S5 - Unit Three Flashcards
What is food security?
The ability of human populations to access food of sufficient quantity and quality
What do we need for food security and what does each component mean?
- Quantity: Sufficient quantity of food available
- Quality: Food is nutritious and varied to provide a balanced diet
- Access: People have money to obtain the available food
Why must food production be sustainable?
So as to not degrade the natural resources on which agriculture depends
What does food production ultimately depend on?
Photosynthesis
What characteristics do crop breeders try to develop into their crops?
- high nutritional values
- resistance to pest and diseases
- physical characteristics suited to rearing and harvesting
- ones which can survive particular environments
How can food production be increased?
- with the use of fertilisers
- breeding higher yielding crops
- protecting crops from pests, diseases and competition by using minimal doses of pesticides, fungicides and herbicides
- developing pest resistant crops
What does the length of a food chain correlate to?
The quantity of energy in the food at the end (the longer the food chain, the less energy at the end)
Why do livestock produce less food per unit area than crops?
Due to loss of energy between trophic levels
When is livestock used instead of crops when producing food?
When the habitats are unsuitable for crops to grow
Why is food security so important?
Because feeding over 8 billion people requires a sufficient and sustainable supply of food
What can be done to improve characteristics in crops and animals?
What does this involve?
Selective breeding
When breeders develop crops and animals with higher food yields, higher nutritional values, pest and disease resistance and the ability to thrive in particular environmental conditions
What are plant field trials?
When crops are grown in different environments to compare the performance of different plant cultivars or treatments to evaluate GM crops under the same experimental conditions
What are the design features in plant field trials?
- Selection of treatments involving one variable
- Inclusion of several replicates
- The randomisation of treatments
What is the reason for each design feature in a plant field trial?
- For valid comparisons
- To take into account the variability within the sample
- To eliminate bias when measuring treatment effects
What is inbreeding?
The fusion of two gametes from close relatives
What does inbreeding involve?
Selected related plants or animals being bred for several generations until the population breeds true to the designed type due to elimination of heterozygotes.
What are the effects of inbreeding?
Inbreeding depression which is an increase in the frequency of individuals who are homozygous for recessive deleterious
What does cross breeding with animals involve?
Individuals from different breeds producing a new cross breed population with improved characteristics
How can new alleles be introduced to plant or animals lines?
By crossing a cultivar or breed with an individual with a different, desired genotype
What is an F1 hybrid?
An individual resulting from a cross between two genetically dissimilar parents
What benefits do F1 hybrids often have?
Increased vigour and yield
What advantages does an increase in vigour give to a plant?
Increased disease resistance and growth rate
Why are F1 hybrids not usually bred together?
Because the F2 produced would show too much variation
What do breeding programs use on plants?
Recombinant DNA technology
What is a monoculture?
A vast population of a single species of crop plant cultivated over a large area for economic efficiency
What can reduce a crop plants productivity?
Weeds that compete with the crop and pests and diseases damaging them
Where exactly do weeds often grow?
In the spaces between plants in a monoculture
What do weeds do that reduces plant productivity?
Release chemical inhibitors or acting as hosts for pests and diseases
What properties do annual weeds have?
- Short lifecycle
- Quickly colonise spaces or vacant land
- Rapid growth
- Produce high number of seeds
- Long term seed viability
What are the properties of perennial weeds?
- Vegetative reproduction (ie. asexually)
- Have adapted storage organs that provide food if conditions are harsh
What are common pests to crop plants?
Invertebrate animals:
insects, nematode worms and molluscs
What do exactly do pests do to plants?
Reduce their yields due to them damaging leaves - reducing the area available to carry out photosynthesis
What can cause diseases in plants?
Pathogens: fungi, bacteria and viruses
How can pathogens be spread?
Via the air, soil or by insects
Farming methods of controlling weeds are…
Preventative and require long term planning
What are examples of farming methods of controlling weeds?
- Ploughing
- Weeding
- Crop rotation
What are herbicides used for?
Used to kill weeds
What are insecticides used for?
Used to kill insects
What are fungicides used for?
Used to control fungal diseases
What are molluscicides used for?
Used to kill mollusc pests ie. snails
What are nematicides used for?
Used to kill nematode pests
ie. microscopic worms
What two types of herbicides are there?
