Modes of Nutrition In Plants

Question 1 What are insectivorous plants? Give example?

Question 2 What are plant parasite?Give example?

Question 3 What are saprophytes? Give examples?

Question 4 Explain”Fungi can be useful as well as harmful”?

Question 5 What do you understand by term symbiosis?

Question 6 Explain the symbiotic relationship of Rhizobium bacteria and leguminous plants?

Question 7 Explain the symbiotic relationship of algae and fungus?

☛ Also Read NCERT Solutions for Chapter 1 Nutrition In Plants

Depending on their mode of obtaining food, all the heterotrophic plants can be divided into two main groups:

(1) Parasites and
(2) Saprophytes

 

Parasites

A plant (or animal) which lives on or inside another organism (called host) and derives the food from it, is called a parasite.

Those non-green plants which obtain their food from the living bodies of other plants (or animals) are called plant parasites.

The living organism (from whose body food is obtained) is called ‘host’ of the parasite. 

The parasite plants climb on the host plants from which they get all the food.

A parasite plant produces certain special type of roots (called sucking roots) which penetrate into the host plant. The parasite sucks the food materials from the host through these special roots.

For example : Cuscutta. It is called Amarbel in Hindi. Cuscutta plant is a yellow, tubular structure twining around the stem and branches of a tree. The tree on which Cuscutta plant climbs is called its host. Since Cuscuta plant does not have the green pigment called chlorophyll, it cannot synthesise its own food. Cuscuta plant takes readymade food from the tree (or plant) on which it climbs. Since Cuscuta plant deprives the host tree of valuable nutrients, it is called a parasite.

Examples of plant parasites are Mistletoe, Wheat rust and Corn smut.

Saprophytes

Those non-green plants which obtain their food (or nutrition) from dead and decaying organic matter are called saprophytes.

The non-green plants called fungi derive their food from dead and decaying organic matter, so fungi are saprophytes.

Some of the common fungi are mushroom, bread mould and yeast.

We see small, fluffy, umbrella-like plants growing on rotting wood during the rainy season These are a kind of fungus called mushrooms. They take their nutrition from the rotting wood of a dead tree, so they are saprophytes.

The saprophytic plants (fungi) secrete digestive juices on the dead and decaying organic matter and convert it into a solution. They absorb the nutrients from this solution. This mode of nutrition in which plants take in nutrients from dead and decaying organic matter is called saprophytic nutrition.

Fungi also grow on pickles, leather objects, clothes and other articles which are left uncleaned in hot and humid weather for a considerable time. The growth of fungi may spoil many thing during the rainy season. It is due to the growth of fungus that our leather shoes kept in the house sometimes get  spoiled during the rainy season.

 

Fungi can be useful as well as harmful

(1) Mushrooms are eaten as a vegetable

(2) Yeast is used for producing alcohol.

(3) Some fungi are also used for making medicines. For example: the Penicillium fungus is used in making an antibiotic called penicillin.

Fungi also cause diseases in plants and human beings. Sometimes the whole crops standing in the field are destroyed by fungus.

The skin disease (called ringworm) in humans is caused by fungus.

Insectivorous Plants

Those green plants which obtain their food partly from insects are called insectivorous plants.

The insectivorous plants have specialised leaves to catch the insects. The insectivorous plant grow only in those soils which do not contain sufficient nitrogen mineral.

These insectivorous plants trap insects by various methods, kill them and digest them to obtain nitrogen compounds (like amino acids).

Some common examples of the insectivorous plants (or carnivorous plants) are : Pitcher plant, Sundew Venus fly-trap and Bladderwort.

In the pitcher plant, the lamina (or blade) of the leaf is modified into a hollow tube called pitcher. The leaf apex (top part of leaf) forms a lid which can open or close the mouth of the pitcher. Inside the pitcher, there are hair which are directed downwards. When an insect falls in the pitcher, the lid closes automatically. The trapped insect gets entangled in the hair

of the pitcher and hence cannot come out. After some time, the insect dies in the pitcher. The walls of the pitcher secrete digestive juices which digest the proteins present in the body of insect to form simpler nitrogen compounds (like amino acids).These simpler nitrogen compounds are absorbed by the walls of the pitcher and used by the whole pitcher plant. 

Insectivorous plants are green and carry out photosynthesis to obtain a part of the food required by them.

Insectivorous plants feed on insects to obtain the nitrogen compounds needed for their growth. Insectivorous plants are “partial heterotrophs”.

Symbiotic Plants

The living together of two different species of plants as if they are parts of the same plant and help each other in obtaining food is called symbiosis. This type of nutrition involving symbiosis occurs in the plants called lichens.

In lichens, the green coloured plant called ‘alga‘ (autotroph) and non-green plant ‘fungus’ (saprophyte) live together. The fungus holds the alga cells in its mat of web-like hyphae (thin filaments). The fungus plant absorbs the water and mineral salts from the surroundings and supplies them to alga. The alga plant being green, prepares the food by photosynthesis and shares it with fungus. Thus, both alga and fungus gain mutually from one another by living together.

The condition where two different organisms live together an other to survive is called symbiotic relationship. Another example of symbiotic relationship is provided by Rhizobium bacteria and leguminous plants. Rhizobium bacteria cannot make their own food. Rhizobium bacteria

live in the root nodules of leguminous plants (such as gram, peas, beans, pulses, etc.). Rhizobium bacteria convert nitrogen gas of air into water soluble nitrogen compounds (called nitrates) and give them to the leguminous plants for their growth. In leguminous plants give food and shelter to Rhizobium bacteria. Thus, Rhizobium bacteria and leguminous plants have symbiotic relationship.

Another example of symbiotic relationship is provided by Rhizobium bacteria and leguminous plants. Rhizobium bacteria cannot make their own food. Rhizobium bacteria live in the root nodules of leguminous plants (such as gram, peas, beans, pulses, etc.). Rhizobium bacteria convert nitrogen gas of air into water soluble nitrogen compounds (called nitrates) and give them to the leguminous plants for their growth. In leguminous plants give food and shelter to Rhizobium bacteria. Thus, Rhizobium bacteria and leguminous plants have symbiotic relationship.

 

Notes for Chapter 1 Nutrition In Plants  Photosynthesis Modes of Nutrition in Plants Replenishment of Nutrients in the Soil