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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