To compare the required activation energy for cellular respiration and photosynthesis, we need to consider the nature of the reactions.
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Cellular Respiration is an exothermic process, meaning it releases energy. In this reaction, glucose (and other organic molecules) is broken down to produce energy in the form of ATP, with carbon dioxide and water as byproducts. Because it is exothermic, the products (CO2 and H2O) are at a lower energy state than the reactants (glucose and oxygen). However, it still requires some energy to initiate the reaction; this is known as the activation energy.
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Photosynthesis is an endothermic process, meaning it requires energy input (typically from sunlight). In this reaction, carbon dioxide and water are converted into glucose and oxygen, capturing energy in the process. The products (glucose and oxygen) are at a higher energy state than the reactants (CO2 and H2O), hence the requirement for energy input.
Given these considerations, the activation energy for each reaction can be analyzed as follows:
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For Cellular Respiration: The activation energy required to initiate the reaction is relatively low compared to the energy that the reaction subsequently releases (it is easier to activate the reaction because the products are lower in energy).
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For Photosynthesis: The activation energy is relatively high because it requires energy input from sunlight to convert low-energy reactants (CO2 and H2O) into higher-energy products (glucose and O2).
Thus, we can conclude:
- Cellular respiration needs a smaller amount of energy to activate the reaction because the products are at a lower energy state than the reactants.
- Photosynthesis needs a higher amount of energy to activate the reaction because the products are at a higher energy state than the reactants.
Therefore, the most accurate statement from your options would be:
Cellular respiration needs a smaller amount of energy to activate the reaction because the products are at a lower energy state than the reactants.