C H AP T E R O U T LI N E Science Helps Us Understand the Natural World 1.1 Scientists use a preferred method 4 1.2 Control groups allow scientists to compare experimental results 6
THE CELL THEORY:
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Fire Ants Have a Good Defense ire ants have a red to reddish-brown color, but even so, they most likely take their name from the ability to STING. Their stinger protrudes from the rear, but in a split second, they can grab a person’s skin with their mandibles and position the stinger between their legs to sting from the front. The stinger injects a toxin into the tiny wound, and the result is a burning sensation. The next day, the person has a white pustule at the site of the sting. The success of this defense mechanism is clear because most animals, including humans, try to stay away from bees, wasps, and ants— and any other animal that can sting. Living usually in an open, grassy area, fi re ants sting in order to defend their home, which is a mound of soil that they have removed from subterranean tunnels. They use the tunnels to safely travel far afield when searching for food, which they bring back to their nest mates. The queen and many worker ants live in chambers within the mound or slightly below it. The queen is much larger
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Organisms Are Composed of Cells 1.3 Cells are the fundamental unit of living things 9
THE GENE THEORY:
Genes Control the Traits of Organisms 1.4 Organisms have a genetic inheritance 10
THE THEORY OF HOMEOSTASIS:
Organisms Are Homeostatic 1.5 Organisms regulate their internal environment 11
THE THEORY OF ECOSYSTEMS:
Organisms Live in Ecosystems 1.6 The biosphere is divided into ecosystems 12
THE THEORY OF EVOLUTION:
Organisms Are Related and Adapted to Their Environment 1.7 The ancestry of species can be determined 13 1.8 Evolutionary relationships help biologists group organisms 14 1.9 Evolution through natural selection results in adaptation to the environment 16 1.10 Evolution