LEARNING OBJECTIVES

6.L.2 Understand the flow of energy through ecosystems and the responses of populations to the biotic and abiotic factors in their environment.

6.L.2.1

• Summarize how energy derived from the sun is used by plants to produce sugars (photosynthesis) and is transferred within a food chain or food web (terrestrial and aquatic) from producers to consumers to decomposers.

6.L.2.2

• Explain how plants respond to external stimuli (including dormancy and forms of tropism) to enhance survival in any environment.

6.L.2.3

• Summarize how the abiotic factors (such as temperature, water, sunlight, and soil quality) of biomes (freshwater, marine, forest, grasslands, desert,Tundra) affect the ability of organisms to grow, survive and/or create their own food through photosynthesis.

CONTENT

RESOURCES

6.L.2.1

• Food provides molecules that serve as fuel and building material for all organisms

• Plants use the energy from light to make sugars from carbon dioxide and water

• Green plants are the producers of food that is used directly or indirectly by consumers

• Plants can use the food they make immediately or store it for later use

• Energy flows through ecosystems in one direction, from the sun through producers to consumers to decomposers.

• Matter is transferred from one organism to another and between organisms and their environments

• Water, nitrogen, carbon dioxide, and oxygen are substances cycled between the living and non-living environments

• Investigate how decomposers return nutrients to the environment—such as fungi on fallen logs, mold on bread

• Explore the importance and role of bacteria in the guts of animals and plant roots at it relates to the recycling of matter.

6.L.2.2

• Changes in environmental conditions can affect the survival of individual organisms and entire species

• Dormancy is a period of inactivity in a mature seed prior to germination; seed remains dormant until conditions are favorable for growth and development of the new plant

• Plants have mechanisms that enable them to respond to their environment

• Plants grow, reproduce, and shift the position of their roots, stems and

• leaves in response to environmental conditions such as gravity, sunlight, temperature and day length

• Tropism is a plant’s turning or bending movement of an organism toward or away from an external stimulus such as light, heat or gravity

• If the tropism is positive, the plant grows toward the stimulus

• If the tropism is negative, the plant grows away from the stimulus

• This enhances the survival rate for that plant in a given environment.

6.L.2.3

• The world contains a wide diversity of physical conditions, which creates a wide variety of environments: freshwater, marine, forest, desert, grasslands, mountain, and others

• In any particular environment, the growth and survival of organisms depend on the physical conditions

• Environmental factors that affect an organism’s ability to survive in its environment, such as food availability, predators, and temperature, are limiting factors

• A limiting factor is any biotic or abiotic factor that restricts the existence, number, reproduction, or distribution of organisms

• For example, at high elevations, temperatures are too low, winds too strong and the soil too thin to support the growth of large trees

• Vegetation is limited to small, shallow-rooted plants, mosses, ferns and lichen

• Factors that limit one population in a community may also have an indirect effect on another population. For example, a lack of water could limit the growth of grass in a grassland, reducing the number of seeds produced

• The population of rabbits dependent on those seed for food will also be reduced and the hawks depending on the rabbits will be reduced too as a result of a decrease in their food supply

• Another factor for survive is the ability of an organism to withstand fluctuations in biotic and abiotic environmental factors

• The limits of an organism’s tolerance are reached when the organism receives too much or too little of some environmental factor

• Organisms become fewer as conditions move toward either extreme of the range of tolerance (too much or too little).