Selective and Systemic
What are the differences between the two types of herbicides?
Selective: mimics natural plant hormones
Systemic: transported to all plant tissues and structures
What properties do selective herbicides have?
- Have a greater effect on certain plant species
- They can be applied to crops which are established in a field as they only target certain weeds
How to systemic herbicides kill plants?
- Spread through the plants oragsn, killing it and preventing them from growing back
How do selective herbicides kill plants?
- They contain synthetic plant hormones, speeding up the plants growth to use up all their food stores and kill them
How do systemic fungicides and pesticides work?
They’re absorbed by crops and transported to all parts of the plant giving them protection from disease causing fungi / pests by poisoning them
What are problems with pesticides?
- May be toxic to non-target species
- May persist in the environment for a long time
- Bioaccumulation could occur
- Biomagnification could occur
- May produce pest populations which are resistant to the chemical
What is bioaccumulation?
The build up of a chemical in an organism
What is biomagnification?
The increase in the concentration of a chemical moving between trophic levels
What are the pro’s and con’s of biological control?
Pros:
- Do not cause harm to non-target organisms or accumulate in food chains
- Pests cannot become resistant (unless control method is a virus)
Cons:
- Control species may itself become an invasive species or a parasite
- May pray upon or be a pathogen of other species
What is integrated Pest Management?
A combination of chemical, biological and cultural control
What is animal welfare?
The physical and mental well-being of animals
How is animal welfare measured?
Animal behaviour, physiology, lifespan and reproduction
What are the Freedoms for Animals?
Freedom…
- From hunger and thirst
- From chronic discomfort
- From pain, injury and disease
- To express normal behaviour
- From fear and the avoidance of stress where possible
What are the costs of free range farming?
- Requires more land
- More labour intensive
What are the benefits of free range farming?
- Produce can be sold for a higher price
- Animals have a better quality of life
What are behavioural indicators of poor animal welfare?
- Stereotypy
- Misdirected behaviour
- Failure in sexual and parental behaviour
- Altered levels of activity
What is stereotypy?
Persistent, repetitive movement
What is misdirected behaviour in animals?
Behaviour directed inappropriately towards the animal inflicted by itself
What are examples of misdirected behaviour?
- Mutilation
- Excessive licking, plucking or chewing feathers / hair / limbs
What is meant by ‘failure in sexual and parental behaviour’ in animals?
Animals failing to reproduce successfully or rejecting their young or being ineffective parents
What is light?
A form of electromagnetic radiation which travels in waves
What are the fates of light?
83% is absorbed by photosynthetic pigments
12% is reflected
5% is transmitted
What are the three types of photosynthetic pigments?
Chlorophyll A and B and carotenoids
What does having multiple photosynthetic pigments mean for a plant?
A wider range of wavelengths of light can be absorbed
What do absorption spectrums show?
The separation of light of each wavelength by each pigment
What do action spectrums show?
The effectiveness of photosynthesis at each light wavelength
What happens in stage one of photosynthesis?
- In the chloroplast, light energy is captured by chlorophyll A and B and carotenoids which have different absorption spectra.
- Absorbed light excites electrons in pigment Molecules,
Transfer of these electrons
through the ETC release energy
to generate ATP by ATP synthase. - Energy is also used for photolysis in which water is split into hydrogen ions - which are transferred to the NADP to make NADPH - and oxygen which diffuses out of the cell (evolves)
What is stage 2 of photosynthesis, what is it known for and where does it take place?
- The Calvin cycle
- Being temp dependant
- The storma of the chloroplast
What are the fates of glucose?
- Used as a respiratory substrate
- Synthesised into starch
- Passed onto other biosynthetic pathways for the production of other metabolites
What is symbiosis?
A co-evolved, intimate relationship between members of two different species
What are the different types of symbiosis?
- Parasitism
- Mutualism
What is parasitism?
When the parasite benefits by gaining energy or nutrients and the host is harmed by the loss of these resources.
Why do parasites partake in symbiosis?
Because they often have a limited metabolism and cannot survive without contact with a host
How can parasites be transmitted?
- Direct contact
- Resistant life cycle stages
- The use of a vector
What are resistant life cycle stages?
When a parasite is able to survive adverse conditions for long periods of time until they come into contact with a new host
What is a vector?
