Plant diseases and photosynthesis Flashcards
Booklet 2 (29 cards)
Balanced chemical equation for photosynthesis
6CO2 + 6H2O = 6O2 + C6H12O6
Photosynthesis is the process by which plant convert ….. and…… into …… and other organic molecules using ……. …….. with the release of ……
This process absorbs energy and so photosynthesis is an ……….. reaction
CARBON-DIOXIDE and WATER
into GLUCOSE
Using LIGHT ENERGY
release of OXYGEN
is an ENDOTHERMIC REACTION
How can we prove that a leaf has done photosynthesis?
The glucose made from photosynthesis is used to make different substances or is stored as starch so you would test for starch
3 Examples of different molecules the glucose can be used to make
1 cellulose for the plant cell wall
2 amino acids for proteins
3 lipids for fats
What is used to test for starch and what is the colour before and after it has reacted with starch
Iodine
Before it’s is usually a yellow/orange colour
If it reacts with starch it will turn blue/black
Solutions used and colour change to test for
1 glucose
2 proteins
1 use the blue Benedict’s solution - glucose
Solution would change from blue to green yellow or red depending on how much sugar present
2 use Biuret solution - Protein
Solution changes from blue to purple
In the testing for starch practical why do place the boiled leaf in a boiling tube with ethanol
Removes chlorophyll to make the colour change easier to see
Why do we use a Bunsen burner for the water but a hot water bath for the ethanol ( testing for starch )
Because water is not flammable so it’s is more efficient using a Bunsen burner however ethical is highly flammable so heating it directly could cause a fire
What does it mean if part if the plant remains yellow/brown
No starch - no photosynthesis in that area
What would you expect if you covered parts of the leaf with foil before the experiment
The area covered to remain yellow/orange because there would be no photosynthesis with no light - no starch
Name two control variables in this experiment ( testing for starch )
Time the leaf is boiled, temperature leaf is boiled
One independent variables ( testing for starch )
Light exposure e.g. parts covered with foil
What is a limiting factor in photosynthesis
A factor that when in short supply will prevent photosynthesis from working at it’s fastest rate
If it is warm and bright what is the limiting factor of photosynthesis
The Co2 concentration
How does light intensity increase with the rate of photosynthesis
Light level increases the rate of photosynthesis increase steadily but only up to a certain point.
Because beyond that point photosynthesis will not increase because either temperature of Co2 is limiting
Why does the temperature affect the rate photosynthesis
Because temperature affects the enzymes involved in photosynthesis
Enzymes work more slowly at low temperatures
Describe the purpose of the practical (pondweed light)
to investigate how light intensity affects the rate of photosynthesis in pondweed.
Plants can be affected by which 3 pathogens
Viral
Bacterial
Fungal
Other than pathogens what are two other elements that cause plant diseases
Mineral deficiency
Pests
One example for these pathogens
Viral
Bacterial
Funagl
Viral- tobacco mosaic virus
Bacterial- crown gall
Fungal- rose black spot
What is the result of a plant with diseased leaves e.g. rose black spot
Damaged leaves/chloroplasts
Less photosynthesis
Less glucose
Less aerobic respiration
Less growth
3 ways diseases can be spread
Pests/vectors - travelling insects
Contact - infected plants contact healthy plants
Sanitation - gardener’s use the same tools
What are 3 examples of physical defences
1) waxy cuticle - barrier
2) cell wall - contains cellulose
3) layers of dead cells around their stems - e.g. bark
What are 2 examples of chemical defences
1) plants may produce antibacterial chemicals
2) plants may produce poisons which can deter organisms that eat plants
