Students who demonstrate understanding can: Analyze and interpret data to provide evidence for the effects of resource availability on organisms and populations of organisms in an ecosystem.
Clarification statement: Emphasis is on cause and effect relationships between resources and growth of individual organisms and the numbers of organisms in ecosystems during periods of abundant and scarce resources.
Official wording from the Next Generation Science Standards (NGSS Lead States, 2013). NGSS is a registered trademark of WestEd. Neither WestEd nor the lead states and partners that developed the NGSS were involved in the production of this page, and they do not endorse it. View on nextgenscience.org
Food, water, light, space and shelter are limited in every ecosystem, and the amount available shapes how many organisms can live there. When resources are plentiful, individuals grow well and populations can increase. When resources become scarce, organisms compete, growth slows, fewer offspring survive, and populations shrink. Students analyze and interpret data, such as population graphs, field counts or tables, to find these cause-and-effect patterns.
A classic data set is a predator and prey graph, such as lynx and snowshoe hares, where the predator population rises after the prey population peaks and falls after the prey declines. Another is a pond in which algae explode after fertilizer runs in and then crash when nutrients run out. Students learn to read axes, describe trends, link a change in a resource to a later change in a population, and recognize the lag between cause and effect.
The skill is interpretation, not memorization, so students should always cite specific values or trends from the data as evidence.
Students sometimes think a population will rise without end if conditions are good. Data show that populations level off or crash once a limiting resource runs short.
Predator and prey numbers rise and fall in cycles. Predators usually decline when prey become scarce, which allows the prey to recover.
Population responses often lag behind the change in resources, so a graph's peaks for predator and prey do not line up.
A deer population on an island was 200 in year 1, 600 in year 4 and 1,000 in year 6, then fell to 300 by year 8 after a harsh winter destroyed much of the plant food. Explain the pattern.
Answer: Abundant food allowed the population to grow to 1,000; when food became scarce, the population crashed to 300, showing that resource availability limits population size.
Give students real or realistic data sets and a short set of sentence starters: 'As ___ increased, ___ ...' and 'This is evidence that ...'. Simulations, such as a bean-grab game for food competition, let students generate their own data before analyzing published graphs.
Assessment items almost always include a graph or table, so practice identifying the independent and dependent variables and quoting specific values.
Original questions written for this standard. Choose an option or type your answer, then press Check. Every question has a worked explanation.
Answer: A) The population will increase
With abundant resources and little predation, more rabbits survive and reproduce.
Answer: D) Predators have more food when prey are plentiful, so more predator young survive
Plentiful prey means more food for predators, and their numbers rise after a short delay.
Answer: limiting factor (also accepted: a limiting factor, limiting resource)
A limiting factor, such as food or space, restricts population growth.
Answer: B) Squirrels that eat acorns
Squirrels depend on acorns for food, so a shortage reduces their survival and reproduction.
Answer: A) Barnacle numbers stop rising once the rock surface is covered
If numbers level off when there is no more surface, space is the limiting resource.
Answer: competition
Competition increases when resources are limited.
Develop a model to describe the movement of matter among plants, animals, decomposers, and the environment.
Use mathematical and/or computational representations to support explanations of factors that affect carrying capacity of ecosystems at different scales.
A full lesson with slides, activities and an exit ticket on resources and populations, pitched to grades 6-8 and editable in PowerPoint or Google Slides.
Make a lesson βA printable, differentiated worksheet on MS-LS2-1 with an answer key, ready in about a minute.
Make a worksheet βTurn resources and populations into a quiz students answer online that marks itself, with a class summary for you.
Build a test βPopulation graphs, field counts and tables showing how organisms and populations change during periods of abundant and scarce resources.
Yes. The clarification statement includes the growth of individual organisms as well as the numbers in a population.