Something that carries the parasite from one organism to another without suffering from disease
What are advantages of secondary hosts to parasites?
- Provide a way of getting from one host to another due to the fact they are immotile
- They can exploit the secondary host by using it as a site for asexual reproduction
What is mutualism?
When both partner species in symbiosis benefit from the interaction
What are mutualism symbiotic relationships described as and what does it mean?
- interdependent
- one cannot live without the other
What behaviours are adapted to group living that social groups have?
- Social hierarchy
- Cooperative hunting
- Social defence
What is a social hierarchy?
A rank order of within a group of animals, consisting of a dominant and subordinate members
What is an advantage to having a social hierarchy?
It increase the chances of the dominant animals alleles being passed on to offspring
What are the advantages to to cooperative hunting?
- The subordinate animals may gain more energy than from foraging alone
- Less energy is used per individual
- Larger pray can be caught and the chances of success increase
What are the advantages to social defence?
Increase the chance of survival as some individual can forage for food while the others watch for predators
What is altruism?
When an organism performs a behaviour which is harmful to itself but beneficial to another individual
What is reciprocal altruism?
When the roles of the donor and recipient reverse
Why is altruistic behaviour common between kin?
Because the donor may benefit indirectly in terms of there being an increased chance of survival of shared genes in the recipients offspring
What is kin selection?
The evolutionary strategy that favours the reproductive success of an organisms relatives
What are examples of social insects?
Bees, wasps, termites and ants
What are social insects?
Insects with a social structure where division of labour occurs and only a few fertile individuals reproduce
What do the ‘workers’ apart of a social insect group do?
Defending the hive, collecting pollen and carrying out waggle dances to show the direction of food
What are primates?
A group of highly evolved mammals
What organisms are primates?
Apes, lemurs and monkeys
What have primates developed?
A long period of parental care which allows for the learning of complex social behaviour
What does complex social behaviour in primates support?
A social hierarchy which reduces conflict among the group
What do dominant primate members do to assert their authority?
Use ritualistic threat displays and physical attacks
What is appeasement behaviour?
A submissive display by subordinate individuals
What methods reduce tension among primate groups?
Appeasement behaviour and grooming
What factor can change an individuals status in a primate group?
Having a baby and forming alliances
What is biodiversity?
The variation of life on earth
What components of biodiversity can be measured?
- Genetic, species and ecosystem diversity
What is genetic diversity?
Genetic variation shown by the number and frequency of all the alleles within a population
With regards to genetic diversity, what happens to the population if another population of a species dies out?
Limit its ability to adapt to changing environmental conditions
What does species diversity refer to?
- The species richness
- The relative abundance
What does ‘the species richness’ and ‘relative abundance’ mean?
- The no. of different species in an ecosystem
- The proportion of each species in an ecosystem
What does ecosystem diversity refer to?
The no. of distinct ecosystems within a defined area
What are threats to biodiversity?
Overexploitation
What does overexploitation mean?
When individuals are being removed from a population at a greater rate than can be replaced by reproduction
What can result from overexploitation?
Small populations losing genetic variation necessary to enable evolutionary responses to environmental change
What does the term ‘bottleneck effect’ mean?
When small populations may lose genetic variation necessary to enable evolutionary responses to environmental change
What is habitat fragmentation?
The formation of several habitat fragments whose total surface area is less than that of the original habitat
What can the degradation of the edges of habitats result in?
Increased competition between species as the fragment becomes smaller
What is a habitat corridor?
Used to link isolated habitat fragments, allowing species to move between fragments
What benefits do habitat corridors bring?
Increased access to food and choice of mates
What is meant by ‘introduced species’?
Species that humans have moved intentionally/accidentally to a new geographical location
What is meant by ‘naturalised species’?
Species that have become established within wild communities
What is meant by ‘Invasive species’?
Naturalised species that spread rapidly and eliminate native species, reducing species diversity
How do invasive species outcompete native species?
They are free from predators, parasites, pathogens and competitors due to them not being in their native habitat
What can invasive species do?
- Outcompete native species for resources
- Prey upon native species
- Hybridise with native species
WHat might invasive plant species do?
- Cost the economy from damage dealt to buildings
- Cause health problems
- Reduce overall biodiversity in an ecosystem
