Exam 1 Study Guide: Challenges of Aquatic vs. Terrestrial Ecosystems Flashcards
Identify thermal properties of water. What makes water unique for life
Dissolved salts lower freezing point, high specific heat, ice is less dense than liquid water. Water also requires specific energy to evaporate
Compare viscosity to surface tension
Viscosity: a fluid’s resistance to flow, thick, large animals can swim fast but smaller animals have long appendages to slow sinking and stay near the surface.
Surface tension: the cohesive force between water molecules at the surface, allowing organisms like water striders to walk on water
How does water move between the environment and these organisms?What role do solutes play?
Osmosis: movement of water across membranes from low to high solute
concentration. Solutes create osmotic pressure which influences water retention and loss
Define osmoregulation. Distinguish hyperosmotic organisms from hypoosmotic organisms.
-Hyperosmotic: freshwater organisms whose tissues contain higher solute
concentration than the surrounding, must eliminate excess water while retaining solutes.
-Hyposmotic: saltwater organisms whose tissue contains lower concentration than the surrounding, must drink water and excrete excess solutes while retaining water.
-Osmoregulation: the process of maintaining water and solute balance in an organism
What happens when carbon dioxide meets water? What are some real-life
implications of this (i.e., ocean acidification)?
It forms carbonic acid which then forms carbonate ions. Ocean acidification is when
excess o2 from fossil fuels increases acidity which affects marine life like coral
reefs.
Explain challenges of gas exchange in aquatic ecosystems
Oxygen is less available in water than air, adaptation for gas exchange.
How do some aquatic organisms get oxygen from the environment (i.e., fish with hemoglobin)?
For fish with hemoglobin, the countercurrent flow can be helpful to extract O2 out of water with gills. Also works for heat exchange.
List the steps for photosynthesis and name the compounds involved
Light dependent reactions convert light energy into ATP and NADPH while splitting water to release O2.
What are some environmental conditions that could impact photosynthesis?
Light intensity, temp, water availability, CO2 concentration.
Compare and contrast the different types of photosynthesis (C3 , C4 , CAM). Which type is the most common? Be able to give examples of plants for each.
-C3 is the most common. It uses Rubisco for carbon fixation but is less efficient in
hot/dry conditions
EX: rice and wheat.
-C4 is more efficient in high light + temp, it uses PEP carboxylase to concentrate
CO2 in specialized cells reducing photorespiration
EX: corn
-CAM is adapted to arid conditions, opens stomata at night to fix co2 minimizing water loss
EX: cacti
Summarize the importance of surface area to volume ratios for organisms. Why does does this ratio matter?
Small organisms have higher S:V ratios which allow for efficient gas exchange and nutrient uptake. Larger organisms develop adaptation (folding structures) to maintain efficiency.
Explain Liebig’s Law of the Minimum. Give an example of this law.
Growth is limited by the scarcest resource relative to demand. In deserts water is
the most limiting factor even if sunlight and nutrients are abundant.
Interpret the graph on Shelford’s Law of Tolerance (population size compared to
environmental factor)
Organisms have optimal ranges for environmental factors. Populations decrease when
conditions move towards tolerance limits.
Ex: coral reed bleach when water temp
exceeds tolerance range.
