Living Things! Factors that affect living things are: • Biotic factors – things that are alive or were alive (other organisms) • Abiotic factors – things that are non-living (temperature, water etc.) • The interaction of all biotic and abiotic factors creates an ecosystem.
Ecology • The branch of biology that studies the way living things interact with each other and with their physical environment. • It looks at the ways an organism is affected by its surroundings and how the environment is affected by the presence and activities of the organisms.
Roles of Organisms All living things need energy to survive and grow. The source of this energy is the sun. Plants through photosynthesis (an endothermic process) create food (sugar), to store energy for later use. To release stored energy from the sugar the plants carry out respiration ( an exothermic process). Not all organisms can produce their own food, so some must depend on other organisms as a source of food (energy). • Organisms can be either producers,consumers or decomposers (detritivores)in terms of energy flow through an ecosystem.
Producers:are self feeding organisms (autotrophs) that make organic molecules (glucose) during the process of photosynthesis. Photosynthesis uses energy from the sun plus the inorganic molecules CO2 and H2O. Examples: Algae, grasses, trees, etc.
Consumers: are heterotrophs, organisms that cannot make their own food, they depend on other living organisms for food. Primary Consumers:Herbivores that each vegetation Ex. : Grasshoppers, rabbits, snails, etc. Secondary Consumers:Carnivores that eat the herbivores Ex. : cats, ladybugs, foxes, owls, etc. Tertiary Consumers:Top carnivores.Ex. : Lions, bears, wolves, etc.
The Decomposers (Detritivores):They decompose dead organic material or wastes to return essential nutrients to the soil. These nutrients help plants grow.Ex. : Bacteria and mushrooms
Trophic (feeding) level • refers to the organisms position in the food chain • Autotrophs are at the base (first trophic level). • Organisms that eat autotrophs are called herbivores or primary consumers (second trophic level). • An organism that eats herbivores is a carnivore and a secondary consumer. (third trophic level) • A carnivore that eats a carnivore that eats a herbivore is a tertiary consumer (forth trophic level). • Omnivores eat both animals and plants.
Energy and Nutrient Flow Through the Ecosystem The movement of energy is shown by the dark arrows. The movement of the inorganic nutrients is shown by the open arrows
Food Chains and Webs • A food chain is the path of food from a given final consumer back to a producer. (The arrow points to the consumer.) grass grasshopper mouse snake hawk Identify the autotrophs and heterotrophs, and classify each as a herbivore, carnivore, etc.
Food Webs Identify the autotrophs and heterotrophs, and classify each as a herbivore, carnivore
The real world is more complicated than a simple food chain. A more realistic depiction of who eats whom is called a food web which depicts interlocking food chains.
Questions to answer • From the previous slide identify: • 1. Producers • 2. Primary consumers • 3. Secondary consumers • 4. Tertiary consumers • 5. Top carnivores
ENERGY • At each level of the food chain, about 90% of the energy consumed is lost in the form of heat. The total energy passed from one level to the next is only about one-tenth of the energy received from the previous level organism. As you move up the food chain, there is less energy available to pass on to the next level. • As you move up the food chain animals get larger and need more food to meet their energy needs. NOTE!! Each organism in the food chain is only transferring one-tenth of its energy consumption to the next organism.
To summarize • The ultimate source of energy (for most ecosystems) is the sun. • The ultimate fate of energy in ecosystems is for it to be lost as heat. • Energy and nutrients are passed from organism to organism through the food chain as one organism eats another. • Decomposers remove the last energy from the remains of organisms and release nutrients back into the soil. • Inorganic nutrients are cycled, energy is not.
Ecological Pyramids: represent graphically the structure of an ecosystem Pyramid of Energy Flow : shows the energy that flows through each trophic level; notice that there is less energy at each higher level.
Pyramid of Biomass: measures the biomass ( g/m² ) of the organisms in a food chain (dry mass).
Feeding the human population is big business (effort and monetary) • To prevent crops from being eaten by insects, agriculture has turned to various chemicals that kill the insects or that interfere with their life-cycle (reproduction) • In small doses, these chemicals are not harmful to other organisms, however, when they enter the food chains and move to high trophic levels, the quantities accumulate and can cause harm.
Bioamplification (Bio-magnification): • Accumulation of toxins in a food chain so that the major effects are found in the food predators. • Example: DDT: a pesticide used in the 50s and 60s to control populations of body lice, fleas and mosquitoes). Later used as a crop pesticide, after which sign of trouble appeared!!!!!
All the Earth’s ecosystems make up what is called the ecosphere or biosphere Climate is the main factor that determines whether a given species will thrive in an area. Biologists have divided the terrestrial (land) portion of the biosphere into biomes (collection of ecosystems that are similar) Biomes are large regions with a distinct climate and specific life forms Each biome is made up of many ecosystems with communities adapted to varieties in soil, climate and other factors throughout the biome.
Biodiversity: the genetic diversity, species diversity and ecological diversity that are important to life on this planet. It is the results of adaptations in organisms that have developed over billions of years in response to: *the variety of environments found on earth *competition amongst organisms for resources
A Population • Group of organisms of the same species living in the same place at the same time • Individuals may come and go, but the population can remain the same • Ex: The flamingos of Lake Victoria in Africa. • Assembled for yearly migration.
In a food web, each organism survives by gaining energy from the trophic level below it. The size of the populations then, are continually adjusted by the species interactions with both its food supply and it’s predators.
Carrying capacity: the largest population of a species that an environment can support. • 4 main factors that determine the carrying capacity: 1. materials and energy: energy, water, carbon, and other essential nutrients 2. food chains: the population size is limited by the size of the populations at lower trophic levels. (Prey limited by their predators and their food supply). 3. competition: each organism has the same need as any other. They compete for resources such as food, water, mates, space. 4. density: depending on their size, environment and way of life, different species have different needs for space.