Question

NPP = GPP – R

Net primary production = ______________        =   GPP – energy used for cellular respiration

Gross primary production = ________________ production of primary producers

Respiration = ______________________

Thus NPP is the amount of energy available to primary consumers   = primary production

1. Explain the different ways in which primary production is influenced in terrestrial and aquatic ecosystems

Primary production:   terrestrial ecosystems influenced by water, temperature, and nutrient availability

Evapotranspiration rate measures the amount of water entering the atmosphere through the processes of (evaporation / transpiration) from the soil and ( evaporation / transpiration) of plants.

Evapotranspiration rate will be ( low / high ) in deserts and ( low / high) in tropical rain forests.

Nutrients, key elements in usable forms, may be 2 limiting factors on land are ( N   / C / P / H / O)

A limiting factor is one in shortest supply for growth.

Primary production : aquatic ecosystems influenced by light and nutrient availability

Regions in water bodies where light penetrates is called ( photic / aphotic ) zone

Nutrients are important to aquatic productivity too.

Nutrients are more available in areas of ( upwelling / downwelling) and ( along the coast / in the middle of the ocean)

2. Describe the factors that limit secondary production in ecosystems.

( Primary / Secondary ) productivity is that of the consumers . The more plant biomass and thus the more primary production leads to an ( increased / decreased ) biomass of herbivores. But recall that only 10% of the energy from the 1^st trophic level is transferred to the 2^nd trophic level.

As transformers of energy (Plants and algae   / animals) are the most important organisms on th planet.

Pyramid of Numbers Pyramid of Biomass Pyramid of Energy Which of these pyramids is inverted? What is the producer in this food chain? Which of these pyramids is never inverted ? 4. Explain how the process of biomagnification can occur at higher trophic levels is the tendency of certain chemicals to concentrate in higher trophic levels in food chains. Biomagnification of a toxic chemical such as DDT can cause serious harm to an organism. What happened to some bird eggs in the United States after DDT had been used for a long time? Is DDT banned in the United States? Is DDT banned all over the world? DDT persists in the environment for a long time and tends to accumulate in fat tissue which means in biological tissues since they contain lipids.

Answer 1

The pyramid of numbers is inverted as it can be seen that in this case a single large tree can support many fleas that support other insects and birds which are dependent on these insects. hence in this case the food chain is inverted.

The tree is the producer. Always in a food chain or food web the plants form the primary producers.All the other organisms are dependent on them directly or indirectly.

The pyramid of energy can never be inverted because the energy content always decreases at every trophic level and it cannot be the other way round.Producers have the maximum energy content and occupy the base of the pyramid. Then on the energy can only decrease past each trophic level.

Bioaccumulation and Biomagnification.

High concentrations of DDT disturbs the calcium metabolism in birds which causes thinning of the eggshell,premature breaking and eventually causes decline in the bird population.

DDT was banned long ago in the US due to its adverse ill effects on the environment.

There are some countries that still continue to use DDT as a pesticide but most of the developed countries have realised the effects and banned it before its too late.