Bioenergetics Flashcards
What is Photosynthesis
-Plants use light as their source of energy. To trap the light, plants carry out the process of photosynthesis.
-Because this takes in light energy, it is an endothermic reaction.
-Photosynthesis takes place in the leaves of the plant. These contain chlorophyll which can absorb light energy.
What is the Equation for Photosynthesis
Carbon Dioxide + Water 🡢 Glucose + Oxygen
Explain what is Meant by the Term Limiting Factor
A limiting factor is any factor which limits the rate of photosynthesis.
Describe what Happens to the rate of Photosynthesis as Light Intensity Increases
-As light intensity increases, the rate of photosynthesis increases steadily but only up to a certain point.
-Beyond that, it won’t make any difference- as light intensity increases, the rate will no longer increase.
-This is because it’ll either be carbon dioxide levels or temperature which is now the limiting factor, not light.
Describe how Greenhouses can Prevent Light from Becoming the Limiting Factor
-Use greenhouses constructed from glass or alternative materials that enable maximum transmission of light.
-Position plants for maximum light absorption.
Artificial lighting systems can be used:
-with increased light intensities
-that provide optimum wavelengths of light for photosynthesis
-that lengthen a plant’s growing season so that crops can be grown in more months of the year
Describe what Happens to the rate of Photosynthesis as Carbon Dioxide Levels Increases
-As carbon dioxide levels increase, the rate of photosynthesis increases steadily but only up to a certain point.
-Beyond that, it won’t make any difference- as carbon dioxide levels increase, the rate will no longer increase.
-This is because it’ll either be light intensity or temperature which is now the limiting factor, not carbon dioxide levels.
Describe how Greenhouses can Prevent Carbon Dioxide from Becoming the Limiting Factor
-Use paraffin heaters on a small scale
-On a larger scale, use carbon dioxide wastes from industrial processes that has been cleaned up before use
-Can use liquid carbon dioxide, applied through pipes, though this can be expensive
-Sometimes use fungi, grown as a mycelium in bags around the greenhouse, that add carbon dioxide through their respiration
Describe how Temperature Affects the Rate of Photosynthesis
-Often, if temperature is the limiting reactant, it is because it is too low. The enzymes needed for photosynthesis work more slowly at low temperatures.
-However, if the plant gets too hot, the enzymes needed for photosynthesis will become denatured.
Describe how Greenhouses can Prevent Temperature from Becoming the Limiting Factor
-Greenhouses help to trap the sun’s heat, and make sure that the temperature doesn’t become limiting.
-In winter, a farmer might use a heater as well to keep the temperature at the ideal level.
-In summer, it might get too hot so shades or a ventilation system might be installed to cool things down.
Describe the Benefit of Using Oil Burners in Greenhouses
-Burning oil generates heat and also releases carbon dioxide.
-Both temperature and carbon dioxide concentration can be limiting factors so by using oil burners, we ensure that the rate of photosynthesis is very high.
-Light intensity can also be a limiting factor but in practise, during the day, the light intensity in a greenhouse is very high.
Describe how Chlorophyll Levels Affect the Rate of Photosynthesis
-Variegated plants have a lower level of chlorophyll than non-variegated plants.
-This means that variegated plants can trap less light energy and will have a lower rate of photosynthesis.
Describe how Glucose is Used in Respiration
-Glucose produced by photosynthesis can be used for respiration.
-Glucose is broken down with oxygen to provide energy to the cells. Energy is released in a chemical reaction which takes place in the mitochondria.
-Carbon dioxide and water are the waste products.
What does it Mean that Burning Oil in Greenhouses has Economic Benefits
-Burning oil is expensive so this adds to a gardener’s costs.
-However, burning oil should increase the yield of crops.
-If the increased yield offsets the increased cost, then the gardener will make money. This is an economic argument.
Describe how Glucose is Used for Cellulose
-Energy transferred in respiration may be sued to build smaller molecules into bigger molecules.
-Glucose is converted into complex carbohydrates such as cellulose which is used to strengthen cell walls.
Describe how Glucose is Used to Build Proteins
-Some glucose from photosynthesis is used to make amino acids.
-To do so, glucose combines with nitrate ions and other minerals from the soil.
-The acids are built into proteins to be used as enzymes and other things for the plants survival.
-The creation of these proteins uses energy transferred from respiration
Describe the Use of Glucose as Starch
-Some glucose from photosynthesis is converted into starch to be stored.
-Starch is insoluble in water (unlike glucose) so has no effect on how water moves in and out of the plant. Because of this, plants can store a lot of starch- it is the plant’s main energy store.
-Starch is stored in the cells of leaves which provides an energy store. for when it is dark. It is also stored in tubers to help the plant survive winter.
