CHAPTER 24 “ INTERACTIONS OF LIFE” (Page 684)

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’.

Ecology - the study of the relationship between organisms and their environment.

Abiotic factors -the non-living parts of the environment. ex. Soil, water, light, temperature.

Biotic factors - the living organisms. - they need the abiotic factors.

________________________________ ___ 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.

4) Biosphere - made up of all the ecosystems. Read pages

Population Characteristics Population 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.

A census counts the population. The United States Census Bureau does a census every ten years.

ASSIGNMENT: WORKSHEET “COMMUNITIES”

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 Capacity -the largest number of individuals the environment can support. - enough food? - enough space?

Human Populations The world’s population is about 6. 2 billion in 2005

2 billion in billion in million in 1650

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?

ASSIGNMENT: WORKSHEET “POPULATIONS”

Habitat -the place where a population lives. -Every ecosystem has many habitats.

Ex. Forest - birds in the canopy. - badgers underground. - deer on the forest floor.

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?

RELATIONSHIPS BETWEEN POPULATIONS 1. Predator - Prey Relationship - most common within a community

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)

A parasite will not usually kill the host. - because that would also kill the parasite.

ASSIGNMENT: Section Self Check Questions. P /2/4 P /3

3) Commensalism -a relationship between two organisms where one benefits and the other is not affected. -Ex. clownfish and a sea anemone.

4) Mutualism -where both organisms benefit. Ex. remora and shark

Every population needs energy. -starts with plants. -called producers because they can make their own food.

Consumers - organisms that eat other organisms. Herbivores -eat only plants Ex. cows, deer, horses.

Carnivores - eat other animals. Ex. polar bear, lion

Omnivores - eats both plants and animals. Ex. bear, raccoon

Scavengers - eat dead animals. Ex. vulture, hyena

Energy is transferred thru the community by a food chain. - must start with a plant.

Put these organisms into a food chain.

There are many food chains in an environment. - they connect to form a food web. (p. 728).

Energy Pyramid Plants herbivore carnivore Top carnivore

Why is it shaped in a pyramid? Plants herbivore carnivore Top carnivore

Top carnivore = tiger, killer whale, eagle Only 10% of the energy is passed on to the next level.

ASSIGNMENT: WORKSHEET “FOOD CHAINS”

Decomposers -organisms that break down wastes and dead organisms. Ex. Bacteria, mushrooms They return nutrients (oxygen, carbon, nitrogen) to the ecosystem.

These nutrients are then used by plants. - and the cycle starts over again, Ex. Nitrogen Cycle COPY DRAWING ON THE BOARD

ASSIGNMENT: P. 706 Checking Concepts: P. 708 Multiple Choice