Water & Macromolecules Flashcards
(22 cards)
A solution that has a high concentration of H+ ions is classified as:
Acid
The pH scale (ranging from 0 to 14) measures the concentration of H^+ ions in a solution.
• Acidic solutions have a pH less than 7, meaning they have a high concentration of H^+ ions.
• The lower the pH, the stronger the acid (e.g., stomach acid with a pH of ~1-2 is very acidic)
A substance is dropped into water and stirred vigorously. After ten minutes of stirring, it does not appear to have dissolved at all. What inference can you make about the substance?
It is nonpolar.
What does it mean for a cell to have an optimal pH range?
It will only function properly on or around a specific pH that can be any value.
- Each cell has an optimal pH range, which is the specific pH at which its enzymes and biological processes function best. This optimal pH is not always neutral (pH 7)—it varies depending on the type of cell and its environment. *
Which of the following is NOT a function of lipids?
M
Stores information inside cells
What structural feature of the water molecule is primarily responsible for its polarity?
Its bent shape and unequal electron sharing
Explain how the polarity of water molecules leads to hydrogen bonding.
The oxygen atom in water is more electronegative than the hydrogen atoms, so it pulls the shared electrons closer, creating a partial negative charge on the oxygen and partial positive charges on the hydrogens. This charge separation allows the positive end of one water molecule to attract the negative end of another, forming hydrogen bonds.
True/False:
Question: Water’s ability to act as a universal solvent is due to its polar nature.
True. The polarity of water allows it to interact with and dissolve many ionic and polar substances.
Because of the hydrogen bonds between its molecules, water has a high __________, which helps moderate temperature changes in the environment.
specific heat capacity
True or False:
Cohesion in water refers to the attraction between water molecules due to hydrogen bonding.
True
Explanation: Cohesion is the property that causes water molecules to stick together, and this is largely due to hydrogen bonds.
True or False:
Adhesion is the process by which water molecules stick to non-water surfaces, and it is important for capillary action in plants.
True
Explanation: Adhesion refers to the attraction of water molecules to other types of molecules (e.g., in plant cell walls), which helps water move through small spaces.
True or False:
Ice is less dense than liquid water because the hydrogen bonds in ice force the molecules into a tightly packed structure.
False
Explanation: In ice, hydrogen bonds arrange water molecules in an open, lattice-like structure that actually makes ice less dense than liquid water, which is why ice floats.
True or False:
Water’s high heat of vaporization is due to the strong covalent bonds between hydrogen and oxygen within each water molecule.
ule.
False
Explanation: The high heat of vaporization is due to the energy required to break the hydrogen bonds between water molecules—not the much stronger covalent bonds within the molec
True or False:
Biological molecules are typically composed of repeating subunits called monomers that join together via covalent bonds to form polymers.
Answer: True
Explanation: Proteins, nucleic acids, and many carbohydrates are polymers built from repeating monomers through dehydration synthesis reactions.
True or False:
Carbohydrates are composed solely of carbon and hydrogen atoms.
Answer: False
Explanation: Carbohydrates consist of carbon, hydrogen, and oxygen, often in a ratio of approximately 1:2:1 (C:H:O).
True or False:
Dehydration synthesis is the process in which water molecules are removed to join monomers together into larger molecules.
Answer: True
Explanation: In dehydration synthesis, also known as condensation reactions, water is released as monomers are covalently bonded into polymers.
True or False:
Lipids are considered biological molecules even though they are not polymers.
Answer: True
Explanation: Lipids (such as fats, oils, and steroids) are vital biological molecules used for energy storage, membrane structure, and signaling, despite not being composed of repeating monomeric units.
True or False:
Proteins are made up of nucleotides linked by phosphodiester bonds.
Answer: False
Explanation: Proteins are polymers composed of amino acids linked by peptide bonds, not nucleotides.
True or False:
Proteins are made up of nucleotides linked by phosphodiester bonds.
Answer: False
Explanation: Proteins are polymers composed of amino acids linked by peptide bonds, not nucleotides.
True or False:
Nucleic acids, such as DNA and RNA, are polymers made up of nucleotide monomers joined by phosphodiester bonds.
Answer: True
Explanation: DNA and RNA are long polymers where each nucleotide is connected by phosphodiester linkages, forming the backbone of the molecule.
True or False:
The specific three-dimensional structure of a protein is essential for its proper function.
Answer: True
Explanation: A protein’s function is highly dependent on its structure; even minor changes in its shape can affect its activity and interactions.
True or false:
Hydrolysis is the reaction that breaks down polymers into monomers by adding water.
Answer: True
Explanation: Hydrolysis is the reverse of dehydration synthesis; it involves the addition of water to break the covalent bonds between monomers.
True or False:
The diversity and complexity of biological molecules, such as carbohydrates, lipids, proteins, and nucleic acids, are crucial for the wide range of functions needed to support life.
Answer: True
Explanation: Each class of biological molecule has unique properties that enable them to perform specialized roles in cellular structure, energy storage, catalysis, and genetic information storage, among others.
