2.2 Communities and Ecosystems Flashcards
Define ecosystem
A community and the physical enviornment it interacts with
Define community
A group of populations living and interacting with each other in a common habitat.
Community description (high vs low diversity)
a community that has a high diversity is more complex and stable than a community that has a low diversity
Describe photosynthesis in terms of inputs, outputs and energy transformations
- inputs:
sunlight as energy resource, carbon dioxide and water - processes:
chlorophyll traps sunlight; energy is used to split water molecules; hydrogen from water is combined with carbon dioxide to produce glucose. - outputs:
glucose used as an energy source for the plant and as a building block for other organic molecules; oxygen is released to the atmosphere through stomata. - transformations:
light energy is transformed to store chemical energy.
Describe respiration in terms of inputs, outputs and energy transformations
- inputs:
glucose and oxygen - processes:
oxidation processes inside cells - outputs:
release of energy for work and heat
co2 - transformations:
stored chemical energy to kinetic energy and heat
Summarise equation for respiration
glucose + oxygen → carbon dioxide + water (+ energy)
Energy is shown in brackets because it is not a substance. Notice that:
Glucose and oxygen are used up
Carbon dioxide and water are produced as waste products
Define entropy
a measure of the amount of disorder in a system
State how energy in an organism can be lost
Energy is lost in organisms mainly as heat during respiration, a process that converts food and oxygen into usable energy and heat as a byproduct.
define primary producer/autotroph
organisms that can produce their own food. some organisms called chemosynthetic bacteria however make their food from other simple compounds like methane. these dont require sunlight and are often bacteria found in the deep ocean
Describe how plants use some of the end products of photosynthesis
primary producers are self-sufficient when it comes to meals: they produce their own food using light, carbon dioxide, water and sometimes other chemicals too.
Typiclly plants or algae
Summarise the equation for photosynthesis
6CO2 + 6H2O + light energy → C6H12O6 + 6O2
Plants need only light energy, CO2, and H2O to make sugar. The process of photosynthesis takes place in the chloroplasts, specifically using chlorophyll, the green pigment involved in photosynthesis.
Define biomass
The mass of organic material in organisms or ecosystems, usually per unit area
Connection between photosynthesis and the production of biomass?
Photosynthesis produces the raw material for producing biomass.
Biomass contains energy first derived from the sun: Plants absorb the sun’s energy through photosynthesis, and convert carbon dioxide and water into nutrients (carbohydrates).
Define trophic level
the trophic level is the position that an organism occupies in a food chain, or a group of organisms in a community that occupy the same position in food chains - what it eats, and what eats it.
Identify and explain trophic levels in food chains and food webs selected from the local environment.
- Primary Producers (Trophic Level 1): western wheat grassThey convert solar energy into chemical energy stored in carbohydrates.
- Primary Consumers (Trophic Level 2): These are herbivores that eat primary producers. club horned grasshopper They obtain energy by consuming plant material.
- Secondary Consumers (Trophic Level 3): These organisms are carnivores or omnivores that eat primary consumers. Great Plains toad They gain energy by consuming herbivores.
- Tertiary Consumers (Trophic Level 4): These are higher-level carnivores that feed on secondary consumers and, occasionally, primary consumers. Garter snake
- apex predators, which are at the top of the food chain and have no natural predators. Swainson’s Hawk
Define consumer with reference to a named example
feed on other organisms, they do not contain photosynthesis pigments so they cannot make their own food.
e.g. rabbits
Define decomposer with reference to a named example
get their food from the breakdown of a dead organism matter. e.g. fungi
Define an Apex predator with reference to a named example
an organism at the top of the food chain that preys on other animals and has no natural predators. e.g. lion
Explain ecological pyramid
An ecological pyramid is an illustration of the reduction in energy as you move through each feeding (trophic) level in an ecosystem. The base of the pyramid is large, since the ecosystem’s energy factories (the producers) are converting solar energy into chemical energy via photosynthesis. A food chain can also depict a reduction in energy at each feeding level if the arrows, drawn between the different levels, continue to be reduced in size.
Discuss how entropy affects the efficiency of a system
second law of thermodynamics!
When energy transfers between organisms in an ecosystem, most of it is lost as heat, according to the second law of thermodynamics. For example, when a plant is eaten by a herbivore, the herbivore can only use about 10% of the plant’s stored energy. The rest is lost mainly through metabolic processes as heat. This results in an increase in disorder, or entropy, in the ecosystem, decreasing its efficiency.
Define bioaccumulation
Bioaccumulation refers to how pollutants enter a food chain. It is an increase in concentration of a pollutant from the environment to the first organism in a food chain.
Define biomagnification
Biomagnification refers to the tendency of pollutants to concentrate (builds up) as they move from one trophic level to the next. It is an increase in concentration of a pollutant from one link in a food chain to another.
What is a pyramid of numbers used for?
records the number of individuals at each trophic level coexisting in an ecosystem.
Pyramids of numbers can sometimes display different patterns; for example, when individuals at lower trophic levels are relatively large (inverted pyramids).
Advantage pyramid of numbers
- easy method of giving an overview
- good for comparing changes in population numbers over different times
