Unit 3- 1.1 Flashcards
What can food security be defined as?
Quantity- Sufficient food must be available at all times.
Quality- Food is sufficiently nutritious and varied to provide a balanced diet.
Access- People have economic means to obtain the available food.
What can agricultural techniques be used to do?
Improve productivity of the land and make it more efficient for growing high yield crops.
As the area of land suitable for growing crops is limited: what can agriculture do?
- add minerals (fertilliser) or water (irritation systems) to remove factors which may be limiting plant growth.
- Replace existing strains of crops with a higher-yielding cultivar (cultured variety)
- Protect crops from pests (e.g insects) diseases (eg fungi) and competition (from weeds) by using pesticides, fungicides and herbicides.
- Develop pest resistant crop plants.
What is light?`
light is a form of electromagnetic radiation which travels in waves.
what is the distance between two wavelengths called?
Wavelength and is measured in nanometers
What is the three possible fates of white light?
Absorbed, reflected, transmitted.
What is the light energy absorbed by?
Its captured by several different pigments, including chlorophyll, that are present. The different pigments absorb different wavelengths of light.
What colours are absorbed by pigments?
blue, violet, and some red.
What are the four pigments in a leaf?
- Chlorophyll A
- Chlorophyll B
- Carotene
- Xanthophyll
What is an action spectrum?
An action spectrum shows the rate of photosynthesis at each light wavelength.
Where are the photosynthetic pigments contained?
They are contained within the grana. Therefore this is where absorption of light energy and photosynthesis take place.
Where does carbon fixation occur?
stroma of the chloroplast.
What is the process of photolysis?
In the chloroplast, when light energy is absorbed by Chlorophyll a, it’s electrons become excited and are raised to a higher energy state. High energy electrons are captured by the primary energy acceptor.
The electrons are then transferred along an electron transport chain releasing energy. This energy is used by the enzyme ATP synthase to generate ATP.
Some of the energy is also used to split water into hydrogen - which is picked by the hydrogen acceptor NADP to make NADPH and oxygen.
At the end of the first stage of photosynthesis what is hydrogen (in the form of NADPH) and ATP essential for?
It’s essential for the second stage, known as the Calvin Cycle. Which takes place in the stroma of the chloroplast.
What is the process of the Calvin Cycle?
- Carbon dioxide enters the cycle and becomes attached to RuBP (ribulose biphosphate). This reaction is controlled by the enzyme RuBisCO (ribulose bisphosphate carboxylase/oxygenase)
- The Carbon Dixoideand RuBP combine to make 3-phosphoglycerate.
- The 3-phosphoglycerate then joins with the hydrogen from NADPH and is phosphorylated by the addition of inorganic phosphate (Pi) from ATP which supplies the energy.
- This process produces glyceraldehyde-3-phosphate (G3P)
- Some G3P is then used to regenerate RuBP (to continue the process. The remainder is used to synthesis sugars.
