HOW DOES PHOTOSYNTHESIS INFLUENCE PLANT GROWTH AND DEVELOPMENT?

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HOW DOES PHOTOSYNTHESIS INFLUENCE PLANT GROWTH AND DEVELOPMENT? by Mind Map: HOW DOES PHOTOSYNTHESIS INFLUENCE PLANT GROWTH AND DEVELOPMENT?

1. TRANSPIRATIONS

1.1. When a leaf's guard cells shrink, its stomata open, and water is lost. This process is called transpiration.

1.2. In turn, more water is pulled through the plant from the roots. The rate of transpiration is directly related to whether stomata are open or closed.

1.3. Transpiration is a necessary process and uses about 90 percent of the water that enters a plant's roots.

1.4. The amount and rate of water loss depends on factors such as temperature, humidity, and wind or air movement. Transpiration often is greatest in hot, dry (low relative humidity), windy weather.

1.5. Photosynthesis takes place in the part of the plant cell containing chloroplasts, these are small structures that contain chlorophyll. For photosynthesis to take place, plants need to take in carbon dioxide (from the air), water (from the ground) and light (usually from the sun).

2. ENERGY/FOODS

2.1. Photosynthesis process produce foods/ energy for the plant and it is used for plant growth. Foods as product helps in growth of shoots, leaves and to form new buds.

2.2. Auxins promote stem elongation, inhibit growth of lateral buds (maintains apical dominance)

2.3. They are produced in the stem, buds, and root tips. Example: Indole Acetic Acid (IA). Auxin is a plant hormone produced in the stem tip that promotes cell elongation. Auxin moves to the darker side of the plant, causing the cells there to grow larger than corresponding cells on the lighter side of the plant. This produces a curving of the plant stem tip toward the light, a plant movement known as phototropism.

2.4. Auxin also plays a role in maintaining apical dominance. Most plants have lateral (sometimes called axillary) buds located at nodes (where leaves attach to the stem).

3. PHOTOSYNTHETIC RESPONSE TO CO2 CONCENTRATION

3.1. Leaf photosynthesis is readily observed to increase with increasing CO2 concentration (Drake et al., 1997)

3.2. Photosynthesis shifts from limitation by Rubisco kinetics at lower intercellular CO2 concentrations to RuBP regeneration-limited rates at higher concentration.

3.3. At lower radiation levels, photosynthesis is also generally RuBP regeneration limited

3.4. For parts of the day with lower temperature or lower radiation, or for canopies where a proportion of leaves experience reduced light levels through self-shading, the enhancement of photosynthesis is likely to be less. Conversely, for plants experiencing times of high temperatures, the photosynthetic stimulation could be even greater than that measured under moderate temperatures.

4. PHOTOASSIMILATION

4.1. To produce food, a plant requires energy from the sun, carbon dioxide from the air, and water from the soil. During photosynthesis, it splits carbon dioxide into carbon and oxygen, adds water, and forms carbohydrates (starches and sugars). Oxygen is a by-product.

4.2. Carbon dioxide + Water + Sunlight = Sugar + Oxygen or 6 CO2 + 6 H20 + Energy => C6H1206 + 6 02

4.3. Photoassimilates generated in the mesophyll cells, such as sucrose, various oligosaccharides, polyols as well as amino acids, diffuse via plasmodesmata to the bundle sheath cells.

4.4. photoassimilates are translocated by the transport phloem, located in leaf major veins, petioles, stems, and roots, to be distributed between sink organs.

4.5. In apoplastic phloem loading, found for instance in the leaves of cereals, sugar beet, rapeseed, and potato, photoassimilates are first transported from the source cells via the bundle sheath cells to the extracellular compartment, the apoplast, and then by active transport into the sieve tube compartment

4.6. Concentration of sucrose, polyols and amino acids in the source cells is very much higher than in the apoplast, this export does not seem to require any energy input.

4.7. The transport of sucrose and amino acids from the apoplasts to the phloem proceeds via a proton symport

4.8. This is driven by a proton gradient between the apoplast and the interior of the companion cells and the sieve tubes. The proton gradient is generated by an H + -P ATPase present in the plasma membrane.

4.9. The required ATP is produced by mitochondrial oxidation.