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
What is meant by monoculture?
Growing a crop with only one species, increases chance of pest or disease outbreaks
What are characteristics of a perennial weed?
Long life cycles, storage organs, vegetative reproduction
What are characteristics of annual weeds?
Short life cycles, rapid growth, long term seed viability, high seed output
What is a fungicide?
Kills fungi
What is a herbicide?
Kills weeds
What is an insecticide?
Kills insects
What is the difference between systemic and selective herbicides?
Systemic are taken into plant tissues and passed around the plant destroying all parts of the weed, selective only affect plants with broad leaves as they are only absorbed through the leaves
When would you use a selective herbicide?
On grass crops where only weeds with broad leaves are affected
When would a systemic herbicide be useful?
If the weed has underground storage organs that could regrow if left behind
What are some examples of cultural methods for crop protection?
Growing a cover crop
Ploughing
Removal of alternative hosts
Crop rotation
What would be the characteristics of an ideal pesticide?
Specific to host, short lived, safe
What is bio accumulation ?
When the pesticide remains in tissues over time and builds up faster than it can be removed
What is bio magnification?
When the concentration of pesticide increases at each trophic level in a food chain and can reach toxic levels near the top
What is biological control?
Use of a natural predator, parasite or disease to control pest species
What are the risks associated with organisms used for biological control?
Control agent could escape into the wider environment and become invasive, reduce biodiversity or eliminate other species
What is integrated pest management ?
Use of biological control, cultural control and chemical control
What are the costs of providing good animal welfare
Financial cost of providing high quality food and protection from predators, lower yield per unit area. Results in food that are more costly for consumers
What are the benefits or providing good animal welfare?
Higher value and quality of product, healthier animals (Lower risk of disease spreading), increased reproductive success
What are some indicators of poor animal welfare?
Misdirected behaviour, stereotypy, failure of reproductive or parental behaviour, altered levels of activity
How can poor animal welfare be overcome?
Enriching an animals environment, providing company, toys, stimulation
What is the term which describes the study of animal behaviour?
Ethology
What is the name given to a list of animal behaviours?
Ethogram
What is a preference test?
Providing an animal a choice of conditions and observing which it prefers by spending most time in or being attracted to
What is symbiosis?
Co-evolved relationship between members of two different species
What are the two types of symbiosis?
Parasitism and mutualism
What is parasitism?
When the parasite benefits by gaining energy or resources and the host is harmed
What is a parasite?
An organism which gains energy from the host at the hosts expense
What is meant by mutualism?
When both species benefit from e relationship
What is a vector?
Carries a parasite from host to host
Why might parasitical life cycles involve the use of a secondary host?
Allows them to survive until back in contact with primary host
What is an example of mutualism?
Cellulose digesting bacteria living in guts of cows - cows get benefits of sugars produced by breakdown of cellulose and bacteria get warmth and a secure habitat
What evidence is there that chloroplasts and mitochondria have arisen from symbiosis?
Contain ribosomes of similar size to that of prokaryotes, contain DNA similar to prokaryotes, similar size to prokaryotes
What is meant by social hierarchy?
Grouping of individuals within a species dependant of their social position
Why can a social hierarchy be beneficial?
Means that aggression is ritualised, keeps real fighting to a minimum, ensures fittest individuals survive to pass on genes, leads to experienced leadership
What are the advantages of cooperative hunting?
Larger kills than when hunting alone
Individuals gain more energy than if hunting individually
Subordinates benefit from share of kill as well as dominant individuals
What are the benefits of social defence?
Increased protection, more chance of seeing predators
What is meant by altruism?
When the donor is harmed by the behaviour but the recipient benefits
What is meant by reciprocal altruism?
When the altruistic act is returned to the donor in future
What is meant by kin selection?
Providing resources or protection to related individuals- donor gains indirectly through survival of offspring who have some shared genes with donor
Why do social insects provide resources to their queen?
Queen is related to all members of hive so workers benefit indirectly through queen passing on genes she shares with workers
What is a keystone species?
A species which plays a vital role for the survival of other species in an ecosystem (eg bees as pollinators)
Why do primates have long periods of parental care?
To allow for offspring to learn complex social behaviours
What methods are used in social groups to reduce conflict?
Ritualistic display
Appeasement behaviours
Forming alliances
What is meant by ritualistic display?
Making self look bigger and more threatening (eg baring teeth, raising heckles, banging chest)
What is meant by appeasement behaviours?
Reverse of great display to show submission. Includes behaviours like grooming, submissive facial expressions, certain body postures, sexual presentation
Which factors can influence the social structures of primate groups?
Ecological niche, resource distribution and taxonomic group
What is meant by an alliance in social behaviour?
Relationships formed between individuals which increase social status, maintained by grooming
How can alliances in social behaviour benefit organisms?
Increases social status of individuals which can lead to increased access to food or mates
What happens to biodiversity after an extinction event and why?
Gradually increases, as survivors undergo speciation and adaptation
Give some examples of human activities which are contributing to current extinction events?
Over exploitation (overfishing, hunting) Habitat degradation Introduction of invasive species Pollution Greenhouse effect leading to global warming and climate change
What are measurable components of biodiversity?
Genetic diversity, species diversity, ecosystem diversity
What is species diversity?
The species richness (number of different species)
The relative abundance (proportion of each species present)
How can having a dominant species affect species diversity?
Dominant species reduces relative abundance of other species which lowers species diversity
What is genetic diversity?
Number and frequency of alleles present in a population
What is ecosystem diversity?
Number of distinct ecosystems in an area
What is the bottleneck effect?
When a large percentage of population is lost leading to reduced genetic diversity of survivors
Can lead to inbreeding depression
Which factors can affect biodiversity on an island?
Size of island
Distance from mainland
Why is a high edge to interior ratio a problem in habitat fragments?
Forces edge species into interior to compete for resources which can lead to extinction of interior species
Why are habitat corridors used?
To join habitat fragments allowing members to colonise an area and to mate
What is meant by an introduced species?
Foreign species moved intentionally or accidentally into a new area
What is meant by a naturalised species?
Foreign species who are able to survive and reproduce in their new habitat
What is meant by an invasive species?
Foreign species who reproduce rapidly and outcompete with native species
What factors allow introduced species to become invasive?
Free of their usual competitors, predators, pests and parasites so can outcompete native species
What is meant by over Exploitation?
Removing organisms from the environment faster than they can be replaced by reproduction
