Correct Option
The correct option isParasites derive nutrients from living hosts, while saprotrophs feed on dead matter.
Explanation
Heterotrophic nutrition refers to the mode of nutrition where organisms depend on other sources for food as they cannot synthesize it themselves. This is broadly classified into three types based on the source and method of nutrient intake: Holozoic, Parasitic, and Saprotrophic.
Option Analysis
- Parasites consume solid food, while saprotrophs consume liquids. is Incorrect. While saprotrophs typically digest food extracellularly and absorb nutrients in liquid form, the physical state of the food is not the fundamental definition. The primary distinction is the biological status of the food source (living vs. dead).
- Parasites derive nutrients from living hosts, while saprotrophs feed on dead matter. is Correct. The fundamental difference lies in the source of nutrition:
- Parasitic Nutrition: The organism (parasite) derives nutrients from a living host without killing it immediately, often causing harm (e.g., Cuscuta, lice, tapeworms).
- Saprotrophic Nutrition: The organism (saprotroph) feeds on dead and decaying organic matter. They break down complex organic substances outside the body and absorb the simpler compounds (e.g., Fungi like mushrooms, bread mould).
- Parasites are autotrophic, while saprotrophs are heterotrophic. is Incorrect. Both parasites and saprotrophs are heterotrophic. Neither group is autotrophic (capable of photosynthesis or chemosynthesis).
- Parasites are always microscopic, while saprotrophs are macroscopic. is Incorrect. Size is not a distinguishing criterion. Parasites can be macroscopic (e.g., leeches, roundworms) or microscopic (e.g., Plasmodium). Similarly, saprotrophs can be macroscopic (e.g., mushrooms) or microscopic (e.g., bacteria, yeast).
Key Takeaway: The defining characteristic of parasitic nutrition is dependence on a living host, whereas saprotrophic nutrition relies on dead and decaying matter.