Midterm 2- Understanding Molecules and Reactions

How do the valence electrons of hydrogen and oxygen contribute to the formation of a water molecule?

• Hydrogen donates its electron to oxygen, forming a nonpolar bond.

• Oxygen pulls electrons from hydrogen, forming a polar covalent bond.

• Hydrogen and oxygen share electrons equally, forming a nonpolar bond.

• Oxygen donates electrons to hydrogen, forming an ionic bond.

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Explain how the polarity of water molecules leads to the phenomenon of cohesion.

• Water molecules repel each other due to their polar nature.

• Water molecules form hydrogen bonds with each other, leading to cohesion.

• Water molecules form ionic bonds with each other, leading to cohesion.

• Water molecules are nonpolar, which causes them to stick together.

Describe the role of lipids in the cell membrane and how their structure contributes to this role.

• Lipids form a rigid structure that prevents any molecules from passing through.

• Lipids form a flexible bilayer that allows selective permeability due to their hydrophobic tails and hydrophilic heads.

• Lipids form a single layer that allows all molecules to pass freely.

• Lipids form a solid barrier that only allows water to pass through.

Analyze how the concentration gradient affects the process of diffusion in cells.

• Diffusion occurs from low to high concentration, requiring energy.

• Diffusion occurs from high to low concentration, without requiring energy.

• Diffusion occurs from high to low concentration, requiring energy.

• Diffusion occurs from low to high concentration, without requiring energy.

Evaluate the impact of a non-competitive inhibitor on enzyme activity and explain the mechanism involved.

• It binds to the active site, preventing substrate binding.

• It binds to the allosteric site, changing the shape of the active site and reducing enzyme activity.

• It increases the enzyme's affinity for the substrate.

• It binds to the substrate, preventing enzyme interaction.

How does the structure of carbohydrates relate to their function as a quick energy source in the body?

• Carbohydrates have long chains that are difficult to break down, providing sustained energy.

• Carbohydrates have simple sugars that are easily broken down for quick energy.

• Carbohydrates are composed of amino acids that provide energy.

• Carbohydrates are hydrophobic, making them a quick energy source.

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Predict the effect on a cell placed in a hypertonic solution and explain the reasoning behind it.

• The cell will swell because water enters the cell.

• The cell will shrink because water exits the cell.

• The cell will remain the same size because there is no net movement of water.

• The cell will burst because solutes enter the cell.

Discuss how enzymes act as catalysts in biochemical reactions and the importance of their role.

• Enzymes slow down reactions by increasing activation energy.

• Enzymes speed up reactions by lowering activation energy.

• Enzymes are consumed in reactions, providing energy.

• Enzymes are not specific to any reaction and act randomly.

How does the phospholipid bilayer's structure facilitate its function in the cell membrane?

• The nonpolar tails face outward, allowing water to pass freely.

• The polar heads face inward, preventing water from passing.

• The polar heads face outward, interacting with water, while the nonpolar tails face inward, creating a barrier.

• The nonpolar tails face outward, interacting with water, while the polar heads face inward, creating a barrier.

Analyze the role of proteins in cellular functions and provide examples of their diverse roles.

• Proteins only serve as structural components in cells.

• Proteins act as enzymes, signals, and structural components in cells.

• Proteins are only involved in energy storage.

• Proteins are only involved in transporting oxygen.

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