ib biology 4.1 and 4.2

What term can be used to describe clams that eat decaying plant matter? A. Detritivores B. Tertiary consumers C. Saprotrophs D. Decomposers

A. Detritivores

How is energy passed from one trophic level to the next? I. Food II. Light III. Heat A. I only B. I and II only C. II and III only D. I, II and III

A. I only

What are the two components of an ecosystem? A. Community and abiotic environment B. Species and habitat C. Habitat and abiotic environment D. Species and community

A. community and abiotic environment ?? (needs to be a biotic factor w an abiotic factor)

The diagram shows a pyramid of energy for a wetland environment. What units would be appropriate for the values shown? A. kg yr B. kJ m yr C. J m D. mg dry mass m

B. kJ m yr

what is the initial energy source for almost all communities?

the sun

give examples of detritivores and saprotrophs

detritivores: - earthworms, woodlice saprotrophs: - fungi, bacteria

nutrients are cycled and ...

energy flows

Distinguish between the movement of energy and nutrients in an ecosystem. [2]

energy moves through/enters and leaves ecosystems / need a constant source of energy; nutrients cycled between biotic and abiotic environment/in cycles such as C/N;

what other way can nitrogen be fixed?

lightning !!

is the sun a trophic level?

no

energy flows and ...

nutrients are cycled

define autotrophy

organisms that synthesize organic molecules from inorganic molecules

why do we need phosphorous?

- Component of DNA - Component of RNA - Component of ATP

why do we need nitrogen?

- Component of DNA - Component of RNA - Component of proteins

what processes return carbon to the lithosphere?

- decomposition of dead organic material - marine deposits of carbonate

what is denitrifying bacteria?

- denitrifying bacteria convert NO2 back into atmospheric nitrogen (N2) - completing the cycle.

outline how energy flows through trophic levels

- energy enters from sunlight - autotrophs capture sunlight - energy transfer approximately 10% onto next trophic level - energy loss due to material not absorbed/egested/excreted - energy passes to decomposers in the form of dead organic matter - heat energy is lost through cell respiration

what is nitrogen fixing bacteria?

- fix atmospheric nitrogen - usable form for plants is NO2

list reasons for energy loss between trophic levels

- heat energy lost from respiration - organic molecules not consumed - not all parts of consumed material are absorbed by consumer - energy lost in feces & passes onto decomposers instead

what are the sinks of carbon?

- photosynthesis - some diffusion into aquatic ecosystems

list 3 requirements of a sustainable ecosystem

1. nutrient availability 2. detoxification of waste 3. energy availability

how much energy is lost between trophic levels? how much energy is passed on?

90% 10%

What are the main sources of carbon dioxide on earth? A. Cellular respiration of consumers, producers and combustion of fossil fuels B. Photosynthesis and cellular respiration of consumers C. Cellular respiration of producers and combustion of fossil fuels D. Photosynthesis and combustion of fossil fuels

A ??

Which of the following ecological units includes abiotic factors? A. A community B. An ecosystem C. A population D. A trophic level

B. An ecosystem

What name is given to an organism that is able to manufacture its own food from simple chemical materials? A. Heterotroph B. Saprotroph C. Autotroph D. Detritivore

C. Autotroph

What is the mode of nutrition of midge larva? A. Autotroph B. Detritivore C. Heterotroph D. Saprotroph

C. Heterotroph

Slime moulds (Acrasiomycota) are protoctists. They feed on decaying organic matter, bacteria and protozoa. Which of the terms describes their nutrition? I. Detritivore II. Autotroph III. Heterotroph A. I only B. I and II only C. I and III only D. I, II and III

C. I and III only

What units are used when constructing pyramids of energy? A. J B. J m-2 C. J m-2 year-1 D. J kg-1 m-2 year-1

C. J m-2 year-1

What is the initial energy source for all terrestrial communities? A. Water B. Photosynthesis C. Light D. Glucose

C. Light

What is a population? A. Organisms of the same genus living in an ecosystem B. Organisms living together and interacting in the same habitat C. Organisms of a species living together in the same area D. Organisms that can breed together

C. Organisms of a species living together in the same area

At each trophic level energy is lost. How is this energy regained by the ecosystem? A. Heat B. Nutrients C. Photosynthesis D. Recycling

C. Photosynthesis

What is an ecosystem? A. An environment in which an organism normally lives B. A group of organisms of the same species inhabiting an area C. A group of populations living and interacting with each other in an area D. A community and its abiotic environment

D. A community and its abiotic environment

What is a community? A. A group of organisms living and interacting in the same trophic level B. A group of populations living and interacting in a food chain C. A group of organisms of the same species living and interacting in an ecosystem D. A group of populations living and interacting in an area

D. A group of populations living and interacting in an area

In a pond, two species of fish feed on insects and worms. The insects feed on the green plants that live in the water. What constitutes a population in this ecosystem? A. All the living organisms B. All the animals C. All the fish D. All the fish of one species

D. All the fish of one species

define ecosystem

a community and its abiotic environment

give an example of photoautotrophy and chemoautotrophy

photoautotrophy: - green plants, phytoplankton, & algae chemoautotrophy: - deep-sea bacteria

outline how nutrients are cycled through trophic levels

- nutrients cycle within ecosystems - nutrients from weathering rocks enter ecosystem - nutrients recycled by decomposers - nutrients move through food chains by digestion of organisms - nutrients absorbed by producers - nutrients lost by leaching/sedimentation

what are the sources of carbon?

