Base excision repair (BER) systems directly remove the damaged base and replace it in DNA.

TLS Online TPP Program

#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.

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#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.

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#Id: 6060

#Unit 10. Ecological Principles

Mediterranean shrublands (chaparral):  These are located near an ocean and have wet, cool winters and hot, dry summers.  Rainfall is 40 to 100 centimeters per year. 

Fire is a common feature of this biome, and the shrubs are adapted to withstand occasional fires. 

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#Id: 6061

#Unit 10. Ecological Principles

Coral reef ecosystems  Most reefs are located between the Tropics of Cancer and Capricorn, in the Pacific Ocean.  Coral reefs are one of the most diverse ecosystems on our planet, yet they cover less than 1% of the Earth's surface. 

 

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#Unit 10. Ecological Principles

Zone of Lake 

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#Id: 6063

#Unit 10. Ecological Principles

The areas of the lake or pond bottom that are not part of the littoral zone are referred to as the benthic zone. This zone contains fine sediment that is free of plant life because light levels are too low to support plant growth. The major trophic levels in the pelagic zone, or open water areas, are phytoplankton, zooplankton, planktivorous (plankton-eating) fish, and piscivorous (fish-eating) fish. The food web in the pelagic zone is connected to the inshore food web because many mobile organisms from the pelagic zone (especially fish) use the inshore areas for shelter and food.