Ecology Quiz 1

Drake University, Fall 2025

What is ecology?

The study of relationships among organisms and their interactions with living and non-living elements of the Earth.

Who coined the term 'ecology'?

Ernst Haeckel, defining it as 'the body of knowledge concerning the economy of nature.'

What is meant by 'economy of nature'?

The network of interactions that increase or decrease variables in ecosystems.

What does 'edaphic' mean?

Pertaining to soil.

Name the four major principles governing ecosystems.

1) Ecosystems are physical entities. 2) Ecosystems exist in dynamic steady states. 3) Maintenance requires energy expenditure. 4) Ecosystems undergo evolutionary change over time.

What is the ecological hierarchy?

Organisms → Populations → Communities → Ecosystems.

Why is day length important in ecology?

It determines the physical template, influencing soil temperature, water state, and species distributions.

What does 'LAI' stand for and what does it measure?

Leaf-Area Index, a measure of how much light penetrates to lower levels of vegetation.

Why is water unique as a physical parameter?

It remains liquid over a wide temperature range, is less dense as ice, and resists temperature changes.

What is the difference between hypertonic and hypotonic environments?

Hypertonic: more solutes outside, water flows out (dehydration). Hypotonic: fewer solutes outside, water flows in.

What are the most common limiting nutrients in aquatic systems?

Nitrogen (marine) and phosphorus (freshwater).

What four factors affect the temperature of an organism like a cactus?

Radiation, Conduction, Transpiration, and Convection.

What is a Q10 relationship?

The exponential change in metabolism with a 10°C change in temperature, used to distinguish ectotherms.

What is the most important driver of physical template variation?

Climate (temperature, precipitation, solar radiation).

What is a Hadley Cell?

A global air circulation pattern where warm air rises at the equator, cools and sinks around 30° latitude, creating deserts and rainforests.

What is the Coriolis effect?

The deflection of moving air and objects due to Earth's rotation (right in N hemisphere, left in S hemisphere).

What is a rain shadow?

Dry area on the leeward side of a mountain caused by moisture loss on the windward side.

What are epilimnion and hypolimnion?

Epilimnion: warm surface water layer. Hypolimnion: cold deep water layer.

What is lake turnover?

The mixing of surface and deep waters in spring and fall, resuspending nutrients.

What factors determine biome distribution?

Climate, topography, and soils.

Give an example of a biome and its key feature.

Temperate deciduous forest – seasonality in precipitation and temperature, trees lose leaves in winter.

What is the difference between acclimation and adaptation?

Acclimation: reversible phenotypic change in an individual. Adaptation: genetic change over generations.

How do desert plants reduce water loss?

Close stomata, have hairs or spines, recess stomata, waxy cuticle, or no leaves (photosynthesize with stems).

What are C3, C4, and CAM photosynthesis?

C3: most common, efficient but water-costly. C4: adapted for water stress, uses bundle sheath cells. CAM: separates C4 pathway into day/night cycles to save water.

"What does it mean that ecosystems are in a 'dynamic steady state'?"

"Populations ebb and flow over time; change is the norm rather than a constant state."

"Why is environmental science considered change management?",

"Because ecosystems are always changing, so we manage them rather than hold them static."

"Give examples of abiotic vs biotic elements.",

"Abiotic: temperature, water, soil, sunlight. Biotic: plants, animals, fungi, bacteria."

"What is synergism in ecology?",

"When two or more variables interact to produce a greater effect than the sum of individual effects (multiplicative outcome)."

"Why do frogs put water in their stomach when they freeze?",

"To prevent their cells from bursting by controlling where ice forms."

"Why do plants lose water in winter?",

"To prevent their cells from exploding due to freezing water expansion."

"Why can’t upper-level primates swim well?",

They have very low body fat (~1%) and therefore cannot float easily."

"Name the dominant ions in marine vs freshwater systems.",

"Marine: Na+, Cl-, Mg2+, SO4²-. Freshwater: Ca2+, HCO3-."

"Why do still waters smell like sulfur?",

"Anaerobic decomposition releases sulfur compounds in low-oxygen environments."

"What is the heat budget equation for organisms?",

"Heat content = metabolism − evaporation ± radiation ± conduction ± convection."

"Which animals regulate temperature via hypothalamus?",

"Monotremes, marsupials, and placentals. Reptiles do not."

"What are Hadley Cells responsible for?",

"Creating bands of wet tropics and dry deserts at predictable latitudes."

"Why are deserts often found at 30° N/S?",

"Descending dry air from Hadley cells limits precipitation."

"What is orographic precipitation?",

"Moist air rises over mountains, cools, and rains on the windward side, leaving the leeward side dry (rain shadow effect)."

"How do valleys trap heat?",

"Cold air sinks and gets trapped, creating localized thermal inversions."

"What is albedo?",

"The reflectivity of a surface; high albedo means more light is reflected and the surface stays cooler."

"What five factors form soils?",

"Parent material, climate, biotic factors, topography, and time."

"What is laterization?",

"The leaching of silica in tropical soils, leaving iron and aluminum behind."

"Why are lateritic soils nutrient-poor?",

"They lack clay and humus to hold nutrients, requiring renutrification."

"Why do temperate deciduous trees drop leaves?",

"To conserve energy and water during winter when water is frozen and unavailable."

"Why are grasses superior competitors in grasslands?",

"They survive drought better by going dormant when water is unavailable."

"What adaptation do conifers have in boreal forests?",

"Needle-like leaves and thick cuticles that reduce water loss."

"What is aestivation?",

"Summer hibernation strategy used by animals in Mediterranean shrublands."

"What is the root/shoot ratio strategy in nutrient-poor soils?",

"Plants grow more roots relative to shoots to maximize nutrient uptake."

"What is the compensation point in photosynthesis?",

"The light level where photosynthesis produces just enough energy to balance respiration."