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Plant physiology

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Plant physiology is a specialized branch of botany. It focuses on the internal functioning of plants.

Plant physiology
Plant physiology

Scientists who study these processes are called plant physiologists. They investigate the chemical and physical activities that sustain plant life. This field explores many different scales of size and time. Researchers look at tiny molecular interactions within a single cell. They also study large-scale processes like seasonal changes and plant development. Understanding these systems is vital for grasping how life operates on Earth.

Plants rely on complex mechanisms to transform their environment into energy. The process of photosynthesis is a primary example.

Chlorophyll-a-3D-vdW
Chlorophyll-a-3D-vdW

To begin, plants use specialized molecules called pigments to absorb light. Chlorophyll is the most important pigment for this task. It absorbs red and blue wavelengths of light. Because it reflects green light, plants appear green to our eyes. Other pigments, known as carotenoids, act as accessory pigments. These include carotene, lutein, and lycopene. They gather light wavelengths that chlorophyll cannot absorb easily. This captured energy helps power the chemical reactions needed to manufacture nutrients.

Once nutrients are created, they must move through the plant. Plant cells have unique features that help manage this. For example, plant cells possess a rigid cell wall to maintain their shape. Different tissues are specialized to perform specific tasks. Roots and rhizoids anchor the plant in the soil. They also acquire essential minerals. Leaves catch sunlight to produce food. To keep both organs alive, the plant must transport materials between them. Plants use specialized vascular tissue to move minerals from roots to leaves. They also move manufactured nutrients from leaves back down to the roots.

Plants also manage their growth through chemical signaling. They produce chemicals called plant growth regulators, or phytohormones.

Auxin
Auxin

These hormones signal cells in one part of the plant to respond to another. Unlike animals, plants do not have specific organs dedicated to making hormones. Instead, hormones are produced in various locations and influence many processes. They regulate which tissues grow upward or downward. They also control flowering, seed development, and dormancy. Some hormones, like the gas ethylene, control the ripening of fruit. Others help plants respond to light through a process called photoperiodism. This allows plants to bloom based on the length of the night.

To build their structures, plants require specific chemical elements. These elements are categorized by the amount a plant needs. Macronutrients are required in large quantities. These include nitrogen, carbon, oxygen, hydrogen, potassium, calcium, magnesium, phosphorus, and sulfur. For example, nitrogen is essential for making proteins and nucleic acids. Magnesium is a critical component of chlorophyll. In contrast, micronutrients are needed only in trace amounts. These include iron, boron, manganese, zinc, copper, molybdenum, nickel, and chlorine. Most micronutrients are absorbed as ions dissolved in water from the soil.

Pigments also serve many roles beyond photosynthesis. Anthocyanins are water-soluble pigments that appear red to blue.

orange violet pansies
orange violet pansies

These pigments are found in leaves, stems, roots, flowers, and fruits. In some tropical plants, anthocyanins help maximize light use. Another class of pigments is called betalains. These are red or yellow and are found only in the order Caryophyllales. They are responsible for the deep red color in beets. While scientists are still studying their exact purpose, betalains may have fungicidal properties. These pigments help plants interact with their environment and attract pollinators.

Plant physiology has immense significance for human society. Many plant compounds have pharmacological activity. For instance, salicylic acid is used to create aspirin. Other plants provide morphine or digoxin for medicine. Drug companies spend billions of dollars researching these compounds. Plants also provide raw materials like rubber and biofuel.

Latex dripping
Latex dripping

Even the colors in our food, like the red in tomatoes, come from plant physiology. By studying these systems, we connect biology to chemistry, ecology, and medicine. This knowledge helps us manage crops and understand the natural world.

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🖼️ Images & Media (10)
File:Kiemtafel (germination table).jpg
Kiemtafel (germination table).jpg
File:Plant physiology.png
Plant physiology.png
File:Latex dripping.JPG
Latex dripping.JPG
File:Chlorophyll-a-3D-vdW.png
Chlorophyll-a-3D-vdW.png
File:orange violet pansies.jpg
orange violet pansies.jpg
File:Auxin.jpg
Auxin.jpg
File:Poinsettia 2.jpg
Poinsettia 2.jpg
File:Arabidopsis thaliana.jpg
Arabidopsis thaliana.jpg
File:Powdery mildew.JPG
Powdery mildew.JPG
File:Portrait of J.B. van Helmont, Aufgang...1683 Wellcome L0003194.jpg
Portrait of J.B. van Helmont,...
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