1,25-dihydroxycholecalciferol stimulates the reabsorption of calcium & phophate ions from kidney.

TLS Online TPP Program

#Id: 5982

#Unit 10. Ecological Principles

In the frozen tundra of the Arctic, over 100 years may be needed to decompose 75% of the litter mass. Tree species with high lignin: nitrogen ratios were more resistant to decomposition

TLS Online TPP Program

#Id: 5983

#Unit 10. Ecological Principles

TLS Online TPP Program

#Id: 5984

#Unit 10. Ecological Principles

Top-down control - Higher trophic levels determine the sizes of the lower trophic levels Bottom-up control - Size of a higher trophic level is determined by lower trophic level 

TLS Online TPP Program

#Id: 5985

#Unit 10. Ecological Principles

Strength of mortality factors varies with plant productivity, the rate of production of plant biomass. For very simple systems, where few plants exist, not enough plant material is available to support herbivores, and plants must be resource limited, that is, limited by competition.

 

  

TLS Online TPP Program

#Id: 5986

#Unit 10. Ecological Principles

TLS Online TPP Program

#Id: 5987

#Unit 10. Ecological Principles

Green Earth hypothesis Which stated that since the Earth appears “green,” and plants are common, herbivores must have little impact on plant abundance.

They suggested that herbivores must therefore be limited by their predators.