Final Exam Review

The Finale

Chapter 20 Lesson 3

Energy in Ecosystems

How does energy move in ecosystems?

• Flows in one direction• Sun producers consumers• Producers – photosynthetic, chemosynthetic• Consumers – herbivores, omnivores,

carnivores, detritivores, decomposers

How is the movement of energy in an ecosystem modeled?

• Food chain – One feeding relationship– Arrow shows relationships– Energy decreases

• Food web– Interconnected food chains in a community– Food choices

Modeling continued

• Energy Pyramid– Show the amount of energy available in each step of a

food chain• Steps: trophic levels

– Bottom trophic level: producers (100%)– Next trophic level: consumers that eat producers (10%)

• Primary consumers

– Highest trophic level: consumers that eat other consumers (1%)• Secondary consumers

Chapter 21 Lesson 1

Populations

What defines a population?

Biosphere

Ecosystems

Community

Populations

What factors affect the size of a population?

• Competition• Limiting factors

Population Informationcontinued

• Measurement: catch-and-release, population density, sample count

• Biotic potential – no limits• Carrying capacity • overpopulation

Chapter 21 Lesson 2

Changing Populations

How do populations change?

• Population Increases– Birthrate– Exponential growth

• Population Decreases– Death rate– Extinction species– Threatened species– Engdangered species

• Movement and Migration

Why do human populations change?

• Birthrate• Deathrate• Movement• Can increase carrying capacity of environment• Positive and negative effects of human

population increase• Increases due to:– Medical care - Sanitation - Food -Resources

Human Populations continued

• Decreases due to:– Disease– Natural disasters– Environmental disasters/change

• Movement and Immigration

Chapter 21 Lesson 3

Communities

What defines a community?

• All living things in the same ecosystem at the same time

• Habitats– All the things you need to survive

• Niches– What you do to survive

How do the populations in a community interact?

• Energy Roles– Producers– Consumers

• Relationships– Predator-Prey – Cooperative – same species– Symbiotic

• Mutualism – both species benefits• Commensalism – one species benefits• Parasitism – one species benefits, the other is harmed

Genetics

The Final Frontier

The Reproduction of Living Things

Brief #3 – Traits and Genes

DNA & Chromosomes

• DNA– Chemical molecule– Double helix shape– Located in the nucleus– Mutation: a change in the DNA

• Chromosomes – Made from DNA

Genes

• Genetic instructions• Determines the traits• Connect the double helix• Base pairs– A, T, G, C– A and T– G and C

• Dominant – controls• Recessive - hidden

Traits

• Expression of the genes• Usually made from two genes• Dominant– Hides the expression of another trait– Dd or DD

• Recessive– Expression is hidden– Dd

Punnett Square

• Illustrates all of the possible genetic combinations

Don’t forget to look over the four packets:• Horses and zebras• Left-handedness• Corn• Genetically modified foods