AUTOTROPHICS

The mode of nutrition in which organisms synthesize their own food using inorganic materials such as carbon dioxide, water, and minerals is called autotrophic nutrition Organisms that exhibit this kind of nutrition are autotrophs (auto: self; trophy: nutrition). Green plants are also called producers as they produce food for all living organisms.

GREEN PLANTS

Think about what Earth looks like from outer space. You probably see the blue of the oceans and the green land of the continents. Why does the land look green? Because of plants! But what makes plants green? That's a little more complicated. Plants look green because of a natural pigment called chlorophyll. Chlorophyll absorbs the red, blue, and other wavelengths of light, and it reflects the green back to your eyes, so that is what you see.

ESSENTIAL COMPONENTS FOR PHOTOSYNTHESIS

CHLOROPLAST

ROOT

STOMATA

CHLOROPLAST

The chloroplast contains chlorophyll but Does chlorophyll have any other uses in plants, besides making them appear green? Definitely! Chlorophyll and light energy are both important for plants in another way, too. Plants trap light energy from the sun. They combine this light energy with carbon dioxide from the air as well as water. They turn these into sugars that act as food for the plant. This whole process is called photosynthesis. Chlorophyll traps the light from the sun to be used for photosynthesis, so without chlorophyll, plants could not survive!

BELOW IS THE MICROSCOPIC VIDEOS OF THE PLANT CELL WHICH CONTAINS CHLOROPLAST

CHLOROPLAST IN WATERWEED PLANTS

(AQUATIC PLANT)

CHLOROPLAST IN CERATODON PURPUREUS PLANT

LEAF

CHLOROPLAST

STOMATA

• Stomata, also called Stoma, plural Stomata, or Stomas, any of the microscopic openings or pores in the epidermis of leaves and young stems. Stomates are generally more numerous on the underside of leaves. They provide for the exchange of gases between the outside air and the branched system of interconnecting air canals within the leaf.

• A stomate opens and closes in response to the internal pressure of two sausage-shaped guard cells that surround it. The inner wall of a guard cell is thicker than the outer wall. When the guard cell is filled with water and it becomes turgid, the outer wall balloons outward, drawing the inner wall with it and causing the stomate to enlarge.

• Guard cells work to control excessive water loss, closing on hot, dry, or windy days and opening when conditions are more favourable for gas exchange. At dawn a sudden increase in stomatal opening, reaching maximum near noon, is followed by a decline because of water loss. Recovery and reopening are then followed by another decline as darkness approaches.

• The concentration of carbon dioxide in the air is another regulator of stomatal opening in many plants. When carbon dioxide levels fall below normal (about 0.03 percent), the guard cells become turgid and the stomata enlarge.

CLOSING OF STOMATA

LEAF SECTION - SHOWING THE STOMATA

Below are close-up diagrams from different perspective to illustrate the cross section of the leaf - You would be able to see the veins of the leaf, the upper layer of the leafs and the lower layer of leafs and also showing the stomata opening.

ROOTS

GENERAL OVERVIEW

• Root is that part of a vascular plant normally underground. Its primary functions are anchorage of the plant, absorption of water, dissolved minerals and conduction of these to the stem.

Primary or Main Functions of Roots:

  • Anchorage: Roots take part in fixation of the plant and supporting the aerial shoot system.

  • Absorption of Water: Roots absorb water from soil.

  • Absorption of Minerals: Roots absorb mineral salts from soil.

  • Prevention of Soil Erosion: Roots hold the soil particles firmly to prevent soil erosion.

  • Transport: They take part in transport of absorbed water and minerals to shoot system. Similarly, root has channels for the flow of organic food from aerial parts.

Secondary or Accessory Functions of Roots:

  • Storage: It occurs in fleshy roots.

  • Climbing: Roots help some of the weak stemmed plants to cling and hence climb up a support, e.g., Ivy, Tecoma, Betel, and Money Plant.

  • Perennation: In many biennial and perennial plants e.g., Trichosanthes.

  • Nitrogen Fixation: Nodulated roots of Pea, Bean, Gram, Methi, etc.

  • Aeration: Prop roots, knee roots and pneumatophores of Mangrove plants, e.g., Rhizophora, Heritiera, Sonneratia.

  • Floating: By storing air (e.g., Jussiaea = Ludwigia) some of the roots function as floats.

  • Balancing: Free floating plants usually possess a cluster of adventitious roots from their nodes and bases to help in balancing the plants over the water surface, e.g., Lemna, Pistia, Eichhornia.

BELOW IS THE FAST FORWARDED VIDEO OF POTATO PLANT ROOTS GROWING.

POTATOES GROWING ROOTS (FAST FORWARD)

ROOTS TRANSPORT WATER AND MINERAL THROUGH

XYLEM

PHLOEM

Play Video

Transport in Plants - Xylem and Phloem

PHOTOSYNTHESIS

• The leaves of green plants have a green pigment In some plants, this green pigment may also be present in the stem and some other parts of the plant. This green pigment is called chlorophyll. Chlorophyll is present in the form of tablets called chloroplast. Green chloroplast has the tendency to trap the energy of sunlight.

