Bioenergetics flashcards

Bioenergetics is the study of how living organisms obtain and use energy. Students must understand photosynthesis, the process by which plants convert light energy into glucose using carbon dioxide and water, releasing oxygen as a by-product. The overall equation and the factors that limit the rate of photosynthesis are essential knowledge. Students also need to understand aerobic and anaerobic respiration, including their equations, where they occur in the cell, and the conditions under which each takes place. Aerobic respiration releases energy from glucose using oxygen, while anaerobic respiration occurs without oxygen and produces different products in animals and plants. The concept of metabolism, how organisms use energy for movement, growth and maintaining body temperature, and the role of ATP as the energy currency of cells are also important aspects of this topic.

1. Card 1

   What is the overall word equation for photosynthesis?

   Carbon dioxide + water -> glucose + oxygen. Light energy is absorbed by chlorophyll to drive this reaction.

2. Card 2

   What is the overall word equation for aerobic respiration?

   Glucose + oxygen -> carbon dioxide + water. This process releases energy and occurs continuously in living cells.

3. Card 3

   Where in the cell does aerobic respiration mainly take place?

   Aerobic respiration mainly occurs in the mitochondria, which is why cells with high energy demands contain many mitochondria.

4. Card 4

   What are the three limiting factors of photosynthesis?

   Light intensity, carbon dioxide concentration, and temperature are the three main limiting factors that can slow the rate of photosynthesis.

5. Card 5

   What is the word equation for anaerobic respiration in animal cells?

   Glucose -> lactic acid. This releases a small amount of energy and causes muscle fatigue during intense exercise.

6. Card 6

   What is the word equation for anaerobic respiration in yeast?

   Glucose -> ethanol + carbon dioxide. This process is called fermentation and is used in brewing and bread-making.

7. Card 7

   What is the symbol equation for photosynthesis?

   6CO2 + 6H2O -> C6H12O6 + 6O2. The glucose produced can be used for respiration or converted into other biological molecules.

8. Card 8

   What does the term 'limiting factor' mean in the context of photosynthesis?

   A limiting factor is the variable that is in shortest supply and therefore controls the rate of photosynthesis, even if other conditions are ideal.

9. Card 9

   Why do plants photosynthesise and respire at the same time?

   Plants need energy from respiration at all times, but they can only photosynthesise in light. During daylight, the rate of photosynthesis exceeds respiration.

10. Card 10

    What is oxygen debt and how is it repaid?

    Oxygen debt is the extra oxygen needed after exercise to break down lactic acid. It is repaid by continued deep breathing after exercise stops.

11. Card 11

    What is metabolism?

    Metabolism is the sum of all chemical reactions occurring in an organism, including building molecules, breaking them down, and releasing energy from respiration.

12. Card 12

    How does increasing light intensity affect the rate of photosynthesis?

    As light intensity increases, the rate of photosynthesis increases until another factor becomes limiting, after which the rate levels off into a plateau.

• Many students incorrectly state that plants only photosynthesise and do not respire, when in fact plants carry out both processes simultaneously at all times.
• Students often confuse the products of anaerobic respiration, writing lactic acid for yeast or ethanol for human muscles, when these products are specific to each organism.
• A common error is to say that a high light intensity always increases the rate of photosynthesis, without recognising that another factor such as carbon dioxide concentration may become limiting.

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