Higher Level Ecology Flashcards
What does the pyramid of numbers represent?
The number of organisms at each trophic level in a food chain
What does the Pyramid shape tell you?
Number of organisms decline as you go up due to large energy losses between each trophic level
Body size of the organism usually increases as you go up a pyramid of numbers
What are the limitations of the pyramids of numbers?
They did not take into account the size of the organisms
A huge oak tree may be represented by a narrow rectangle
What are the two main shapes of pyramids?
Normal pyramid and inverted pyramid
What factors control populations?
Completition
Predation
Parasitism
Symbiosis
What is competition?
active struggle between organisms for a resource that is in short supply
What would plants compete for?
Space, light, water and minerals
What would animals compete for?
Food, water, shelter, territory, mates
What is intra-specific competition and give an example
It takes place between members of the same species
Rabbits compete with eachother for food
What is inter specific competition and give an example
Occurs between members of different species
Blackbirds and thrushes for insects
How do animals avoid competition?
Adapt to their environments, which may involve changes in feeding habitats, camouflage and reproductive strategies
What are the two main types of competition?
Contest competition and scramble competition
What is contest competition?
Involves an active physical confrontation between two individual organisms
What is scramble competition and give an example
All of the competing individuals get some of the resource
Overcrowding of seedlings in flower beds
What does scramble competition cause?
Large changes in population sizes and in general reduces the numbers in a population
An adaptive technique to survive competition
Blackbird ‘song’ to warn competitors to stay away
Yellow petals of buttercups to attract insect pollinators
What is predation?
It’s the catching, killing and eating of another organism
What is a predator?
It’s an organism that catches, kills and eats another organism
What is prey?
It’s the organism that is eaten by the predator
Adoptions of predators
Hawks - excellent eye sight
Ladybirds - strong mouth parts to enable them to chew aphids
Fox - reddish fur for camouflage to avoid detection by rabbits
Long canine teeth to kill prey
Great speed to outrun prey to capture
Adaptions of prey
Rabbit -
Digs narrow underground burrows
Long ears - detect predator
White tail - conspicuous warning signal to other rabbits
What is parasitism?
It occurs when two organisms of different species live in close association and one organism obtains it’s food from, and to the disadvantage of the other organism
What are the two types of parasites?
Exoparasites and endoparasites
What are Ectoparasites and example
Lives on outside of host, Feed on outside of host eg, mosquito
What are endoparasites and example
Feed in a living host, bacteria of disease
How do parasites differ from predators?
Smaller than the host, often attack from within, they’re dependent on the one particular host, don’t kill only do small amount of damage
What is symbiosis?
Occurs when two organisms of different species live in close association and at least one of them benefits
What is mutualism?
Form of symbiosis where both organisms benefit from association
Example of symbiosis mutualism
Nitrogen fixing bacteria and legumes - bacteria provide nitrates for plant to make protein and plant provides carbohydrates and anaerobic conditions
How does symbiosis influence human population?
Increases number of both organisms
What are the factors that contribute to predator-prey interactions
Availability of food -increase in prey, increase in predators, prey killed off less food so they decline
Movement of predators
Factors affecting human growth
War, famine, contraception, disease
How do different types of mouth parts reduce competition?
They eat different food - or different parts of food
Adoration of plants as prey
Thorns such as cacti
Effects of predation in ecosystem
Maintains prey species at sustainable level
Major factor in evolution of prey species
List two species from an ecosystem you have studied which are involved in a predator-prey relationship
Ladybirds and aphids
Draw a graph to show how population numbers fluctuate in a predator-prey relationship and explain fluctuations
[page 33 in exam papers]
The number of prey builds up and therefore the number of predators will rise
As a result, there’s more prey being killed and so the number will fall
In turn, this will result in fewer predators and so numbers will fall as they die or move away
Eventually, the number of prey will rise again and cycle will begin again
Graph of phytoplankton
Page 82
Suggest two reasons why the human population increased so rapidly from the mid 1880’s
Better living conditions
Better nutrition
Improved medicine
Suggest what could happen to biological diversity as the human population continues to increase
Inc - more people different
Mention three main ways in which waste can be minimised
Reduce
Reuse
Recycle
What is the role of microorganisms in pollution control
Decomposers
Name three factors that controls wild populations
Competition Predation Disease Parasitism Hunting
What deduction can be made in a particular area where the population of a predator did not decline following a big reduction in the population of its main prey
Different prey
What deduction can be made when mortality levels resulting from infection tend to decline over the years
Immunity develops
What deduction can be made where some members of the species remain in a general area throughout life and some members are migratory and the mortality levels tend to be higher in the migratory part of the population
Hazards encountered on migration
What deduction can be made when there is a greater variety of herbaceous plants in areas where grazing species such as rabbits are more plentiful than in areas where grazing species are less plentiful
Reduced competition
Where are primary producers found in a pyramid of numbers
Bottom
Construct a simple inverted pyramid of numbers using named examples
Robin [small]
Ladybird [kinda big, smaller than aphids]
Aphids [big]
Oak tree [small]
Spider mites [small but not as small as oak tree and smaller than greenfly]
Mites [largest]
Greenfly [larger than oak tree]
Oak tree [smallest]
Suggest an alternative to the use of pesticide for controlling the population of a species
Biological control
Genetically modified plant
When the pesticide killed both the predator and the prey, the prey quickly reinvaded the strawberry fields while their predator returned much slowly, why did this happen?
Predator eliminated
Developed resistance to pesticide
Food available
Comment on relative sizes due to pyramid of numbers
Broader = smaller it is Narrower = larger it is
If the population of prey decreases suggest a possible consequence for the predators
Death, Migration
Competition is generally more intense between members of the same species than between members of different species?
True
Same niche, same requirements for food, shelter, breeding etc
Suggest two reasons why birds migrate
Climate
Breed
Food
Suggest three possible effects of the disappearance of a plant on the populations of other plants and animals in the ecosystem
Animals dependant on plant as good may die or migrate
