Q.1 Cellular respiration is an exothermic reaction and photosynthesis is an endothermic reaction. How does the required activation energy compare for these two reactions?
1. Cellular respiration needs a smaller amount of energy to activate the reaction because the products are at a lower energy state than the reactants.
2. Photosynthesis needs a higher amount of energy to activate the reaction because the products are at a lower energy state than the reactants.
3. Photosynthesis needs a smaller amount of energy to activate the reaction because the products are at a lower energy state than the reactants.
4. Cellular respiration needs a higher amount of energy to activate the reaction because the products are at a lower energy state than the reactants.
Q.2 How do enzymes affect chemical reactions?
1.They lower activation energy.
2.They provide activation energy.
3.They increase activation energy.
4.They eliminate activation energy.
Q.3 Which lists the correct order of steps involved in the formation of an enzyme-substrate complex?
1.enzyme-substrate complex forms > enzyme binds to substrate at active site > chemical reaction takes place > products are released
2.enzyme binds to substrate at active site > enzyme-substrate complex forms > chemical reaction takes
3.chemical reaction takes place > products are released > enzyme binds to substrate at active site > enzyme-substrate complex forms
4.enzyme binds to substrate at active site > chemical reaction takes place > products are released > enzyme-substrate complex forms .
A.1 The correct answer is option 1 - Cellular respiration needs a smaller amount of energy to activate the reaction because the products are at a lower energy state than the reactants.
Explanation: In cellular respiration, the reactants (glucose and oxygen) have a higher energy state than the products (carbon dioxide and water). As a result, cellular respiration releases energy in the form of ATP. The activation energy required to start the reaction is relatively low because the products are at a lower energy state, making it easier for the reaction to proceed.
On the other hand, in photosynthesis, the reactants (carbon dioxide and water) have a lower energy state than the products (glucose and oxygen). Photosynthesis is an endothermic reaction that requires energy from sunlight to convert the reactants into higher-energy products. Therefore, photosynthesis needs a higher amount of energy to activate the reaction.
A.2 The correct answer is option 1 - They lower activation energy.
Explanation: Enzymes are biological catalysts that speed up chemical reactions without being consumed in the process. They achieve this by lowering the activation energy required for a reaction to occur. Activation energy is the minimum energy needed for reactant molecules to collide and undergo a chemical reaction. Enzymes reduce the activation energy by stabilizing the transition state of the reaction, allowing it to proceed more quickly.
A.3 The correct answer is option 2 - Enzyme binds to substrate at the active site > Enzyme-substrate complex forms > Chemical reaction takes place.
Explanation: The formation of an enzyme-substrate complex involves several steps. First, the enzyme binds to the substrate at its active site. The active site is a specific region of the enzyme that recognizes and binds to the substrate molecule. This binding forms the enzyme-substrate complex.
Once the enzyme-substrate complex is formed, it undergoes a conformational change, allowing the chemical reaction to take place. Enzymes provide an environment that promotes the conversion of substrates into products by facilitating the necessary interactions, such as breaking and forming of chemical bonds.
After the chemical reaction occurs, the products are released from the active site, and the enzyme is free to bind other substrates and continue the catalytic cycle. Therefore, the correct order of steps is: Enzyme binds to substrate at active site > Enzyme-substrate complex forms > Chemical reaction takes place.