Science ObjectDigital resources are stored online in your NSTA Library.
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Interdependence of Life SciPack. It explores species relationships.
All organisms, both land-based and aquatic, are interrelated by their need for resources. One example of a network of interconnections is called a food web; it is a model of the interdependence among the organisms in populations of different species. Predator-prey and parasitic relationships are examples of interspecies relationships, interdependence that occurs among organisms in different species in a food web.
Interspecies relationships can be categorized as positive, negative, or neutral for the fitness of the individuals and their populations who are involved. A change in the population of one species can affect the population of another species. Intra-species relationships, or interdependence among organisms of the same species, can also affect a population.
- Given the specific nature of an interspecies relationship, categorize the relationship between two interrelated populations as positive, negative or neutral for each population.
- Given a description of a change to one population depicted in a food web, predict changes that might occur in the size and rate of growth for other populations depicted in the food web.
- Given a line graph displaying changes in population sizes and rates of growth for a number of populations in a community, along with a description of the trophic relationships among populations, generate plausible hypotheses about causes of the changes depicted in the graph.