Set 7 - Part 4 - Ecosystem - Khan Academy

celine's version from 2018-02-22 19:24

Section 1

Question Answer
A ____________ consists of all the populations of all the species that live together in a particular
The concepts of ecosystem and community are closely related—the difference is that an ecosystem includes the ____________, while a community does not. physical environment
A community is the ____________, or living, component of an ecosystem.biotic
In addition to the biotic component, the ecosystem also includes an ____________ component—the physical environment.abiotic
An ____________ consists of a community of organisms together with their physical environment.ecosystem
Ecosystems can be of different sizes and can be ____________, ____________, or ____________. marine, aquatic, or terrestrial
Ocean ecosystems are most common on Earth, as oceans and the living organisms they contain cover ____________ of the Earth's surface. 75%
Freshwater ecosystems are the rarest, covering only ____________ of the Earth's surface.1.8%
Broad categories of terrestrial ecosystems are called ____________.biomes
Terrestrial ecosystems are grouped into broad categories called biomes, based largely on ____________.climate
Examples of terrestrial biomestropical rain forests, savannas, deserts, coniferous forests, deciduous forests, and tundra

Section 2

Question Answer
In ecosystems, both matter and energy are ____________. Energy flows through the system—usually from light to heat—while matter is ____________.conserved, recycled
Both energy and matter are ____________, neither created nor destroyed, but take different routes through ecosystems.conserved
Matter is ____________; the same atoms are reused over and over. Energy flows through the ecosystem, usually entering as __________ and exiting as heat.recycled, light
Energy, unlike matter, cannot be___________ in ecosystems. Instead, energy flow through an ecosystem is a one-way street—generally, from light to heat.cannot be
____________ is the steady state of an ecosystem, in which its composition and identity remain generally constant despite fluctuations in physical conditions and the makeup of the biotic community.Equilibrium
Ecosystems may be knocked out of equilibrium by ____________, disruptive events that affect their composition.disturbances
Examples of disturbances that knock out ecosystemslightning in a prairie or forest ecosystem, acid rainfall, deforestation, algal blooms, and the introduction of invasive species
Two parameters that ecologists use to describe how an ecosystem responds to disturbance are resistance and resilience
The ability of an ecosystem to remain at equilibrium in spite of disturbances is calledresistance
How readily an ecosystem returns to equilibrium after being disturbed is calledresilience
Ecosystems with higher biodiversity tend to be more stable with greater ____________ and ____________ in the face of disturbances, disruptive events.resistance and resilience

Section 3

Question Answer
Producers, or ____________, make their own organic molecules.autotrophs
Autotrophs are also known as ____________self-feeders
Two basic types of autotrophsphotoautotrophs & chemoautotrophs
Autotrophs which use energy from sunlight to make organic compounds—sugars—out of carbon dioxide in photosynthesis. photoautotrophs
Examples of photoautotrophsPlants, algae and cyanobacteria
Autotrophs which use energy from chemicals to build organic compounds out of carbon dioxide or similar molecules.chemoautotrophs
Chemoautotrophs use energy from chemicals to build organic compounds out of carbon dioxide or similar molecules. This is called ____________.chemosynthesis
Consumers, or ____________, get organic molecules by eating other organisms.heterotrophs
Heterotrophs, also known as ____________, can't capture light or chemical energy to make their own food out of carbon dioxide. other-feeders
____________ get organic molecules by eating other organisms or their byproducts.heterotrophs
Examples of heterotrophsHumans, animals, fungi, and many bacteria
A linear sequence of organisms through which nutrients and energy pass as one organism eats chain
In a food chain, each organism occupies a different ____________, defined by how many energy transfers separate it from the basic input of the chain.trophic level
Parts of a typical food chainprimary producers, primary consumers, secondary consumers, tertiary consumers, quaternary consumers,
Each of the categories/parts of a food chain is called a ____________trophic level
At the base of the food chain lie the ____________. They are autotrophs and are most often photosynthetic organisms such as plants, algae, or cyanobacteria.primary producers
The organisms that eat the primary producers are called ____________. Primary consumers are usually herbivores, plant-eaters, though they may be algae eaters or bacteria eaters.primary consumers
The organisms that eat the primary consumers are called ____________. Secondary consumers are generally meat-eaters—carnivores.secondary consumers
The organisms that eat the secondary consumers are called ____________. These are carnivore-eating carnivores, like eagles or big fish.tertiary consumers
Some food chains have additional levels known as ____________, carnivores that eat tertiary consumers.quaternary consumers
Organisms at the very top of a food chain are called ____________apex consumers
Humans are ____________that can eat both plants and animals.omnivores
Organisms that break down dead organic material and wastes.decomposers
____________ play a critical role in keeping ecosystems healthy. When they break down dead material and wastes, they release nutrients that can be recycled and used as building blocks by primary producers.Decomposers
____________ are the key decomposers in many ecosystems; they use the chemical energy in dead matter and wastes to fuel their metabolic processes.Fungi and bacteria
Decomposers that are detritus eaters or debris eatersdetritivores
Examples of detritivoresearthworms, crabs, slugs, or vultures

