Unit 1 Chapter 2: Interdependence among Organisms

Practice flashcards based on Unit 1, Chapter 2 (Interdependence among Organisms), reviewing ecological interactions, carrying capacity, resource types, and population growth models.

What two components make up an ecosystem?

An ecosystem is made of all the living (biotic) and nonliving (abiotic) components in an environment.

In scientific investigations, what is the distinction between an observation and an inference?

An observation is direct evidence recorded only from what is seen or detected without assigning meaning (e.g., 'the ant moved quickly behind a plant when the spider approached'), whereas an inference assigns an interpretation or meaning to that evidence (e.g., 'the ant hides to avoid the spider').

What laboratory safety precaution must be taken when focusing a compound light microscope on high power?

You must use only the fine adjustment knob; using the coarse adjustment knob on high power can crack the microscope slide and damage the microscope.

What laboratory procedure is illustrated in this diagram?

Preparing a wet mount slide by placing $2\text{--}3$ drops of a water sample onto a slide with a depression and carefully covering it with a coverslip.

What is the biological definition of symbiosis?

Symbiosis is a close and prolonged interaction between organisms of different species, including mutualism, parasitism, and commensalism.

How do ecologists classify mutualism in terms of its effect on species, and what is an example?

Mutualism is classified as a $+ / +$ interaction where both organisms benefit, such as the interaction between flowering plant species and the insects that pollinate them.

How is a predator-prey interaction defined and classified by its effect on the species involved?

It is classified as a $+ / -$ interaction where one organism (the predator) eats another (the prey), benefiting the predator and harming (often killing) the prey.

How does parasitism operate within an ecosystem, and what is its classification code?

Parasitism is classified as a $+ / -$ interaction where one organism (the parasite) lives on or in another organism (the host) as a habitat and food source, which harms the host and may or may not kill it over time.

Why is competition classified as a $- / -$ interaction?

In competition, both organisms are harmed through the expenditure of effort and resources necessary to obtain a shared, limited resource such as food, space, sunlight, nutrients, or water.

What is commensalism, and what example is observed between African buffalo and Cattle Egrets?

Commensalism is a $+ / 0$ interaction where one organism benefits while the other is unaffected. For example, the Cattle Egret benefits by foraging insects stirred up after an African buffalo grazes or by riding on its back, while the buffalo remains unaffected.

What is herbivory?

Herbivory is the ecological interaction between plants and the animals that eat them.

How do gray wolf pack hunting dynamics differ when hunting small prey versus large hoofed mammals?

A wolf hunting alone can only capture small prey like beavers and rabbits, whereas capturing large hoofed mammals (such as deer, elk, moose, and caribou) requires coordination and communication among pack members led by the alpha male and female.

In environmental science, what are 'the Commons'?

The Commons are shared spaces and publicly shared resources that communities collectively manage and enjoy, such as public pastures, walkways, and community gardens.

What is ecological carrying capacity?

Carrying capacity is the maximum number of individuals of a certain species that a habitat can support without destroying its ability to renew itself.

What is the difference between a renewable resource and a nonrenewable resource?

Renewable resources (such as fish, trees, and wildlife) can be naturally replenished if not used faster than they regenerate, whereas nonrenewable resources (such as fossil fuels and hard coal) exist in fixed amounts and cannot be replenished once exhausted.

What distance does the average meal in the United States travel from farm to plate?

$$1500\text{ food miles}$$

How does industrialized agriculture differ fundamentally from local agriculture?

Industrialized agriculture produces large quantities of monocrops far from consumers, relies heavily on chemical inputs and machinery, and prioritizes corporate profit; local agriculture operates on a smaller scale close to home, grows a variety of crops, and typically values organic practices, living wages, and manual labor.

Where does San Francisco's municipal tap water originate, and how far does it travel?

It travels $164\text{ miles}$ through gravity-fed pipes from the Tuolumne River's Hetch Hetchy Valley in Yosemite National Park, stored behind the O'Shaughnessy Dam.

How did the indigenous Ohlone people historically maintain water sustainability in the San Francisco Bay Area?

They lived within the local carrying capacity for over $10,000\text{ years}$ by using local freshwater sources (such as Mountain Lake, El Polin Spring, and Los Lobos Creek) and migrating seasonally when supplies diminished rather than pumping water from afar.

What was the giant palm tree native to Rapa Nui, and what happened to it?

The giant palm was the Jubaea palm, an extinct tree estimated to reach $20\text{ meters}$ ($65\text{ feet}$) in height that covered the island when Polynesian voyagers arrived but was completely lost to deforestation and seed predation.

What are moai, and what were they carved from on Rapa Nui?

Moai are large human monolith statues ranging from $2\text{--}10\text{ meters}$ in height, carved by the Rapanui from compacted volcanic tuff (ash) using stone tools.

What population trajectory and decline mechanism does Hypothesis 1 propose for Rapa Nui?

Hypothesis 1 proposes that settlers arrived between $800$ and $900\text{ CE}$, deforestation and population peaked simultaneously, and environmental collapse led to starvation, internal warfare with weapons, and population decline down to $2,000\text{--}3,000$ before European arrival in $1722$.

According to Hypothesis 2, what factors caused the population collapse of the Rapanui?

Hypothesis 2 posits that settlers arrived around $1200\text{ CE}$ and maintained a stable, sustainable population of about $3,000$ using agricultural tools called mata'a until European colonizers arrived in $1722$, bringing lethal diseases and slave raids that caused a crash to just $111$ survivors by $1877$.

What role did introduced Polynesian rats play in the deforestation of Rapa Nui according to Hypothesis 2?

A large population of introduced rats fed on the seeds of the Jubaea palm, preventing new forest seedlings from germinating and growing.

What is a limiting factor in an ecosystem?

A limiting factor is any biotic or abiotic condition that slows or restricts the growth of a population.

What five abiotic limiting factors are highlighted as determining carrying capacity in ecosystems?

Climate, temperature, water, light, and space.

What is population density?

Population density is the number of individuals of a species in relation to the amount of space that the population occupies.

What are the characteristics of exponential population growth, and what does its curve look like?

Exponential growth occurs under ideal conditions with unlimited resources, where the population growth rate accelerates as population size increases, forming a distinctive J-shaped curve.

What is logistic population growth, and what shape does its curve form?

Logistic growth occurs when resource limitations and other limiting factors cause the population growth rate to slow and level off at the habitat's carrying capacity, forming a flattened S-shaped curve.

How rapidly has the global human population grown since 1820?

The human population was $1\text{ billion}$ in $1820$, took $110\text{ years}$ to double to $2\text{ billion}$ in $1930$, reached $3\text{ billion}$ in the $1960\text{s}$, doubled to $6\text{ billion}$ in $1999$ (in under $40\text{ years}$), and is projected to reach $9\text{ billion}$ by $2040$.