INTERACTIONS OF LIFE
Chapter 24
What is the Biosphere?
• Biosphere: part of the Earth the supports life
• The top portion of Earth’s crust
• All the waters on Earth’s surface
• Surrounding atmosphere
• Made up of different environments that are home
to different kinds of organisms.
What is an Ecosystem?
• Ecosystem: all of the organisms living in an area
and the non-living parts of their environment.
• The study of these interactions occurring
between organisms and their environment is
ecology.
What are Populations & Communities?
• Population: made up of all of the organisms in an
ecosystem that belong to the same species.
• Community: all of the populations in an
ecosystem.
What are the Levels of Organization?
• Smallest
• Organism (individual living
thing)
• Population (living things-same
species)
• Community (living things- all
species)
• Ecosystem (all of the living and
non-living parts)
• Biome (whole region)
• Biosphere (life supporting Earth)
• Largest
What are the Levels of Organization?
What is an Organism’s Habitat Vs. Niche?
• Habitat: the place where an organism lives
• Must provide food, shelter, water, temperature
• Example: trees are a woodpecker’s habitat
• Niche: an organism’s role in its environment
• Example: how an organism obtains food, shelter,
finds a mate, cares for its young, and avoids
danger
How do Organisms Live Together?
• Competition: two or more organisms seek the same
resource at the same time.
• Competition for food, living space, mates or other
resources can limit the size of a population.
• Competition is usually most intense between
members of the same species.
How is Population Size Determined?
• Population Size indicates whether a population is
healthy and growing.
• Population Density: the size of a population per a
specific area.
• Measured by Trap-Mark-Release method and sample
count method.
What Elements Affect Population Size?
• Limiting Factor: any living or non-living feature that
restricts the number of individuals in a population.
• Carrying Capacity: the largest number of individuals
of one species that an ecosystem can support.
What Elements Affect Population Size?
• Biotic Potential: the highest rate of reproduction
under ideal conditions.
• Birth and death Rates
• Movement of organisms into or out of an area
(immigration/emigration)
How do Populations Grow?
• Beginning Growth: during the first few
years, population growth is slow
• Exponential Growth: the population grows
quickly as the number of adults increases
• Eventually, the population will reach its
carrying capacity.
How do Populations Grow?
How do Organisms Produce Food?
• The sun is the source of energy that fuels most life on
Earth
• Organisms that use the sun to make their own food are
producers
• Plants use photosynthesis
• Other organisms without access to the sun use
chemosynthesis
How do Organisms Consume Food?
• Consumers: organisms that obtain energy by eating
other organisms.
• Herbivores: eat plants (deer and rabbits)
• Carnivores: eat animals (frogs and lions)
• Omnivores: eat both plants and animals (pigs and
humans)
• Decomposers: eat dead organisms
What is a Food Chain?
• Food Chain: a
model of the
feeding
relationships in an
ecosystem.
What is Symbiosis?
• Symbiosis: any close relationship between species.
• Mutualism: relationship where both species benefit
• Commensalism: one species benefits and one is
unaffected
• Parasitism: one organism benefits and the other is
harmed
How Do Species Interact?
• Predator/Prey Interactions
• Predator: consumer that captures and eats
other consumers
• Prey: organism that is captured and eaten by
predator
How Do Species Interact?
• Cooperation: how organisms work together to improve
survival.
• Example: insects living in social groups, where each
individual performs a certain task
• Example: white-tailed deer alerting other deer to the
presence of a coyote