Basic Chemistry
What property of electrons allows them to form chemical bonds?
Their ability to be shared or transferred between atoms
Why does water bead up on a waxed surface but spread out on glass?
Wax is non-polar (repels water), while glass is polar (attracts water).
Why do carbohydrates provide quick energy compared to lipids?
Their bonds are easier to break down into glucose for ATP production.
Why do prokaryotes still carry out essential life processes without organelles?
They use membranes and cytoplasm for metabolic reactions.
Why is the cell membrane described as “selectively permeable”?
It regulates entry and exit of molecules based on size, polarity, or transport needs.
Why do noble gases rarely form bonds with other elements?
Their outer electron shells are already full and stable
Why does sweating cool the body at the molecular level?
Evaporation uses heat energy to break hydrogen bonds, removing heat from the skin.
Why does the order of amino acids in a polypeptide matter?
It determines how the protein folds, which dictates function.
Why does the nucleus have pores in its envelope?
To allow RNA and proteins to move in and out for gene expression.
Why does cholesterol help stabilize animal cell membranes?
It prevents membranes from becoming too rigid in cold or too fluid in heat.
Why are covalent bonds generally stronger than ionic bonds in biological systems?
Covalent bonds share electrons directly, while ionic bonds are weakened in aqueous environments.
Why do coastal regions have milder climates than inland areas?
Water’s high heat capacity moderates temperature changes.
Why can phospholipids form bilayers while triglycerides cannot?
Phospholipids have hydrophilic heads and hydrophobic tails; triglycerides are fully hydrophobic.
Why does the rough ER appear “rough” under a microscope?
Ribosomes attached to its surface give it a studded appearance.
Why does facilitated diffusion not require energy?
Molecules move down their concentration gradient with help from transport proteins.
Why do atoms with similar electronegativity values tend to form non-polar bonds?
Neither atom pulls electrons strongly enough to create partial charges.
Why does salt dissolve in water but oil does not?
Salt ions interact with polar water, oil is non-polar and cannot form hydrogen bonds.
Why are enzymes considered catalysts?
They lower activation energy, speeding reactions without being consumed.
Why do chloroplasts and mitochondria both have folded inner membranes?
Folding increases surface area for energy reactions (photosynthesis and respiration).
Why do plant cells not burst in hypotonic solutions while animal cells can?
The rigid cell wall resists osmotic pressure.
Why do polar molecules often align themselves in an electric field?
Their partial charges are attracted to opposite charges in the field.
Why does the density of water drop when it freezes, unlike most substances?
Hydrogen bonds lock molecules farther apart in a crystal lattice.
Why can mutations in nucleic acids alter protein function?
A change in DNA sequence can change amino acids, altering protein shape and activity.
Why does the cytoskeleton constantly rearrange itself?
To support cell shape, enable movement, and adapt to changing conditions.
Why is the sodium-potassium pump essential for nerve function?
It maintains electrochemical gradients needed for action potentials.