unit 3 - made using online summery notes Flashcards
What is food security?
The ability of human populations to access food of sufficient quality and quantity.
What has led to concerns about food security?
The rapidly increasing human population and rising demand for food worldwide.
What is a key part of food security?
Access to food, including affordability.
What is sustainable food production?
Food production that meets current demands without negatively impacting the ecosystem and natural resources.
What are some common sources of human food?
- Cereals
- Potato
- Roots
- Legumes
What factors affect food production?
- Light availability
- Available nutrients
- Water in the soil
- Competition with other plants
What practices can increase food production efficiency?
- Control of limiting factors
- Planting higher yield strains
- Removing competition using pesticides
- Developing pest-resistant crops
Why is livestock production less efficient than crop production?
About 90% of energy is lost between trophic levels, making it more energy and water-intensive.
What is photosynthesis?
The process by which green plants trap light energy to make carbohydrates.
What happens when light strikes a leaf?
- 12% is reflected
- 5% is transmitted
- 83% is absorbed
What are the principal pigments involved in photosynthesis?
- Chlorophyll a
- Chlorophyll b
What is photolysis?
The process by which water is split into oxygen and hydrogen during photosynthesis.
What is the Calvin Cycle?
A series of enzyme-controlled reactions that fix carbon dioxide without requiring light.
What is the role of glucose produced in photosynthesis?
- Energy source for respiration
- Building material for cellulose
- Energy storage as starch
What is selective breeding?
Manipulating DNA of crops and animals to improve certain desirable characteristics.
What are plant field trials used for?
- Investigating performance of cultivars
- Assessing effects of environmental conditions
What is inbreeding?
Reproduction between closely related individuals to develop desired characteristics.
What is inbreeding depression?
A decline in vigor, size, fertility, and yield due to increased homozygosity for deleterious alleles.
What is crossbreeding?
Introducing new alleles by breeding individuals from different breeds to improve characteristics.
What is genetic sequencing?
A process to determine the precise sequence of DNA nucleotides in an organism.
What is monoculture?
The production of a single species of plant, often genetically identical.
What are the characteristics of annual weeds?
- Rapid growth
- Short lifecycle
- Large number of seeds
- Long-term seed viability
What are some common invertebrate pests?
- Molluscs (slugs and snails)
- Nematodes (microscopic worms)
- Herbivorous insects (e.g., aphids)
What are cultural control methods?
- Ploughing
- Timing of sowing
- Early weed removal
- Destruction of crop residue
- Cover crops
- Crop rotation
What types of pesticides are used in chemical control?
- Herbicides
- Fungicides
- Molluscicides
- Nematicides
What is bioaccumulation?
The build-up of a chemical in an organism over time.
What is biomagnification?
The increase in concentration of a chemical as it moves up trophic levels in a food chain.
What is bioaccumulation?
The build-up of a chemical in an organism.
Chemicals like DDT persist in the environment and accumulate over time.
What is biomagnification?
An increase in the concentration of a chemical moving between trophic levels of a food chain.
This may lead to poisoning of animals further along the food chain.
What problem does selective pressure from pesticide use create?
It produces a resistant population of pests.
When is the use of fungicides most effective?
When applied as a preventative measure based on disease forecasts.
What is biological control?
A method that reduces pest populations using a natural parasite, predator, or pathogen of the pest.
Why is timing important in biological control?
It helps avoid resistance, persistence, and the introduction of harmful chemicals.
What is an example of a parasite used in biological control?
The wasp Encarsia for controlling glasshouse whitefly.
What is Integrated Pest Management?
A combination of cultural, chemical, and biological control methods.
What does animal welfare refer to?
The wellbeing of an animal, including its ability to express natural behaviours.
What is a disadvantage of intensive farming?
It gives animals very limited space and is less ethical than free-range farming.
What are the long-term benefits of free-range farming?
- Increased growth of animals
- Increased success rate of breeding
- Higher quality end products
- Improved image and marketing
What is stereotypy in animals?
Repetitive movement that expresses distress.
What is misdirected behaviour?
Normal behaviour directed at the animal itself, its environment, or others.
What does failure in sexual behaviour mean?
Animals may stop demonstrating mating behaviours or become physiologically incapable of mating.
What is apathy in animals?
Very low levels of activity, shown by animals lying, sitting, or standing in the same position for long periods.
What does symbiosis mean?
Living together; close relationships between members of two different species.
What are the two categories of symbiosis?
- Parasitism
- Mutualism
What is parasitism?
A relationship where one species benefits at the expense of another.
How do parasites typically survive?
By gaining nutrients and/or energy from their host.
What is mutualism?
A relationship where both species benefit from the interaction.
Give an example of mutualism.
Herbivores hosting cellulose-digesting protozoa/bacteria in their guts.
What is social behaviour in animals?
Behaviour exhibited by individuals living in social groups that benefits survival.
What is social hierarchy?
A system that organizes individuals into an order of rank.
What are appeasement behaviours?
Behaviours used by subordinate individuals to reduce conflict.
What is co-operative hunting?
Hunting strategy relying on cooperation between social group members.
What is altruism?
Behaviour that is detrimental to the donor but beneficial to the recipient.
What is reciprocal altruism?
A situation where donor and recipient roles are reversed later.
What is biodiversity?
The variety of species found in an ecosystem.
What are the three measurable components of biodiversity?
- Genetic diversity
- Species diversity
- Ecosystem diversity
What does genetic diversity refer to?
Genetic variation of the number and frequency of alleles of a specific gene.
What is species diversity composed of?
- Number of different species
- Proportion of each species
What is ecosystem diversity?
The number of distinct ecosystems in a defined area.
What is overexploitation?
The excessive use of a resource, such as over-fishing or over-harvesting.
What does ecosystem diversity refer to?
The number of distinct ecosystems in a defined area.
What can biodiversity measurements be used for?
To monitor ecosystem change and for conservationists to decide on species to support.
Define overexploitation.
Over-fishing and over-harvesting that can lead to extinction if not stopped in time.
What is the bottleneck effect?
When a population has been almost wiped out, resulting in a loss of genetic information.
How does a small surviving population affect genetic diversity?
It can lead to poorer reproductive rates due to inbreeding.
What is habitat fragmentation?
When a habitat is broken up into smaller fragments or sections.
What are the consequences of habitat fragmentation?
Habitat loss, increased competition between species, and decreased biodiversity.
What are habitat corridors?
Links between habitat fragments that allow movement of animals between them.
What are introduced species?
Species moved by humans into a new geographic location where they are not naturally found.
What are naturalised species?
Introduced species that have become established in a new location.
Define invasive species.
Naturalised species that spread rapidly and outcompete or prey on native species.
True or False: Invasive species can eliminate native species.
True.
Why do invasive species spread rapidly in new locations?
Because these locations are free of predators, parasites, and competitors.
