1. Populations & Communities Obj: 11B
Investigate and analyze how organisms, populations, and communities respond to external factors.

2. What is an organism?
An individual living thing, such as a bacterium, protist, fungi, plant, or animal.

3. What is a population?
A group of one species of organisms that live together in a certain area.
Examples:
Humans living in the city of Houston
Tree frogs living in a forest

5. What is a community?
A group of populations of different species that interact with one another.
Example:
Populations of tree frogs, snakes, birds, as well as other animals and plants all living together on a tropical island

7. What is an ecosystem?
Communities in the environment
Includes abiotic (non-living) and biotic (living) factors.
Example: the tropical island

9. How do organisms respond to external factors?
When a rabbit senses that a predator is near…

10. It runs away or hides in a burrow

11. When a skunk feels threatened…

12. It sprays its attacker with a foul-smelling liquid

13. When an opossum is attacked…

14. It curls into a ball, and pretends to be dead.

15. Plants that grow as vines, such as pumpkin and ivy, produce tendrils that can wrap around surfaces

16. Roots of plants tend to grow toward wet soil, while the leaves grow toward light

17. How do populations respond to external factors?
Predator & prey relationships
Competition among predators
Invasive species outcompete natives
Disease

18. Predation

19. Competition

20. Invasive species
Asian carp were introduced to Michigan lakes to control algae.
Now introduced species outcompeting native fish for food.

22. Pythons in the Everglades in Florida

25. Disease

29. How do communities respond to external factors?
What happens to the snake population when the toad population dies out due to disease?

30. Volcano Explosion

33. Oil Spills

36. The Role Microorganisms
11C: Summarize the role of microorganisms in both maintaining and disrupting the health of both organisms and ecosystems.

37. What is a microorganism?
Any organism that cannot be seen without the aid of a magnifying glass or microscope
Examples – bacteria, protists, fungi
Found in almost every habitat on Earth

39. How can microorganisms maintain the health of other organisms?

40. Mutualistic Relationships
Microorganism gains benefits such as a warm environment to inhabit and gain nutrients
Animal or plant may gain benefits such as protection from other microorganisms or a supply of enzymes they need but cannot produce

41. Example – bacteria living in guts of termites & cows to produce enzymes to digest cellulose
Example - Fungi & plants form relationship called mycorrhizae.

42. The Fungi collect water & minerals and deliver them to plant roots
The Plants provide the fungi with nutrients made through photosynthesis.

44. Example – Plants called legumes contain bacteria of the genus Rhizobium in structures on their roots called nodes.
The Rhizobium fixes atmospheric nitrogen so that is is available for plants to use.

46. How can microorganisms disrupt the health of organisms?

47. Parasitic Relationships
Some microorganisms causes diseases in a host. These microorganisms are called pathogens.
Pathogens cause a disease by killing the host cells, releasing toxins, or interfering with the processes within the host’s body.

48. Lyme Disease
Caused by at least three species of bacteria belonging to the genus Borrelia.

49. Tetanus
Caused by the bacteria Clostridium tetani.

50. Strep Throat
Caused by the bacteria Streptococcus pyogenes.

51. How do microorganisms maintain the health of ecosystems?

52. Mutualistic Relationships
Microorganisms recycle nutrients. Decomposers break down organic matter of dead plants & animals.
Some bacteria living on the ocean floor feed on oil that seeps from the ground.

53. How do microorganisms disrupt the health of ecosystems?

54. Pathogens (microorganisms that cause disease) can kill off large numbers of a plant or animal species that is important to the health of the ecosystem.

55. Example
In oak forests, many animals depend on the acorns that fall each autumn for food.
What would happen if a pathogen infected the oak trees and prevented them from producing acorns?

56. Oak Wilt
Caused by the fungus Ceratocystis fagacearum.

58. Algal blooms in aquatic ecosystems such as oceans can block sunlight and cause death of plants along with organisms that eat the plants.
Bacteria populations rise because of an increase in food supply of dead organic matter.
Oxygen levels drop because of the bacteria population increase. Fish and other organisms then die. These areas are called dead zones.