- respiration - decomposition - burning of fossil fuels

why is it difficult to classify an organism to one trophic level?

- some organisms are omnivores - some organisms alter their diet over their life cycle - seasonal changes

The scarlet cup fungus (Sarcoscypha coccinea) obtains its nutrition from decaying wood by releasing digestive enzymes into the wood and absorbing the digested products. Which of the following terms describe(s) the fungus? I. Autotroph II. Heterotroph III. Saprotroph A. III only B. II and III only C. I and III only D. I, II and III

B. II and III only

In ecosystems the amount of energy that passes from one trophic level to the next is called the conversion efficiency. What is the average conversion efficiency from primary to secondary consumers in most ecosystems? A. 1 % B. 10 % C. 50 % D. 90 %

B. 10 %

The energy passing from the detritivores to the predatory invertebrates in this food web is 14 000 kJ m year. Approximately how much energy (in kJ m year) passes from the predatory invertebrates to the carnivores? A. 140 B. 1400 C. 14 000 D. 140 000

B. 1400

Which term best defines a group of populations living and interacting with each other in an area? A. Ecology B. Community C. Species D. Ecosystem

B. Community

The following statements refer to a pyramid of energy. I. Some material is not assimilated by each trophic level. II. Energy transformations are never 100 % efficient. III. Heat is lost during photosynthesis. Which of the statements give the reason why a pyramid of energy is narrower at the top than at the bottom? A. I only B. I and II only C. II and III only D. I, II and III

B. I and II only

What best describes the mode of nutrition of a heterotroph? A. It ingests only non-living organic matter. B. It obtains organic molecules from other organisms. C. It synthesizes its organic molecules from inorganic substances. D. It produces its organic molecules from chemical reactions using light.

B. It obtains organic molecules from other organisms.

What is recycled in an ecosystem? A. Nitrogen, carbon and energy are all recycled. B. Nitrogen and carbon are recycled but not energy. C. Nitrogen is recycled but not carbon or energy. D. Nitrogen, carbon and energy are not recycled.

B. Nitrogen and carbon are recycled but not energy.

Which statement describes the term species? A. Members of the same ecological community B. Organisms that reproduce together to produce fertile offspring C. Organisms of the same type in a population D. The first word in the binomial name of an organism

B. Organisms that reproduce together to produce fertile offspring

Which of the following is the best definition of a population? A. A group of individuals that can interbreed and produce fertile offspring B. The number of individuals of the same species in a given area C. A group of species living and interacting with each other in a given area D. The total number of individuals in a given area

B. The number of individuals of the same species in a given area

What is the ecological role of saprotrophic bacteria? A. To recycle energy in dead organic matter B. To digest dead organic matter and release nutrients from it C. To ingest dead organic matter and prevent it from accumulating D. To produce dead organic matter by killing organisms

B. To digest dead organic matter and release nutrients from it

Which pair of statements is correct? A. autotroph-obtains organic molecules from other organisms heterotroph-synthesizes organic molecules from inorganic molecules B. autotroph-synthesizes organic molecules from inorganic molecules heterotroph-obtains organic molecules from other organisms C. autotroph-synthesizes inorganic molecules from organic molecules heterotroph-synthesizes organic molecules from inorganic molecules D. autotroph-obtains inorganic molecules from other organisms heterotroph-obtains inorganic molecules from other organisms

B. autotroph-synthesizes organic molecules from inorganic molecules heterotroph-obtains organic molecules from other organisms

Why do food chains in an ecosystem rarely contain more than five organisms? A. Nutrients are recycled by the decomposers back to the producers. B. Nutrients are lost from the ecosystem when organisms die. C. The conversion of food into growth by an organism is not very efficient. D. Energy is recycled by the decomposers back to the producers.

C. The conversion of food into growth by an organism is not very efficient.

Which represents a correct food chain from this web? A. stickleback → midge larva → unicellular algae B. ciliates → Daphnia → stickleback → dragonfly nymph C. diatom → midge larva → caddisfly larva → stickleback D. filamentous algae → mayfly nymph → leech → stickleback

C. diatom → midge larva → caddisfly larva → stickleback

Which group of organisms in the carbon cycle converts carbon into a form that is available to primary consumers? A. Decomposers B. Saprotrophs C. Detritus feeders D. Producers

D. Producers

Which organisms externally digest dead organic matter and then absorb the nutrients? A. Autotrophs B. Detritivores C. Heterotrophs D. Saprotrophs

D. Saprotrophs

distinguish between detritivore & saprotroph

detritivore: - ingests non-living organic matter then digests - ingest then digest saprotroph: - lives on non-living organic matter & secretes digestive enzymes - digests then absorb

Describe what is meant by a food chain. [1]

food chain shows feeding/trophic relationships;b. showing which organism/animal eats which organism;c. showing the flow of energy from producer/autotroph to top consumer/top carnivore / through trophic levels;