The correct option is (c) 1 and 3 only.
Explanation
Organisms are classified based on cellular organization into unicellular (single-celled) and multicellular (many-celled) categories. Unicellular organisms function as independent units where a single cell represents the entire life form.Statement-wise Analysis:
- Statement 1 is Correct: In unicellular organisms, a single cell constitutes the whole organism. This single cell is capable of independent existence. Common examples include Amoeba, Paramecium, and bacteria.
- Statement 2 is Incorrect: Mushrooms are macroscopic, multicellular fungi. Similarly, the statement explicitly mentions "multicellular algae," which by definition are not unicellular. While there are unicellular fungi (e.g., Yeast) and unicellular algae (e.g., Chlamydomonas), the examples provided in the statement are multicellular.
- Statement 3 is Correct: A defining characteristic of unicellular organisms is that the single cell performs all essential life functions, including nutrition, respiration, excretion, growth, and reproduction. Unlike multicellular organisms, they do not exhibit tissue-level division of labor.
Key Takeaway: Unicellular organisms (e.g., Bacteria, Protozoa, Yeast) carry out all metabolic processes within a single cell, whereas multicellular organisms (e.g., Mushrooms, Plants, Animals) rely on specialized cells and tissues.