the rate of photosynthesis Flashcards
(23 cards)
How is glucose used inside plant cells?
Examples of ways in which plant cells can use glucose include:
Respiration
Storage, in the form of starch
The production of cellulose cell walls
Conversion into lipids and amino acids
What are the four main factors that limit the rate of photosynthesis?
-Temperature
-Light intensity
-Carbon dioxide concentration
-chlorophyll levels
- less water -affects chloroplasts
True or False?
Water is a limiting factor in photosynthesis.
-Water is not considered a limiting factor in photosynthesis; this is because plants need relatively little water for photosynthesis,
-and a lack of water also influences a plant’s ability to absorb light and carbon dioxide.
Why does the rate of photosynthesis slow down at low temperatures?
-Photosynthesis occurs slowly at low temperatures because molecules (such as enzymes involved in photosynthesis) have little kinetic energy.
-This means that fewer successful collisions take place.
Why do very high temperatures cause photosynthesis to stop?
At very high temperatures 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. This continues until another factor becomes limiting.
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. This continues until another factor becomes limiting.
why on a sunny day may carbon dioxide be more commonly the limiting factor
Plants release carbon dioxide during respiration, a process that occurs continuously, and this release is more prominent at night when photosynthesis (the process of using sunlight to convert CO2 into energy) is not taking place.
how does temperature affect the rate of photosynthesis
increasing the temperature increases the rate of photosynthesis as the kinetic energy of the particles is increased.
- the rate decreases past a certain temperature as enzymes become denatured
how does chlorophyll affect the rate of photosynthesis
The more chloroplasts a plant has, the faster the rate of photosynthesis-
The amount of chlorophyll can be affected by:
diseases (such as tobacco mosaic virus)
lack of nutrients (such as magnesium)
loss of leaves (fewer leaves means fewer chloroplasts)
what is a limiting factor
an environmental factor which can restrict the rate of photosynthesis
True or False?
In a graph of light intensity against the rate of photosynthesis, the part of the graph where the line is horizontal indicates a point where light intensity is the limiting factor.
(Higher Tier Only)
False.
In a graph of light intensity against rate of photosynthesis, the level part of the graph shows a point at which a factor other than light intensity is limiting, e.g. temperature or carbon dioxide concentration.
True or False?
The relationship between distance and light intensity is directly proportional.(Higher Tier Only)
False.
The relationship between light intensity and distance is inversely proportional because as the distance increases, the light intensity decreases.
What is shown by the inverse square law? (Higher Tier Only)
The inverse square law shows the relationship between light intensity and distance between the light source and the plant.
light intensity equation
light intensity ⍺ 1/distance² .
how can farmers use their knowledge of limiting factors to increase their profits
By understanding which factors (like light, temperature, water, or nutrients) are holding back plant growth, farmers can take steps to increase those factors, resulting in faster growth, higher yields, and potentially better quality crops, leading to greater profits.
Explain in terms of limiting factors why the plant growing in a tropical rainforest are so much bigger than plants that grow in a UK woodland and why both are bigger than the plants on the Arctic tundra. (6)
Tropical rainforest: high light intensity, warm temperature and plenty of moisture. Relatively few limiting factors allowing plants to get very large.)
UK woodland: low light intensity, short days in winter, cold temperatures.(most growth is in spring and summer-less time for growth than in tropical rainforest so plants are smaller.)
Arctic tundra: no light all winter, lack of water due to frozen ground(low temperatures limiting factor on photosynthesis for most of year. So plants are much smaller and slower-growing than in a tropical rainforest or UK woodland.)
Limiting factors of photosynthesis: Light intensity - describe the graph:
A = increase in light, increases the rate of photosynthesis, light = limiting factor
B = increase in light doesn’t change rate of photosynthesis, no longer limiting factor, line plateaus, light or CO2 could no longer be limiting factor
Limiting factors of photosynthesis: Concentration of CO2 - describe the graph:
A – no carbon dioxide, no photosynthesis
B – as carbon dioxide concentration increases, so does rate. - therefore CO2 is the limiting factor
C – increasing carbon dioxide concentration no longer increases rate of photosynthesis - therefore, it is no longer the limiting factor, line plateaus
Limiting factors of photosynthesis: Temperature - describe the graph:
-Initially as temperature increases so does the rate of photosynthesis. Particles have more kinetic energy. More frequent, successful enzyme collisions.
-Optimum = temperature goes to max rate.
-After an optimum temperature the rate of photosynthesis decreases and the enzymes that control photosynthesis denature. Temperature too high so enzymes involved in photosynthesis begin to denature, rate of photosynthesis decreases until 0.
Limiting factors of photosynthesis: Amount of chlorophyll
The more chlorophyll the higher the rate of photosynthesis - so chlorophyll is limiting factor as rate of photosynthesis increases
-There is a limit to the amount of chlorophyll a leaf can hold - chlorophyll no longer limiting factor
-Limiting factors of photosynthesis: Amount of chlorophyllas amount of chlorophyll cannot increase and any increase wouldn’t affect the rate of photosynthesis
How does the amount of chlorophyll affect the rate of photosynthesis?
-More chlorophyll = more light absorbed for photosynthesis
= more photosynthesis = more glucose produced
=more glucose converted to starch
= more substrates for respiration = more energy released for growth
= more crop yield.
Less water - affects chloroplasts
