Evolution + Ecology - Unit 10 Honors Biology

abiotic factor

factor in an environment that is non-living, but affects populations. (ex: climate, precipitation, soil nutrient content)

biotic factor

a factor in an environment that is living and affects populations of other living things (ex: competition, parasitism, predator-prey relationships)

population

a group of organisms of the same species living in the same place

community

many populations of different species living in the same area

ecosystem

a biological community of interacting populations/communities and the abiotic factors of the environment.

biome

a large geographic area characterized by specific climate and precipitation

biosphere

all the parts of Earth where life is found

lithosphere

all the land on earth; the upper crust

hydrosphere

all the water on earth; 97% is salt water, 3% is fresh. Most of the fresh water is locked up in glaciers.

atmosphere

layers of gases over the land and water. made up primarily of nitrogen gas and about 20% oxygen

trophic level

a step in a food chain or energy pyramid. it represents energy available to other organisms within that community who might eat those organisms.

How much of the energy from one trophic level reaches the next level?

Only 10% of an organism’s energy is available to other organisms.

What happens to the energy that is “lost” between trophic levels?

It is used by organisms to sustain their own life functions.

Why are energy pyramids wide at the bottom and narrower at the top?

As a result of the 10% rule, it takes a large number of lower order producers or consumers to support the energy needs of a smaller number of higher order consumers at the top of the food chain.

What is the difference between a food chain and a food web?

A food chain is a series of direct eating relationships between organisms. It shows the one way flow of energy between those organisms in that chain. A food web shows all eating relationships for a particular organism AND gives a picture of how energy flows throughout an ecosystem. It is a more realistic representation of energy transfers.

Which way does the arrow point on a food chain/web?

to the organism who will get the energy by eating the other organism

producer

any organism that can make it’s own food through chemosynthesis or photosynthesis.

consumer

any organism that has to acquire it’s energy by eating or decomposing another living organism.

herbivore

any organism that eats only plant matter

omnivore

any organism that eats both plant and animal matter

carnivore

any organism that eats only animal matter

deomposer

any organism that gets energy by breaking down the remains of other organisms

Why are decomposers and detritivores important to the environment?

They are nature’s recyclers. By breaking down dead organic matter and waste products, they return nutrients to the earth and keep it from getting overrun with the remains of other living things.

How does the movement of matter through an ecosystem compare to the movement of energy?

Energy flow is unidirectional, or a one way flow of energy from the organism eaten to the one who ate them. Matter is a cycle. Matter can change it’s form and cycle between living things, the land, water, atmosphere, and back again.

How does the cycling of water different from the cycling of carbon, nitrogen, and phosphorus?

It primarily involves physical changes of states rather than chemical transformations

How does the water cycle work?

Water moves within the biosphere as a liquid, evaporates to become a gas, condenses into water vapor in the form of clouds and then comes back down through precipitation as a liquid

How are carbon and nitrogen similar?

Both have gaseous compounds as part of our atmosphere and can be found in various compounds in our soils, living organisms, and in water (carbon).

What is the only nutrient without a gaseous form?

phosphorus

nitrogen fixation

the process by which nitrogen-fixing bacteria found in nodules on plant roots take atmospheric nitrogen gas (N2) and convert it to usable forms of nitrogen for plants to use to build tissues, like nitrates or nitrites.

What happens to nitrates and nitrites after carbon fixation?

They are passed along to other organisms as they consume producers.

denitrification

the process by which another class of bacteria break down dead and other organic matter converting nitrogen compounds back into nitrogen gas, which is returned to the atmosphere. This completes the nitrogen cycle.

What is the difference between a niche and a habitat?

A habitat is where an organism lives, while a niche is an organism’s role in their habitat

What is an alternate definition for a niche?

Any description of an organism’s activities within their habitat and how it relates to other organisms

fundamental niche

the entire set of conditions under which an animal (population, species) can survive and reproduce itself

realized niche

the set of conditions actually used by given animal (population, species) after interactions with other species (predation and especially competition) have been taken into account

In what ways do competition and other environmental factors lead to niche partitioning?

Niche partitioning is the process by which natural selection drives competing species to use different resources or different parts of their niches.

What happens when the differentiation of realized ecological niches occurs?

Coexistence and competition reduction occurs

How many species can occupy the same niche in the same habitat?

None

What is the competitive exclusion principle?

No two species can occupy the same niche in the same habitat at the same time or one species will be “excluded” (a.k.a suffer or die)

What happens when species need very similar resources?

Each species will utilize a greater extent of their fundamental niche

interspecific competition (+ example)

competition between two different species needing similar resources (ex: Lions and Cheetahs)

intraspecific competition (+ example)

competition with members of your own species (ex: Two oak tree saplings competing for access to sunlight as they grow on the forest floor)

mutualism (+ example)

both members benefit from association (ex: Goby fish (a home) and the shrimp (protection))

commensalism (+ example)

one organism benefits and the other is neither harmed nor helped (ex: Rag worm (food morsels and safety within the shell) and hermit crab (nothing))

parasitism (+ example)

one organism benefits and the other is harmed or killed (ex: ticks (food) and a dog (bites that are itchy and irritating))

How does parasitism differ from predation?

In predator-prey relationships, the predator intends to kill and consume the prey organism. In parasitism, it is possible that the host species could die, but often the host is simply weakened or made ill.

What is succession?

the process where a community matures

pioneer species (+ example)

the first species into a new area that previously has not been inhabited. Often they are responsible for helping to make soil so that vegetation can come into the area (ex: lichen)

climax community

the mature, stable and established community that exists after periods of succession

What does a climax community contain?

They have mature vegetation and the types do not fluctuate. Other living organisms live in ecological balance in that community

When does primary succession occur? (+ example)

when new land is exposed and an opportunity to develop that land exists (might occur after a glacier recedes and exposes rock that has no other life forms or soil present on it_

When does secondary succession occur? (+ example)

when an existing habitat undergoes a dramatic change (ex: tornado or hurricane, or humans abandoning farmland)

Which is faster, primary or secondary succession, and why?

Secondary succession, because soil is still present

In what ways is secondary succession an important process in maintaining homeostasis within an ecosystem?

allows ecosystem to move towards climax communities again