Chapter 5: Higher Level Ecology Flashcards
what is a distorted pyramid of numbers?
when the pyramid does not have the largest number of organisms at the bottom
what is an inverted pyramid of numbers?
when the pyramid starts the with smallest number at the bottom and gets bigger
what are the 4 factors that control population?
competition
predation
parasitism
symbiosis
what is competition?
when organisms of the same or different species fight for the same resources that are in short supply e.g. shelter, food
what are the kind of competition is there?
intra-specific competition
inter-specific competition
what is inter-specific competition?
it is between members of different species
what is intra-specific competition?
it is between members of the same species
what are the two types of competition and explain them?
contest competition - involves an active physical confrontation between two organisms - one winner
scramble competition - each organism tries to acquire as much of the resource as possible - they both win but will soon run out of resource
what is predation?
the act of some animals capturing and killing other animals for food
what is a predator?
an animal that hunts, captures, kills other animals for food
what are 4 adaptations of predators?
keen senses and sharp teeth
change diet to suit prey availability
live and hunt in packs
camouflage
what is prey?
an organism that are hunted and eaten
what are 4 adaptations of prey?
plants may have thorns, stings or spines
nasty taste when eaten e.g. giant hogweed
faster than predator
camouflage
what does a graph representing predator/prey relationship look like?
predation initially increases the number of predators and decreases the number or prey
but when one decreases so does the other and when one increases so does the other
this cycle repeats itself
why does the population of prey and predator never go to zero?
the species may become extinct
what are parasites?
an organism that benefits from another and does harm to it
what is symbiosis?
where two organisms of different species have a close, specific relationship with each other where at least one benefits and no harm is done to the other
what is mutualism?
symbiosis
give an example of a symbiotic relationship between organisms.
bacteria living in the colon - bacteria produce vitamin B2 and vitamin K
the body gives suitable environment for the bacteria to live
what is population density?
the measurement of the numbers of a species of a stated area
why does a population increase?
increase in birth rate, decrease in death rate, immigration
why does a population decrease?
high mortality rate and emigration
explain the 4 steps in the normal population curve.
- organisms arrive and adapt to their new environment
- growth takes place rapidly due to newly available food
- growth constraints are felt - predation, overcrowding, available food
- growth settles at a level that the environment can support
what percentage of the world live in asia?
66%
what is the main cause of increased population?
decreased death rates
what years was the great irish famine?
1845-47
what are the four factors affecting population?
war, famine, disease, contraception
what are the four controls of disease?
vaccines - reduce the incidence of the following diseases: diphtheria, whooping cough, tetanus, polio, meningitis, tb
sanitation and insecticides - control malaria, yellow fever, sleeping sickness
anaethetics - improved surgical methods
antibiotics - prevent deaths that would have been causes by bacteria
what affect does war have on population?
reduces the population, the effects can be temporary, increased birth rates immediately after
what affect does contraception have on human population?
increased availability of contraception has led to a decrease in birth rates, developed countries have an average of 2.1 children per family, the fertility rate in developing countries has decreased from 6.1 in 1970 to 3.5 today
