Flashcards
Population Growth and Pest Control
Flashcards do conjunto (23)
- 1Define Population Growth.It is a group of organisms of a single species interbreeding and occupying a particular area.
- 2Why do they live in a population?-Greater chance of mating.
-Work together for protection from predators.
-If disease; better adapted to changing environment - 3—Lag phase: slow growth because of producing enzymes.
Log phase: No limiting factor. Rapid population growth
Stationary Phase: Population reaches its max. size. Factors limiting its population growth.
Death Phase: Limiting factor causes bacteria to decline. Lack of nutrients/ build up of waste products - 4What is environmental resistance and name some examples.It is all the factors which may limit the growth of a population
These include:
-Food Availability
-Parasitism
-Predators
-Disease
-Weather
-Competition
-Accumulation of toxic waste - 5Define Carrying Capacity.The most population number that can be held in a population before a decrease in a single species OVER A LONG PERIOD OF TIME
- 6Define Immigration and EmigrationImmigration: Individuals joining a population permanently.
Emigration: Individuals leaving a population permanently. - 7Name factors which can affect population size?Density Dependent factors: Food, parasitism, accumulation of toxic waste, disease.
Density Independent: (FFF) Frost, Fire, Floods - 8-Describe Population Fluctuations. -What happens below, on and over the set point?-Population Fluctuations are regulated by the balance between the production rate and death rate.
-Set point; is the number of most species that lie near an equilibrium
-Population Increase S.P; Leads to a population decrease as more competition. Less resources.
-Population Decrease S.P; Leads to a population increase as less competition. More resources - 9Comp What do plants and animals compete for?Plants compete for:
SUNLIGHT
NUTRIENTS
SPACE
WATER
Animals compete for:
FOOD
SHELTER
SPACE
REPRODUCTIVE PARTNER - 10Comp Describe intra specific competition?It's a competition for resources between members of the same species
It's also the best driving force behind natural selection - 11Comp Describe Inter-specific competition?Competition for resources, i.e FOOD, SPACE, WATER, LIGHT between members of different species.
In general, one will out compete the other. - 12Define Pest Control?It is an ORGANISM which COMPETES with or ADVERSELY affects a POPULATION of organism that are of ECONOMIC importance.
- 13Typical Nature of pests?-Feed of crops and animals.
-Compete with crop organisms for resources
-Directly cause disease in crop organisms
-Spoil food when it's being stored or transported. - 14Define Chemical Control and how it can be applied?It involves the use of HERBICIDES, FUNGICIDES and INSECTICIDES to kill pests.
It can be applied by; Spray, Powder, Smoked, Animal food - 15What is a pesticide?It is a poisonous chemical weed to control organisms considered harmful to agriculture or organism involved in disease transmission.
- 16What are the advantages of Chemical control?-Application doesn't require a high level of skill
-Very effective means of control
-Pests are eradicated cheaply and quickly
-Chemicals can be applied on a small scale such as a single field. - 17What are the disadvantages of Chemical control?-Same pesticide could harm fish, birds and mammals by contamination of food.
-Long term exposure to pesticide can cause harm to humans. Eg Farmers using sheep dips.
-Pests become resistant to the pesticide.
-Eradication may result in a resurgence of the pest. - 18How Biological control works?-Beneficial organisms are deployed against the undesirable pest/target
-Pests act as a food source for the introduced organism
-Reduction in numbers of the pest as they are eaten, therefore their numbers are kept below economical damage threshold
-However pests are not eradicated completely as this would leave no food source for introduced predator ad would die out. - 19Advantages of Biological Control?-No environmental contamination.
-Usually highly specific to one pest.
-Can be used in glass house situations.
-Provides long term control if population equilibrium is established. - 20Disadvantages of Biological Control?-Very few successful examples of this strategy.
-Biological Control agents are slow to build up in numbers.
-Success involves a high level of skill and research
-Detailed knowledge of life cycle of pesticide is required. - 21Describe carbon cycle?
- 22Describe Nitrogen Cycle?
- 23How can humans improve the circulation of nitrogen?-By fixing atmospheric nitrogen artificially using chemical processes that convert into fertilisers.
-Large amounts of animal waste from stock rearing used as manure
-Micro organisms can be used for making compost and silage
-Sewage disposal boosts organic nitrogen supplies