AP Biology Questions: Chloroplast Structure and Function Practice Quiz

🧪 Topic Summary

Chloroplasts are the organelles in plant cells and eukaryotic algae that conduct photosynthesis. They absorb sunlight and use it in conjunction with water and carbon dioxide to produce energy in the form of sugars (glucose). Chloroplasts contain several key structures including thylakoids (where the light-dependent reactions occur), grana (stacks of thylakoids), and stroma (the fluid-filled space around the grana where the Calvin cycle takes place). Understanding these components is crucial for grasping how photosynthesis works.

The process of photosynthesis involves two main stages: the light-dependent reactions and the light-independent reactions (Calvin cycle). During the light-dependent reactions, which occur in the thylakoid membranes, light energy is converted into chemical energy in the form of ATP and NADPH. These energy-rich molecules then power the Calvin cycle in the stroma, where carbon dioxide is fixed and converted into glucose. The structure of the chloroplast is optimized to facilitate these reactions, making it a highly efficient energy-producing powerhouse.

🔬 Part A: Vocabulary

Match the terms with their definitions:

Answer Key:

• 🔑 1-D
• 🔑 2-B
• 🔑 3-A
• 🔑 4-C
• 🔑 5-E

📝 Part B: Fill in the Blanks

Fill in the blanks in the following paragraph using the words provided: stroma, thylakoids, ATP, light, glucose, Calvin cycle.

The process of photosynthesis begins when plants absorb _________ energy. This energy is used to create _________ and NADPH, which power the _________. This cycle occurs in the _________ of the chloroplast, where carbon dioxide is converted into _________. The _________ are the site of the light-dependent reactions.

Answer Key:

• 💡 light
• 💡 ATP
• 💡 Calvin cycle
• 💡 stroma
• 💡 glucose
• 💡 thylakoids

🤔 Part C: Critical Thinking

Explain how the structure of a chloroplast contributes to its function in photosynthesis. Be specific about the roles of the thylakoids, grana, and stroma.

Sample Answer:

• 🌿 The thylakoids provide a large surface area for light-dependent reactions due to their membrane structure.
• ☀️ Grana, being stacks of thylakoids, maximize the efficiency of light capture.
• 💧 The stroma provides the necessary enzymes and environment for the Calvin cycle to occur, allowing for the synthesis of glucose.