Unit 2 Ecology Application

Unit 5 – Ecosystems: Stability in an ecosystem is a balance between competing effects such as nutrient recycling, food webs, and composition of producers and decomposers

Describe how energy in an ecosystem moves through a food chain/food web. What type of organisms would be at the top/bottom?

Given the food chain below, what type of change would have to most severe impact and why?

Grasses → crickets → field mice → hawks

• Describe how energy and matter move through an ecosystem differently:___________________________________

• What happens to most of the energy? ________________________________________________________________

• How much energy transfers to the next trophic level? ____ %

• Describe and provide an example of both a biotic and abiotic factors.______________________________________

Ecological Relationships Exponential and Logistic Growth Graph Analysis

Define & provide examples:

Producer: Consumer: Decomposer:

Carrying Capacity

----------------------------------- Sketch both graphs above & describe the conditions for each:

Describe what happens to the population between 1900-2000:

Ecological Pyramids Name and sketch each below:

• Birth rate and immigration → increase / deacrease population size

• Death rate and emigration → increase / deacrease population size

Questions Analysis: Identify important terms/facts in each question & provide a response Rabbits introduced into Australia over 100 years ago have become a serious pest to farmers. Rabbit populations increased so much that they displaced many native species of plant eaters. What is the most logical explanation for their increase in numbers?

In a pond, the primary producer is a green alga, Spirogyra; the primary consumer is the crustacean Daphnia; the secondary consumer is a small fish, the bluegill; and the tertiary consumer is a larger fish, the smallmouth bass. What changes can be expected in the pond if the Daphnia are killed with pesticides?

Scientists found that, over a period of 200 years, a mountain pond was transformed into a meadow. During that time, several communities of organisms were replaced by different communities. Which of these best explains why new communities were able to replace older communities?

• Define Biodiversity:  

Unit 2 Ecology Study Guide

I. Ecology • Ecology → interactions among organisms and environment.

II. Energy Flow • Photosynthesis: main source of energy • Autotrophs – producers → plants and algae • Heterotrophs – consumers (primary, secondary, etc.)

III. Feeding Relationships and Energy • Energy flows : 1 - way direction

o Producers → 1st → 2nd →3rd level consumers • Food webs - each step/link in a food chain = trophic level

IV. Ecological Pyramids • 3 Types = energy pyramid , biomass pyramid, and pyramid of

numbers o Energy Pyramid – amounts of energy at each level o Biomass – mass of organic (living) matter o Numbers – relative numbers of individuals

• Energy Transfer o Only about 10% of the energy transfers → trophic levels o Energy used for respiration, movement, etc. o Some energy lost as heat

V. Nutrient Cycles • Nutrients = life sustaining chemical substances • Water cycle, carbon cycle, nitrogen cycle, & phosphorus cycle • Oxygen (O2), Carbon Dioxide (CO2), and Water (H2O) all

cycle through process of photosynthesis & cellular respiration • All cycles pass through both living (biotic) and nonliving

(abiotic) components of an ecosystem.

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I. Populations • 3 Characteristics : • Geographic Distribution – area inhabited by a population • Density – number of individuals per unit area (how many) • Growth Rate – fluctuations in population size

II. Population Size • 3 factors affect population size: number of births, number of

deaths, and number of individuals that enter or leave a population

III. Types of Growth o Exponential Growth →“J-curve” o Individuals reproduce at a constant rate o Unlimited resources = little competition

• Logistic Growth → “S” Curve o Increased completion, fewer resources; growth slows

• Carrying Capacity = ecosystem cannot support further growth

IV. Limits to Growth • Limiting factor- causes population growth to decrease

o Density-dependent limiting factors = competition, predation, parasitism, and disease

o Density independent limiting factors = weather, natural disasters, human activity

V. Biodiversity • Variety of life in an in the biosphere = ↑ natural resource • Invasive Species: non-native species introduced in foreign

environment – disrupts/ competes in local ecosystem.