Cell Organelles: Chloroplast MCQs Quiz | Class 9
Class IX Science (Code 086) Quiz on Unit II: Organization in the Living World. This quiz covers the topic Cell Organelles: Chloroplast, focusing on its role in photosynthesis, structure, and plant-specific features. Attempt these 10 MCQs to test your knowledge, check your score, and download the answer key PDF for revision.
Overview of Chloroplasts
Chloroplasts are specialized organelles found in plant cells and algae. They are responsible for photosynthesis, the process by which light energy is converted into chemical energy (glucose). Chloroplasts belong to a family of organelles called plastids.
Key Structural Features
- Double Membrane: Like mitochondria, chloroplasts are bounded by two membrane layers (outer and inner).
- Stroma: The fluid-filled space inside the inner membrane, containing enzymes, DNA, and ribosomes.
- Thylakoids: Flattened, sac-like structures where light-dependent reactions occur.
- Grana: Stacks of thylakoids (singular: granum).
- Chlorophyll: The green pigment located in the thylakoid membranes that traps solar energy.
Functions and Significance
The primary function of the chloroplast is to synthesize food (glucose) using carbon dioxide, water, and sunlight. Because they manufacture food, they are often called the “Kitchen of the Cell.”
Semi-Autonomous Nature
Chloroplasts contain their own circular DNA and ribosomes (70S). This allows them to synthesize some of their own proteins and replicate independently of the cell cycle, making them semi-autonomous organelles.
| Feature | Description |
|---|---|
| Location | Plant cells and some protists (algae); absent in animal cells. |
| Pigment | Chlorophyll (green) and carotenoids. |
| Main Process | Photosynthesis (Light and Dark reactions). |
Quick Revision Points
- Chloroplasts are a type of chromoplast containing chlorophyll.
- The light reaction of photosynthesis occurs in the grana/thylakoids.
- The dark reaction (Calvin cycle) occurs in the stroma.
- Leucoplasts are colorless plastids used for storage (starch, oils, proteins), distinct from chloroplasts.
Extra Practice Questions
- What is the specific term for colorless plastids? (Answer: Leucoplasts)
- Which metallic element is found in the center of the chlorophyll molecule? (Answer: Magnesium)
- Name the small connecting channels between thylakoids of different grana. (Answer: Stroma lamellae)
- Why are chloroplasts not found in onion bulb cells? (Answer: Because onion bulbs grow underground and do not perform photosynthesis.)
- What kind of ribosomes are found inside chloroplasts? (Answer: 70S Ribosomes)
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