Section 4

Question Answer
A graph that shows all the trophic—eating-related—interactions between various species in an web
Food webs don't usually show ____________decomposers
Only about 10% of the energy that's stored as biomass in one trophic level—per unit time—ends up stored as biomass in the next trophic level—per the same unit time. This is called10% rule of energy transfer
If the primary producers of an ecosystem store 20,000 kcal/m2//year of energy as biomass. This is the amount of energy per year that's made available to the primary consumers, which eat the primary producers. The 10% rule would predict that the primary consumers store only ____________ of energy in their own bodies, making energy available to their predators—secondary consumers—at a lower rate.2,000 kcal/m​2/year
Why does so much energy (90%) exit the food web between one trophic level and the next?1. In each trophic level, a significant amount of energy is dissipated as heat as organisms carry out cellular respiration and go about their daily lives. 2. Some of the organic molecules an organism eats cannot be digested and leave the body as feces, poop, rather than being used. 3. Not all of the individual organisms in a trophic will level get eaten by organisms in the next level up. Some instead die without being eaten.
Energy transfer between trophic levels is inefficient—with a typical efficiency around ____________. This inefficiency limits the length of food chains.10%
Difference between food chains and food websFood chains are linear sequences of organisms that show how nutrients and energy pass as one organism eats another. Food webs are more complex graphs consisting of many interconnected food chains.
Food webs are generally more realistic representation of consumption relationships in ecosystems.

Section 5

Question Answer
____________ is simply the amount of matter that's stored in the bodies of a group of organisms.Biomass
The rate at which energy is added to the bodies of organisms in the form of biomass.productivity
2 basic types of productivityGross primary productivity, or GPP & Net primary productivity, or NPP
The rate at which solar energy is captured in sugar molecules during photosynthesis (energy captured per unit area per unit time). Producers such as plants use some of this energy for metabolism/cellular respiration and some for growth (building tissues).Gross primary productivity, or GPP
Gross primary productivity minus the rate of energy loss to metabolism and maintenance. In other words, it's the rate at which energy is stored as biomass by plants or other primary producers and made available to the consumers in the ecosystem.Net primary productivity, or NPP
____________ is the overall rate of energy capture. Gross productivity
____________ is lower, adjusted for energy used by organisms in respiration/metabolism.Net productivity
Energy transfer between trophic levels is inefficient. Only ___________ of the net productivity of one level ends up as net productivity at the next level.10%
Why is energy transfer inefficient?Not all the organisms at a lower trophic level get eaten by those at a higher trophic level. Some molecules in the bodies of organisms that do get eaten are not digestible by predators and are lost in the predators' feces (poop). The dead organisms and feces become dinner for decomposers. Finally, of the energy-carrying molecules that do get absorbed by predators, some are used in cellular respiration, instead of being stored as biomass.
Visual representations of energy flow, biomass accumulation, and number of individuals at different trophic levels.Ecological pyramids
3 types of ecological pyramidsEnergy pyramids, Biomass pyramids, Numbers pyramids
Pyramids represent energy flow through trophic levels and shows rates of energy flow through trophic levels, not absolute amounts of energy stored.Energy pyramids
Pyramids represent the amount of energy that's stored in living tissue at the different trophic levels.Biomass pyramids
Pyramids show how many individual organisms there are in each trophic level. They can be upright, inverted, or kind of lumpy, depending on the ecosystem.Numbers pyramids
Energy pyramids are always ___________. Biomass pyramids are usually ___________ but rarely are ___________.upright, upright, inverted (Upright means narrower at each successive level - wide at the bottom and get narrower at each successive level)

Recent badges