Bellwork Friday, 10/17

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BellworkFriday, 10/17

• Insecticides are poisons used to kill insects.
  Many farmers spray insecticides on their crops.
  One year a farmer sprayed a new insecticide on
  his potato plants, and it killed nearly all of
  the bugs. He again sprayed his potato plants the
  next year, and it only killed about 75 of the
  bugs. He again sprayed his plants the following
  year, and it only killed about 50 of the bugs.
  In other words, the insect population became
  resistant to this insecticide. How does this
  process occur?
• a.The insects displayed a behavioral adaptation
  by flying away each year when the farmer was
  spraying. Then the next year they returned in
  larger numbers.
• b.Due to natural variation in the insect
  population some small percentage of bugs were not
  effected in the first year of spraying. These
  survivors then passed along their insecticide
  resistant genes to the next generation.
• c.The plants displayed a structural adaptation to
  the insecticide. Each year after being sprayed
  the plants slowly changed their physical
  characteristics in order to repel the insects.
• d.This process is called natural selection. It
  occurs when organisms randomly move from one
  territory to another. The insects simply moved
  around each year.
• EXPLAIN WHY YOU THINK YOUR ANSWER IS CORRECT IN 1
  SENTENCE (PROVIDE EVIDENCE)!!!!

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Chapter 5Section 1 Geologic History
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• Objective
• Contrast relative dating with absolute dating.

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• Relative Dating
• Scientists use different methods to determine the
  age of objects in sedimentary rocks.
• One method, Relative dating, examines a fossils
  position within rock layers to estimate its age.

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• The bottom layers of rock are usually the oldest,
  and the top layers are usually the youngest.
• Scientists can use the order of rock layers to
  determine the relative age of objects within the
  layers.

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• For example, fossils in the bottom layers are
  usually older than fossils in the top layers.

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• The Geologic Column
• To make relative dating easier, geologists
  combine data from all of the known rock sequences
  around the world.

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• From this information, geologists created the
  geologic column an ideal sequence of rock
  layers that contains all of the known fossils and
  rock formations on Earth, arranging layers from
  oldest to youngest.

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• Paleontology
• Paleontology is the science involved with the
  study of past life. Scientists who study past
  life are called paleontologists.
• Paleontologists collect data by studying fossils.

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• Section 2 Looking at Fossils

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• Objective
• Explain how fossils can be used to determine the
  history of changes in environments and organisms.

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• The remains or physical evidence of an organism
  preserved by geologic processes is called a
  fossil.
• Trace fossils are any naturally preserved
  evidence of animal activity.

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• A cavity in rock where a plant or animal was
  buried is called a mold.
• A cast is an object that is created when sediment
  fills a mold and becomes rock.

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• History of Changing Organisms
• Scientists study the relationships between
  fossils to interpret how life has changed over
  time.
• Since the fossil record is incomplete,
  paleontologists look for similarities between
  fossils over time to try to track change.

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• Using Fossils to Date Rocks
• Scientists have found that particular types of
  fossils appear only in certain layers of rock.

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• By dating rock layers above and below these
  fossils, scientists can determine the time span
  in which the organism lived.
• If the organism lived for a relatively short
  period of time, its fossils would show up in
  limited layers.