B8. Photosynthesis Flashcards
Define the term photosynthesis
The process by which plants use light energy to produce carbon compounds such as carbohydrates
What is the energy conversion that occurs during photosynthesis?
Light energy into chemical energy
What is the role of chloroplasts in photosynthesis?
The role of chloroplasts is to absorb light energy during photosynthesis
How is glucose inside plant cells?
Respiration
Storage, in the form of starch
The production of cellulose cell wall
Conversion into lipids and amino acids
What is the word equation for photosynthesis?
carbon dioxide + water ➡ glucose + oxygen
What is the role of water in the photosynthesis equation?
Water is a reactant in photosynthesis. It reacts with carbon dioxide to produce glucose and oxygen
What are the products of photosynthesis?
Glucose and oxygen
What happens to oxygen in photosynthesis?
Oxygen is produced as a waste products and released from leaves via the stomata.
What is the chemical formula for glucose?
C₆H₁₂O₆
Define the term endothermic reaction
An endothermic reaction is a chemical reaction which absorbs energy from its surroundings e.g. photosynthesis absorbs light energy
Is photosynthesis an exothermic or endothermic reaction?
Endothermic
Define the term limiting factor in the context of photosynthesis?
A factor that limits the rate of photosynthesis
What are the three main factors that limit the rate of photosynthesis
Temperature
Light intensity
Carbon dioxide concentration
Why does the rate of photosynthesis slow down at low temperatures?
Photosynthesis occurs slowly at low temperatures because molecules have little kinetic energy. This means that fewer successful collisions take place
Why do very high temperatures cause photosynthesis to stop?
The enzymes that control photosynthesis denature meaning that the reaction can no longer take place
What is the effect of increasing light intensity on the rate of photosynthesis?
The higher the light intensity, the faster the rate of photosynthesis
What is the effect of increasing carbon dioxide concentration on the rate of photosynthesis?
The higher the carbon dioxide concentration, the faster the rate of photosynthesis
What is shown by the inverse square law?
The inverse square law shows the relationship between light intensity and distance between the light source and the plant
How can the use of a greenhouse help to increase the yield of crop plants?
A greenhouse can increase the yield of crop plants because levels of carbon dioxide, water, light and temperature can be controlled more carefully whilst crops are kept free of pests. This supports an increase in the rate of photosynthesis, therefore increasing the growth of plants
How should a farmer determine the cost-effectiveness of using greenhouses to grow their crops?
The farmer will need to consider the cost of setting up the greenhouses as well as the running costs involved. They would then need to calculate the potential yield increase that they would expect to receive from the setup in order to work out their income.
A practical is done to investigate the effect of light intensity on the rate of photosynthesis. What is the independent variable?
Light intemsity
A practical is done to investigate the effect of light intensity on the rate of photosynthesis. What is the dependent variable?
The rate of photosynthesis
A practical is done to investigate the effect of light intensity on the rate of photosynthesis. Give two control variables
Maintain the same environmental temperature
Using the same species, length and age of plant in each repeat
Dissolving sodium hydrogen carbonate in the water to maintain carbon dioxide levels
In an investigation into the effect of temperature on photosynthesis, why should light intensity be controlled?
Light intensity should be controlled when investigating the effect of temperature on the rate of photosynthesis as light intensity is a limiting factor
In an investigation into the effect of light intensity on the rate of photosynthesis in aquatic plants, what is the predicted outcome?
In an investigation into the effect of light intensity on the rate of photosynthesis, the predicted outcome that the rate of photosynthesis will increase with light intensity. This will continue until another factor becomes limiting
Why does bubble production decrease as distance between the light source and the aquatic plant increases in a line graph?
The number of bubbles produced decreases as the light moves further away from the pondweed because light intensity decreases with distance; this means that the rate of photosynthesis decreases and so less oxygen is produced
Name three uses of glucose from photosynthesis
Respiration
Storage by conversion into insoluble starch
Production of fat or oil for storage
Production of cellulose, which strengthens the cell wall
Production of amino acids for protein synthesis
What mineral ion is used by plants to produce proteins?
As well as utilising the glucose produced in photosynthesis, plants require nitrate ions absorbed from the soil to produce proteins
How does glucose facilitate the uptake of mineral ions in the roots of plants?
Glucose is transported to the root hair cells where it is used in respiration to provide energy for the uptake of mineral ions by active transport
In what form is glucose stored in plants and animals?
Glucose is stored as starch in plants and glycogen in animals
What is the function of cellulose in plant cells?
Cellulose provides structural support to plant cells and allows them to maintain a regular shape
