Plant nutrition Flashcards
Photosynthesis
the process by which plants synthesize carbohydrates from raw materials using energy from light.
Photosynthesis reaction
Carbon dioxide + water → glucose + oxygen (in the presence of light and chlorophyll)
Chlorophyll
green pigment that is found in chloroplasts.
Chlorophyll transfers energy from light into
in chemicals, for the synthesis of carbohydrates.
Uses of glucose:
glucose used in respiration to provide energy
Protein contains not only carbon, hydrogen, oxygen, but also
nitrogen
Therefore, in
order to make amino acids plants need a source of
nitrogen, and they get this nitrogen from nitrite ions. They use this nitrate ion to make amino acids and use this amino acid to make protein which is used for growth. If the plant cannot get enough nitrate ions, it will not be able to synthesize protein effectively. And so will not grow quickly or strongly.
Chlorophyll is not a protein, but it contains
nitrogen. It also contains magnesium
a plant needs magnesium ions as well as nitrite ions to make
chlorophyll.Without these ions, the plant will look yellow and not green, suggesting that there are not plenty of chlorophylls present. If the plant cannot make lots of chlorophyll, it will not be able to photosynthesize well, and will therefore not grow well.
Limiting factors for photosynthesis are
1) light intensity
2) carbon dioxide concentration
3) temperature
Light intensity.
As the light intensity increase, the rate of photosynthesis increase until the the plant is photosynthesizing as fast as it can.
Carbon dioxide concentration.
The more carbon dioxide a plant is given the faster it can photosynthesis. But once the carbon dioxide concentration reaches a certain level, there is no further increase in the rate of photosynthesis.
Temperature.
As the temperature increase, the rate of photosynthesis is also increased. But after the optimum temperature, the rate of reaction decreases.
Stomata.
Carbon dioxide diffuses into the leaf through the stomata. If the stomata are closed, photosynthesis cannot take place because the plant lacks one of its raw materials - carbon dioxide. Stomata are often closed during hot weather to prevent water loss. This means that on a really hot or bright day,photosynthesis may slow down.
Leaves have large surface area and are thin
- This large surface area allows a large amount of sunlight to fall onto the leaves. The large surface area also increases the rate at which carbon dioxide can diffuse into the leaf from the air. Being thin means that sunlight can pass right through the leaf, allowing many cells inside it to photosynthesise. The thinness also helps carbon dioxide to reach all the cells quite quickly by diffusion
