2.5.2 Factors Affecting Photosynthesis Flashcards
Plants do not have unlimited supplies of their raw materials so their rate of photosynthesis is limited by, what?
by whatever factor is the lowest at that time
What is a limiting factor defined as?
a limiting factor can be defined as something present in the environment in such short supply that it restricts life processes
In photosynthesis, what are the 3 main limiting factors
Temperature
Light intensity
Carbon dioxide concentration
Although water is necessary for photosynthesis why is it not considered a limiting factor
it is not considered a limiting factor as the amount needed is relatively small compared to the amount of water transpired from a plant so there is hardly ever a situation where there is not enough water for photosynthesis
The number of chloroplasts or the amount of chlorophyll in the chloroplasts can affect what?
the rate of photosynthesis
How does temperature affect photosynthesis
The temperature of the environment affects how much kinetic energy all particles have – so temperature affects the speed at which carbon dioxide and water move through a plant
In photosynthesis, how does a lower temperature affect it?
The lower the temperature, the less kinetic energy particles have, resulting in fewer successful collisions occurring over a period of time
In photosynthesis, how does increasing temperature affect it?
Increasing temperature increases the kinetic energy of particles, increasing the likelihood of collisions between reactants and enzymes which results in the formation of products
What is a repercussion of high temperature
enzymes that control the processes of photosynthesis can be denatured – this reduces the overall rate of photosynthesis
How does The intensity of the light affect photosynthesis
The intensity of the light available to the plant will affect the amount of energy that it has to carry out photosynthesis
The more light a plant receives, does photosynthesis occur faster, or slower?
The more light a plant receives, the faster the rate of photosynthesis
Name one of the raw materials needed for photosynthesis
Carbon dioxide is one of the raw materials required for photosynthesis
the more carbon dioxide that is present, what happens?
the faster the reaction can occur
This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply
Do chloroplasts affect the rate of photosynthesis?
The number of chloroplasts (as they contain the pigment chlorophyll which absorbs light energy for photosynthesis) will affect the rate of photosynthesis
The amount of chlorophyll can be affected by, what?
Diseases (such as tobacco mosaic virus)
Lack of nutrients (such as magnesium)
Loss of leaves (fewer leaves means fewer chloroplasts)
(Leaf Structure) What is the description of Wax Cuticle
Protective Layer on top of the leaf prevents water from evaporating
(Leaf Structure) What is the description of the Upper Epidermis
Thin and transparent to allow light to enter the palisade mesophyll layer underneath it
(Leaf Structure) What is the description of Palisade Mesophyll
Column shaped cells tightly packed with chloroplasts to absorb more light, maximizing photosynthesis
(Leaf Structure) What is the description of Spongy Mesophyll
Contains internal air spaces that increases the surface area to volume ratio for the diffusion of gases (mainly carbon dioxide)
(Leaf Structure) What is the description of Lower Epidermis
Contains guard cells and stomata
(Leaf Structure) What is the description of Guard Cell
Absorbs and loses water to open and close the stomata to allow carbon dioxide to diffuse in, oxygen to diffuse out
(Leaf Structure) What is the description of Stomata
Where gas exchange takes place; Opens during the day, closes during the night. Evaporation of water also takes place from here, in most plants, found in much greater concentration on the underside of the leaf to reduce water loss.
(Leaf Structure) What is the description of Vascular Bundle
Contains xylem and phloem to transport substances to and from the leaf.
(Leaf Structure) What is the description of Xylem
Transports water into the leaf for Mesophyll cells to use in photosynthesis and for transpiration from stomata
(Leaf Structure) What is the description of Phloem
Transports sucrose and amino acids around the plant
Photosynthesis provides a source of carbohydrates, but plants contain and require many other types of biological molecules, such as:
such as proteins, lipids and nucleic acid (DNA)
Carbohydrates contain the elements:
carbon, hydrogen and oxygen
What are the 2 fundamental mineral ions required by plants?
nitrogen and magnesium, without a source of these elements, plants cannot photosynthesise or grow properly
Plants obtain these elements in the form of, what?
mineral ions actively absorbed from the soil by root hair cells
Mineral’ is a term used to describe, what?
any naturally occurring inorganic substance
What is the function of Magnesium and deficiency
Function: Magnesium is needed to make chlorophyll
Deficiency: Causes yellowing between the veins of leaves (chlorosis)
What is the function and deficiency of Nitrate
Function: Nitrates are a source of nitrogen needed to make amino acids(to build protein)
Deficiency: Causes stunted growth and yellowing of leaves
