Environmental Science Chapter 5 Notes Environmental Science

Objectives Describe how energy is transferred from the sun to producers and then to consumers. Describe one way in which consumers depend on producers. Identify two types of consumers. Explain how energy transfer in a food web is more complex than energy transfer in a food chain. Explain why an energy pyramid is a representation of trophic levels.

Classroom Catalyst

Catalyst Answer Venus Flytrap and Pitcher Plant- plants that eat animals

Energy flow in an Ecosystem Energy comes from the sun. Sun enters ecosystem when organisms use sunlight to make sugars through photosynthesis Producers or autotrophs make own food (plants) Consumers or heterotrophs get energy indirectly by eating autotrophs or other heterotrophs.

Photosynthesis

One exception Certain bacteria can make food without sunlight. Use chemicals and thermal vents in the ocean. Creates pockets of life deep undersea.

Types of Consumers Herbivore- eat only plants Carnivore – eat only animals Omnivores- eat plants and animals Decomposers- bacteria, fungi

Cellular Respiration An organism obtains energy from the food it eats. This food must be broken down within its body. The process of breaking down carbohydrates to yield energy is called cellular respiration. Cellular respiration occurs inside the cells of most organisms.

Cellular Respiration

Energy travels through the ecosystem. Flow of energy very complex. Food Chain- the sequence in which energy is transformed from one organism to the next. Many food chains make up a food web.

Food Chain

Food Web

Biomagnification Increase in concentration of substance that occurs in a food chain. Substance is stored in fat layer and next consumer to eat it takes it in Substance cannot be broken down or breaks down very slowly Pesticides, metals Ex- DDT and bald eagle

Trophic Levels Each step or level in a food chain Available energy decreases as you go up trophic levels. (only 10% passed on) Energy lost as heat and used in cellar respiration. Producers on bottom

Energy Pyramid Each layer of the pyramid represents one trophic level. Producers form the base of the energy pyramid, and therefore contain the most energy. The pyramid becomes smaller toward the top, where less energy is available.

How Energy Loss Affects an Ecosystem Usually only 4 to 5 energy levels. Decreasing amounts of energy at each trophic level affects the organization of an ecosystem. Energy loss affects the number of organisms at each level. Energy loss limits the number of trophic levels in an ecosystem.

How Energy Loss Affects an Ecosystem Organisms that feed on top of food chain are usually quite small and don’t need much energy. Ex-parasites and fleas. Less organisms at top of food chain. There are not enough herbivores to support lots of carnivores.

Checking understanding… DNC Which statement is not true about consumers? A. get energy indirectly from the sun B. also called heterotrophs C. make their own food. D. they sometimes eat other consumers

Checking understanding… DNC Which is arranged from lowest to highest trophic level? A. bacteria, frog, eagle, mushroom B. Algae, deer, wolf, hawk C. grass, bass, minnow, snake D. grass, mouse, snake, eagle

Checking understanding… DNC Which of the following pairs probably belong in the same trophic level? A. humans and cows B. bears and deer C. humans and bears

Checking understanding… DNC Energy lost between trophic levels a. Can be captured only by parasitic organisms B. cools the surrounding environment C. evaporates in the atmosphere D. used in the course of normal living

Checking understanding… DNC From producer to secondary consumer, about what % of energy is lost? A. 10 B. 90 C. 99 D. 100