Photosynthesis Flashcards
Define photosynthesis
A process whereby carbon dioxide and water are combined, in the presence of chlorophyll and light energy, to form energy rich carbohydrates. During this process oxygen is released
Photosynthesis can be done by heterotrophs or autotrophs. Why?
Autotrophic organisms since they manufacture their own food and are therefore producers in any ecosystem
Where does photosynthesis occur?
Within the chloroplast of plant cells
Requirements for photosynthesis?
- carbon dioxide: from atmosphere
- water: absorbed by root and delivered via xylem
- chlorophyll (present in chloroplast)
- energy (sunlight)
- enzymes
Products of photosynthesis?
- glucose: high-energy; soluble; converted to insoluble starch and stored
- oxygen: released into atmosphere via stomatal pores
Reaction for photosynthesis
6CO² + 6H²O~> C⁶H¹²O⁶ + 6O²
Carbon dioxide + water ~light, chlorophyll, enzymes~> glucose + oxygen
Photosynthesis is divided into 2 phases the…?
Light dependent phase(light phase)
-Light energy is essential
Light independent phase(dark phase)
-Light is not required
Where do Light dependent reactions occur?
On photosynthetic membranes
Structure of a chloroplast
- starch grain(stores starch)
- intergranum
- granum(stack of thylakiods)
- stomata
- thylakiod
- double membrane
Function of the double membrane?
Permeable to oxygen, CO², water and glucose
Function of the granum(Stack of thylakiods) and the intergranum?
Stacked thylakiods increase area for light absorption
The intergranum connects one granum to another
Function of the thylakiod?
- photosynthetic membranes
- contains chlorophyll for photosynthesis
List the functions of the stroma
- a semi-liquid that bathes the interior of chloroplasts
- contains enzymes for light independent phase for photosynthesis
- has ribosomes which make enzymes for photosynthesis
Where does the light phase(light-dependent) take place?
In the grana (of the chloroplast)
Where does the dark phase(light-independent) take place?
In the stroma (of the chloroplast)
What happens during the light phase?
In the grana of the chloroplast, chlorophyll molecules absorb radiant energy.
Some of energy is used to split water(from soil) into hydrogen and oxygen by process of photlysis.
Oxygen released through stomatal pores.
Energized hydrogen taken up by carrier and uses in next phase
Define photolysis
A process whereby energy(light) is used to split water into hydrogen and oxygen
What happens during the dark phase(light-independent)
Immediately after the light phase, carbon dioxide from the atmosphere enters the leaf through the stomatal pores.
In the stroma of the chloroplast, the carbon and oxygen of CO², combines with the energized hydrogen(released in light phase) to form glucose.
Energy required from this phase come from the light phase
List the factors that affect the rate of photosynthesis
- Carbon dioxide concentration
- Light intensity
- Temperature
Explain how carbon dioxide concentration affects photosynthesis
Carbon dioxide is essential for photosynthesis. When CO² concentration is low, the rate of photosynthesis is low. (Directly proportional)
Explain why the rate of photosynthesis drops at very high CO² levels
The excess CO² combines with H²O to form carbonic acid. Acidic conditions damage enzymes(that control photosynthesis) causing the drop in the rate of photosynthesis
Describe the relationship between light intensity and the rate of photosynthesis
Directly proportional
Low light intensity, low rate of photosynthesis.
Light intensity increases, rate of photosynthesis also increases up to optimum
What happens when light intensity increases beyond optimum?
Light intensity does not result in an increase in the rate of photosynthesis
How does Temperature affect the rate of photosynthesis?
As temperature increases, rate of photosynthesis also increases until an optimum temperature of 25°C is reached
What happens to the rate of photosynthesis when the temperature increases above the optimum temperature(I.e. 25°C)
Causes the rate of photosynthesis to rapidly decline
What is the purpose of a greenhouse?
A greenhouse has a structure built specially for growing plants in a controlled environment.
Allows sunlight to get to plants while preventing pests, birds and other animals
Name a few variables controlled in a greenhouse
The amount of water and nutrients
Other environmental conditions are CO² levels, light and temperature
What is the purpose of carbon dioxide enrichment in a green house system
Rate of photosynthesis increases. This will result in an increase in plant growth and crop yield
Optimum light in a greenhouse system
Amount of light in green house adjusted ot optimum light to maximize rate of of photosynthesis.
Artificial light- enhances light conditions
Shade cloths- reduce amount of light that gets to plants
Why is temperature kept at optimum in a greenhouse system?
Maximize plant growth
Cold days- heaters are used
Hot fays- fans are used
>Plant in greenhouse grow in an ideal temperature to improve crop yield
What does ATP stand for
Adenosine triphosphate
What is ATP?
Adenosine triphosphate is an organic compound and hydrotrope that provides energy to drive many processes in living cells, such as muscle contraction, nerve impulse propagation, condensate dissolution, and chemical synthesis.
-The high energy carrier in plants and animals
Purpose of ATP
High-energy carrier.
When ATP breaks down, energy is released and is used by the cell for metabolic work
Where is ATP formed
Some ATP is formed in the cytosol while most is formed within the mitochondria
