D4.2 Stability and change

Explain the movement of energy and inorganic nutrients in an ecosystem.

Explain the movement of energy and inorganic nutrients in an ecosystem.

State the distance from the city centre at which the highest proportion of plants sampled contained HCN.

Outline the relationship shown in the graph.

Deduce whether the pattern of cyanogenesis was the same in all of the areas around all four cities.

Using all of the data so far, suggest whether exposure to freezing temperatures in the four cities is supported as a reason for the differences in HCN production in T. repens.

Describe the effect of temperature on the total biomass.

Compare and contrast the effects of temperature on the biomass of autotrophs and heterotrophs with added nutrients.

Explain the effect of temperature on the rate of photosynthesis in this mesocosm.

Suggest reasons for the decreases in biomass of autotrophs as temperature rises, despite the increases in photosynthesis.

Suggest two abiotic factors, other than temperature and nutrient supply, that may affect the production of biomass of the grasslands.

Compare and contrast the design of both mesocosms (vertical flow and horizontal flow).

State two variables measured by the probes.

1: 

2: 

Outline the requirements for sustainability within a sealed mesocosm.

State the distance from the city centre at which the highest proportion of plants sampled contained HCN.

Outline the relationship shown in the graph.

Deduce whether the pattern of cyanogenesis was the same in all of the areas around all four cities.

Using all of the data so far, suggest whether exposure to freezing temperatures in the four cities is supported as a reason for the differences in HCN production in T. repens.

State the distance from the city centre at which the highest proportion of plants sampled contained HCN.

Outline the relationship shown in the graph.

Deduce whether the pattern of cyanogenesis was the same in all of the areas around all four cities.

Using all of the data so far, suggest whether exposure to freezing temperatures in the four cities is supported as a reason for the differences in HCN production in T. repens.

Describe the effect of temperature on the total biomass.

Compare and contrast the effects of temperature on the biomass of autotrophs and heterotrophs with added nutrients.

Explain the effect of temperature on the rate of photosynthesis in this mesocosm.

Suggest reasons for the decreases in biomass of autotrophs as temperature rises, despite the increases in photosynthesis.

Suggest two abiotic factors, other than temperature and nutrient supply, that may affect the production of biomass of the grasslands.

Describe the effect of temperature on the total biomass.

Compare and contrast the effects of temperature on the biomass of autotrophs and heterotrophs with added nutrients.

Explain the effect of temperature on the rate of photosynthesis in this mesocosm.

Suggest reasons for the decreases in biomass of autotrophs as temperature rises, despite the increases in photosynthesis.

Suggest two abiotic factors, other than temperature and nutrient supply, that may affect the production of biomass of the grasslands.

Compare and contrast the design of both mesocosms (vertical flow and horizontal flow).

State two variables measured by the probes.

1: 

2: 

Outline the requirements for sustainability within a sealed mesocosm.

Sea otters are considered keystone species in this environment. Suggest how the presence of sea otters could affect the algae population.

Sea otters are considered keystone species in this environment. Suggest how the presence of sea otters could affect the algae population.

Label with a P on the $x$-axis the level of commercial sea fishing activity that would result in maximum sustainability.

Label with a P on the $x$-axis the level of commercial sea fishing activity that would result in maximum sustainability.

Duckweed (Lemna gibba) is a plant that grows on the surface of water. It was grown in cultures and the percentage increase in total area covered per day was obtained. The graph shows the specific growth rates per day for duckweed measured over 22 days.

^{Material from: Mkandawire, M. and Dudel, E.G., Assignment of Lemna gibba L. (duckweed) bioassay for in situ
ecotoxicity assessment, published 2005, Aquatic Ecology, reproduced with permission of SNCSC.}

Suggest reasons for the slowing down of duckweed population growth after day 6.

Suggest two reasons, other than elevation, for the differences in nitrogen concentration in leaves of pitcher plants.

Duckweed (Lemna gibba) is a plant that grows on the surface of water. It was grown in cultures and the percentage increase in total area covered per day was obtained. The graph shows the specific growth rates per day for duckweed measured over 22 days.

^{Material from: Mkandawire, M. and Dudel, E.G., Assignment of Lemna gibba L. (duckweed) bioassay for in situ
ecotoxicity assessment, published 2005, Aquatic Ecology, reproduced with permission of SNCSC.}

Suggest reasons for the slowing down of duckweed population growth after day 6.

Suggest two reasons, other than elevation, for the differences in nitrogen concentration in leaves of pitcher plants.

Describe how toxins such as DDT might concentrate in the bodies of birds.

Deduce, giving reasons, which brown pelican population decreased the most in the years following the study.

Outline the biomagnification of DDE in brown pelicans.

Describe how toxins such as DDT might concentrate in the bodies of birds.

Describe how toxins such as DDT might concentrate in the bodies of birds.

Describe how toxins such as DDT might concentrate in the bodies of birds.

Deduce, giving reasons, which brown pelican population decreased the most in the years following the study.

Outline the biomagnification of DDE in brown pelicans.

Describe how ingested plastics can cause problems to marine birds.

Describe how ingested plastics can cause problems to marine birds.

Outline how the prickly pear cactus may become an ecological problem in Kruger National Park.

Outline how the prickly pear cactus may become an ecological problem in Kruger National Park.