Unit 3 - All Flashcards
What is meant by sustainable food production?
Growing food without degrading natural resources on which agriculture depends
How can we improve crop production with limited area for crop growing?
- growing higher yielding cultivars
- protecting crops from weeds and pests
- using fertilisers
- identifying and reducing the limiting factors of photosynthesis
Why is farming livestock less efficient than farming crops?
Energy is lost at each tropic level
What is an action spectrum?
Shows the rate of photosynthesis at different wavelengths of light
What is an absorption spectrum?
Shows which wavelengths of light have been absorbed by the plant
Which wavelengths of light are absorbed by chlorophyll?
Blue (and red)
Which wavelengths of light are absorbed by the carotenoids
Green
What is the advantage of having the carotenoids pigments
It extends the range of wavelengths of light that can be absorbed by plants
What are he three fates of light when it strikes a leaf?
Absorbed, reflected and transmitted
Decline what happens in photolysis
Light energy excites electrons which are passed into the electron transport chain to generate ATP
Some of this energy is used to split water into hydrogen which is picked up by NADP and oxygen which is released
Describe what happens in the Calvin cycle
Carbon dioxide combines to RuBP to form intermediates by the enzyme RuBisCO. Intermediates (3-phosphoglycerate) accept hydrogen from NADPH and is phosphorylated by ATP to form G3P.
G3P molecules are either converted into glucose or can be used to regenerate RuBP
Which enzyme is responsible for fixing carbon dioxide to RuBP?
RuBisCO
Which coenzyme combines with hydrogen and takes it to the Calvin cycle?
NADP
What is food security?
Having access to food of sufficient quality and quantity
What happens to the glucose made by photosynthesis?
Either used in respiration, used to synthesis starch, used to synthesise cellulose or used in other biosynthetic pathways
What is meant by net assimilation?
The overall increase in biomass made by the plant
What is meant by productivity?
Rate at which plants generate new biomass
What is meant by economic yield?
Mass of desired product
What is. Meant by biological yield?
Total plant biomass produced (includes unneeded parts)
How is harvest index calculated?
Dry mass of economic yield/ dry mass of biological yield
The purpose of replicating treatments in field trials is to?
Take into account he variability within the plants being grown
What is the purpose of careful selection of treatments in a field trial?
To ensure valid comparisons can be made
What is the purpose of randomising treatments in a field trial?
To eliminate a bias when measuring the effects of the treatments
Which characteristics may plant breeders try to select for?
Improved yield
Improved resistance to pests or disease
Ability to thrive in particular environments
What is meant by discrete variation?
Fits into discrete categories
What type of inheritance causes discrete variation?
Single gene inheritance
What is continuous variation?
Wide range of characteristics
What type of inheritance causes continuous variation?
Polygenic inheritance
What is a test cross?
Used to identify organisms with unknown genotypes
How is a test cross conducted?
Cross unknown individual with homozygous recessive individual
What is inbreeding?
Crossing related individuals
What is outbreeding?
Crossing unrelated individuals
Why can inbreeding be harmful?
Can lead to inbreeding depression
What is inbreeding depression?
A build up of homozygous recessive deleterious alleles that can cause reduced yield and vigour
Why is inbreeding depression less likely to occur in plants?
Years of natural selection has eliminated deleterious alleles
What is an F1 hybrid?
Produced by a cross between two genetically dissimilar parents who have desired traits
Why can an F1 hybrid be useful?
Shows hybrid vigour - increased yield, fertility or other beneficial characteristics
How can offspring showing the desired f1 traits be maintained?
Back cross with parents or maintain and continue to breed original parents
Why is the F2 generation produced by cross breeding often not useful?
Shows genetic variability so not all offspring will show desired traits
Why can the F2 generation produced by cross breeding sometimes be useful?
Introduces new variation
How could breeders create organisms with particular alleles without doing test crossing?
Genomic sequencing
How could breeders create organisms with particular alleles without breeding?
Genetics transformation technology