Nutrition in Plants and Animals - Other Modes of Nutrition: Parasitic, Saprotrophic, and Symbiosis
Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Parasitic Nutrition: A mode of heterotrophic nutrition where an organism (the parasite) lives on or inside another organism (the host) and derives its nutrition directly from the host. An example is (Amarbel), which lacks chlorophyll and absorbs nutrients using specialized roots called haustoria.
Saprotrophic Nutrition: The process in which organisms take in nutrients from dead and decaying organic matter. These organisms, called saprotrophs (e.g., Fungi), secrete digestive juices onto the matter to convert it into a solution and then absorb the nutrients.
Symbiosis (Symbiotic Relationship): A close association between two different organisms where they live together and share both shelter and nutrients for mutual benefit.
Lichens: A classic example of symbiosis where a chlorophyll-containing partner (Alga) and a fungus live together. The fungus provides shelter, water, and minerals, while the alga prepares and provides food through photosynthesis.
Rhizobium and Legumes: A symbiotic relationship where the bacterium lives in the root nodules of leguminous plants. The bacteria convert atmospheric nitrogen () into a soluble form like nitrates () that the plant can use, and in return, the plant provides food and shelter to the bacteria.
Insectivorous Plants: Plants like the Pitcher plant () that perform photosynthesis but grow in nitrogen-deficient soil. They trap and digest insects to fulfill their nitrogen requirements, acting as partial heterotrophs.
📐Formulae
💡Examples
Problem 1:
Why do farmers grow leguminous plants like pulses in rotation with other crops?
Solution:
Farmers grow leguminous plants to naturally replenish the nitrogen content of the soil. The symbiotic bacteria present in the root nodules of these plants convert atmospheric into soluble nitrates (), reducing the need for chemical nitrogenous fertilizers.
Explanation:
This is an application of the symbiotic relationship between plants and bacteria to maintain soil fertility.
Problem 2:
A piece of bread left in a moist, warm place develops a fluffy, cotton-like growth. Identify the mode of nutrition and the organism.
Solution:
The organism is a Fungus (like Bread Mould), and the mode of nutrition is Saprotrophic Nutrition.
Explanation:
Fungi thrive in moist environments and obtain nutrients by breaking down the complex organic matter of the bread into simpler forms through external secretion of enzymes.
Problem 3:
Compare the roles of Algae and Fungi in a Lichen.
Solution:
In a Lichen, the Alga contains chlorophyll and performs the reaction to provide food. The Fungus provides the physical structure (shelter) and absorbs water and minerals for the Alga.
Explanation:
This mutualistic dependency ensures both organisms survive in harsh environments where they might not survive individually.