Tag: metabolism, cell respiration, and photosynthesis

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Questions Related to metabolism, cell respiration, and photosynthesis

Multiple choice biology metabolism, cell respiration, and photosynthesis metabolism enzymes carbohydrate metabolism

In a reaction, reactants form a transition state, before the formation of products. Which of the following is affected by the action of enzyme?

  1. Products only

  2. Reactants only

  3. Transition state only

  4. Products and reactants

  5. Transition state and products
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Any chemical reaction includes the formation of transition state between reactant and product. Formation of transition state requires high energy content of reactant molecules for alignment of reacting groups, the formation of transient unstable charges, rearrangements of chemical bonds etc. The energy required for formation of the transition state is termed as activation energy. Enzymes enhance the rate of reaction by lowering down the activation energy of transition state. Thus, the correct answer is option C.

Multiple choice biology metabolism, cell respiration, and photosynthesis metabolism enzymes carbohydrate metabolism

An enzyme increases the rate of a reaction by?

  1. enzymes speed up reactions by lowering activation energy.

  2. Increasing the rate of random collisions of molecules

  3. Removing the product of the reaction so allowing it to continue

  4. Bringing the reacting molecules into precise orientation with each other
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation


  • Enzymes provide activation energy for the reactions they catalyze.
  • Catalysts lower the activation energy for reactions. 
  • The lower the activation energy for a reaction, the faster the rate. Thus enzymes speed up reactions by lowering activation energy.so, option A is correct.

Multiple choice biology metabolism, cell respiration, and photosynthesis metabolism enzymes carbohydrate metabolism

Biochemical reactions are carried out by enzymes

  1. By decreasing the energy of the reactants

  2. By increasing the activation energy of the reaction

  3. By decreasing the activation energy of the reaction

  4. By increasing the energy of the products of the reaction

  5. By decreasing the energy of the products of the reaction
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Any chemical reaction includes the formation of transition state between reactant and product. The energy required for formation of the transition state is termed as activation energy. Enzymes enhance the rate of reaction by lowering down the activation energy of transition state. Thus, the correct answer is option C.

Multiple choice biology metabolism, cell respiration, and photosynthesis metabolism enzymes carbohydrate metabolism

Energy released from enzyme-substrate interaction is

  1. Activation energy

  2. Binding energy

  3. Constant energy

  4. Variable energy
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The transition state is the state of the activated complex which is highly unstable and readily changes into the product.  At the transition state, the enzyme attaches to the substrate to form an enzyme-substrate complex by forming a weak chemical bond. Binding energy is the free energy that is released by the formation of weak interactions between a complementary substrate and enzyme.

So, the correct answer is option B.

Multiple choice biology metabolism, cell respiration, and photosynthesis metabolism enzymes carbohydrate metabolism

Chemical reactions require energy for

  1. Oxidation

  2. Entropy

  3. Activation

  4. Enthalpy
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Chemical reactions take place mainly at a specific temperature in presence of a catalyst. The substrate and product have different energy state. The energy gap between the substrate and the product is known as activation energy which is the minimum energy required to initiate a reaction. In presence of a catalyst, the activation energy lowers and the substrate changes into the product.

So, the correct answer is option C.

Multiple choice biology metabolism, cell respiration, and photosynthesis metabolism enzymes carbohydrate metabolism

Energy required for start of a chemical reaction is

  1. Activation energy

  2. Entropy

  3. Potential energy

  4. Kinetic energy
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Entropy is a measure of thermal energy.
Potential energy is the energy stored in an object at a particular height.
Kinetic energy is the energy stored in an object in motion.
Enzymes are proteins which accelerate the rate of the reaction. The substrate and product have different energy state. The energy gap between the substrate and the product is known as activation energy which is the minimum energy required to initiate a reaction. The enzymes lower the activation energy and lead to the faster conversion of substrate to the product.
So, the correct answer is option A.
Multiple choice biology metabolism, cell respiration, and photosynthesis metabolism enzymes carbohydrate metabolism

Activation energy is required for :

  1. Bringing reactants together

  2. Destabilisation of bonds of reactants.

  3. Both A and B

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Activation energy is the energy required to bring reactants into a transition state, which involves both bringing them together in the correct orientation and destabilizing their existing bonds to facilitate the reaction.

Multiple choice biology metabolism, cell respiration, and photosynthesis metabolism enzymes carbohydrate metabolism

Enzymes increase the rate of biochemical reaction through 

  1. Changing equilibrium

  2. Lowering activation energy

  3. Forming reactant-product complex

  4. Forming enzyme-product complex.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Enzymes are biological catalysts. A catalyst is a chemical that increases the rate of a chemical reaction without itself being changed by the reaction. Without a catalyst, the amount of energy required for the reaction is large. Enzymes and catalysts both affect the rate of a reaction. The lower the activation energy for a reaction, the faster the rate of chemical reaction. Thus enzymes speed up reactions by lowering activation energy.

So, the correct answer is option B.

Multiple choice biology metabolism, cell respiration, and photosynthesis metabolism enzymes carbohydrate metabolism

Enzymes enhance rate of reaction by

  1. Combining with product

  2. Forming reactant-product complex

  3. Changing equilibrium of reaction

  4. Lowering activation energy
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enzymes are proteins which accelerate the rate of the reaction. The substrate and product have different energy state. The energy gap between the substrate and the product is known as activation energy which is the minimum energy required to initiate a reaction. The enzymes lower the activation energy and lead to the faster conversion of substrate to the product.

So, the correct answer is option D.

Multiple choice bio-chemistry carbohydrate metabolism metabolism enzymes metabolism, cell respiration, and photosynthesis

State whether the following statements are true or false.
The totality of metabolism in humans must include both anabolism and catabolism.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Metabolism includes both the synthesis of biomolecules(known as anabolism) and breaking down of substrates to generate energy(known as catabolism).

So, the correct option is 'The totality of metabolism in humans must include both anabolism and catabolism.'