Ecosystem flash cards

1. 1.Define an ecosystem.

   A functional unit of nature where living organisms (biotic community) interact among themselves and with the surrounding physical environment (abiotic).

   Hint: biotic + abiotic interacting unit

2. 2.Who coined the term 'ecosystem'?

   A.G. Tansley (1935).

   Hint: British ecologist, 1935

3. 3.Ecosystems are classified into which two broad types?

   Terrestrial (forest, grassland, desert) and aquatic (pond, lake, wetland, river, estuary, ocean).

   Hint: land vs water

4. 4.Give examples of man-made (artificial) ecosystems.

   Crop fields (agroecosystems) and aquarium.

   Hint: human-created, e.g. farm

5. 5.What is the biosphere?

   The sum of all ecosystems on Earth; the largest, completely self-sustaining ecological unit.

   Hint: all ecosystems together

6. 6.What are the two main structural components of an ecosystem?

   Biotic components (living organisms) and abiotic components (physical/chemical environment).

   Hint: living + non-living

7. 7.Name key abiotic factors of an ecosystem.

   Light, temperature, water, soil, inorganic and organic materials (minerals, nutrients).

   Hint: climatic + edaphic + nutrients

8. 8.List the biotic components of an ecosystem by function.

   Producers (autotrophs), consumers (heterotrophs), and decomposers (saprotrophs).

   Hint: three functional groups

9. 9.What are the four functional aspects of an ecosystem?

   Productivity, decomposition, energy flow, and nutrient cycling.

   Hint: P, D, E, N

10. 10.Name the two aspects into which the structure of an ecosystem is described.

    Species composition and stratification (vertical layering of organisms).

    Hint: what species + how layered

11. 11.What is stratification? Give a forest example.

    Vertical distribution of different species occupying different levels; in a forest — trees (top), shrubs (middle), herbs/grasses (bottom).

    Hint: vertical layers of a forest

12. 12.Define standing crop.

    The amount of living biomass (mass of living material) present in an ecosystem at a given time, per unit area.

    Hint: living biomass at a moment

13. 13.How is standing crop measured/expressed?

    As mass of living organisms (biomass) or number of individuals per unit area; biomass in terms of fresh or dry weight.

    Hint: biomass or number per area

14. 14.Why is dry weight preferred over fresh weight for biomass?

    Because water content of tissues varies; dry weight gives a more accurate measure of biomass.

    Hint: water content varies

15. 15.Define primary production.

    The amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis.

    Hint: biomass made by plants

16. 16.In what units is primary production expressed?

    Weight (g⁻²) or energy (kcal m⁻²); as a rate it is per unit time.

    Hint: g/m² or kcal/m²

17. 17.Define Gross Primary Productivity (GPP).

    The rate of production of organic matter (total assimilation of energy) during photosynthesis.

    Hint: total energy fixed

18. 18.Define Net Primary Productivity (NPP).

    GPP minus the energy used in respiration (R) by producers: NPP = GPP − R. It is the biomass available for consumption by heterotrophs.

    Hint: GPP minus respiration

19. 19.Write the relation between GPP, NPP and respiration.

    NPP = GPP − R, where R = respiratory loss by plants.

    Hint: NPP = GPP − R

20. 20.Which productivity (GPP or NPP) is available to consumers (herbivores and decomposers)?

    Net Primary Productivity (NPP).

    Hint: the 'net' one

21. 21.Define secondary productivity.

    The rate of formation of new organic matter by consumers (heterotrophs).

    Hint: consumers' production rate

22. 22.On what does productivity of an ecosystem depend?

    On the plant species, environmental factors, availability of nutrients, and the photosynthetic capacity of plants.

    Hint: species + environment + nutrients

23. 23.What is the approximate annual net primary productivity of the whole biosphere?

    About 170 billion tons (dry weight) of organic matter per year.

    Hint: ~170 billion tons/yr

24. 24.Do oceans have high or low productivity per unit area, and what is their share of total production?

    Oceans have very low productivity per unit area, yet contribute a large share (about 55 billion tons) because of their vast area.

    Hint: low per area, huge area

25. 25.Define decomposition.

    The process by which decomposers break down complex dead organic matter (detritus) into inorganic substances (CO₂, water, nutrients).

    Hint: detritus → inorganic nutrients

26. 26.What is detritus?

    Dead plant remains (leaves, bark, flowers) and dead animal remains, including fecal matter — the raw material for decomposition.

    Hint: dead organic matter

27. 27.Name the steps of decomposition in order.

    Fragmentation, leaching, catabolism, humification, and mineralisation.

    Hint: F, L, C, H, M

28. 28.What happens during fragmentation?

    Detritivores (e.g. earthworms) break detritus into smaller particles, increasing surface area.

    Hint: break into small pieces

29. 29.What is leaching in decomposition?

    Water-soluble inorganic nutrients seep down (percolate) into the soil horizon and get precipitated as unavailable salts.

    Hint: soluble nutrients wash down

30. 30.What is catabolism in decomposition?

    Bacterial and fungal enzymes degrade detritus into simpler inorganic substances.

    Hint: enzymatic breakdown

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