Choose an angiosperm with at least 1 unusual organ, characteristic, modification
ID: 282760 • Letter: C
Question
Choose an angiosperm with at least 1 unusual organ, characteristic, modification, or adaptation.
Describe the anatomy (structure) and physiology (function) of the angiosperm you chose.
Explain the unusual characteristic(s) or modification(s) and how it differs from the standard root, stem, leaf, or flower.
What benefit does the modification provide to the plant you chose?
Research at least 1 other plant, or review posts made by your peers to devise a potentially advantageous new adaptation that would benefit your plant.
Consider the environment, potential threats, and changing climate, and then come up with an adaptation that would further benefit your angiosperm. Explain the potential concern your plant will face and how your new adaptation would benefit the plant. For example, gypsy moth is an introduced species spreading west and south from New England. The caterpillars can strip all of the leaves from a maple tree but do not eat the waxy leaves of holly that produce a toxin, theobromine. If maple trees had waxy, toxic leaves like the holly, then they would be protected from these pests.
Explanation / Answer
Example 1:
Legumes like alfalfa, clover, pea, groundnut, beans, chickpeas etc have nodules in their roots which host the nitrogen fixing bacteria. This adaptation helps in nitrogen fixing and gain nitrogen in the form of nitrates. Bacteria provide the plants with reduced nitrogen forms which conserves the energy of the plants than non reduced forms.
This adaptation can also be used by the companion crop when the root nodule is sloughed off into the soil. Thus legumes are called as green manure crops, as they increase the nitrogen in the soil and helps in next crops when they are grown on the same soil. This adaptation also benefits the legumes as well as companion crop to prevent water or soil loss.
Structure and function: Root nodule is a specialzed organ where bacteria can be hosted intracellularly without inhibiting or altering plant cell functions. The bacteria invades the root cells and they are pinched from endoplasmic reticulum in vesicle and sequestered. The movement of bacteria towards the nodules is based upon legume signalling (which involves release of flavones or isoflavones by which bacteria attach to the root hairs) and bacteria signalling where bacteria release nodulation factors in response to legume signalling. The root hairs curl around the bacterium which results in bacterial entrapment. The root hair experiences growth inward and makes tube. The infection thread further allows the bacteria to move inward.
Unusual characteristic: Formation of root nodule on the roots of legumes is the unusual characteristic of this modification.
N2 --Nitrogenase---> 2NH3
The enzyme nitrogenase facilitates the above reaction in the root nodule which is an exergonic reaction and thus helps in nitrogen fixation.
Benefit: Nitrogen fixation
Further benefit: The root nodules of legumes and nitrogen fixing bacteria mutualistic relationship is dependent upon the bulk density of the soil, legume spacing, rooting, plant and bacterial species. By enabling the above factors the adaptation can be further benefitting the plant
Example 2: Xerophytes have adaptations for extreme tropical climates. They have smaller leaves, densely packed spongy mesophyll, thicker waxy cuticle on leaves, closing stomata in pits, hair on the surface of the leaves, rolled leaves
Structure and function: The leaves have lesser surface area which reduces the water loss through transpiration
Densely packed spongy mesophyll reduces the rate of water loss, thicker waxy cuticle on leaves reduces evaporation and thus the reduces teh need of water uptake, closing stomata in pits reduces evaporation as well as helpful in air entrapment that lowers the water potential gradient. Rolling of leaves prevent the lower epidermis from being exposed to the atmosphere
Benefit: All the above said adaptations will help the plant to survive with meagre water resources and extreme temperatures
Example 3: Rhizome
Structure and function: Rhizome is a stem modification which is typically horizontal stem that is under or partially in the groun and bears the leaves on its upper surface and roots on the lower surface
Unusual characteristic:Growing horizontally instead of vertically, staying partially or completely under ground unlike normal stem
Benefit: It helps in rapid invasion and spread of the plant in its habitat. It also helps in optimum utilization of the nutrients
Further benefit: By condensation of the rhizome and avoiding the boundary or limiting its surroundings the plant will be benefitted from rapid spread and immense growth.
Example 4: Tendril
Anatomy and function: Tendril is a stem modification which is slender, coiling structure which helps in providing the support to the plant. It is usally located in the axil of a leaf.
Unusual characteristic: It helps in providing mechanical support and spread of the plant by anchoring nearby plants or supports and thus help in accumulation of light energy (sunlight) and nutrients
Benefit: Mechanical support
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