Organisms in their Environment
Vocabulary An organism is a living thing. E.g. a fish
Vocabulary A habitat is where an organism lives E.g. a pond
Vocabulary A group of the same kind of organisms living in the same habitat are called a population.
Vocabulary All the populations of organisms together in a habitat are called the community.
Vocabulary The habitat and the community together are called the ecosystem.
Ecosystems A distinct, self-supporting system of organisms interacting with each other and with a physical environment..
The Composition of Ecosystems
Components of Ecosystems Whatever the size, ecosystems usually have the same components Producers Consumers Decomposers A physical environment
Producers Producers are green plants that produce chemical energy from light energy. They do this by a process called photosynthesis.
Consumers Organisms that cannot make their own source of food (e.g. animals) to get energy have to get it by eating or consuming other organisms. As organisms eat each other, the energy is passed from one organism to another. We can show this in a FOOD CHAIN.
Decomposers Decay dead material and help recycle nutrients
Physical Non-biological components (abiotic) Water Soil Rocks
Ecosystems Complete the table of Biotic and Abiotic organisms we have discussed.
Habitats Within each ecosystem there are a range of habitats Grasses Ponds Trees Litter
Populations
Populations Within the ecosystem are organisms of a particular species. These make up a particular population
Communities The population of all species in a particular ecosystem at any one time form a community
Factors Affecting Animals Water Food Space Predators Disease Seasons/Weather
Factors Affecting Plants Water Food Space Insects Disease Seasons/Weather Sun
Carrying Capacity The carrying capacity of a biological species in an environment is the population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment.
Population graphs The growth of a wild population can be logged on a graph. The graph line looks like a flattened S. It is called a sigmoid curve. This graph shows 4 phases of population growth.
Population graphs 1. A slow start when there are only a few fertile members 2. Maximum growth when birth rate greatly exceeds death rate.
Population graphs 3. Decelerating growth as environmental resistance starts (e.g. lack of food) 4. Steady population numbers when the birth rate and death rate is about equal.
Stages of Population Growth Stage 1 decrease in birth rates Stage 2 birth rates greater that death rates Stage 3 death rates begin to increase Stage 4 birth and death rates remain low
Population Growth All populations undergo three distinct phases of their life cycle: growth stability decline
Interaction In An Ecosystem
Interaction in An Ecosystem Organisms in an ecosystem are continually interacting with each other Feeding among the organisms Competing with each other Interaction between organisms and the environment
Interaction in An Ecosystem As organisms eat each other energy some energy is passed on Most energy is lost in the form of heat and waste. All energy originates from the sun.
Interaction in An Ecosystem Plants trap solar energy to produce chemical energy in the form of glucose Process called photosynthesis
Interaction in An Ecosystem Organisms that convert solar energy to chemical energy are called producers autotrophic They produce their own energy C 6 H 12 O 6
Interaction in An Ecosystem Organisms that consume producers for energy are called consumers Heterotrophic As organisms consume each other they will transfer some of the energy. However, most is lost in the form of heat.
Feeding Relations Feeding relationships are best illustrated with food chains
Food Chains Rabbits eat grass. Foxes eat rabbits. Grass Energy from the sun is transferred to chemical energy by photosynthesis Rabbit When the rabbit eats the grass, the energy stored in the grass is transferred to the rabbit. Fox When the fox eats the rabbit, the energy stored in the rabbit is transferred to the fox. That s what the arrow is showing!
Grass Rabbit Fox
The arrow in the food chain means eaten by
Primary and Secondary consumers The primary consumer is the first consumer in the food chain. These eat the plants The secondary consumer is the second consumer in the food chain. These eat other animals.
Producers and Consumers Leaf Worm Bird Producer consumer consumer
Tropic Levels The different stages in a food chain Producer, consumer, consumer
Feeding Relations Herbivore Carnivore Omnivore
Food Chain Most food chains go up to only 5. Why is this?
Decomposers Decomposers are bacteria and fungi. They get their food by decomposing (breaking down) dead plants and animals in to simple substances like carbon dioxide, nitrates and other minerals. They are very important because they provide all the nutrients in the soil for plants to grow.
The Circle of Life!! Yum. Tasty bug Yum. Tasty plant Yum. Tasty nitrates! Round and round The nutrients go!!
Food webs Obviously, all organisms eat a variety of food shown by many food chains. We can link these food chains together to make food webs. Look at these food chains:
Food chains Leaves earthworm hedgehog Leaves earthworm fox Leaves rabbit fox Leaves caterpillar hedgehog
Link the food chains together to make a food web hedgehog rabbit Leaves
More! Blackbirds eat earthworms, Falcons eat rabbits and blackbirds. Add Falcons and blackbirds to your food web.
Ecological Pyramids
Ecological pyramids Diagrams that represent the relative amounts of organisms at each trophic level in a food chain Pyramid of numbers Pyramid of biomass Pyramid of energy
Key points Pyramids of number show the number of living organisms at each stage of the food chain (trophic level).
Key points Look at this food chain: Wheat Mice Owl 50 10 2 Complete the paragraph in your worksheet. Complete the pyramid 2 owls 10 mice 50 wheat
Pyramids of number are not always pyramidal in shape Grass Rabbit Fox 200 blades of grass 6 rabbits 1 fox 25 fleas Fox Rabbit Grass Oak tree Caterpillar sparrow 1 oak tree 150 caterpillars 25 sparrows Sparrow Caterpillar Tree
Key points We use Pyramids of Biomass to show the amount of energy available at each trophic level (level of the food chain).
Key Points If we draw a pyramid of Biomass it will always look like a pyramid: Human Cow Grain There is always less biomass as you go up the food chain because energy is always lost. (Not all the energy in the plant is transferred to the primary consumer and not all the energy in the primary consumer is transferred to the secondary consumer.)
Energy Pyramid Only 5 to 20% of energy is transferred to the next trophic level due to: predator avoidance not all digestible not all accessible all organisms respire 10% used as a rule of thumb by ecologists
Hmmm. Considering the energy gets less and less as you move up the food chain, wouldn t it be better for humans to eat grain? Wouldn t we get more energy that way?? Human Cow Grain
Answer YES!!!!! There is more energy available in plant products compared to animal products. This is because there is always more energy the further down a food chain you eat. However, energy isn t the only reason to eat food and other food is eaten to get a balanced diet.
Summary Energy is lost in a food chain due to: Movement Excretion To keep a warm blooded animal at the right temperature Useful energy is energy used to make an organism bigger. Only this energy can be passed on to another organism when it is eaten.