Chemistry of life

What property of water helps to moderate Earth’s temperature and even our constant internal body temperature?

• Cohesion

• Adhesion

• Density

• Specific heat capacity

As food travels through the digestive system, it is exposed to a variety of pH levels. The stomach has a pH of 2 due to the presence of hydrochloric acid (HCl), and the small intestine has a pH ranging from 7 to 9. HCl converts pepsinogen into pepsin, an enzyme that digests proteins in the stomach. Which of the following most likely happens to pepsin as it enters the small intestine?

• It becomes inactive

• It begins to replicate

• Its shape changes to engulf large proteins

• Its activity increases to ingest more proteins

The 4 macromolecules are

• vitamins, lipids, water, micronutrients
• micronutrients, macronutrients, water, vitamins
• Lipids, Waxes, Vitamin A, Water
• Carbohydrates, Lipids, Proteins, Nucleic Acids

Based on the graph, what temperature does this enzyme work best? 

• 15 C
• 40 C
• 30 C
• 47 C

A water strider can skate along the top of a pond because:

• Low surface tension of water

• Hydrogen bonds result in water cohesion (surface tension)

• Covalent bonds result in water cohesion

• Water striders have adapted to take advantage of water cohesion

Enzymes are an example of

• Lipids

• Carbohydrate

• Protein

• Nucleic Acid

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Water is essential for life. Its special properties make water the single most important molecule in plant life. Which of the following properties of water enables it to move from the roots to the leaves of plants?

• Water expands as it freezes

• Water is an excellent solvent

• Water exhibits cohesive behavior

• Water is able to moderate temperature

An enzyme speeds up a reaction by

• lowering the activation energy.
• raising the activation energy.
• releasing energy.
• absorbing energy.

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What happens when enzymes are heated to a high temperature?

• The enzymes die.

• The shape of the enzyme are changed and it denatures

• The enzymes' amino acid sequence changes.

• The enzymes remain the same

Which of these is NOT true?

• Enzymes can denature (change shape) when the temperature gets too high.
• Enzymes can only be used once in a chemical reaction. 
• Extreme pH can denature enzymes.
• Enzymes speed up chemical reactions. 

Tags

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