Across
- 5. Process in which certain organisms (mostly specialized bacteria) extract inorganic compounds from their environment and convert them into organic nutrient compounds without the presence of sunlight. Compare photosynthesis.
- 6. Rate at which all the plants in an ecosystem produce net useful chemical energy; equal to the difference between the rate at which the plants in an ecosystem produce useful chemical energy (gross primary productivity) and the rate at which they use some of that energy through cellular respiration. Compare gross primary productivity.
- 8. Organism that cannot synthesize the organic nutrients it needs and gets its organic nutrients by feeding on the tissues of producers or of other consumers; generally divided into primary consumers (herbivores), secondary consumers (carnivores), tertiary (higher-level) consumers, omnivores, and detritivores (decomposers and detritus feeders). In economics, one who uses economic goods.
- 9. Complex process that occurs in the cells of most living organisms, in which nutrient organic molecules such as glucose (C6H12O6) combine with oxygen (O2) and produce carbon dioxide (CO2), water (H2O), and energy. Compare photosynthesis.
- 13. Community of different species interacting with one another and with the chemical and physical factors making up its nonliving environment.
- 14. Consumer organism that feeds on detritus, parts of dead organisms, and cast-off fragments and wastes of living organisms. The two principal types are detritus feeders and decomposers.
- 16. Populations of all species living and interacting in an area at a particular time.
- 18. Conversion of atmospheric nitrogen gas into forms useful to plants by lightning, bacteria, and cyanobacteria; it is part of the nitrogen cycle.
Down
- 1. Single factor that limits the growth, abundance, or distribution of the population of a species in an ecosystem. See limiting factor principle.
- 2. Organism that digests parts of dead organisms and cast-off fragments and wastes of living organisms by breaking down the complex organic molecules in those materials into simpler inorganic compounds and then absorbing the soluble nutrients. Producers return most of these chemicals to the soil and water for reuse. Decomposers consist of various bacteria and fungi. Compare consumer, detritivore, producer.
- 3. The rate at which an ecosystem's producers capture and store a given amount of chemical energy as biomass in a given length of time. Compare net primary productivity.
- 4. Living organisms. Compare abiotic.
- 7. Percentage of energy transferred from one trophic level to another in a food chain or web.
- 10. The whole mass of air surrounding the earth. See stratosphere, troposphere.
- 11. Cyclic movement of nitrogen in different chemical forms from the environment to organisms and then back to the environment.
- 12. Variety of different species (species diversity), genetic variability among individuals within each species (genetic diversity), variety of ecosystems (ecological diversity), and functions such as energy flow and matter cycling needed for the survival of species and biological communities (functional diversity).
- 15. Place or type of place where an organism or population of organisms lives. Compare ecological niche.
- 17. Organic matter produced by plants and other photosynthetic producers; total dry weight of all living organisms that can be supported at each trophic level in a food chain or web; dry weight of all organic matter in plants and animals in an ecosystem; plant materials and animal wastes used as fuel.
- 19. Study of the interactions of living organisms with one another and with their nonliving environment of matter and energy; study of the structure and functions of nature.
- 20. Nonliving.