1. Which of these characteristics affects the diffusion of oxygen into the icefish's blood?
- Icefish have scaleless skin.
- Icefish gills are white.
- Icefish have clear blood.
- Icefish hearts are colorless.
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2. Icefish live in very cold waters (-1.8 °C) where temperatures are below blood's freezing point. Which statements are true about icefish adaptations for cold water? (Note: More than one answer is correct.)
- Icefish lack hemoglobin, which prevents blood from freezing.
- Icefish lack red blood cells, which prevent blood from freezing.
- Icefish have antifreeze proteins, which prevent blood from freezing.
- Icefish lack red blood cells, which reduces the viscosity (thickness) of blood, allowing it to flow more freely at cold temperatures.
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3. Which statement is true of notothenioids?
- Notothenioids can live in very cold, nutrient-rich waters where other fish species cannot.
- All notothenioids lack functional globin genes. (Globin genes encode hemoglobin.)
- All notothenioids lack a functional antifreeze gene.
- All notothenioids have colorless blood.
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4. How did the icefish antifreeze gene arise?
- The antifreeze gene was caused by a single mutation.
- An existing gene was duplicated. It then acquired mutations, which caused it to have a different function.
- Cold Antarctic waters caused the mutation that created the antifreeze gene.
- The icefish antifreeze gene evolved before Antarctica broke away from South America.
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5. Which of the following statements about the "death" of the icefish globin gene are accurate?
- Natural selection in very cold waters caused the mutations that destroyed the globin gene.
- Loss of the icefish globin gene reduced the fitness of the icefish.
- Mutations destroyed the function of the icefish globin gene.
- Icefish DNA shows no trace of the globin gene.
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6. A strong selective pressure (like very cold water) can …
- … cause individuals with an advantageous mutation to have a reproductive advantage.
- … cause mutations.
- … cause individuals to evolve.
- … cause the environment to change.
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7. Compare the "birth" and "death" of icefish genes.
- The "birth" of the antifreeze gene and the "death" of the globin gene were both caused by duplication.
- Both the "birth" of the antifreeze gene and the "death" of the globin gene involved eliminating unnecessary genes.
- The "birth" of the antifreeze gene and the "death" of the globin gene are both examples of "inventing something new from something old."
- Both the "birth" of the antifreeze gene and the "death" of the globin gene were caused by mutation.
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