiad (Class 7) Science. Open each question or exercise to read its content, reference answers and available explanation.

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Respiration in organisms questions and exercises with answers

Showing questions 1–30 of 49.

Which two products form when oxygen fully breaks down glucose in cells?Read the answer and worked solution →A tired sprinter's leg muscle works with too little oxygen. Which waste builds up there?Read the answer and worked solution →Dough rises when yeast respires without oxygen. Which gas puffs up the dough?Read the answer and worked solution →Where inside a cell does the first stage of breaking down glucose, glycolysis, occur?Read the answer and worked solution →Which muscle contracts and moves down mainly to draw air into a human's lungs?Read the answer and worked solution →During quiet breathing at rest, which part of the breathing cycle is largely passive?Read the answer and worked solution →The lungs have no muscles of their own. When do they expand?Read the answer and worked solution →About what percentage of fresh air by volume is oxygen?Read the answer and worked solution →Which gas makes up the largest share of the air we breathe in?Read the answer and worked solution →Roughly what share of the air we breathe out by volume is carbon dioxide?Read the answer and worked solution →Fresh air is 21 percent oxygen, exhaled air about 15. Why the drop?Read the answer and worked solution →Air pressure roughly halves every 5,500 m climbed. How does it compare at 11,000 m with sea level?Read the answer and worked solution →A climber gets less oxygen per breath. How does the body cope?Read the answer and worked solution →What do we call fast and deep breathing brought on by exercise?Read the answer and worked solution →Which term means overly shallow breathing?Read the answer and worked solution →Why is breathing through the nose better than through the mouth?Read the answer and worked solution →What is the main job of breathing in the lungs?Read the answer and worked solution →Gas exchange in alveoli is by diffusion. What does that mean?Read the answer and worked solution →Even after breathing out as hard as possible, what is still in a mammal's lungs?Read the answer and worked solution →During hard exercise, which muscles help push the diaphragm upward as you breathe out?Read the answer and worked solution →Why does your breathing become deeper when you run?Read the answer and worked solution →Which process needs oxygen to make ATP from food?Read the answer and worked solution →A cell breaks down 5 glucose molecules by glycolysis. How many pyruvate molecules result?Read the answer and worked solution →Without oxygen, one glucose gives 2 ATP by fermentation. How many ATP do 12 glucose give?Read the answer and worked solution →Aerobic respiration gives 38 ATP per glucose, fermentation 2. Which is true?Read the answer and worked solution →Why can fermentation still help a sprinter even though it gives little ATP?Read the answer and worked solution →Which of these is a fuel commonly used by cells in respiration?Read the answer and worked solution →What is ATP often called in cells?Read the answer and worked solution →In which part of a plant or animal cell does most aerobic respiration after glycolysis occur?Read the answer and worked solution →Plants make oxygen in photosynthesis. Do they also respire?Read the answer and worked solution →

Worked practice questions

Which two products form when oxygen fully breaks down glucose in cells?

  1. Lactic acid and water
  2. Alcohol and carbon dioxide
  3. Carbon dioxide and water
  4. Oxygen and some starch
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Correct answer: C. Carbon dioxide and water

Full oxidation of glucose with oxygen ends in carbon dioxide and water, with energy trapped as ATP.

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A tired sprinter's leg muscle works with too little oxygen. Which waste builds up there?

  1. Ethanol
  2. Lactic acid
  3. Starch
  4. Glycerol
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Correct answer: B. Lactic acid

With low oxygen, muscle cells ferment pyruvate and the waste product formed is lactic acid.

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Dough rises when yeast respires without oxygen. Which gas puffs up the dough?

  1. Plain oxygen gas
  2. Plain nitrogen gas
  3. Carbon dioxide gas
  4. Plain hydrogen gas
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Correct answer: C. Carbon dioxide gas

Yeast fermentation gives ethanol and carbon dioxide, and the trapped carbon dioxide gas makes the dough swell.

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