Ecology Study Guide Bio

    Humans have persecuted predators such as coyotes (Canis latrans), causing severe reduction in the number of large carnivores throughout the world. The diagram represents part of a food web in Texas, USA.

What is a possible outcome for the lagomorph population in this ecosystem if coyote numbers were controlled by killing them to reduce losses of domestic livestock?

If we kill coyotes, the lagomorph population will increase. Fewer predators, more rabbits. Rodents and foxes will increase. Eggs might decrease because there’s more foxes.

Which statement applies to transfers in an ecosystem?

What is transferred? Energy and nutrients
The same amount isn’t transferred.
Only 10% of energy makes it to the next organism. The rest of the energy is being used for respiration, and lost as heat.
But energy isn’t limited because the sun comes up the next day and the energy is replenished.
But nutrients have to be recycled.

 What is a difference between detritivores and saprotrophs?

Both eat dead stuff. Detritivores ingests internally, saprotrophs secrete enzymes to digest externally.

 A self-sustaining system is set up in a sterile, sealed, transparent glass bottle with damp, sterilized soil and a small garden plant. If the system remains sterile, what could be the reason that the plant fails to grow and dies?

Not enough nutrients.

 What is a community?

All the living things in an ecosystem. 

A group of different species populations that live in the same area and interact with one another.

The table contains information about the diet of some animals.

Which pyramid of energy represents this information?

C

 The diagram shows part of a food chain. The left box represents producers and the right box primary consumers. Arrows show energy flows.

Which forms of energy are represented by X and Y?

Big boxes are producers, so X is light energy. Plants then take the light energy and give Y is chemical energy. 

(The arrows going down is the waste: energy that is not used by the consumers. Arrow going top is released heat)

What is exchanged between a sealed mesocosm and the surrounding external environment?

Energy (get light from sun and release heat)

In a woodland ecosystem, each tree provides food for numerous aphids, which feed on the sap of the tree. The aphids are eaten by carnivorous beetles, as shown in the food chain.

Oak Tree → Aphids → Beetles

Which pyramid of energy represents this relationship?

Beetles at the top, then aphids, then oak tree.

 Over time, the hull of a sunken ship may become colonized by a wide range of marine organisms. What term is used to describe all of the organisms living in and on a sunken ship?

Community

   The diagram shows the energy flow between five “sinks” in a terrestrial ecosystem.

In a typical terrestrial ecosystem, which trophic level would have the highest biomass?

The producers would have the highest biomass

(The one on the top of the food chain would have the biggest biomass. But think about whole population biomass, which would be producers)

Which organism would be classified as a saprotroph?

Fungus

The diagram shows the flow of energy through an ecosystem in kJ m–2 y–1.

What percentage of the energy passed from primary producers to primary consumers is lost to cellular respiration by tertiary consumers?

(Basically have to figure out what the arrows represent)

At primary producers, only 20,000 make it to the primary consumer. Take 80 (from the energy lost by cellular respiration by the tertiary consumer) and divide it by the percentage of energy passed from primary producers to primary consumers -> 80/20,000 = 4/1,000 = 0.004 = 0.4%

 Which level(s) of ecological complexity involve(s) biotic factors but not abiotic factors?

I. Community

II. Ecosystem

III. Population

Community and population

How can a chi-squared test be used in ecological research?

(To see if there’s a correlation between the environment and organisms?)

 Plankton are major producers in marine ecosystems. Only a small proportion of the energy harvested by plankton is passed to the primary consumers. Which process in phytoplankton results in the largest loss of energy that could otherwise be utilized by consumers?

Respiration (energy lost as heat)

   What is the ecological term for a group of different types of organisms that live together and interact with each other?

Community

 Hummingbirds eat flower nectar and small insects. To which nutritional group do they belong?

Primary and secondary consumers (eat flower = primary. Insect = secondary)

Which organism can best be described as a saprotroph?

Fungus

   The diagram shows the food web for an aquatic ecosystem in which letters R–Z represent individual species.

Which organism is a tertiary consumer?

R,S, T, are probably producers.

W is primary. Y is secondary. Z is possible tertiary.

W -> V -> U

W -> V -> X

So U, X, Z are all possible tertiary consumers

The Silver Springs feed into the Silver River in Florida. The diagram shows a pyramid of energy for the Silver Springs ecosystem. The units are kJ m^–2 y^–1.  What do level I and level III represent in the pyramid of energy?

I = Producers or trophic level 1

II = Secondary consumer or trophic level 3

  Which is not essential in a viable mesocosm?

Consumers (Because you need producer, water, sunlight, oxygen, but don’t have to have consumers)

Herbivore

The diagram shows interactions between food chains in an ecosystem in the African savannah. Which arrows indicate the flow of chemical energy?

Everything except I. II and III are chemical.

The Australian pitcher plant (Cephalotus follicularis) is a green plant that traps and feeds on flies and other live insects. What is this plant’s mode of nutrition?

(Feeds on flies = secondary consumer. But it's a plant so it’s a producer.)

Primary producer and primary consumer.

In 1789 Gilbert White, a naturalist, observed eight breeding pairs of swifts (Apus apus) in the English village of Selborne. On average, each pair of swifts produces two offspring per year. This would allow the population to rise to 1030 swifts over 200 years. A bird survey carried out in 1983 revealed only 12 breeding pairs in this village.

What could have prevented the numbers rising to 1030?

I.   The number of nesting sites remained the same.

II.  The food supply of the swifts remained constant.

III. Predatory birds in the area were exterminated.

The number of nesting sites remained the same and the food supply of the swifts remained constant. (I and II).

