The correct option is (c) 1 and 3 only.
Explanation
Vacuoles are membrane-bound organelles found in the cytoplasm of both plant and animal cells, as well as in some unicellular organisms. They act as storage sacs for solid or liquid contents, including water, sap, excretory products, and other materials not immediately useful to the cell. The membrane surrounding the vacuole is known as the tonoplast.
Statement-wise Analysis
- Statement 1 is Correct. There is a distinct difference in vacuole size between plant and animal cells. In plant cells, vacuoles are very large and permanent, often occupying 50% to 90% of the cell volume to provide turgidity and rigidity. In contrast, animal cells typically possess vacuoles that are much smaller in size and are often temporary.
- Statement 2 is Incorrect. In Amoeba, the food vacuole is a critical structure formed when the organism engulfs food particles. Inside the food vacuole, digestive enzymes break down the food for the organism's use. Therefore, food vacuoles are present, not absent.
- Statement 3 is Correct. In many unicellular organisms like Amoeba, specialized vacuoles called contractile vacuoles play a vital role in osmoregulation and excretion. They collect excess water and wastes from the cell body and expel them into the surrounding environment to maintain the cell's internal balance.
Key Takeaway: Vacuoles are significantly larger and central in plant cells compared to the small, temporary vacuoles in animal cells. Specialized vacuoles, such as contractile vacuoles for osmoregulation and food vacuoles for digestion, are essential features of unicellular organisms like Amoeba.