Download Chapter 13 Study Guide

Chapter 13 Test Study Guide-7th Grade
LESSON 13.1
<>Each of the organisms in an ecosystem fills the energy role of producer, consumer, or decomposer.
producers -organisms that make their own food (Ex: plants and some bacteria)
consumers-organisms that obtain energy by feeding on other organisms (Ex: animals)
Carnivores-type of consumers that eat only animals.
Scavenger-type of carnivore that feeds on dead organisms
Herbivore-type of consumers that eat only plants.
Omnivore-type of consumers that eat both plants and animals.
decomposer-organisms that break down wastes and dead organisms (Ex: some bacteria and fungi)
<>Energy moves through an ecosystem when one organism eats another.
A food chain is a series of events in which one organism eats another and obtains energy.
*Be able to construct and analyze the relationships between organisms in a food chain. See pgs 492.
A food web is a combination of multiple overlapping food chains in an ecosystem.
*Be able to construct and analyze the relationships between organisms in a food web. See pg 493.
*Be able to identify an organism as either a producer, first-level consumer, second-level consumer, etc…
in a food web. See pg 493.
<>The most energy is available at the producer level of the pyramid. As energy moves up the pyramid,
each level has less energy available than the level below.
Energy pyramid-diagram that shows the amount of energy that moves from one feeding level to another
in a food web.
*Know how to calculate the amount of energy in an energy pyramid. See pg 494 for example.
*Be able to identify the levels in an energy pyramid. See pg 494 for example.
LESSON 13.2
<>The process of evaporation, condensation, and precipitation make up the water cycle.
Evaporation-the process by which molecules of liquid water absorb energy and change to a gas
(Water changes states of matter, from Liquidgas)
Condensation-the process by which a gas changes to a liquid
(Water changes states of matter, from gasliquid)
Precipitation-any form of water that falls from clouds and reaches Earth’s surface as rain, snow, sleet, or
hail.
<>In ecosystems, the processes by which carbon and oxygen are recycles are linked. Producers,
consumers, and decomposers all play roles in recycling carbon and oxygen.
Producers take in carbon dioxide and release oxygen through photosynthesis. They make carbon
molecules that consumers eat. (Ex: humans eat plant products to obtain carbon molecules for energy.)
Consumers break down the carbon molecules in the process of digestion. Consumers release carbon
dioxide into the atmosphere.
Increasing levels of carbon dioxide are a major factor in global warming.
Human activities impact the levels of carbon and oxygen in the air. (Ex: burning oil and plant-based fuels
increases the amount of carbon dioxide in the atmosphere, cutting down trees decreases the amount of
carbon dioxide they take in for photosynthesis, etc…)
<>In the nitrogen cycle, nitrogen moves from the air into the soil, into living things, and back into the air
or soil.
Nitrogen fixation-the process of changing “free” nitrogen from the air into a usable form. This is usually
done by nitrogen-fixing bacteria.
Nitrogen fixation is important because it allows plants to take up nitrogen from the soil that they would
otherwise not be able to obtain from the air. In turn, when consumers eat plants, they can obtain the
nitrogen they need to make important life-sustaining molecules.
*Be familiar with the water cycle, the carbon and oxygen cycles, and the nitrogen cycles. See lesson
13.2.