Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Ecology at the organismic level focuses on physiological ecology, which studies how organisms are adapted to their environments for survival and reproduction. The hierarchy includes: Organisms Populations Communities Biomes.
Temperature: The most ecologically relevant environmental factor. It affects the kinetics of enzymes and through it the metabolic activity and other physiological functions of the organism. Eurythermal organisms can tolerate a wide range of temperatures, while Stenothermal organisms are restricted to a narrow range.
Water: The second most important factor. For aquatic organisms, the chemical composition and of water are vital. Salinity (measured as parts per thousand) is in inland waters, in the sea, and in some hypersaline lagoons.
Homeostasis: The process by which organisms maintain a constant internal environment (e.g., constant body temperature of and constant osmotic concentration) despite varying external environmental conditions.
Regulators vs. Conformers: Regulators (e.g., birds, mammals) maintain homeostasis by physiological or behavioral means. Conformers ( of animals and nearly all plants) cannot maintain a constant internal environment; their body temperature or osmotic concentration changes with the ambient environment.
Adaptations: These are morphological, physiological, or behavioral attributes that enable an organism to survive and reproduce. Examples include the Allen's Rule, which states that mammals from colder climates generally have shorter ears and limbs to minimize heat loss (reducing the Surface Area to Volume ratio).
Suspension and Dormancy: To avoid stressful external conditions, organisms may enter stages of suspended development such as Hibernation (winter sleep in bears), Aestivation (summer sleep in snails and fish), or Diapause (a stage of suspended development in many zooplankton species).
📐Formulae
💡Examples
Problem 1:
An individual travels to Rohtang Pass (altitude ) and experiences 'Altitude Sickness' with symptoms like nausea and heart palpitations. How does the body physiologically adapt to this stress after a few days?
Solution:
The body compensates for low availability by: (i) Increasing Red Blood Cell () production, (ii) Decreasing the binding affinity of hemoglobin, and (iii) Increasing the breathing rate.
Explanation:
At high altitudes, the atmospheric pressure is low, leading to inadequate intake. The physiological shift in the hemoglobin-oxygen dissociation curve ensures more is released to the tissues despite lower saturation.
Problem 2:
Why are very small animals like shrews and hummingbirds rarely found in polar regions?
Solution:
Small animals have a larger surface area relative to their volume (High ratio).
Explanation:
Since heat loss is a function of surface area, small animals tend to lose body heat very fast in cold environments. To maintain internal body temperature, they must expend significant energy through metabolism to generate heat, which is energetically expensive for their small size.
Problem 3:
Differentiate between Euryhaline and Stenohaline organisms regarding their environment.
Solution:
Euryhaline organisms can tolerate a wide range of salinities, whereas Stenohaline organisms are restricted to a narrow range of salinity.
Explanation:
This is a classification based on osmotic tolerance. Most freshwater organisms cannot live for long in sea water and vice versa because of the osmotic problems they would face ( or stress).