Test 1 Study Guide

What is the first step in the scientific method?

Make observations and ask questions

After forming a hypothesis, scientists typically:

Evaluate the hypothesis through research methods

Why is the scientific method considered self-correcting?

Results can lead to revised hypotheses and new questions

Which of the following is NOT a common method used by ecologists?

Astrological predictions

A major challenge in studying the natural world is that it is:

Vast, complex, and interconnected

The amphibian parasite example discussed in the chapter illustrates that:

Events in nature are interconnected

Because natural systems are interconnected:

Actions can have unexpected side effects

Ecology is best defined as:

The scientific study of interactions between organisms and their environment

Ecology differs from environmental science because:

Ecology is a scientific discipline focused on interactions among organisms and their environment

Which level of biological organization can be studied by ecologists?

All of the above

List the four major steps of the scientific method.

1. Make observations and ask questions

2.  Use previous knowledge or intuition to develop hypotheses

3. Evaluate hypotheses by experimentation, observational studies, or quantitative models

4. Use the results to modify the hypotheses, pose new questions, or draw conclusions about the natural world

Why do ecologists use a variety of methods rather than relying on a single approach?

No single approach works in all situations

Explain what is meant by the statement that the natural world is "interconnected."

Any action can have unanticipated side effects

Give one example of how human actions can have unanticipated ecological consequences.

People both depend on and affect the natural environment

What is a hypothesis, and how is it used in scientific research?

Hypothesis: an educated guess from an observation

Experimentation, observational studies, or quantitative models

Compare an observational study with a controlled experiment. What is one advantage of each?

Observational Study: Allows researchers to study real-world behavior and investigate topics where it would be hard to manipulate variables

Controlled Experiment: They can prove a clear cause-and-effect relationship because controlling variables and random assignment help eliminate hidden factors

Why might an ecologist combine field observations, experiments, and quantitative models when studying a problem?

No single method can fully explain complex ecological systems

In an ecological experiment, why is it important to include a control group?

It provides evidence to prove that any observed changes are caused by the specific treatment rather than natural environmental shifts or outside factors

Why are replication and random assignment important in experimental design?

They eliminate bias and reduce error

The chapter states that ecological knowledge is always changing. Why is it important for scientists to remain open to revising their understanding of natural systems?

Natural systems are complex, dynamic, and constantly shifting due to new environmental pressures

Which statement best describes the difference between weather and climate?

Weather refers to current atmospheric conditions, while climate refers to long-term average weather patterns

The primary source of energy that drives Earth's climate system is:

Solar radiation

Atmospheric circulation cells are primarily established by:

Latitudinal differences in solar radiation

The Coriolis effect is caused by:

Earth's rotation

Ocean currents are driven by:

Surface winds and differences in water temperature and salinity

Why do coastal areas generally experience smaller seasonal temperature fluctuations than inland areas?

Ocean water has a higher heat capacity than land

A mountain's leeward side is typically drier because:

Most moisture is lost as air rises over the windward slope

Seasonal changes in temperature in temperate regions are primarily caused by:

Earth's axial tilt

In temperate lakes, spring and fall turnover occurs because:

Density differences among water layers break down, allowing mixing

Oxygen concentrations in aquatic ecosystems are often low when:

Consumption by organisms exceeds the slow diffusion of oxygen into water

What is the difference between weather and climate?

Weather: Current conditions – temperature, precipitation, humidity, and cloud cover 
Climate: Long-term description of weather, based on averages and variation measured over decades 

Why is climate considered the most fundamental component of the physical environment for organisms?

Climate determines the geographic distribution and physiological functioning of organisms

What are the major factors that drive Earth's climate system?

Energy derived from solar radiation 

How do differences in solar radiation across Earth's surface contribute to atmospheric circulation?

They create uneven heating

What is the Coriolis effect, and how does it influence global wind patterns?

Coriolis effect: When winds are deflected due to the rotation of the earth 
It shapes the direction of global wind belts

How do differences in the heat capacity of land and water influence atmospheric circulation and weather patterns? 

They create differential heating that drives local breezes, seasonal monsoons, and moderates global climate patterns 

What two main factors drive ocean currents?

Surface winds and differences in water temperature and salinity

Why are winds and ocean currents important for transferring energy around the planet?

They transfer energy from the tropics to higher latitudes

What factors determine global temperature patterns?

