Chapter 2: Adaptations to Aquatic Environments (Vocabulary Flashcards)

Vocabulary flashcards covering key terms and concepts from Chapter 2 on adaptations to aquatic environments.

Photic Zone

The sunlit surface layer of water where most solar radiation is absorbed; photosynthesis is largely restricted to this zone as light diminishes with depth.

Diffusion

The passive movement of molecules from an area of higher concentration to one of lower concentration; in water, diffusion limits the uptake of dissolved gases.

Semipermeable membrane

A membrane that allows only certain molecules to pass through, reducing free movement of solutes.

Osmosis

The movement of water across a semipermeable membrane to balance solute concentrations.

Tissue solute concentrations are lower than surrounding water, causing water to move out of the organism; organisms may drink and retain water to compensate.

Hyposmotic

Hyperosmotic

Tissue solute concentrations are higher than surrounding water, causing water to move into the organism; often accompanied by active uptake of minerals.

Osmoregulation

The set of mechanisms that maintain proper solute balance in a body, often involving active transport to regulate water and ion levels.

Boundary Layer

A region of unstirred air or water surrounding a surface where gas exchange is slowed due to limited replacement of removed gases.

Carbon dioxide diffuses slowly in water; plants convert CO2 to bicarbonate (HCO3−) or carbonate (CO3^2−) to support photosynthesis.

CO2 diffusion in water

Bicarbonate (HCO3−)

A soluble inorganic carbon form produced from CO2, abundantly available and used in photosynthesis.

Carbonate (CO3^2−)

A form of inorganic carbon derived from CO2 that contributes to carbonate minerals and photosynthesis processes.

Saturation

The upper limit of solubility for a substance in water; beyond this, minerals precipitate (e.g., CaCO3 forming limestone).

What determine acidity; what is the negative logarithm of the hydrogen ion concentration.

Hydrogen ions (pH)

Acidity

The concentration of hydrogen ions in a solution; concept underlying pH.

pH

A scale measuring how acidic or basic (alkaline) a solution is; calculated as pH = -log[H+].

Acid Rain

Rain formed when SO2 and NO2 react with water to form acids, lowering pH and mobilizing metals like aluminum in soils; harmful to aquatic life.

Excess inputs of nitrogen and phosphorus promote algal blooms; when blooms die and decompose, oxygen is consumed, leading to hypoxic or anoxic conditions.

Eutrophication

Hypoxia

Condition of low dissolved oxygen in water, harmful to fish and invertebrates, often following eutrophication.

Complete absence of oxygen in an environment; anaerobic conditions where microbes use alternative energy sources

Anoxia

Microcystis

A genus of cyanobacteria that can form harmful algal blooms and produce neurotoxins.

Cyanobacteria

Photosynthetic bacteria (including Microcystis) that can form blooms and release toxins affecting water quality and health.

Neurotoxins

Toxic substances produced by certain algae (e.g., some cyanobacteria) that can harm nervous systems in wildlife and humans.

Coastal trees that cope with salt by excluding salts at roots, accumulating organic solutes in roots, and secreting salt from leaves to maintain osmotic balance.

Mangroves

Glycerol

A cryoprotectant molecule produced by some Arctic fish that helps prevent freezing by lowering freezing point and reducing ice formation.

Glycoproteins

Cryoprotective proteins that help prevent freezing in some organisms, often working with glycerol to enable supercooling.

Hypothetical or experimental preservation of organisms at low temperatures for potential future revival; not a standard ecological adaptation.

Cryonics

Thermophiles

Organisms (often archaea) that thrive at very high temperatures, some up to 110°C.

Q10

A coefficient that describes how the rate of a physiological process changes with a 10°C change in temperature (commonly a 2–4× difference).

Thermal Optima

The temperature range in which an organism performs best, determined by factors like enzymes, lipids, and body form.

Coral Bleaching

Stress response where corals expel their symbiotic algae due to elevated water temperatures, leading to whitening and potential death; can begin with as little as 1°C above average.

Human-caused changes in water temperature (e.g., power plant effluent) that affect aquatic life and ecosystem processes.

Thermal Pollution