Life Sciences

LS2 Ecosystems: Interactions, Energy, and Dynamics

• LS2.A  Interdependent Relationships in Ecosystems
• LS2.B  Cycles of Matter & Energy Transfer in Ecosystems
• LS2.C  Ecosystem Dynamics, Functioning, and Resilience 
• LS2.D  Social Interactions and Group Behavior

LS2.A  Interdependent Relationships in Ecosystems

Plants depend on water and light to grow. (2.LS2.1)

Plants depend on animals for pollination or to move their seeds. (2.LS2.2)

The food of almost any kind of animal can be traced back to plants. (5.LS2.1)

Organisms are related in food webs in which some animals eat plants for food and other animals eat the animals that eat plants. (5.LS2.1)

Some organisms, such as fungi and bacteria, break down dead organisms (both plants and animals) and therefore operate as "decomposers." (5.LS2.1)

Decomposition eventually restores (recycles) some materials back to the soil. (5.LS2.1)

Organisms can survive only in environments in which their particular needs are met. (5.LS2.1, 5.LS2.2)

A healthy ecosystem is one in which multiple species of different types are each able to meet their needs in a relatively stable web of life. (5.LS2.1, 5.LS2.2)

Newly introduced species can damage the balance of an ecosystem. (5.LS2.1, 5.LS2.2)

Organisms, and populations of organisms, are dependent on their environmental interaction both with other living things and with nonliving factors. (7.LS2.1)

In any ecosystem, organisms and populations with similar requirements for food, water, oxygen, or other resources may compete with each other for limited resources, access to which consequently constrains their growth and reproduction. (7.LS2.1)

Growth of organisms and populations increases are limited by access to resources. (7.LS2.1)

Predatory interactions may reduce the number of organisms or eliminate whole populations of organisms. Mutually beneficial interactions, in contrast, may become so interdependent that each organism requires the other for survival. Although the species involved in these competitive, predatory, and mutually beneficial interactions vary across ecosystems, the patterns of interactions of organisms with their environments, both living and nonliving, are shared. (7.LS2.2)

Ecosystems having carrying capacities, which are limits to the number of organisms and populations they can support. These limits result from such factors as the availability of living and nonliving resources and form such challenges such as predation, competitions, and disease. (B.LS2.1, B.LS2.2, EN.LS2.1, EN.LS2.2)

Organisms would have the capacity to produce populations of great size were it not for the fact that environments and resources are finite. This fundamental tension affects the abundance (number of individuals of species in any given ecosystem). (B.LS2.1, B.LS2.2, EN.LS2.1, EN.LS2.2)

LS2.B  Cycles of Matter & Energy Transfer in Ecosystems

Matter cycles between the air and soil, and among plants, animals and microbes as these organisms live and die. (5.LS2.1) 

Organisms obtain gases and water from the environment, and release waste matter (gas, liquid or solid) back into the environment. (5.LS2.1)

Food webs are models that demonstrate how matter and energy is transferred between producers, consumers, and decomposers as the three groups interact within an ecosystem. (7.LS2.3)

Transfers of matter into and out of the physical environment occur at entry level. (7.LS2.3)

Decomposers recycle nutrients from dead plants and animal matter back to the soil in terrestrial environments or TO the water in aquatic environments. (7.LS2.3)

The atoms that make up organisms in an ecosystem are cycled repeatedly between the living and nonliving parts of the ecosystem. (7.LS2.3)

Plants or algae form the lowest level of the food chain. (B.LS2.4, EN.LS2.4)

At each link upward in a food web, only a small fraction of the matter consumed at the lower level is transferred upward to produce growth and release energy in cellular respiration at the higher level. (B.LS2.4, EN.LS2.4)

Given this inefficiency, there are generally fewer organisms at higher levels of a food web. (B.LS2.4, EN.LS2.4)

Some matter reacts to release energy for life functions, some matter is stored in newly made structures, and much is discarded. (B.LS2.4, EN.LS2.4)

The chemical elements that make up the molecules of organisms pass through food webs and into and out of the atmosphere and soil, and they are combined and recombined in different ways. (B.LS2.4, EN.LS2.4)

At each link in an ecosystem, matter and energy are conserved. (B.LS2.4, EN.LS2.4)

Photosynthesis and cellular respiration (including anaerobic processes) provide most of the energy for live processes. (B.LS2.3)

Photosynthesis and cellular respiration are important components of the carbon cycle, in which carbon is exchanged among the biosphere, atmosphere, oceans, and geosphere through chemical, physical, geological, and biological processes. (B.LS2.5) 

LS2.C  Ecosystem Dynamics, Functioning, and Resilience

Ecosystems are dynamic in nature; their characteristics can vary over time. (7.LS2.4)

Disruptions to any physical or biological components of an ecosystem can lead to shifts in all its populations. (7.LS2.4)

Biodiversity describes the variety of species found in Earth's terrestrial and oceanic ecosystems. (7.LS2.5)

The completeness or integrity of an ecosystem's biodiversity is often used as a measure of its health. (7.LS2.5) 

A complex set of interactions within an ecosystem can keep its number and types of organisms relatively constant over long periods of time under stable conditions. (B.LS2.2, B.LS2.6, EN.LS2.2, EN.LS2.6)

If a modest biological or physical disturbance to an ecosystem occurs, it may return to its more or less original status (i.e., the ecosystem is resilient) as opposed to becoming a very different ecosystem. (B.LS2.2, B.LS2.6, EN.LS2.2, EN.LS2.6)

Extreme fluctuations in conditions or the size of any populations, however, can challenge the functions of ecosystems in terms of resources and habitat availability. (B.LS2.2, B.LS2.6, EN.LS2.2, EN.LS2.6)

Anthropogenic changes (induced by human activity) in the environment can disrupt an ecosystem and threaten the survival of some species. (EN.LS2.7) 

LS2.D  Social Interactions and Group Behavior

Being part of a group helps animals obtain food, defend themselves, and cope with changes. (3.LS2.1)

Groups may serve different functions and vary dramatically in size. (3.LS2.1)