1. Interactions of Life
Chapter 24

2. 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.

3. 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.

4. 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.

5. 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

6. What are the Levels of Organization?

7. 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

8. 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.

9. 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.

10. 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.

11. 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)

12. 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.

13. How do Populations Grow?

14. 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

15. 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

16. What is a Food Chain?
Food Chain: a model of the feeding relationships in an ecosystem.

17. 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

18. How Do Species Interact?
Predator/Prey Interactions
Predator: consumer that captures and eats other consumers
Prey: organism that is captured and eaten by predator

19. 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