QUESTION: Which of the following is not composed of a single cell only?
- Hydra
- Brewer’s Yeast
- Protozoa
- Zygote
Answer: Hydra
| Aspect | Cellular Level | Introduction | Structure | Role |
| Hydra | Multicellular | A small aquatic organism belonging to the phylum Cnidaria, often found in freshwater habitats. | Hydra has a simple structure with a tubular body, tentacles with stinging cells (cnidocytes) and a central digestive cavity. | As a multicellular organism, it exhibits various specialized cell types and tissues. |
| Brewer’s Yeast | Unicellular | It is a single-celled fungus. | Yeast cell is round or oval in shape. Yeast cell have a cell wall, cytoplasm, nucleus and other organelles. | It is commonly used in brewing and baking industry. It plays a role in fermentation processes by converting sugars into alcohol and carbon dioxide. |
| Protozoa | Unicellular | Microscopic, single-celled eukaryotic organisms found in various habitats. | Protozoa exhibit diverse structures based on their types, with some having cilia, flagella, or pseudopodia for movement and feeding. | They are important components of microbial ecosystems and can be pathogenic or beneficial. |
| Zygote | Single cell | The initial cell formed by the fusion of two gametes during fertilization. | Zygote has combination of genetic material coming from male and female gametes. It often undergoes multiple cell divisions to develop into an embryo. | Zygote is the mark of the beginning of the development of a new multicellular organism. |