Unit 2 Chapter 5.1
Ecology
Biosphere
• All life on Earth and all parts of the Earth where life exists
• Includes land, water and atmosphere
Ecology
• Ecology – the scientific study of the interactions
between organisms and their physical environment.
• Environment – all conditions or factors surrounding an
organism.
• Environment includes two main types of factors:
• Biotic factors – living factors in the environment
• Example: fish, snails, algae and plants
• Abiotic factors – non-living factors in the environment
• Example: water, gravel, temperature, light
Energy, Producers and consumers
• Energy is needed for growth, reproduction and all
processes in the body
• Without energy we cannot live!!!
• Where does all energy on Earth come from?
• The sun!!!
• Only certain organisms can capture energy from the sun and
convert it into a form they can use
• These include algae, certain bacteria and plants
• Energy is converted into a form living cells can use
Primary Producers
• These organisms are called autotrophs or primary producers because they can make their own
food using light energy from the sun and are the first producers of energy rich compounds other
organisms need to survive
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Use energy from sun to convert inorganic compounds into organic molecules (sugar)
Organisms that eat autotrophs then use energy stored in the bonds of these organic molecules
Without autotrophs there would be no energy or food for organisms on the planet!!!!!
Remember Photosynthesis??
Can there be life without light?
• Yes!
• About 30 years ago scientists found ecosystems around deep ocean
vents where it is very dark.
• These organisms use a process called chemosynthesis to harness
energy from inorganic molecules instead of photosynthesis since
there is no light
Consumers
• Heterotrophs – cannot capture light energy from the sun
• Must get energy from other organisms by consuming them
• That is why they are also called consumers!
• There are several different types of consumers depending on what they eat!
Types of Consumers
• Herbivore – eat plant leaves, roots, seeds, fruits
• Examples: cow, caterpillars, deer
• Carnivore – kill and eat other animals
• Examples: snakes, dogs, cats, river otter
• Omnivores – eat both plants and animals
• Examples: humans, bears, pigs
• Scavengers – eat carcasses of other animals that have
been killed by predators or have died of natural
causes
• Example: vultures
Types of Consumers
• Decomposers – feed by chemically breaking down organic matter
(dead plants and animals)
• Produces detritus: small pieces of decaying plants and animals
• Example: Bacteria and fungus
• Detritivores – chew or grind up detritus particles into smaller pieces
• Examples: mites, shrimp, snails and crabs
Cellular Respiration: Burning the Fuel
• An organism obtains energy from the food it eats.
• This food must be broken down within its body.
• The process of breaking down carbohydrates to yield
energy is called cellular respiration.
• Cellular respiration occurs inside the cells of most
organisms.
Cellular Respiration: Burning the Fuel
• During cellular respiration, cells absorb oxygen and
use it to release energy from food.
• Through cellular respiration, cells use glucose (sugar)
and oxygen to produce carbon dioxide, water, and
energy.
Cellular Respiration: Burning the Fuel
• Part of the energy obtained through cellular
respiration is used to carry out daily activities.
• Excess energy is stored as fat or sugar.
Energy Transfer
• Each time an organism eats another organism, an
energy transfer occurs.
• This transfer of energy can be traced by studying food
chains, food webs, and trophic levels.
Food Chains
• Primary produces and consumers are linked through feeding
relationships
• Energy is passed from producers to various consumers
• Food chain – organisms transfer energy by eating and being eaten
• Can vary in size from big to small
Food Webs
• Many animals eat more than one kind of food
• So feeding relationships in an ecosystem are usually
much more complicated than a chain
• Food web – shows the network of feeding
interactions
• Food web links together all the food chains in an
ecosystem
Disturbance in food webs
• A change in a population of just one of the species in the food web
can affect all the other species! What would happen if a toxin killed
all the spiders?
Ecological Pyramids
• Each step in a food chain or food web is called a
trophic level
• Primary producers always make up the first level
• Consumers make up the other levels
• Ecological pyramids show the trophic levels in an
ecosystem and the relative amount of energy and
matter at each level
• Three types: pyramids of energy, pyramids of biomass and
pyramids of numbers
Pyramids of Energy
• Each level stores a small portion of energy from the
previous level
• Energy is stored in the tissues
• Organism spend a lot of the energy they get on life
processes like respiration and growth
• Most of the remaining energy is lost to the
environment as heat
• Show the relative amount of energy available at each
trophic level of a food chain or web
Energy Transfer
• The efficiency of energy transfer from one trophic level to another
varies
• Typically 10% of the energy available at one level transfers to the
next
• The lower the consumer is on the pyramid the less energy it receives
• The amount of original energy from the producer is very small once it
reaches this consumer