BIO 600

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BIO 600

• Class 1

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Science Misconceptions

• QUESTION 1 FALSE
• A widely held misconception in life science is
  that deoxygenated human blood, the blood
  returning to the heart and lungs in veins, is
  blue.
• After all, when we look at the blood vessels in
  our arms, legs, and hands, they look blue.
  Shouldn't it be because the blood inside them is
  blue? It's not quite that simple.
• First, are we sure that the vessels we're seeing
  through the skin are veins? Could they be
  arteries carrying oxygen-rich blood? If that's
  the case, shouldn't they look bright red? Some
  very small ones do look bright red--they're the
  tiny blood vessels near the skin's surface. And
  there's our clue. When we look at larger blood
  vessels not so near the skin surface, such as the
  ones we can see on our arms and hands, the light
  allowing us to see is refracted by the skin and
  vessel walls, causing the vessels to take on a
  bluish color. So we think of the blood inside the
  vessels as being blue.

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Science Misconceptions

• QUESTION 2 FALSE
• A common misconception is that the Earth's
  proximity to the sun gives us the seasons.
  Because it is warmer in the summer than in the
  winter, it is easy to see how one would think
  that the Earth must be closer to the sun during
  the summer. In fact, the distance between the
  Earth and the sun doesn't really change all that
  much throughout the year. The orbit of the Earth
  around the sun is a slight ellipse. Textbook
  diagrams, however, typically show an exaggerated
  ellipse as in Figure 1.
• So what is the cause of the Earth's seasons? It's
  the tilt of the Earth on its axis. The tilt of
  the Earth is constant throughout the year at
  23.5 from perpendicular. During summer in the
  United States, the northern hemisphere is tilted
  toward the sun and receives more direct rays from
  the sun. During winter in the United States, the
  southern hemisphere is tilted toward the sun
  receiving the more direct rays. That is why
  seasons in the northern and southern hemisphere
  are always the opposite of one another.

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Science Misconceptions

• QUESTION 3 True
• This statement is true, but be careful. It's easy
  to state this fact without a clear picture of how
  atoms and molecules are arranged in matter. A
  common misconception surrounding this concept is
  that matter is continuous, that there are no
  spaces between atoms and molecules. According to
  this faulty theory, when air in a balloon heats
  up, for example, the balloon expands because the
  molecules of gas get bigger filling up the space.
  In actuality, as molecules of gas are heated,
  they gain energy. With increased energy comes
  increased activity, and the molecules are able to
  move farther apart. Gas molecules will continue
  to move in one direction until they encounter a
  barrier such as another molecule or the wall of
  the balloon. Energized gas molecules move at a
  faster rate and strike barriers with more force.
  The energized gas molecules in the balloon strike
  the walls of the balloon with more force, causing
  the balloon to expand.
• One of the best ways to debunk the idea of
  continuous matter is to revisit one of the most
  fundamental characteristics of gases--that they
  expand to fill their container (without any
  change in temperature). If it is thought that
  there are no spaces between atoms, then how are
  they able to expand? Expansion would require
  additional space between molecules, so we know
  the theory is a misconception.

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Science Misconceptions

• QUESTION 4 FALSE
• This statement is a misconception. The term
  "weightlessness" is more accurately described as
  microgravity, where objects are in a continuous
  freefall pattern. Astronauts are constantly in
  two-dimensional motion (that which occurs along
  the x-axis while also occurring along the
  y-axis). We know that for every movement in the
  x-direction there is a corresponding movement in
  the y-direction. To understand how this affects
  astronauts in space, let's first consider motion
  on the Earth, in which the y-direction is
  dictated largely by the pull of gravity. When you
  throw a ball, it doesn't reach its peak and drop
  straight down it curves back toward the Earth
  because motion is still occurring in the
  x-direction. Eventually the ball does hit the
  ground. However, in space, the object (in this
  case the astronaut) continues to fall in the
  y-direction because the surface of the Earth is
  constantly curving away from him or her, allowing
  additional motion. The velocity of the space
  shuttle in the x-direction perpetuates this
  motion so a continual "free fall" is experienced
  and the astronaut seems to be weightless although
  gravity continues to act on him or her.
• To understand this concept, we need to remember
  there is gravity in space. In fact, according to
  Newton's Law of Universal Gravitation any two
  masses exert force on one another. It is this
  attraction, or "pull," between the spacecraft and
  the Earth that keeps the spacecraft traveling in
  an orbit.