Final Exam Review - Day 1

Break down the Trophic Levels starting from the base (of a pyramid).

• Producers like plants (lowest)

• Primary Consumers

• Secondary Consumers

• Tertiary Consumers (Highest)

• Decomposers (at the end, breaking down dead organisms)

How much energy travels between trophic levels?

Only 10% of the energy from the previous trophic level.

Why is a lot of energy lost between trophic levels?

• Heat

• Not digested properly.

Do natural ecosystems follow a food chain or food web? Why?

A food web because natural systems are typically composed of multiple interconnected food chains.

Does removing one species from a food chain/web have any effects, if at all?

Yes, removing even one species could result in the overpopulation of prey species, with lack of supply propagating down the system.

• Heterotrophs

• Autotrophs

• Organisms that feed on other organisms for energy (ex: consumers, decomposers).

• Organisms that can make their own energy (ex: plants).

Summarize these core processes of the Water Cycle:

• Evaporation

• Transpiration

• Condensation

• Precipitation

• Infiltration

• Runoff

• Water from oceans + lakes turns into gas.

• Water vapor releases from plants.

• Water vapor in the atmosphere forms clouds.

• Rain falls back to the ground.

• Water seeps into the soil.

• Water flows from land into rivers and oceans.

Summarize how these human impacts affect the Water Cycle:

• Deforestation

• Urbanization

• Overusing groundwater

• Increases runoff and flooding, decreases transpiration.

• Increases runoff and decreases infiltration.

• Aquifers deplete and more saltwater.

Summarize these core processes of the Carbon Cycle:

• Photosynthesis

• Cellular Respiration

• Decomposition

• Sedimentation

• Combustion

• Plants absorb Carbon dioxide.

• Organisms release Carbon dioxide during cellular respiration.

• Decomposing releases Carbon dioxide.

• Carbon is stored in rocks and fossil fuels.

• Burning fossil fuels releases Carbon dioxide.

Summarize how these human actions impact the Carbon Cycle:

• Burning fossil fuels

• Deforestation

• Ocean acidification

• Releases lots of Carbon dioxide.

• Plants take in less Carbon dioxide.

• Carbonic acid is created since oceans absorb excess Carbon dioxide.

What are the 5 processes of the Nitrogen Cycle?

1. Nitrogen fixation - Nitrogen gas converts into Ammonia.

2. Nitrification - Ammonia is turned into Nitrite, Nitrate.

3. Assimilation - Plants absorb nitrate.

4. Ammonification - Waste + dead matter creates more ammonia.

5. Denitrification - Nitrates are turned back into Nitrogen gas.

Summarize these human impacts on the Nitrogen Cycle:

• Synthetic Fertilizers

• Burning fossil fuels

• Increases eutrophication (algal blooms).

• Contributes to acid rain.

Summarize the core processes of the Phosphorous Cycle:

• Weathering

• Assimilation

• Sedimentation

• Weathering of rocks releases phosphate.

• Plants absorb phosphate from weathering.

• Phosphate goes back to rock over millions of years.

Summarize these human impacts on the Phosphorous Cycle:

• Fertilizers

• Mining phosphate rock

• It causes runoff that leads to eutrophication.

• Disrupts ecosystems.

Which cycle is the:

• slowest

• never enters the atmosphere

Phosphorous Cycle

Is Water cycle a physical or chemical process?

Physical because water only changes state, not makeup.

Which is the largest carbon sink within the Carbon Cycle?

Oceans.

Can plants use Nitrogen gas directly?

No, they need nitrates.

Carrying Capacity

The maximum number of individuals in a species that an environment can support long-term.

What are the 7 limiting factors of Carrying Capacity?

• Food

• Water

• Shelter

• Space

• Disease

• Predation

• Climate

What happens as a population:

• nears the carrying capacity

• exceeds the carrying capacity

• Resources are limited

• Deaths outnumber births.

What does the curve of Carrying Capacity typically look like? Describe why.

An S-shaped curve because the population rises exponentially until it exceeds carrying capacity, at which the rate of increase goes down and deaths outnumber births.

Survivorship Curve

A graph showing the number or proportion of individuals surviving to each age for a given species or group.

What population metrics do ecologists consider when choosing a population for a Survivorship curve?

They look for a cohort- or a group of individuals in the same species- that are part of the same population and born at the same time.

Describe the Type 1 Survivorship curve.

• High survivorship throughout lifespan and the majority of population reaches maturity.

• Loss of life occurs at later ages.

• Typical of K selected species like humans.

Type 2 Survivorship Curve

Loss of life occurs at a constant rate throughout lifespan, regardless of age.

Type 3 Survivorship Curve

• Most of the population die out at early ages and few reach maturity.

• Loss of life occurs really early on.

• Typical of r selected species.

