Key Area 1 Flashcards
Natural factors which may affect food production
Drought
Pests
Flooding
Disease
Desertification
Resistance to insecticides
Give two reasons for an increased demand in food production.
- Increase in human population
- Concern for food security
Explain what “sustainable food production” means.
Does not degrade the natural resources on which agriculture depends
Define a cultivar (cultivated variety)
A plant (or group of plants) selected for desirable characteristics and easily propagated
Give examples of plant crops
Plant crop examples include cereals, potato, roots and legumes.
List some characteristics that plant breeders try to develop
higher nutritional values
• resistance to pests and diseases
• physical characteristics suited to harvesting
• ability to thrive in particular environmental
conditions (e.g. drought)
Outline how plant breeders can produce plants that can thrive in particular environmental conditions.
breeding of higher yielding cultivars, use of fertiliser, protecting crops from pests, diseases and competition.
Explain why livestock produce less food per unit area than plant crops in terms of loss of energy.
Due to loss of energy between trophic levels.
Describe the circumstances in which the farming of animals should take place.
In habitats unsuitable for growing crops (e.g. sheep farming on hillsides).
State the 3 fates of light striking a leaf.
• Absorption
• Transmission
• Reflection
State the role of photosynthetic pigments.
To absorb light energy from the sun.
State the difference between the absorption spectrum and the action spectrum.
The absorption spectrum shows the different wavelengths of light that are absorbed by each pigment.
The action spectrum shows the rate of photosynthesis at each wavelength.
Give examples of leaf pigments, describing their roles and absorption spectra.
Chlorophyll a – main pigment Chlorophyll b – main pigment Carotene – accessory pigment* Xanthophyll – accessory pigment*
What happens when light hits chlorophyll
absorbed energy excites the electrons
Name, state the location of and describe the events which occur in the first stage of photosynthesis.
Light-dependent stage – occurs in grana of chloroplast
1.light energy is absorbed by the chlorophyll exciting the electrons.
2. Electron passed along transport chain pumping hydrogen into grana
3. Energy also used to split water
4. Hydrogen picked by NADP to make NADPH
for carbon fixation (Calvin cycle)
5. Hydrogen ions used by ATP synthase to make ATP for carbon fixation (Calvin cycle)
What 2things from the light dependent stage are used in the Calvin cycle
ATP
hydrogen
What is bound to the acceptor NADP to form NADPH2.
Hydrogen
Name, state the location of and describe the events which occur in the second stage of photosynthesis.
Calvin Cycle (carbon fixation) – occurs in stroma of chloroplast
The carbon fixation stage (Calvin Cycle) is a series of enzyme controlled reactions which does not require light.
Carbon dioxide enters the cycle and becomes attached to RuBP (ribulose bisphophate) by the enzyme RuBisCO to produce 3-phosphoglycerate (3PG).
The 3-phosphoglycerate that is produced is phosphorylated by ATP and combined with hydrogen from NADPH to form G3P (glyceraldehyde-3-phosphate). G3P is used to either regenerate RuBP or can be used to synthesise sugars, for example glucose.
The Calvin Cycle is the temperature-dependent part of photosynthesis.
State the enzyme involved in the fixation of carbon dioxide to RuBP.
Rubisco
State what is phosphorylated by ATP.
3GP G3P
What is used to regenerate RuBP.
G3P
State the possible uses of the sugar created in photosynthesis.
Respiration
Starch (storage carbohydrate)
Cellulose (structural carbohydrate)
What will increased food production will depend on.
factors that control plant growth
light availability
available nutrients
water in the soil
competition with other plants
What is plant productivity
rate of generation of new biomass per unit area per unit of time.
What is net assimilation
increase in mass due to photosynthesis
minus the loss due to respiration.