Latitudial variation in solar radiation, oceanic circulation patterns, and the distribution of continents

How does elevation affect temperature, and why?

It decreases the heat capacity of the air

How do atmospheric circulation cells influence global precipitation patterns?

Driving large-scale bands of rising and sinking air that dictate where moisture condenses into rain or where dry air suppresses clouds

What role do semi-permanent pressure cells play in determining patterns of precipitation?

They change positions with the seasons, influencing weather patterns

Why do coastal regions generally experience less seasonal temperature variation than inland regions?

Because ocean water has a higher heat capacity than land

Explain the difference between the climates of windward and leeward mountain slopes

Windward: Cool and wet 
Leeward: Warm and dry

How does vegetation influence regional climate through albedo, evapotranspiration, and surface winds?

Albedo: Reduces surface albedo, which retains more energy

Evapotranspiration: Cools the air by using heat from the air to evaporate water

Surface winds: Slows down air movement and alters heat

How does the tilt of Earth's axis produce seasonal changes in temperature and precipitation?

By altering the angle and duration of sunlight reaching each hemisphere as the planet revolves around the Sun

Why do temperate lakes undergo seasonal mixing during spring and fall turnovers?

Because oxygen from the top and bottom of the lake mix, and nutrients trapped at the lake bottom are released

What causes climate variations over years to decades (such as El Niño and similar oscillations)?

The daily and seasonal cycles associated with changes in solar radiation as Earth rotates on its axis and orbits the sun

What are the three major astronomical factors associated with long-term climate cycles over hundreds to thousands of years?

Eccentricity, obliquity, and precession

How do salinity, pH, and oxygen concentrations influence the chemical environment of ecosystems?

Salinity: Balance between inputs of salts and gains (by precipitation) and losses (by evaporation) of water 

pH: Inputs of salts from the breakdown of rock minerals, organic acids from plants, and acidic pollutants 

Oxygen Concentrations: Oxygen availability decreases as elevation increases 

Why do ecologists primarily use plants to categorize terrestrial biomes?

Plant growth forms reflect environmental conditions and climate

Which environmental factors most strongly determine the location of terrestrial biomes?

Temperature and precipitation

Which human activity has had the greatest impact on the distribution of terrestrial biomes?

Agricultural land conversion

Which of the following is NOT one of the nine major terrestrial biomes?

Coral reef

Along mountain slopes, ecosystems often resemble global biomes because:

Climate changes with elevation

Near the source of a stream, organisms primarily depend on:

Coarse terrestrial detritus

In lakes, photosynthetic plankton are generally restricted to the:

Surface waters where light penetrates

Which ecosystem occurs at the boundary between terrestrial and marine environments?

Estuary

The organisms found along ocean shorelines are strongly influenced by:

Tides and substrate stability

Organisms in the open ocean and deep benthic zones are largely distributed according to:

Light availability and proximity to the bottom

Why do plant growth forms provide a useful way to classify terrestrial biomes? 

Plants are immobile, so they must be able to cope with its environmental extremes as well as its biological pressures. They also reflect climate zones and rates of disturbance

Explain how temperature and precipitation influence the distribution of plant growth forms across Earth.

Temperature influences the distribution of plant growth forms directly through its effect on the physiological functioning of plants

Precipitation influences the availability of water

How do human activities cause differences between the potential and actual distributions of biomes?

The potential and actual distributions of terrestrial biomes differ because of human activities, particularly conversion of land for agriculture, forestry, and grazing

List the nine major terrestrial biomes:

1. Tropical rainforests

2. Tropical dry forest

3. Savanna

4. Desert

5. Chaparral

6. Temperate grassland

7. Temperate forest

8. Boreal forest

9. Tundra

Describe how food sources change from headwater streams to large rivers

Food sources in river ecosystems shift dramatically from small headwater streams to large rivers, driven by changes in stream width, sunlight, and organic matter inputs

How do the feeding strategies of stream organisms change as a river flows downstream?

They shift in a highly predictable pattern known as the River Continuum Concept

Explain how water depth and light penetration affect the distribution of organisms within lakes

Photosynthetic plankton are limited to the surface layer of water where there is enough light for photosynthesis

Zooplankton occur throughout the pelagic zone, feeding on detritus as it falls through the water

Compare the environmental conditions that support coral reefs, kelp forests, and seagrass beds

Coral reefs: Warm, ecosystem engineers, highest taxonomic and morphological diversity on Earth

Kelp forests: Temperate, large stands on seaweed (brown algae)

Seagrass beds: Submerged flowering plants

How do tides and substrate type influence organisms living along coastlines?

