productivity test

1. Autotroph

• Definition: An organism that produces its own food using sunlight (photosynthesis) or chemicals (chemosynthesis).

• Example: Plants, algae, and some bacteria are autotrophs.

2. Heterotroph

• Definition: An organism that consumes other organisms for energy.

• Example: Animals, fungi, and most bacteria are heterotrophs.

3. Trophic Level

• Definition: A step in a food chain or food web, representing an organism’s feeding position.

• Example: Producers (plants) → Primary consumers (herbivores) → Secondary consumers (carnivores).

4. Trophic Cascade

• Definition: When a change in one trophic level affects multiple levels in an ecosystem.

• Example: Removing wolves from Yellowstone led to an overpopulation of deer, which damaged vegetation.

5. Abiotic

• Definition: Non-living factors in an ecosystem.

• Example: Water, sunlight, temperature, and soil.

6. Biotic

• Definition: Living organisms in an ecosystem.

• Example: Plants, animals, bacteria.

7. Salinity

• Definition: The amount of salt in water.

• Example: The ocean has a high salinity, while freshwater lakes have low salinity.

8. Water Clarity

• Definition: How clear or murky water is, often affected by sediments, algae, and pollution.

9. Limiting Resource (Listed Twice—Same Definition)

• Definition: A resource that limits population growth due to its scarcity.

• Example: Food, water, space, and sunlight can be limiting resources.

10. Decomposition

• Definition: The breakdown of dead organisms into nutrients by decomposers.

• Example: Fungi and bacteria decompose dead leaves into soil nutrients.

11. Detritivore

• Definition: An organism that feeds on dead organic material (detritus).

• Example: Earthworms, crabs, and some insects.

12. Nutrient Regeneration

• Definition: The recycling of nutrients back into the ecosystem through decomposition.

• Example: Decomposers release nitrogen and phosphorus into the soil.

13. Ecological Niche

• Definition: The role an organism plays in an ecosystem, including its habitat, diet, and interactions.

• Example: A bee’s niche includes pollinating flowers and making honey.

14. Gross Productivity

• Definition: The total amount of energy produced by autotrophs in an ecosystem.

15. Net Productivity

• Definition: The energy left over after autotrophs use some for their own growth and metabolism.

16. Standing Stock

• Definition: The total biomass (living material) in a given area at a certain time.

17. Nitrogen Fixation

• Definition: The process where bacteria convert nitrogen gas (N₂) into a usable form (like ammonia) for plants.

• Example: Legume plants have nitrogen-fixing bacteria in their roots.

18. Denitrification

• Definition: The process where bacteria convert nitrogen compounds back into nitrogen gas (N₂), returning it to the atmosphere.

19. Competition

• Definition: When two or more organisms fight for the same resource (food, space, mates).

• Example: Lions and hyenas compete for prey.

20. Predation

• Definition: When one organism hunts and eats another.

• Example: A wolf hunting a deer.

21. Symbiosis

• Definition: A close relationship between two different species.

• Example: Mutualism, commensalism, and parasitism.

22. Commensalism

• Definition: A symbiotic relationship where one species benefits and the other is unaffected.

• Example: Barnacles on a whale—they get a ride but don’t harm or help the whale.

23. Parasitism

• Definition: A symbiotic relationship where one species benefits, and the other is harmed.

• Example: Ticks feeding on a dog.

24. Mutualism

• Definition: A symbiotic relationship where both species benefit.

• Example: Bees pollinate flowers while getting nectar for food.

25. Exponential Growth

• Definition: Population growth that keeps increasing rapidly, with no limits.

• Example: Bacteria growing under ideal conditions.

26. Logistic Growth

• Definition: Population growth that slows and levels off when it reaches the environment’s carrying capacity.

• Example: A deer population stabilizing due to limited food.

27. Biomass

• Definition: The total mass of living organisms in a specific area.

• Example: The amount of trees in a forest.

28. Stabilizing Selection

• Definition: A type of natural selection where average traits are favored over extreme ones.

• Example: Human birth weight—babies that are too small or too large have lower survival rates.

29. Directional Selection

• Definition: A type of natural selection where one extreme trait is favored over the average.

• Example: Giraffes with longer necks surviving better than shorter-necked ones.