Chapter 1 – Nutrition in Plants

Chapter 1 – Nutrition in Plants

 

1. What is Nutrition? (What is Nutrition?)

• Nutrition is the method of taking in food and using it by living organisms.
• All living organisms need food to survive and grow.

 

2. Modes of Nutrition

Nutrition in living organisms is mainly of two types:

1. Autotrophic Nutrition:

• • ‘Auto’ means self and ‘Trophos’ means nourishment.
  • Organisms that produce their own food  are called autotrophs.
  • Green plants are autotrophs.

1. Heterotrophic Nutrition:

• • ‘Hetero’ means other and ‘Trophos’ means nourishment.
  • Organisms that depend directly or indirectly on  others  (plants or other animals)  for their food are called  heterotrophs.
  • Humans and most animals are heterotrophs.

 

3. Photosynthesis in Plants

• Green plants make their own food, and this process  is called photosynthesis.
• Photosynthesis is the process in which green plants make their food (carbohydrates)  from carbon dioxide and water  using the energy of sunlight.
•  Components required for photosynthesis:
  • Carbon dioxide (CO2):  It enters the leaves from the atmosphere through tiny pores  called stomata.

 

 

•  Process:
  • Chlorophyll-containing cells in leaves make carbohydrates (food) and oxygen using carbon dioxide and water in the presence of sunlight  .
  • Equations:

Carbon Dioxide + Water ChlorophyllSunlightCarbohydrates + Oxygen

• • Products :
    • Carbohydrates : It is a plant food. Later it is stored in the leaves as starch.
    • Oxygen: It is a by-product that is released from the leaves into the atmosphere. It’s necessary for life.
•   Leaf – Food Factories of the Plant:
  • Leaves are plant food factories because food is formed in leaves.
  • Chlorophyll is present only in leaves, so photosynthesis mainly occurs in leaves.
  • Other  green parts of the plant (such as green stems and branches)  can also photosynthesize.
  • Desert Plants: They have prickly or scale-like leaves to reduce water loss by  transpiration. The green stems of such plants carry out photosynthesis.

 

 

 

4. Other Modes of Nutrition in Plants

Some plants are also heterotrophs:

1. Parasitic Nutrition:

• • There are some plants that do not have chlorophyll and cannot make their own food.
  • They depend on other plants for their nutrition. Such plants are  called parasites.
  • Example:  Cuscuta. It is a yellow tube-like structure that draped over the trunks and branches of other trees. It derives nutrients from the  ‘host plant’.

1. Insectivorous Plants:

• • There are some plants that catch pests and digest them.
  • These plants are  called insectivorous plants.
  • This is because these plants grow in soil where there is a lack of nitrogen, and by digesting insects they make up for the lack of nitrogen.
  • Examples:  Pitcher Plant, Venus Flytrap.
  • The leaf of the ghataparni turns into the shape of a pitcher that has a lid. The inside of the pitcher has hair bent downwards. When an insect enters the pitcher, the lid closes and the insect gets stuck in the hair. The pitcher contains digestive juices that digest the insect.

 iii.  Saprophytic Nutrition:

• • There are some living organisms that derive nutrition from dead and  decaying substances.
  • These are  called  saprophytes.
  • Examples:  Fungi such as mushrooms, mildew growing on bread.
  • These living organisms secrete digestive juices on dead and dissolved substances and convert them into simple solutions, then absorb nutrients from them.

1. Symbiotic Relationship:

• • Some living organisms live together and share with each other for habitat and nutrition. This relationship is  called a symbiotic relationship.
  • Example: Lichens.
    • It  consists of an algae and a fungus.
    • Algae contain chlorophyll, so it provides food by photosynthesis.
    • The fungus provides algae with space, water, and minerals to live.

 

5. Replenishment of Nutrients in the Soil

• Plants constantly absorb nutrients (e.g. nitrogen, phosphorus, potassium)  from the soil.
• This leads to a lack of nutrients in the soil.
• Methods of nutrient replenishment:
  •  Adding Fertilizers and Manures:  These replenish the essential nutrients (nitrogen, potassium, phosphorus, etc.)  in the soil.
  •  Crop rotation: Growing one crop after another that helps in retaining soil nutrients (such as leguminous crops after grains).
  •  Rhizobium Bacteria:
    • These   bacteria   live in the nodules of roots of leguminous plants (e.g. chickpeas, peas, moong, pulses).
    • These convert atmospheric nitrogen into a useful form in the soil, thereby increasing soil fertility.
    • This is an example of a symbiotic relationship.