They influence how organisms survive, where they live, and how they interact

Why are populations of organisms generally less dense in the open ocean and deep benthic zones than in productive coastal habitats?

They receive much less sunlight and nutrients than coastal habitats

Why is the physical environment considered the ultimate determinant of a species' geographic distribution?

It affects an organism's ability to survive, grow, and reproduce

Which term describes a short-term physiological, morphological, or behavioral adjustment made by an individual organism?

Acclimatization

Which term describes traits that evolve in a population through natural selection?

Adaptation

Adaptations and acclimatizations often involve trade-offs because they:

Require energy and resources that could be used for other functions

Temperature influences organismal functioning primarily through its effects on:

Enzymes and membranes

An organism's body temperature will increase when:

Energy gains exceed energy losses

Which mechanism can plants use to regulate their temperature?

Control of transpiration

Which statement correctly contrasts ectotherms and endotherms?

Ectotherms regulate temperature through environmental heat exchange, while endotherms generate substantial internal heat

Water movement in biological systems is influenced by all of the following EXCEPT:

Thermal potential

A freshwater fish is typically ________ to its environment and must ________.

hyperosmotic; take up solutes from the environment

Explain why the physical environment ultimately limits where a species can live

Every organism has specific survival needs and tolerance ranges for non-living factors like temperature, water, and nutrients

Compare and contrast acclimatization and adaptation

Acclimatization: Adjusting to stress through behavior or physiology

Adaptation: Enhances an individual’s survival, growth, and reproduction

Why do acclimatization and adaptation often involve trade-offs?

They require an investment of energy and resources by the organism

Describe how temperature affects the physiological functioning of organisms

It controls physiological activities through its effects on enzymes and membranes

How can gains and losses of energy determine whether an organism's body temperature rises or falls?

By the net balance between energy gains and energy losses

Describe two ways plants regulate temperature and two ways animals regulate temperature

Terrestrial plants may modify their energy balance by controlling transpiration, increasing or decreasing absorption of solar radiation, or adjusting the effectiveness of convective heat loss

Animals modify their energy balance mainly through behavior and morphology to adjust heat losses and gains and, in the case of endothermic animals, metabolic heat generation and insulation to lower heat loss

Explain how ectothermy and endothermy differ and how these strategies influence geographic distributions

Ectothermy: The regulation of body temperature through energy exchange with the external environment

Endothermy: The regulation of body temperature through internal heat generation

What are the three major components of water potential that influence water movement in organisms?

Solute concentration, pressure, and tension

How can organisms control water gain and water loss, and what trade-offs might result from these mechanisms?

By adjusting their resistance to water movement

Explain the challenges faced by organisms living in hyperosmotic and hypoosmotic environments

Hypoosmotic: Aquatic animals have to expend energy to excrete salts against an osmotic gradient

Hyperosmotic: Organisms must take up solutes from the environment to compensate for solute losses to the surrounding water

Which statement correctly distinguishes autotrophs from heterotrophs?

Autotrophs obtain energy from sunlight or inorganic compounds, while heterotrophs consume organic compounds

Chemosynthesis is a process in which:

Bacteria and archaea use energy from inorganic compounds to synthesize sugars

The light-driven reactions of photosynthesis produce:

ATP and NADPH

The Calvin cycle is responsible for:

Fixing carbon dioxide into carbohydrates

Which of the following is an example of acclimatization in a photosynthetic organism?

Short-term changes in leaf physiology in response to reduced light availability

What is a major trade-off associated with closing stomates?

Reduced CO₂ uptake for photosynthesis

High temperatures can reduce photosynthetic efficiency in C₃ plants because they increase:

Photorespiration

How does the C₄ photosynthetic pathway improve photosynthetic efficiency?

It concentrates CO₂ around the Calvin cycle, reducing photorespiration

CAM plants reduce water loss by:

Opening stomates at night and closing them during the day

Which digestive system feature improves energy and nutrient assimilation in heterotrophs? 

Specialized chambers and separate regions for digestion and absorption