This is urgent i need asap
this is worth 70 points
check my answer plz

1. which of the following are biotic factors and which are abiotic factors?
rain and grass are biotic; wind and humidity are abiotic.
algae and fungi are biotic; temperature and rainfall are abiotic.
oxygen and sunlight are biotic; maple trees and spiders are abiotic.
fish and whales are biotic; plankton and bacteria are abiotic.
2. why is it useful for an ecologist to identify the keystone species in an ecosystem?
the keystone species is only important in early stages of succession, and so the ecologist can
safely ignore changes in its population at later stages.
the keystone species is the most susceptible to pollution, and so its numbers give an
indication of the levels of pollutants in an area.
the keystone species is critical to maintaining the stability of an ecosystem, and changes in its
population indicate changes in ecosystem health.
the keystone species is important for the cycling of matter and must be maintained or the
biogeochemical cycles will be affected.
3. competition over resources occurs between organisms
participating in an herbivorous relationship.
forming a symbiotic relationship.
attempting to occupy the same niche.
initiating primary succession after a disturbance.
4. the lowest trophic level in an ecosystem
has the lowest quantity of stored energy.
has the greatest biomass.
is made up of heterotrophs
contains detritovores.
5. what is true of the energy that is passed from one trophic level to the next in a food chain?
about 10% of the energy passed from one level to the next is released as heat.
about 10% of the stored energy of one level becomes stored energy at the next higher level.
the energy at each level increases by about 10% with each move up in trophic level.
the total energy at all trophic levels is constant, but only about 10% is available for use by
organisms for life functions.
6. autotroph is to producer as heterotroph is
herbivore.
consumer.
decomposer.
carnivore.
7. which of the following is true of population cycles?
population cycles signal an imbalance in an ecosystem.
keystone species are necessary to establish population cycles.
a new species introduced to an ecosystem tends to stabilize population cycles in the
ecosystem.
population cycling maintain a healthy ecosystem.
8. an example of a pioneer species is
a sparrow.
a lichen.
an earthworm.
a spider.
9. why are human disturbances often of more concern than natural disturbances?
human disturbances last much longer than natural disturbances so that a damaged ecosystem
may have little or no chance of recovery.
human disturbances are stronger than natural disturbances and so the recovery needed is
much greater.
human disturbances often cover much wider areas than natural disturbances, which means
that more ecosystems are affected.
human disturbances affect all types of ecosystems, whereas natural disturbances are limited
to certain types of ecosystems.
10. suppose a particular community is concerned about a fox population that kills and eats chickens on the
local farms. what is the best course of action by this community?
kill the foxes.
trap and transport the foxes out of the region.
introduce rabbits as an alternative source of food for the foxes.
build enclosures for the chickens that the foxes cannot access.
and i need 100% to get a 45% to a 67%

1. The right answer is B

In ecology, the biotic factors represent all the interactions of the living on the living in an ecosystem. Opposable to abiotic factors, they constitute a part of the ecological factors of this ecosystem. These are food resources, trophic predation, cooperation, competition, parasitism, etc.

2. The right answer is C.

A keystone species is a species that has a disproportionate effect on its environment in terms of numbers or biomass.

Some species affect many other organisms in an ecosystem.

When a keystone species disappears, an ecosystem can be significantly degraded and possibly relatively fast, making it a species of heritage interest. It is not necessarily a large species, or a species with significant numbers or productivity, but a species that structures its ecosystem or ensures its ecological balance.

3. The right answer is C

The competition exists when:

* Individuals of the same species or different species, search for and exploit the same resource present in limited quantities

* The resources are not limited but the competing organisms are harming (a shelter, a nesting site ...)

4. The right answer is B.

Biomass is the total mass of living matter present at a given trophic level in an ecosystem. It can also relate to a given population in a community. Biological productivity is the increase, the accumulation of biomass according to a given time. A productive ecosystem is not necessarily rich in biomass. Note that the higher the trophic levels, the lower the number of individuals and the biomass. There is, for example, a lot more phytoplankton than big predators like the shark in the oceans. The presence of species at the top of the food web is generally a sign of good health of the ecosystem: for simplicity, the ecosystem is quite productive for ensure the survival of the most resource-intensive species.

5. The right answer is B.

(The rest is used for metabolic processes or lost as heat. )

In an ecosystem, a light energy flow ensures primary production in chlorophyll plants. These are the food source available to herbivorous consumers (themselves a nutritional resource for carnivores). There is therefore a circulation of organic matter which, starting from the green plants, crosses the consecutive links of the ecosystem. This organic material is potential chemical energy that is transferred from producers to consumers.

Because of the nutritional loss that occurs at each stage of consumption, the energy flow gradually decreases, and this is why we often represent the network of ecosystem transfers in the form of a pyramid, whose base corresponds to the producers and the eventual super-predator peak that is fed by one or more levels of consumers interposed between primary producers and him. This is to say the precarious situation of superpredation.

6. The right answer is B. consumer.

The term "heterotroph" refers to an organism that is unable to synthesize its own components and thus uses sources of exogenous organic matter. This mode of nutrition is characteristic of all living beings that are neither chlorophyllous plants, nor cyanobacteria, nor certain bacterial species capable of photosynthesis or chemosynthesis, these being autotrophic. In other words, animals, fungi, some plants, protozoa and most prokaryotes are heterotrophic.

7. The right answer is B.

A population with a population is a phenomenon where populations fluctuate (increase and decrease) over a predictable period of time.

Are keystone species. A number of factors influence demographic changes, such as food availability, predators, disease, and climate.

8. The right answer is B. Lichen.

Pioneer species is a forms of life that colonize or recolonize an ecological area.

Lichens are composites resulting from a symbiosis between at least one heterotrophic fungus called mycobiont, representing 90% of all, and microscopic cells with chlorophyll (green algae or cyanobacteria autotrophic for carbon) called "photobionts".

9. The right answer is A.

An industrial disaster is linked to an accident in one of the phases of industrial production, in the mining or during the transportation of this production, in particular the transport of oil, which caused many oil spills. The damage is persistent (nuclear radiation takes several years to disappear, there are still residues of black tides in the oceans that go asphixier aquatic fauna and flora, and the pollution has caused a permanent global warming ...).

10. The right answer is D.

The fox is a predator for chickens, it is also the most common in our campaigns. He has always been around poultry houses, hoping for easy processes. Because face to him, the chicks is hardly more likely to escape. It is not uncommon to find all the fowl devoured by the fox, even in the middle of the day.

yes its like the dead sea which is full of salt which makes you stay afloat

so yes an egg will float in salt

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