In this Grade 5 lesson from Science: A Closer Look, Chapter 2, students learn how abiotic and biotic factors control population sizes in ecosystems, including the roles of limiting factors and carrying capacity. Students also explore how organisms compete for resources like food, water, and space, and examine symbiotic relationships such as mutualism, commensalism, and parasitism. Hands-on inquiry activities reinforce how both living and nonliving parts of an ecosystem interact to determine which populations can survive and thrive.
Section 1
Organisms Compete for Limited Resources
Plants and animals struggle to obtain food, water, space, and other necessities within ecosystems. Both organisms within a population and different populations compete to access these limited resources for survival.
Section 2
Habitats and Niches Help Organisms Avoid Competition
Animals occupy specific physical spaces (habitats) and perform unique roles (niches) within their environments. This specialization allows different species to coexist without directly competing for the same resources.
Section 3
Symbiotic Relationships Connect Different Species
Organisms form three main types of symbiotic relationships: mutualism benefits both species, commensalism benefits one without harming the other, and parasitism benefits one while harming the host.
Section 4
Limiting Factors Control Population Size
Biotic factors (like food availability) and abiotic factors (like temperature and rainfall) restrict population growth in ecosystems and determine the carrying capacity—the maximum number of organisms an environment can support.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter
Expand to review the lesson summary and core properties.
Section 1
Organisms Compete for Limited Resources
Plants and animals struggle to obtain food, water, space, and other necessities within ecosystems. Both organisms within a population and different populations compete to access these limited resources for survival.
Section 2
Habitats and Niches Help Organisms Avoid Competition
Animals occupy specific physical spaces (habitats) and perform unique roles (niches) within their environments. This specialization allows different species to coexist without directly competing for the same resources.
Section 3
Symbiotic Relationships Connect Different Species
Organisms form three main types of symbiotic relationships: mutualism benefits both species, commensalism benefits one without harming the other, and parasitism benefits one while harming the host.
Section 4
Limiting Factors Control Population Size
Biotic factors (like food availability) and abiotic factors (like temperature and rainfall) restrict population growth in ecosystems and determine the carrying capacity—the maximum number of organisms an environment can support.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter