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Nutrition in Plants
Introduction:
- Food is crucial for all living organisms.
- Nutrients like carbohydrates, proteins, fats, vitamins, and minerals are essential for our bodies.
- Nutrition is the mode of taking food by an organism and its utilisation by the body.
Plants’ Mode of Nutrition:
- Unlike animals, plants can make their own food.
- They use water, carbon dioxide, and minerals from their surroundings to prepare food.
- This process is known as autotrophic nutrition, making plants autotrophs.
Heterotrophic Nutrition:
- Animals and most other organisms rely on plants for food.
- They are termed heterotrophs because they consume food prepared by other organisms.
Questions to Explore:
- Where are the food factories in plants located?
- Do all parts of a plant produce food, or only specific parts?
- How do plants obtain raw materials from their surroundings, and how do they transport them to their food factories?
Photosynthesis: The Plant’s Food-Making Process
Photosynthesis is the process by which plants make food using chlorophyll, sunlight, carbon dioxide, and water.
Leaves: Food Factories:
- Leaves play a vital role as food factories in plants.
- They receive all necessary raw materials for photosynthesis.
Raw Material Transport:
- Water and minerals from the soil are absorbed by roots and transported to leaves.
- Carbon dioxide from the air enters through tiny pores called stomata on leaf surfaces.
Role of Chlorophyll:
- Chlorophyll, the green pigment in leaves, captures sunlight energy.
- This energy is used to synthesize food from carbon dioxide and water.
Photosynthesis Process:
- Photosynthesis combines carbon dioxide and water in the presence of sunlight to produce carbohydrates and oxygen.
- The equation for photosynthesis: Carbon dioxide + water = Carbohydrate + oxygen.
Importance of Photosynthesis:
- Photosynthesis is essential for food production and oxygen release.
- It sustains life by providing food for organisms and producing oxygen necessary for survival.
Activity to demonstrate Photosynthesis:
- Conducting an iodine test on leaves to observe starch presence indicates photosynthesis occurrence.
- Leaves, even if not green, can perform photosynthesis due to chlorophyll presence.
Algae and Photosynthesis:
- Algae, often seen as green patches in water bodies, contain chlorophyll and perform photosynthesis.
Synthesis of Plant Food:
- Photosynthesis synthesizes carbohydrates, which are then used to create proteins and fats.
- Nitrogen, required for protein synthesis, is obtained by plants from soil bacteria or nitrogen-rich fertilizers.
Cell : The Building Blocks of Life
What are Cells?
– Cells are tiny units that make up the bodies of living organisms.
– They are like the bricks that make up a building.
– Cells can only be seen under a microscope.
Cell Structure:
– Each cell is enclosed by a thin outer boundary called the cell membrane.
– Most cells have a centrally located structure called the nucleus.
– The nucleus is surrounded by a jelly-like substance called cytoplasm.
Photosynthesis Beyond Leaves:
– Photosynthesis, the process of making food, also occurs in green stems and branches of plants.
– Some desert plants have modified leaves to reduce water loss, so their green stems carry out photosynthesis.
Other Modes of Nutrition in Plants
Some plants lack chlorophyll and cannot make their own food. They depend on other plants for nutrition, using the heterotrophic mode of nutrition.
Parasitic Plants:
Plants like Cuscuta (Amarbel), twines around other plants and derives nutrients from them. It’s called a parasite because it deprives its host of nutrients.
- Carnivorous (Insectivorous) Plants: Some plants can trap and digest insects for nutrients. For instance, the pitcher plant has a modified leaf forming a pitcher-like structure. Insects get trapped inside, digested by the plant’s juices, and absorbed as nutrients.
- Reason behind Carnivorous behavior of plants: These plants may not get all necessary nutrients from the soil alone, leading them to adopt carnivorous behaviors to supplement their diet.
Saprotrophs: Nature’s Recyclers
- Saprotrophic Nutrition: Fungi absorb nutrients from dead and decaying matter, a process known as saprotrophic nutrition.
- Organisms with this mode of nutrition are called saprotrophs.
- Mushrooms and fluffy patches seen in moist soils or on rotting wood are examples of fungi.
Activity to Observe Fungi in Household objects:
Conduct an experiment by moistening a piece of bread and observing the appearance of fluffy patches. These patches are actually fungal growth.
- Effects of Fungi: Fungi grow on various items like pickles, leather, and clothes, especially in hot and humid weather, causing spoilage. Discuss with parents about fungal issues at home.
- Spread of Fungal Spores: Fungal spores are airborne and germinate on wet and warm surfaces. Understanding this can help protect items from fungal spoilage.
Symbiosis
- Symbiotic Relationships: Some organisms, like certain fungi and plants, share a symbiotic relationship where they mutually benefit each other. For instance, fungi living inside plant roots exchange nutrients with the plant.
- Lichens: Lichens are unique partnerships between algae and fungi. The fungus provides shelter and nutrients, while the alga(having chlorophyll) produces food through photosynthesis, benefiting both partners.
Maintaining/Replenishing Soil Nutrients
Maintaining Soil Nutrients
- Farmers and gardeners often spread manure or fertilisers in fields or gardens to replenish soil nutrients. But why is this necessary?
- Nutrient Depletion & Nitrogen Deficiency: Plants absorb minerals and nutrients from the soil, leading to a decline in their levels over time.
- Crop plants, especially, absorb a lot of nitrogen, causing the soil to become deficient in this nutrient. While nitrogen gas is abundant in the air, plants cannot utilize it directly.
Two ways to replenish plant nutrients in the soil:-
(a) Adding Fertilizers & manures-
Fertilisers and manures contain essential nutrients like nitrogen, potassium, and phosphorous, which need to be added periodically to enrich the soil.
(b) Growing Leguminous crops-
Rhizobium, a bacterium, converts atmospheric nitrogen into a usable form. It forms a symbiotic relationship with leguminous plants like gram, peas, and beans, providing them with nitrogen in exchange for food and shelter.
Symbiotic Relationship
The association between Rhizobium and leguminous plants is significant for farmers as it reduces the need for nitrogenous fertilisers.
This relationship illustrates how plants and bacteria mutually benefit each other.
Autotrophs
Most plants are autotrophs, producing their own food through photosynthesis. However, some plants are parasitic or saprotrophic..Tap to read more about them.
Heterotrophs
Some plants are parasitic or saprotrophic, obtaining nutrients from other organisms. Animals, on the other hand, are heterotrophs, relying on plants or other animals for food. Insectivorous plants, which trap and digest insects for nutrients, could be considered partial heterotrophs due to their unique feeding habits.
Chapter Summary:
- All organisms need food for energy and body maintenance.
- Green plants make their food through photosynthesis, making them autotrophs.
- Plants like Cuscuta are parasites, obtaining food from host plants.
- Plants use simple substances like carbon dioxide, water, and minerals for food synthesis.
- Photosynthesis requires chlorophyll, water, carbon dioxide, and sunlight.
- Carbohydrates are the complex substances produced during photosynthesis.
- Chlorophyll in leaves absorbs solar energy for photosynthesis.
- Oxygen is a byproduct of photosynthesis.
- Oxygen released is vital for the survival of living organisms.
- Fungi that obtain nutrients from decaying matter are saprotrophs.
- Some plants and all animals rely on others for nutrition, known as heterotrophs.
keywords
- Autotrophic
- Chlorophyll
- Heterotrophs
- Host
- Insectivorous
- Nutrient
- Nutrition
- Parasite
- Photosynthesis
- Saprotrophs
- Saprotrophic
- Stomata
