Nutrition in Plants

• Food is essential for all living organisms
• Carbohydrates, proteins, fats, vitamins, and minerals are components of food and are called nutrients
• All organisms need food, but only plants can create their own
• Humans and animals get food from plants or plant-eating animals, thus depending directly or indirectly on plants

Mode of Nutrition in Plants

• Plants use water, carbon dioxide, and minerals to prepare food
• Nutrients help organisms build, grow, repair, and energize
• Nutrition involves taking and utilizing food
• Autotrophic nutrition involves organisms making food from simple substances, and organisms that do this are autotrophs
• Animals and other organisms consume food prepared by plants and are called heterotrophs

Photosynthesis

• Leaves are the food factories for plants
• Water and minerals from the soil are transported to the leaves
• Carbon dioxide is taken in from the air
• Cells are tiny units that make up the bodies of living organisms
• Cells can only be seen under a microscope
• A cell is enclosed by a cell membrane, which is a thin outer boundary
• Most cells contain a distinct, centrally located spherical structure called the nucleus
• The nucleus is surrounded by a jelly-like substance called cytoplasm
• Leaves intake carbon dioxide through stomata, which are tiny pores surrounded by guard cells
• Vessels transport water and minerals from the roots to the leaves through the stem and branches
• Leaves contain a green pigment called chlorophyll
• Chlorophyll captures sunlight to synthesize food from carbon dioxide and water through photosynthesis
• Chlorophyll, sunlight, carbon dioxide, and water are necessary for photosynthesis
• The sun is the ultimate source of energy for all living organisms
• In the absence of photosynthesis there would be no food or oxygen
• Photosynthesis also takes place in green stems and branches
• Desert plants with reduced leaves transpire with green stems
• During photosynthesis, chlorophyll-containing cells use sunlight, carbon dioxide, and water to make carbohydrates
• The equation of photosynthesis is Carbon dioxide + water + sunlight + chlorophyll = Carbohydrate + oxygen
• Oxygen is released during photosynthesis
• Starch indicates photosynthesis has occurred
• Starch is also a carbohydrate
• Leaves that are not green can still photosynthesize

Synthesis of Plant Food

• Plants synthesize carbohydrates during photosynthesis and use them to produce proteins and fats
• Proteins are nitrogenous and contain nitrogen
• Plants cannot absorb nitrogen in its gaseous form
• Bacteria in the soil convert gaseous nitrogen into a usable form for plants
• Farmers use fertilizers that are rich in nitrogen, so plants can synthesize proteins and vitamins

Other Modes of Nutrition

• Plants without chlorophyll cannot synthesize food
• Plants that can't synthesize food use heterotrophic nutrition
• An example is Cuscuta (Amarbel), which is a parasite that climbs another plant (the host) for readymade food
• Insectivorous plants digest trapped insects for nutrients
• Saprotrophs use saprotrophic nutrition
• Fungi are saprotrophs that get nutrition from dead, decaying matter
• Fungi spores in the air land on wet, warm things and grow
• Symbiosis is when organisms live together and share shelter and nutrients
• Fungi live in plant roots in symbiosis and give back water and certain nutrients
• Lichens involve algae (a chlorophyll-containing partner) and fungi living together
• The alga prepares and provides food while the fungus provides shelter, water, and minerals

Replenishing Nutrients in the Soil

• Farmers use manure and fertilizers for nutrients in the soil
• Fertilizers and manures contain nutrients like nitrogen, potassium, and phosphorous
• Rhizobium is a bacterium that converts atmospheric nitrogen into a usable form
• Rhizobium lives in the roots of legumes and provides them with nitrogen
• This symbiotic relationship reduces the need for nitrogenous fertilizer for leguminous plants

This lesson covers the essentials of nutrition in plants. It explains how plants, unlike animals, can produce their own food through photosynthesis. It details autotrophic and heterotrophic modes of nutrition and the importance of leaves in the process.