Other Modes of Nutrition in Plants

Other Modes of Nutrition in Plants

(A) Parasitic Plants

1. What are parasitic plants?

   • Parasitic plants are those that depend on other plants for their nutrition. They lack chlorophyll or have limited photosynthetic ability and derive nutrients from their host.
   • Example: Cuscuta (Amarbel), Rafflesia, Mistletoe 

2. How does a parasitic plant obtain its food?

   • These plants develop specialized structures called haustoria that penetrate the host plant’s tissues to absorb water and nutrients.
   • Example: Cuscuta absorbs nutrients from the host plant using haustoria. 

3. What is an example of a parasitic plant?

   • Example: Cuscuta (Amarbel), Rafflesia (world’s largest flower, which absorbs nutrients from its host vine). 

4. Why is Cuscuta (Amarbel) called a parasite?

   • Cuscuta lacks chlorophyll and cannot photosynthesize. It twines around a host plant and extracts nutrients, weakening the host.
   • Example: Cuscuta growing on a mango tree absorbs its nutrients.

(B) Insectivorous Plants

1. What are insectivorous plants?

   • These are plants that derive some of their nutrients by trapping and digesting insects and other small organisms.
   • Example: Pitcher plant (Nepenthes), Venus flytrap (Dionaea muscipula), Sundew (Drosera) 

2. Why do insectivorous plants trap insects?

   • They grow in nitrogen-deficient soils, so they trap insects to fulfill their nitrogen requirement.
   • Example: Venus flytrap traps insects to supplement nitrogen intake. 

3. How does a pitcher plant capture and digest insects?

   • A pitcher plant has a modified leaf forming a deep cavity filled with digestive enzymes. Insects get attracted to the nectar, fall inside, and are digested.
   • Example: Nepenthes (Tropical pitcher plant) has slippery walls and a liquid-filled trap. 

4. If the pitcher plant is green, why does it feed on insects?

   • Though green and capable of photosynthesis, pitcher plants lack enough nitrogen from the soil and thus obtain it from insects.
   • Example: Nepenthes is green but still eats insects for nitrogen. 

5. Are insectivorous plants autotrophic or heterotrophic?

   • They are partially heterotrophic because they photosynthesize but also rely on insects for nutrients.
   • Example: Sundew (Drosera) photosynthesizes but also traps insects.

(C) Saprotrophic Plants

1. What are saprotrophic plants?

   • These are non-green plants that obtain nutrients from decaying organic matter.
   • Example: Mushrooms, Mold, Indian Pipe (Monotropa)
     

2. How do fungi obtain their nutrition?

   • Fungi secrete digestive enzymes on dead material, breaking it down into simpler substances, which they then absorb.
   • Example: Bread mold (Rhizopus) breaks down starch into simpler sugars. 

3. Why do fungi grow on bread, leather, and pickles?

   • These materials provide a moist and organic environment that supports fungal growth.
   • Example: Mucor fungus grows on moist bread. 

4. Why do fungi grow more during the rainy season?

   • The damp and humid conditions in the rainy season promote fungal spore germination and growth.
   • Example: Mushrooms appear more frequently in forests after rain. 

5. What is saprotrophic nutrition?

   • It is a mode of nutrition where organisms feed on dead and decaying matter.
   • Example: Fungi like Penicillium decompose dead leaves. 

6. Are mushrooms autotrophs or saprotrophs?

   • Mushrooms are saprotrophs as they depend on decomposed organic matter for food.
   • Example: Agaricus bisporus (Button Mushroom) grows on decomposed organic matter.

(D) Symbiotic Relationships

1. What is symbiosis?

   • It is a mutually beneficial relationship between two different organisms.
   • Example: Lichens (association between fungi and algae). 

2. How do fungi and algae help each other in lichens?

   • Algae produce food through photosynthesis, while fungi provide water, minerals, and protection.
   • Example: Crustose lichens grow on tree bark and rocks. 

3. What is the role of Rhizobium bacteria in plants?

   • Rhizobium bacteria live in the root nodules of leguminous plants and convert atmospheric nitrogen into a usable form.
   • Example: Rhizobium bacteria help pea plants obtain nitrogen. 

4. Why do leguminous plants (peas, beans) help in soil fertility?

   • They house Rhizobium bacteria that fix nitrogen, enriching the soil.
   • Example: Farmers grow soybean and alfalfa to improve soil quality. 

5. How do bacteria help in nitrogen fixation?

   • Certain bacteria convert atmospheric nitrogen into compounds that plants can absorb and use for growth.
   • Example: Azotobacter bacteria fix nitrogen in the soil. 

6. Why are lichens considered unique organisms?

   • They represent a symbiotic association between two different organisms (fungi and algae), functioning as a single unit.
   • Example: Lobaria is a type of lichen found on tree trunks.