Benchmark #1 Study Guide Answer Key

1. Theory = a system of ideas that explains many related observations and is supported by a large body of evidence acquired through scientific investigation Hypothesis = a testable idea or explanation that leads to scientific investigation

2. Dependent variable = in an experiment, the factor that changes as a result of manipulation of one or more other factors (the independent variables) Independent variable = in an experiment, the factor that is deliberately manipulated

3. https://www.khanacademy.org/science/biology/intro-to- biology/what-is-biology/a/what-is-life

4. 4

5. a weak bond between two molecules resulting from an electrostatic attraction between a proton in one molecule and an electronegative atom in the other.  This sticking together of like substances is called cohesion.

6. https://water.usgs.gov/edu/heat-capacity.html

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9. Enzymes are protein molecules which serve as catalysts for chemical reactions. A catalyst is a substance which will decrease the activation energy for a reaction.

10. Change the pH and the enzyme stops working. Increasing the temperature to 60°C will cause a permanent change to the shape of the active site. This is why enzymes stop working when they are heated. We say they have become denatured.

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14. Catalysts play an important part in many chemical processes. Without them, many chemical reactions might not take place due to the amount of activation energy needed to start the reaction. They increase the rate of reaction, are not consumed by the reaction, and are only needed in very small amounts.

15 https://water.usgs.gov/edu/waterproperties.html

16. Large central vacuole chloroplast

17. http://blog.science-matters.org/2012/01/23/the-four-major-classes- of-biomolecules/

18. (part 1)

18. (part 2) STEP 1A section of DNA containing a gene is copied and a messenger molecule called mRNA is formed. STEP 2The messenger molecule (mRNA) carries the DNA copy to the cytoplasm. STEP 3The messenger molecule (mRNA) is fed through the ribosome 3 bases at a time. STEP 4Transfer molecules called tRNA bring the correct AA (amino acid) from the cytoplasm to the ribosome. STEP 5Transfer molecules (tRNA) drop amino acids (AA) off at the ribosome. STEP 6The AA (amino acids) are linked together to form a long protein chain.

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