• Plants absorb water from the soil with the help of its roots. This water is pushed up to the leaves through the stem. Leaves absorb carbon dioxide from the air through pores called stomata. Stomata are more on the underside of a leaf than on its upper surface.

• Light energy from sunlight is trapped by the chlorophyll, which is converted into chemical energy by the chloroplast (green Guard pigment). Using the energy from the sun, a chemical reaction takes place in the green parts of the plant, in which carbon dioxide and water are converted into food. Since the synthesis of food occurs in the presence of sunlight, it is called photosynthesis (photo light;synthesis-combination of components).

• In the process of photosynthesis, the first food product is sugar which is immediately transformed into starch. Along with the production of glucose process. This oxygen is released into the air, maintaining the level of oxygen in the air.

PHOTOSYNTHESIS

INTAKE AND OUTPUT OF LEAF

HETEROTROPHIC

• All the animals and non-green plants cannot prepare their own food. They depend on green plants directly or indirectly for their food. Therefore they are called heterotrophs (hetero-other; trophy-nutrition) and the mode of nutrition is called heterotrophic nutrition. Heterotrophic plants may obtain their food from decaying or plants and animals.

• Heterotrophic plants do not contain chlorophyll. In some cases, the plant may have chlorophyll and can do photosynthesis, yet it is partially dependent on other organisms to derive some additional nutrition.

SOME EXAMPLES OF HETEROTROPHIC NUTRITION

PARASITIC NUTRITION

CASCUTA, RAFFLESIA

SAPROPHYTIC NUTRITION

MUSHROOM, FUNGI

INSECTIVOROUS NUTRITION

PITCHER PLANT

SYMBIOTIC NUTRITION

ALGAE, FUNGUS

PARASITIC NUTRITION - RAFFLESIA

Rafflesia is a parasitic plant which grows on the roots of the host plant. Its stem is highly reduced to fine threads growing into the tissue of the roots of the host plant from where it sucks its food. It is an interesting plant, as it bears the most gigantic (largest) flower in the world. The flower may have a diämeter of more than one meter and weigh approximately 10 kg. It smells bad like putrid meat.

STAGE 1

STAGE 2

STAGE 3

STAGE 4

STAGE 5

STAGE 6 - RAFFLESIA BLOOMING

STAGE 7 - RAFFLESIA DIES

RAFFLESIA

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SAPROPHYTIC NUTRITION - MUSHROOM AND FUNGI

Saprophytes are the organisms that obtain their food from dead and decaying matter. Examples are mushrooms and other fungi and bacteria. They secrete digestive juices on the dead and decaying matter This converts solid matter into liquid. They, then, absorb the nutrients from dead and decaying matter in the form of a liquid and this is known as saprotrophic nutrition. Fungi and bacteria that use this mode of nutrition are known as saprotrophs or saprophytes.

JUNGLE MUSHROOM CLUSTER

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EARTHBALL MUSHROOM

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JUNGLE MUSHROOM

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SHAGGY PARASOL MUSHROOM

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INSECTIVOROUS NUTRITION - PITCHER PLANT AND VENUS FLYTRAP

Another type of nutrition is found in some plants that prepare their own food but feed on insects to fulfill their requirement of nitrogen. The pitcher plant is an example of an insectivorous plant. In the pitcher plant, the leaf is modified to form a pitcher like structure. The apex of the leaf forms a lid like structure. This can open and close the mouth of the pitcher Many hairs like structures are present inside the pitcher. These hairs are directed downwards, When an insect gets attracted towards the pitcher and lands in the pitcher, the lid closes. The insect gets trapped inside the pitcher. The pitcher then secretes digestive juices which digest the insect. Such insect-catching plants are called insectivorous plants. Some other insectivorous plants are Bladderwort, Drosera and Venus flytrap.

PITCHER PLANT

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VIDEO OF THE VENUS PITCHER PLANT IN ACTION

VENUS FLYTRAP

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VIDEO OF THE VENUS FLYTRAP IN ACTION

SYMBIOTIC NUTRITION - ALGAE AND FUNGUS

• In another mode of nutrition, two different kinds of organisms work together for their mutual benefit. For example, algae, which is an autotroph and fungus, which is a saprophyte, live together as lichen. The fungus supplies water and minerals to the cells of the alga, while the algae supply food to the fungus. Such a mutually beneficial relationship is called symbiosis.

• Another common example is a Bacterium named Rhizobium which makes its home in the nodules on the root of leguminous (bean) plants. Rhizobium has the ability of fixing air nitrogen into oxides of nitrogen. An oxide of nitrogen is nutrition for green plants and it makes the soil fertile.

LICHEN ON A FALLEN TREE TRUNK

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LICHEN ON A TREE TRUNK

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LICHEN ON A STEM OF A TREE

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