Unit 2 Lesson 2 Resource Availability in Ecosystems

Unit 2 Lesson 2 Resource Availability in Ecosystems

Exploration 1: Relating Resource Availability to Growth

All living things need the same basic resources to perform their life processes.

• Growth/repair, development, responding to the environment, and reproduction

Multiple Select

Which of the following do most organisms need in order to survive?

• Food

• Clean Air

• Clean Water

• A source of energy

• Space/shelter

Resources may be living or nonliving.

• Living = Food, some types of shelter (like a tree)

• Nonliving = water, sunlight, oxygen

• No matter the resource, organisms must get them from their ecosystem.

Open Ended

List TWO things that might affect the availability of clean water in an ecosystem.

The growth of individuals, as well as populations, depends on the availability of resources.

• Resources may be plentiful enough for a small number of individuals, but not if the population gets too large.

Multiple Choice

What is occurring at point B on the graph?

• Resources are plentiful and the population is continuing to grow larger

• Resources are very scarce and the population is declining

• The amount of resources available can no longer support the growing population

Multiple Choice

What is occurring at point A on the graph?

• Resources are plentiful and the population is continuing to grow larger

• Resources are very scarce and the population is declining

• The amount of resources available can no longer support the growing population

Multiple Select

Which TWO factors might cause a decrease in the rate of reproduction?

• a decrease in the availability of food resources

• an increase in resources such as water

• conditions that limit the availability of shelter resources

• conditions that allow access to new resources that were not previously available

Resource availability depends on a variety of factors.

• Competition with other members of the same population for the same resource.

• Competition with other populations of organisms for the same resource.

Environmental factors can also affect resource availability.

• A good growing season that produces a lot of plants may help a population of deer grow.

• Drought or wildfire may decrease the amount of food available, causing the population to decrease.

Open Ended

List two or three factors that may affect the fish population that the stork and egrets feed on?

Multiple Select

A red-tailed hawk is a bird that eats other birds and small animals, including mammals. Which scenario(s) may likely INCREASE the availability of food resources for a red-tailed hawk population.

• A drought causes plants to produce fewer seeds than usual, limiting food resources for small mammals.

• A disease causes decreases in the populations of mice, voles, ground squirrels, and other small mammals.

• Corn crops left in the field provide abundant food for mice and other small mammals.

• Mosquitoes can feed off the blood of almost any animal, including humans. Their bites can be very unpleasant. They can also transmit a variety of serious diseases. Because of these problems, people try to design solutions to help limit the sizes of mosquito populations. Mosquitoes require standing water, such as ponds or puddles, to reproduce because their larvae live in these types of aquatic environments.

Multiple Choice

Suppose you are tasked with decreasing the mosquito population in a large city with many people. A decrease in which resource would be most effective in decreasing the mosquito population?

• food resources

• plant resources

• water resources

• sunlight resources

Open Ended

Brainstorm actions that might limit the availability of this resource for mosquitoes in the area. How might other species be impacted by this change?

Exploration 2: Predicting the Effects of Limited Resources

• How do animals compete for resources?

• What can happen when resources are not available?

Multiple Choice

Which of the following is more likely to happen when birds can't find a nesting site?

• The birds will wait until a tree becomes available for nesting.

• The birds may move to another area with more shelter resources.

• The birds will build a different type of shelter instead of a nest.

Multiple Choice

What may happen if those birds still cannot find a nesting site?

• They will build a different type of nest.

• Their population may increase since other birds have taken over the nesting sites.

• They may be unable to nest, resulting in a decrease in the population.

• They will evolve a better strategy for reproduction.

Limited Abiotic Resources

• Resources such as air, water, sunlight, soil, and rainfall.

• Other resources may by readily available, but if one important resource is lacking, it may not matter.

When resources are not readily available, they become "limiting factors".

• These are factors that prevent or "limit" the growth of the population.

• If the lack of the resource continues, the population can eventually decline.

Water is a limiting factor in this ecosystem.

Multiple Choice

Which part of the forest will most likely receive the least amount of sunlight as an abiotic resource?

• the forest floor

• the canopy/tops of the trees

• the middle layer

Multiple Choice

What factor might be the most limiting in the upper layers of the forest?

• sunlight

• air flow

• heat

• water

Limiting resources can also be biotic.

• Other organisms (animals, bacteria, fungi, plants), and even decaying organisms

• All things are interconnected and have the potential to impact other factors.

Multiple Choice

Suppose that a fungus destroys the fruits of a tree on which a certain kind of insect feeds. Which of the following is NOT likely to be an effect?

• The insect population will decrease because less food is available to individuals.

• Other animals that feed on the insect will have more food, so their population may increase.

• The decrease in food could continue to the top of the food chain.

• The tree population is likely to decrease.

Multiple Choice

A population of fish greatly increases in size after a short-term increase in food availability. What could most likely be a result?

• Mates may become more difficult to find.

• Predators of the fish will have less food available.

• The fish may have to compete more for food resources.