Food levels

Question 1

autotroph

Answer 1

organism that is able to capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer

Question 2

primary producer

Answer 2

first producer of energy-rich compounds that are later used by other organisms

Question 3

photosynthesis

Answer 3

process used by plants and other autotrophs to capture light energy and use it to power chemical reactions that convert carbon dioxide and water into oxygen and energy-rich carbohydrates such as sugars and starches

Question 4

chemosynthesis

Answer 4

process in which chemical energy is used to produce carbohydrates

Question 5

heterotroph

Answer 5

organism that obtains food by consuming other living things; also called a consumer

Question 6

consumer

Answer 6

organism that relies on other organisms for its energy and food supply; also called a heterotroph

Question 7

detritus

Answer 7

material made up of decaying bits of plant and animal material

Question 8

food chain

Answer 8

a series of steps in an ecosystem in which organisms transfer energy by eating and being eaten

Question 9

phytoplankton

Answer 9

photosynthetic algae found near the surface of the ocean

Question 10

food web

Answer 10

network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem

Question 11

trophic level

Answer 11

each step in a food chain or food web

Question 12

ecological pyramid

Answer 12

illustration of the relative amounts of energy or matter contained within each trophic level in a given food chain or food web

Question 13

biomass

Answer 13

total amount of living tissue within a given trophic level

Question 14

biogeochemical cycle

Answer 14

process in which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another

Question 15

nutrient

Answer 15

chemical substance that an organism needs to sustain life

Question 16

nitrogen fixation

Answer 16

process of converting nitrogen gas into nitrogen compounds that plants can absorb and use

Question 17

denitrification

Answer 17

process by which swell bacteria convert nitrates into nitrogen gas

Question 18

limiting nutrient

Answer 18

single essential nutrient that limits productivity in an ecosystem