CHAPTER 24 “ INTERACTIONS OF LIFE” (Page 684) The Biosphere -the part of the Earth which...
-
Upload
baldwin-randall -
Category
Documents
-
view
219 -
download
0
Transcript of CHAPTER 24 “ INTERACTIONS OF LIFE” (Page 684) The Biosphere -the part of the Earth which...
The Biosphere
- the part of the Earth which supports life.
- high in the air.- underground.- under oceans.
- it would compare to the thickness of the skin on an apple.
- about five miles ‘thick’.
___________________________________The environment is organized into “levels”. (p. 686).
1)Population - organisms of the same species living together.
Ex. All the people in Tokyo.
All the rabbits in Burleigh County.
2) Community
- different populations living together.
Ex. All the rabbits, mice, ants, and elm trees in Bismarck.
3) Ecosystem
- organisms and the non-living environment.
- Can be as small as a potted plant or your backyard.
- As large as an ocean.
Population CharacteristicsPopulation Density -the number of
organisms per unit of space.
Ex. People per square kilometer
Birthrate- the number of
offspring produced in a certain time.
Ex. Babies born in Bismarck over the last year.
Deathrate
- the number of organisms that die over a certain time.
If the birthrate is greater than the deathrate, the population rises.
Population is also effected by:
Immigration - when ‘new’
organisms enter an area.
Emigration- when
members of a population leave an area.
Ex. A sea turtle lays 100 eggs and all survive to adulthood.
Biotic potential
- the number of individuals that could be produced under the best conditions.
Ex. predators, disease, harsh weather, etc.
A population will never reach its biotic potential - because of limiting factors.
Ex. A sea turtle lays 1,800 in its life time.
- 1,400 don’t even hatch
- predators, injury to eggs, temp.
- most hatchlings are prey.
- only three survive to produce.
Carrying CapacityCarrying Capacity
-the largest number of individuals the environment can support.
- enough food? - enough space?
The human population is doubling at a faster rate - increasing the fastest in the last 100 years.
1) Improvements in medicine and sanitation.
2) More food production.
3) Life expectancy has increased.
The birthrate has stayed the same, but the deathrate has dropped a lot.
The lights of cities at night…
Currently, the world’s population will double every 35 years.
- what is the Earth’s carrying capacity?
- Can we produce enough food?
----------------------------------------------------------Habitat
- the place where a population lives.
- Every ecosystem has many habitats.
Many populations can live in the same habitat.
- the habitat of a species may be inside or on another species.
Ex. bacteria in your digestive system.
Each population has a function (or role) for its habitat.
- called a niche.ex. A fox is a predator.
A plant is a producer.
If two organisms occupy the same niche they will compete for food, territory, mates, etc.
-the one that adapts the best will survive.
- smartest? strongest? fastest?
When the predator population is high, the prey population will be low…
- the predators will die of starvation and disease (or emigrate).
- Then the prey population rises.
- This cycle is continuous…
2. Parasitism
- one organism benefits while the other is harmed.
Ex. wood tick on a dog. (parasite)
(host)
3) Commensalism- a relationship
between two organisms where one benefits and the other is not affected.
- Ex. clownfish and a sea anemone.
----------------------------------------Every population needs energy.
- starts with plants.
- called producers because they can make their own food.
Decomposers
- organisms that break down wastes and dead organisms.
Ex. Bacteria, mushroomsThey return nutrients
(oxygen, carbon, nitrogen) to the ecosystem.
These nutrients are then used by plants.These nutrients are then used by plants.- and the cycle starts over again,- and the cycle starts over again,
Ex. Nitrogen Cycle COPY DRAWING ON THE BOARD