This biology worksheet challenges students to identify enzyme composition, explain their function, and label diagrams of activation energy and enzyme-substrate interactions.

Here’s the complete solution to your Enzyme Worksheet, with clear explanations for each question:

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1. What are enzymes made of?

✔ Correct answer: Proteins

> *Explanation:* Most enzymes are proteins — large molecules made of amino acid chains that fold into specific 3D shapes. A few enzymes (called ribozymes) are made of RNA (a nucleic acid), but in introductory biology, enzymes are generally taught as proteins. So, circle “Proteins”.

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2. What do enzymes do?

> Answer: Enzymes are biological catalysts that speed up chemical reactions in living organisms without being used up themselves.

> *Explanation:* They lower the activation energy required for a reaction to occur, allowing metabolic processes (like digestion, respiration, DNA replication) to happen quickly at body temperature. Without enzymes, these reactions would be too slow to sustain life.

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3. Label the following picture:

*(The graph shows two curves representing energy changes during a reaction — one with an enzyme and one without.)*

You should label the graph like this:

- Left vertical arrow (longest): Activation energy without enzyme
- Right vertical arrow (shorter): Activation energy with enzyme
- Top curve (higher peak): Reaction without enzyme
- Bottom curve (lower peak): Reaction with enzyme
- Horizontal axis (x-axis): Progress of reaction / Time
- Vertical axis (y-axis): Energy

> *Explanation:* The graph illustrates how enzymes reduce the activation energy (the energy “hill” a reaction must overcome). The top curve shows the higher energy barrier without an enzyme; the bottom curve shows the lowered barrier when an enzyme is present. This allows the reaction to proceed faster.

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5. Explain what takes place in each step of the diagram:

*(The diagram shows the “lock-and-key” or “induced fit” model of enzyme action.)*

#### Step 1: Substrates approach the enzyme
> The substrate molecules (orange and blue shapes) move toward the enzyme’s active site — the specific region where catalysis occurs. The shape of the active site matches the shape of the substrate(s).

#### Step 2: Formation of enzyme-substrate complex
> The substrates bind to the enzyme’s active site, forming the enzyme-substrate complex. This binding may cause slight changes in the enzyme’s shape (induced fit), which helps bring the substrates closer together and stresses their bonds, making the reaction easier.

#### Step 3: Reaction occurs → Products form
> While bound to the enzyme, the substrates undergo a chemical reaction — they are broken down, rearranged, or combined — forming new molecules called products (the green shape).

#### Step 4: Products released, enzyme unchanged
> The products detach from the enzyme’s active site. The enzyme itself is not consumed in the reaction and can now bind to new substrate molecules to repeat the process.

> *Key takeaway:* Enzymes are reusable catalysts. One enzyme molecule can catalyze many reactions per second.

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✔ Final Answers Summary:

1. Proteins
2. Enzymes speed up chemical reactions by lowering activation energy.
3. Label the graph:
- Left arrow = Activation energy without enzyme
- Right arrow = Activation energy with enzyme
- Top curve = Without enzyme
- Bottom curve = With enzyme
5. Step-by-step explanation (as above)

Let me know if you’d like this formatted as a printable answer key or need help with diagrams! 🧬🔬