3.1 Food Supply, Plant Growth and Productivity Flashcards
Define ‘Food Security’
The ability of a population to access food of sufficient quality and quantity
What are the three factors that influence food security?
- Food Quantity
- Food Quality
- Food Access
Why is food security becoming harder to achieve?
Due to the increasing rate of population growth and lack of available land to grow food
What does food availability depend on?
Sustainable Agricultural Methods
What does ‘Sustainable’ mean in relation to plant growth
Sustainable - does not degrade the natural resources on which agriculture depends on
How can you increase crop production without expanding the area?
- Grow High Yielding Cultivars
- Applying fertilisers
- Reducing pests/diseases
Livestock production produces … due to energy lost between trophic levels.
Livestock production produces less food per unit area than crop plants due to energy lost between trophic levels
What advantage is there to using livestock over crop plants?
Livestock production is often possible where crop plants cannot be grown, i.e. a very steep hill.
What is the word equation for photosynthesis?
Carbon Dioxide + Water —> Glucose + Oxygen
What are some factors that affect the rate of photosynthesis?
Carbon dioxide availability
Temperature
Light intensity
Why are plants produce more food per unit area than livestock?
Due to the energy loss at each tropic level
Why are livestock sometimes chosen over plant production in certain areas?
Chosen in areas unsuitable for plant growth due to ability to grow (eg. mountains)
What is plant productivity?
Rate at which light energy is converted to glucose in photosynthesis
What is the biological yield of a plant?
Total increase in biomass
What are the two stages in photosynthesis?
Light Dependant Stage
Calvin Cycle
Where does the light dependant stage take place?
Chloroplasts
Where does the Calvin Cycle take place?
Chloroplasts
What are the three fates of light hitting a leaf?
- Absorbed
- Reflected
- Transmitted
What is the main photosynthetic pigment?
Chlorophyll a
What regions of the absorption spectrum does chlorophyll A absorb light from?
Red & Blue
What are the two accessory pigments called?
Carotenoids
State an advantage of having accessory pigments
Extend the absorption spectrum and pass energy to chlorophyll
Which regions of the absorption spectrum do the carotenoids absorb?
Yellow and Green
Define the ‘Absorption Spectrum’
Absorption spectrum shows which colours of light are absorbed by the photosynthetic pigments
Define the ‘Action Spectrum’
Action Spectrum shows the rate of photosynthesis at each light wavelength (colour).
How can pigments in a leaf be extracted?
Thin Layer Chromatography
What is the role of light energy in the production of ATP?
Light energy excites the electrons and puts them in a high energy state
Which co-enzyme is responsible for picking up hydrogen?
NADP
What does NADP become after picking up hydrogen?
NADPH
What two products of the light dependant stage enter the calvin cycle?
NADPH and ATP
What is the energy used for in photolysis?
To split water into hydrogen and oxygen
ATP synthase is an enzyme that …
ATP synthase is an enzyme that generates ATP by the flow of Hydrogen ions passing through it
Describe what happens to oxygen after photosynthesis?
Oxygen exits the plant via the stomata.
List the steps of the light dependent stage of photosynthesis?
1 - Consists of a series of carrier proteins attached to the inner mitochondrial membrane.
2 - electrons become excited
3 - electrons transferred along an electron transport chain releasing energy.
4 - Energy is used by the enzyme ATP synthase to generate ATP
5 - Energy is also used for photolysis (split water) into hydrogen and oxygen
6 - Hydrogen picked by coenzyme NADP to make NADPH for carbon fixation stage.
7 - Oxygen evolved as gas through stomata
Describe the steps of carbon fixation (calvin cycle) of photosynthesis?
1 - the enzyme RuBisCO fixes carbon dioxide by attaching it to ribulose bisphosphate (RuBP) to produce 3-phosphoglycerate (3PG)
2 - The 3-phosphoglycerate (3PG) produced is phosphorylated by ATP and combined with hydrogen ions from NADPH to form glyceraldehyde-3-phosphate (G3P). Both the hydrogen and the ATP are generated during the light dependent stage.
3 - G3P is used for the synthesis of glucose and the regeneration of RuBP.
What is the full chemical name of the 3PG, which is involved in photosynthesis?
3-phosphoglycerate (3PG)
What is the full chemical name of the G3P, which is involved in photosynthesis?
glyceraldehyde-3-phosphate (G3P)
What are the fates of the glucose produced as a result of photosynthesis?
1 - used as a respiratory substrate to generate energy (ATP)
2 - converted to cellulose (structural carbohydrate)
3 - converted into starch (storage carbohydrate)
4 - used in other biosynthetic pathways (to make DNA, protein etc.)
