B8 Photosynthesis Flashcards
What type of reaction is photosynthesis?
endothermic
What is the process of photosynthesis?
- algea/plant leaf cells contain green chloroplasts, which contain chlorophyll
- during photosynthesis, energy is transferred from surroundings to chloroplasts by light
- used to convert CO2 + H2O into glucose and oxygen
- oxygen is released to the air
-glucose is either used for respiration by cells or stored as insoluble starch
Where does the energy from photosynthesis come from?
- the breaking of carbon dioxide and water molecule bonds
- from environment by light
What is the chemical equation for photosynthesis?
6CO2 + 6H2O-> C6H12O6 + 6O2
How are leaves adapted for Photosynthesis?
- broad leaves, large SA for light to fall on
- thin leaves, short diffusion distances for gas
- contain chlorophyll in chloroplasts, absorb light
- veins, bring water from xylem to cells, remove photosynthesis products in phloem
- air spaces, allow CO2 to stomata, regulate gas exchange
- guard cells open + close stomata, regulate gas exchange
How are algae adapted for photosynthesis?
aquatic, adapted in the water
- Large SA
- Absorb CO2 dissolved in water
- Oxygen produced also absorbs into water when released
What do plants need to photosynthesise?
light intensity, temperature and CO2 concentration
What is a Limiting Factor in photosynthesis?
When light intensity, temperature or CO2 concentration are in short supply and limit the amount of photosynthesis a plant can manage
How does light intensity affect the rate of photosynthesis?
Plenty of light- lots of photosynthesis
Little to No light- photosynthesis stops
(most plants: brighter light= faster rate of photosynthesis)
How does Temperature affect the rate of photosynthesis?
Temp rises- photosynthesis increases (enzyme controlled reaction speeds up)
Enzymes denature around 40-50 degrees
Temp is too high- enzymes denature, rate of photosynthesis decreases
How does Carbon Dioxide Concentration affect the rate of photosynthesis?
Carbon dioxide is scarce in atmosphere, often limits rate of reaction
Sunny day- low CO2 level
Night time- increase CO2 concentration, plants respire but don’t photosynthesise
Lab/Greenhouse- artificially increase CO2 levels, as conc increases, rates of photosynthesis increase
How do the levels of Chlorophyll in a leaf effect the rate of photosynthesis?
Limited chlorophyll- limited photosynthesis
lack of magnesium= lack of chlorophyll, low photosynthesis rates, plant can die
What is the relationship between light intensity and distance between plant and light source?
Light intensity is inversely proportional to distance^2 between plant and light source
What is the chemical equation for respiration?
6O2 + C6H12O6 -> 6CO2 + 6H2O
What are the uses for energy transferred during respiration?
- build smaller molecules into bigger molecules: plants build glucose-> cellulose (complex carbohydrate), STRENGTHEN CELL WALLS
- convert some glucose into starch (main energy store in a plant)
- convert some glucose into amino acids (build into proteins, many uses ie enzyme)
- convert some glucose to build up fats and oils, energy store in seeds or make cell walls stronger
Why do plants store glucose as starch?
Glucose is soluble in water, could affect water moving in and out of cells by osmosis if stored in the cell. Can affect water balance in plant
Starch is insoluble in water, no effect on water balance in plant-> store large amounts in cells
Where is starch stored?
- Cells of leaves: provides energy store when dark or low light levels (low photosynthesis)
- Special storage areas of a plant: tubers + bulbs full of stored starch, survive through the winter. Found as veg such as potatoes and onions
How are amino acids made in a plant?
they combine sugars, nitrate ions and other mineral ions from the soil
How do algae make amino acids?
they take nitrate ions and other materials they need from the water to live
How are some carnivorous plants adapted to nitrate poor soil?
- they obtain most of their nutrients from animals they catch (insects)
- produce enzymes to digest trapped insects
- use nitrates and other minerals from digested bodies in place of nutrients lacking in soil
Why do plants use glucose to build up fats and oils?
Seeds provide food for new plant to respire as it germinates
How does using a greenhouse affect the rate of photosynthesis?
- glass/plastic building: environment is much easier to control than outside
- atmosphere is warmer, increasing rate of photosynthesis
- can be used to grow fruit that usually doesn’t grow well outside (ie UK: peaches, lemons, oranges)
How do commercial greenhouses take advantage of information about limiting factors?
- control temp, levels of light, CO2 concentration
- use hydroponics (grown in nutrient full water, efficient growth, less staff needed, final product is bigger and cleaner)
- controlled by computer software
What are the positives and negatives of controlling factors in greenhouses?
N- expensive
P- change CO2, temp and light levels in the day, change mineral content in water as plants grow, high profits, crops are clean + soil free, no ploughing or prepping land (can be grown in poor land, cheaper plots?)