What is r in terms of population metrics? What do the following r values represent and look like on a graph:

• +r

• -r

It represents growth rate:

• +r means population growth and creates a S-shaped curve

• -r means population decrease and creates a curve similar to Type 3 (only in looks, not in concept!).

How do you calculate r (growth rate)?

r = births - deaths

What is k in population metrics?

It represents the Carrying Capacity.

Summarize the characteristics of r selected species in these areas:

• Growth

• Longevity

• Environment type

• Maturity and offspring production

• Physical trait(s)

• Species grow quickly.

• Die off very quickly; can’t live long.

• Often live in unstable environments.

• Reach maturity early and create lots of offspring.

• Small body size.

Summarize the characteristics of K selected species in these areas:

• Growth

• Longevity

• Environment type

• Maturity and offspring production

• Physical trait(s)

• Grow slowly.

• Lives for a long time due to parental care.

• Often reside in stable environments.

• Reach maturity later and make fewer offspring.

• Big body size.

Which survivorship curve represents:

• r selected species

• K selected species

• Type 3

• Type 1

What 4 major descriptors are used for Human Populations?

• Density: Number of people per unit area.

• Distribution: How people are spread out across an area.

• Age Structure: Age distribution of population.

• Sex Ratio: Number of males per 100 females.

Rule of 70

Used to approximate the number of years it takes for a population to double in size.

How do you use the rule of 70?

number of years to double population = 70 / [number of the growth rate percent]

When do human populations tend to increase exponentially?

With the introduction of industrialization and better living conditions (more food, sanitation, etc.)

What are the 2 tools we can use to predict future population trends?

1. Age structure diagrams

2. Demographic transition

Age Structure Diagrams

A diagram that shows the age distribution of a population for both genders separately.

Demographic Transition.

Population increase occurs during the transition to industrialization and within it, but begins to decline post-industrialization.

Summarize the 4 stages of the Demographic transition and be sure to include:

• Population growth

• Birth rate

• Death rate

• Pre-Industrial Stage: Population remains stable due to high birth and death rates.

• Transitional Stage: Population rates increase due to more births over deaths; but birth rates start to decline in the later half.

• Industrial Stage: Population rates continue to increase a bit more, but birth rates get lower.

• Post-Industrial Stage: Population rates decline as birth rates decrease due to people having fewer children.

Death rate remains consistent for Transitional, Industrial, and Post-Industrial Stages.

Why do countries enact policies on population count?

To address:

• Overpopulation

• Population decline

What is the main idea of Sustainability?

The earth needs to support populations, society, and economies in balanced levels.

How do these population sizes affect Sustainability:

• Overpopulation

• Population Decline

• More difficulty is placed on the Earth’s environments to support large population sizes.

• More constraints are put on Societies & Economies since fewer people are working.

Rate of Natural Increase

Used to calculate population increase without factoring in immigration and emigration.

What do the following terms mean:

• Crude Birth Rate

• Crude Death Rate

• Births per 1000 people.

• Deaths per 1000 people.

Rate of Natural Increase formula

RNI = (Crude Birth Rate - Crude Death Rate) / 10

Total Fertility Rate

The number of births per woman during her reproductive period.

Replacement-Level Fertility

The number of children a woman must have to replace herself and her partner.

What do Replacement-Level Fertility rates look like for:

• Developed Countries

• Developing Countries

• About 2.1

• More than 3.

Infant Mortality Rate

The number of infant deaths (under age 1) per 1000 births in a year.

Which population tool best indicates a country’s overall health?

Infant Mortality Rate, because lower rates are typical in developed countries that have access to clean, safe resources and support.

Eutrophication

Algal bloom in water due to Nitrogen and Phosphorous entering water.

Why is eutrophication bad?

• Decomposers use up a lot of oxygen to decompose algae, lowering oxygen counts for other organisms.

• Blocks sunlight from reaching plants.

Bioaccumulation

Toxins that build up in one organism over time.

Biomagnification

Toxin concentrations increase in organisms as you move up the food chain.

Acid Rain

Precipitation with a pH less than 5.6 caused when air pollutants react with water vapor.

What 2 elements, when combined, cause acid rain?

Sulfur Dioxide + Nitrogen Oxides.

List 3 sources that Sulfur Dioxide comes from.

• Coal burning

• Smelting

• Industrial processes

List 3 sources that Nitrogen Oxides comes from.

• Vehicles

• Power plants

• Combustion

What are4 environmental impacts of Acid Rain?

1. Soil acidification

2. Kills marine organisms

3. Building damage

4. Forest decline

What are 3 ways to remediate Acid Rain and its effects?

• Reduce sulfur dioxide and nitrogen oxide emissions.

• Cap sulfur dioxide + nitrogen oxide production via policies.

• Add calcium carbonate to oceans.