Limpets are molluscs with conical shells that cling tightly to rocks on seashores. In a study of two species of limpets found on rocks along the Oregon coast, 30 randomly placed quadrats were used to determine how often the two species occurred together. The table shows the data that were collected.

Which statistical method will determine whether these two species occur together by chance or by some kind of interaction?

Chi-square test

Animals in the highest trophic level of a food chain will often be the largest in body size but will be few in numbers. What accounts for the small numbers?

There is the least amount of energy at the top, so it will support the least amount of animals.

The image shows a food web. Which organism in the food web is assigned to its method of nutrition?

(Have to pick the ones that match in the food web, producers and consumer)

The Venus flytrap (Dionaea muscipula) is a photosynthetic plant. It obtains nitrogen but not energy by digesting captured insects.  Which term describes this plant?

Primary producer and primary consumer

The three-toed sloth, Bradypus variegatus, lives in tree tops where it feeds on leaves. It also feeds on algae and fungi which live in its fur.  In which trophic group should the three-toed sloth be classified?

Trophic level 2 (trophic level 1 is producer. Since it eat leaves, its #2)

 Which processes occur in an ecosystem?

I. Biomass increases in each successive trophic level.

II. Inorganic nutrients are recycled.

III. Chemical energy is stored in carbon compounds.

II and III.

 In an area of forest measuring 100 m by 100 m, samples were taken to estimate the number of silver maple (Acer saccharinum) trees in the forest. The number of trees counted in each of five areas of 400 m² was recorded. Approximately how many silver maple trees are in the 10000m² area of forest?

25 total trees. In 400m2 of 5 random quadrats. 

Average of 5 trees per quadrant. 5 average trees x 25 quadrats = 125 trees. 

(If you change the area of forest to 90000 for example. 125/10000 = x/90000 To solve for x to find the number of trees).

 Carbon sinks are any reservoirs that absorb and store carbon dioxide from the atmosphere. Which process increases the size of the carbon sink in oceans?

Photosynthesis (more photosynthesis, more carbon dioxide produced).

 By the end of the 19th century in England, the dark form of the moth Biston betularia formed up to 98 % of the total population in industrial areas. From 1970, the percentage of dark forms decreased significantly. What is an explanation for the decrease?

Because when there was a lot of industry, the trees were dark, matched the moth. After 1970, they started to become more environmentally friendly, so the trees turned into their original light colors. So the moth had to camouflage to that new lighter color (normal color)

The diagram shows part of the carbon cycle involving methane.  Which conditions favour methane production in W, X and Y?

⁃Anaerobic environments

⁃Decomposed organic matter

⁃Waterlogged environments

⁃Specific temperatures (mildly warm)

⁃Neutral and slightly alkaline pH

 The diagram shows a simplified carbon cycle.

Which processes are taking place at X and Y?

X = Respiration

Y = Combustion

Which activity directly contributes the most to recent increases in atmospheric CO₂ concentrations?

Burning of fossil fuels (or combustion)

  What is a potential consequence of the rise in global temperatures?

Ice caps melting, sea level rise, hunting ground for polar bears disappearing, more mosquitoes.

 Which process contributes to the formation of limestone?

Limestone is formed from fossilization of hard parts from marine animals (like shellfish that sink to the bottom of the ocean and turn into limestone. Shells made of calcium carbonate)

  The table shows features of greenhouse gases in the atmosphere. According to the data in the table, which greenhouse gas contributes the most to climate change?

Carbon dioxide

    How do greenhouse gases contribute to global warming?

(have to understand the process)

Light comes in, heat is trapped by the greenhouse layer, and increases the temperature

Which gases have made the most significant contributions to global warming?

Carbon dioxide & water vapor

  The graph shows atmospheric oxygen levels over time.  About 2.5 billion years ago, a significant rise in atmospheric oxygen occurred. What was the cause of this rise?

Evolution of plants (plants evolved about 2.5 billion years ago)

  Under certain conditions, living organisms on Earth produce and release methane. What favours the production of methane?

Anaerobic conditions (no oxygen)

The oceans absorb much of the carbon dioxide in the atmosphere. The combustion of fossil fuels has increased carbon dioxide ocean concentrations. What adverse effect does this have on marine life?

⁃Ocean acidification

⁃Kills corals

⁃Disrupts food webs

In the diagram, which of the processes labelled A to D transfers the largest mass of carbon per year in a woodland ecosystem?

B (atmosphere to plants) (because their whole job is to take in CO2 and make it into oxygen.)

What material is formed when organic matter is not fully decomposed in acidic waterlogged soils?

Peat (aka coal that isn’t fully hardened)

 Which organisms produce methane in anaerobic environments such as waterlogged soils?

Anaerobic bacteria living in the soil.

     In an ecosystem, in the transfer of carbon from producers to consumers, what is carbon transferred as?

I. Carbon dioxide

II. Protein

III. Hydrogencarbonate ions

Carbon dioxide

   The global carbon cycle involves sinks where carbon is stored, and fluxes where carbon is transferred. What are the largest sink and flux?

Largest sink = ocean. 

Flux = photosynthesis

   Which conditions favour peat formation?

Formed when organic matter is not fully decomposed in acidic waterlogged soils

 In addition to carbon dioxide, which of these greenhouse gases is the most significant?

Water vapour

 What describes a possible cause of a negative carbon flux in the atmosphere due to processes occurring in a forest ecosystem?

NF = more going out than coming in. So the atmosphere is releasing more CO2 than getting back. So the carbon is staying in the forest.

Photosynthesis helps the plant grow. If trees are growing super big, the CO2 is staying inside and being used for photosynthesis (storing the carbon rather than giving it back to the atmosphere)

  The diagram shows the carbon cycle. Which two processes correspond to the labelled arrows?

J = combustion

K = Respiration

L = Photosynthesis