The cause of less negative RMP of SA node is that the cell membranes of the sinus fibers are naturally leaky to sodium and calcium ions.

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#Id: 6054

#Unit 10. Ecological Principles

Location        Grass land 

Eurasia Steppes 

North America  Prairie

Argentina  Pampas 

South Africa  Veldts

Australia and Newzeland          Tussocks 

Australia                              Down 

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#Id: 6055

#Unit 10. Ecological Principles

Taiga, Northern Coniferous Forest, or Boreal Forest  The climate is one of short, cool summers and long winters with abundant snowfall. Precipitation is generally between 40 and 70 cm, often occurring in the form of snow.

Most of the trees are evergreens or conifers with tough needles, hence its similarity to temperate rain forest.

TLS Online TPP Program

#Id: 6056

#Unit 10. Ecological Principles

Lack of water is the primary factor that determines that an area will be a desert

Hot desert.

Cold desert 

Desert    Location 

Sahara  N. Africa 

Kolahari                      S. Africa 

Coastal Atacama              Peru

Sonoran               North American 

Simpson          Australia 

 

TLS Online TPP Program

#Id: 6057

#Unit 10. Ecological Principles

Hot Desert  Temperatures are variable from below freezing at night to as much as 50ºC in the day. algae carry on photosynthesis and provide both themselves and the coral animals with the nutrients necessary for growth. 

The skeletons of the corals provide a surface upon which many other kinds of animals live.

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#Id: 6058

#Unit 10. Ecological Principles

 Cold Desert: In the daytime, temperatures can be high in the summer, 21–26ºC, but average around freezing, –24ºC, in the winter.

TLS Online TPP Program

#Id: 6059

#Unit 10. Ecological Principles

Tundra:   Tundra is found at high latitudes, adjacent to ice margins, where insolation is low.  Tundra is the youngest of all biomes as it was formed after the retreat of glaciers 10000 years ago.  Lack of light and rainfall mean (25 cm per year) that rates of photosynthesis and productivity are low. Large part of the year, water can be locked away in permafrost, a layer of permanently frozen soil below 0.5–1 m.