Organisms AND Populations flash cards

1. 1.What are the four levels of ecological organisation studied in ecology?

   Organisms, populations, communities, and biomes (ecosystems) — from the individual up to biome level.

   Hint: From smallest to largest.

2. 2.Define ecology.

   Ecology is the study of interactions among organisms and between organisms and their physical (abiotic) environment.

   Hint: Interactions + environment.

3. 3.What is a habitat?

   The specific place or set of physical conditions where an organism lives (rocky, sandy, marine, freshwater, desert, mountain, etc.).

   Hint: The 'address' of an organism.

4. 4.What are the four major abiotic factors of the environment?

   Temperature, water, light, and soil.

   Hint: Think TWLS.

5. 5.Why is temperature considered the most important/ecologically relevant abiotic factor?

   It affects the kinetics of enzymes, basal metabolism, and other physiological functions; it varies with latitude (tropics to poles) and altitude.

   Hint: Enzyme kinetics and metabolism.

6. 6.What are eurythermal and stenothermal organisms?

   Eurythermal organisms tolerate and thrive in a wide range of temperatures; stenothermal organisms are restricted to a narrow range of temperatures.

   Hint: Eury = wide, steno = narrow.

7. 7.What are euryhaline and stenohaline organisms?

   Euryhaline organisms tolerate a wide range of salinities; stenohaline organisms tolerate only a narrow salinity range.

   Hint: Haline = salt.

8. 8.What is the salinity range of inland waters, sea, and hypersaline lagoons?

   Inland waters <5 ppt (parts per thousand), sea ~30–35 ppt, and hypersaline lagoons >100 ppt.

   Hint: Sea is about 30–35 ppt.

9. 9.For aquatic organisms, why is light important and how does it change with depth?

   Light drives photosynthesis by producers; in deep oceans (>500 m) light is absent, so that zone remains perpetually dark.

   Hint: Photosynthesis and the aphotic zone.

10. 10.How does light affect plants and animals besides photosynthesis?

    Many plants depend on sunlight for photoperiod-dependent flowering; animals use photoperiod and light cues for foraging, reproduction, and migration.

    Hint: Photoperiodism, diurnal/seasonal rhythms.

11. 11.What properties of soil influence the vegetation and animals of an area?

    Soil composition, grain size, aggregation, water-holding capacity, pH, mineral content, and topography.

    Hint: Determines percolation and vegetation type.

12. 12.What determines the sediment characteristics in aquatic environments and why does it matter?

    Sediment characteristics determine the type of benthic (bottom-dwelling) animals that can thrive there.

    Hint: Bottom-dwellers depend on sediment.

13. 13.Distinguish between the external environment and the internal environment of an organism.

    The external environment often fluctuates and may be stressful; organisms try to maintain a relatively constant internal environment (homeostasis) for optimal performance.

    Hint: Homeostasis = constancy of internal milieu.

14. 14.What are the four main ways in which organisms respond to (cope with) stressful abiotic conditions?

    Regulate, conform, migrate, and suspend.

    Hint: R-C-M-S.

15. 15.What does it mean for an organism to be a 'regulator'?

    A regulator maintains homeostasis by physiological (and sometimes behavioural) means, keeping constant body temperature and osmotic concentration despite external changes.

    Hint: All birds, mammals, and a few lower vertebrates/invertebrates.

16. 16.Give examples of thermoregulation in humans in hot and cold conditions.

    In summer/heat we sweat to cool by evaporation; in winter/cold we shiver (a form of exercise producing heat) to raise body temperature.

    Hint: Sweating vs shivering.

17. 17.What is a 'conformer' and how common is it?

    A conformer cannot maintain a constant internal environment; its body temperature and osmotic concentration change with the ambient environment. The majority (99%) of animals and nearly all plants are conformers.

    Hint: Internal state tracks the external one.

18. 18.Why can't most small animals like shrews and hummingbirds afford to be regulators in cold climates?

    Small animals have a large surface area relative to volume, so they lose body heat rapidly; the energy cost of generating heat to thermoregulate is very high, so they may not regulate.

    Hint: High surface-area-to-volume ratio.

19. 19.What is migration as a response to stressful conditions? Give an example.

    Organisms move away temporarily from a stressful habitat to a more favourable area and return when conditions improve; e.g., birds migrating to Keoladeo National Park (Bharatpur) in winter.

    Hint: Move away and return.

20. 20.What is 'suspend' as a strategy, and what is a resting/dormant stage?

    When conditions are unfavourable, organisms reduce metabolic activity and enter a dormant stage. Examples include thick-walled spores in bacteria/fungi, and seeds/vegetative reproductive structures in higher plants that germinate under favourable moisture and temperature.

    Hint: Dormancy; spores and seeds.

21. 21.What is hibernation and which animals show it?

    Hibernation is winter sleep — escaping cold by entering a state of reduced metabolic activity; e.g., bears (and polar bears) hibernate during winter.

    Hint: Escape in time — winter.

22. 22.What is aestivation and give an example?

    Aestivation is summer sleep — escaping heat and desiccation by entering dormancy; e.g., snails and fish aestivate during summer.

    Hint: Summer dormancy to avoid heat/desiccation.

23. 23.What is diapause?

    Diapause is a stage of suspended development seen in many zooplankton species (in lakes and ponds) during unfavourable conditions.

    Hint: Suspended development in zooplankton.

24. 24.What is adaptation in an ecological/evolutionary sense?

    Adaptation is any attribute of an organism (morphological, physiological, behavioural) that enables it to survive and reproduce in its habitat, evolved over long evolutionary time and genetically fixed.

    Hint: Heritable trait aiding survival & reproduction.

25. 25.How are kangaroo rats adapted to the desert with little/no water?

    They meet their water needs through internal fat oxidation (producing metabolic water) and have the ability to concentrate their urine to minimise water loss.

    Hint: Metabolic water + concentrated urine.

26. 26.Name two adaptations of desert plants to conserve water.

    Thick cuticle on leaf surfaces and sunken stomata to reduce transpiration; some (like Opuntia) have no leaves — reduced to spines — and photosynthesis occurs in flattened green stems.

    Hint: Opuntia and CAM.

27. 27.What is the CAM photosynthetic pathway adaptation in desert plants?

    Some desert plants use the CAM (Crassulacean Acid Metabolism) pathway, keeping their stomata closed during the day to reduce water loss and opening them at night to fix CO2.

    Hint: Stomata open at night.

28. 28.State Allen's Rule.

    Allen's Rule: mammals from colder climates generally have shorter ears and limbs to minimise heat loss (reduced surface area).

    Hint: Shorter extremities in the cold.

29. 29.How do polar seals adapt physiologically to conserve heat?

    They have a thick layer of blubber (fat) beneath the skin that acts as an insulator and reduces loss of body heat.

    Hint: Insulating fat layer.

30. 30.How are humans/mammals at high altitudes physiologically adapted to low oxygen (altitude sickness)?

    The body compensates by increasing red blood cell production, decreasing the binding affinity of haemoglobin, and increasing breathing rate.

    Hint: More RBCs, faster breathing.

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