Ecology Test ReviewAnswer Key
Section 4.1: The Role of Climate
1. What is the difference between climate and weather?
Weather is the daily condition of an area (rainy, cloudy, etc.), while climate is the average, year-after-year, temperature and precipitation of an area.
2. What are the four major contributors to climate?
The four major contributors to climate are temperature, sunlight, ocean currents, and wind currents.
Unequal heating of the earth’s surface by the sun, based on latitude, causes climate differences.
3. Define ‘range of tolerance’ and explain why salmon are dying in dammed rivers.
A range of tolerance is the range of abiotic conditions where a species can live. Salmon are dying because dams on rivers are causing an aquatic environment that is outside their range of tolerance. Salmon prefer to lay their eggs in cool, fast-running, rocky rivers, and dams make rivers warm, stagnant, and deep. No salmon babies = dying salmon populations.
4. What are the earth’s three climate zones?
Tropical, temperate, polar
5. What is the greenhouse effect?
The greenhouse effect is the trapping of heat energy from the sun by greenhouse gases. Light energy from the sun enters the atmosphere and is converted to heat energy when it bounces off of earth. Gases capture some of this energy, keeping our planet at a habitable temperature. These gases are carbon dioxide, methane (CH4), and water vapor.
6. What is the greatest contributor to excess CO2 in our atmosphere?
The burning of fossil fuels like coal, natural gas, and oil
7. What are three consequences of global warming?
a. the rise of sea levels from 7-23 inches worldwide
b. stronger storms and droughts as we disrupt global wind and ocean currents
c. extinction of organisms forced outside of their range of tolerance
d. lack of fresh water for communities relying on ice and snow packs
Section 5.1: Populations Basics
8. What are population size and population density?
Population size: the number of organisms in a population (all of the same species)
Population density: the number of organisms per area of land
9. Write an equation representing the growth rate of a population.
(births + immigration) – (deaths + emigration) = growth rate
10. Draw a graph representing exponential population growth. Label the axes.
11. Why is exponential population growth hard to find in nature?
Populations always encounter limiting factors, like space and food, that stop their growth.
5.2: Limits to Population Growth
12. List two biotic and two abiotic factors that limit population growth.
Biotic: predators, disease
Abiotic: natural disasters, habitat destruction
13. Of the above factors you listed, which depend on population density (density-dependent) and which limit population regardless of density (density-independent)?
Biotic factors depend on density, while abiotic factors are density-independent
14. Populations have a carrying capacity. Define carrying capacity and give an example.
Carrying capacity is the maximum amount of organisms an environment can support over time.
For example, northwest forests can only support a few cougars because of a finite amount of food and territory.
15. Answer the following questions for the graph below:
- Describe what the graph is showing.
The graph is showing a population undergoing exponential growth, until it encounters limiting factors and levels off to carrying capacity.
- What do we call this type of graph?Logistic growth
- Put an ‘x’ where the population is increasing exponentially. Put a ‘o’ where the birth and death rate are equal.
- Why is this graph a more accurate representation of population growth than an exponential curve is?
It takes into account limiting factors, like food, disease, and space
Human Impacts on the Environment
16. Define and give an example of:
a. Renewable Resources
Renewable resources will regenerate themselves if used wisely. Ex: fish, trees
b. Non-Renewable Resources
Non-renewable resources will not regenerate themselves; when gone, they’re gone! Ex: fossil fuels
17. List three ways that humans are depleting renewable resources.
Overfishing: taking so many fish that not enough are left to reproduce and replenish stock
Deforestation: cutting trees down without replacing them, or replacing them without time to grow to usable size
Overharvesting: mass planting/harvesting without allowing plants to die and return nutrients to soil
18. What does the movement for sustainable development advocate?
Using the earth’s renewable resources wisely, allowing them to regenerate for use of future generations