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A cactus is adapted to survive in a very (a)   environment.

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Cacti minimize their surface area by replacing leaves for (a)   .

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Spines are also an adaptation that (a)   cacti from animals that might eat them.

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(a)   stems help the cactus to store water.

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A (a)   coating helps the cactus to stop water from escaping.

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Cacti have an extensive (a)   system to collect water from a large area.

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(a)   are organisms which have adapted to live or survive in extreme envirnments.

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Extreme environments may have very high levels of (a)   , high temperatures or high pressures.

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The (a)   which is a type of bacteria is an example of an extremophile.

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To live in extremely hot environments, some bacteria have adapted to produce (a)   that still funcion in very high temperatures.

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Some bacteria can even respire (a)   instead of oxygen.

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(a)   conditions refers to the lack of dissolved oxygen and a high oxidation level of organic matter in the water.