1. Q: What are the four most abundant elements in living organisms?
ANSWER Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N) — often
remembered as CHON.
2. Q: What is an atom?
ANSWER The smallest unit of an element that retains the chemical properties of
that element, composed of protons, neutrons, and electrons.
3. Q: What is a covalent bond?
ANSWER A chemical bond formed by the sharing of electron pairs between atoms,
producing molecules.
4. Q: What is an ionic bond?
ANSWER A chemical bond formed when one atom transfers electrons to another,
creating oppositely charged ions that attract each other.
5. Q: What is a hydrogen bond?
ANSWER A weak attraction between a slightly positive hydrogen atom and a
slightly negative atom (usually O or N) in another molecule or the same molecule.
6. Q: Why is water considered a polar molecule?
ANSWER Because the oxygen end carries a slight negative charge and the hydrogen
ends carry slight positive charges due to unequal electron sharing.
7. Q: What is cohesion in water?
ANSWER The tendency of water molecules to stick to each other due to hydrogen
bonding.
8. Q: What is adhesion in water?
ANSWER The tendency of water molecules to stick to other polar substances.
9. Q: What is specific heat capacity and why is water's high?
ANSWER The amount of energy needed to raise 1 g of a substance by 1°C. Water's
high specific heat is due to hydrogen bonds that must be broken before temperature
rises.
10.Q: What is the pH scale?
ANSWER A logarithmic scale from 0–14 measuring hydrogen ion (H⁺)
concentration; pH 7 is neutral, below 7 is acidic, above 7 is basic.
,11.Q: What is an acid?
ANSWER A substance that donates H⁺ ions (protons) in solution, lowering pH.
12.Q: What is a base?
ANSWER A substance that accepts H⁺ ions or releases OH⁻ ions in solution, raising
pH.
13.Q: What is a buffer?
ANSWER A solution that resists changes in pH by absorbing or releasing H⁺ ions.
14.Q: What are the four major macromolecules of life?
ANSWER Carbohydrates, lipids, proteins, and nucleic acids.
15.Q: What is a monomer?
ANSWER The small subunit that is the building block of a larger polymer.
16.Q: What is a polymer?
ANSWER A large molecule composed of many repeating monomer units joined by
covalent bonds.
17.Q: What is dehydration synthesis (condensation)?
ANSWER A reaction that joins monomers by removing a water molecule to form a
covalent bond.
18.Q: What is hydrolysis?
ANSWER A reaction that breaks polymers apart by adding water to break covalent
bonds.
19.Q: What are the monomers of carbohydrates?
ANSWER Monosaccharides (simple sugars) such as glucose and fructose.
20.Q: What is the function of carbohydrates?
ANSWER Primary energy source for cells; structural support (cellulose in plants);
energy storage (starch, glycogen).
21.Q: What is the difference between starch and cellulose?
ANSWER Both are glucose polymers; starch uses alpha-glucose and is digestible for
energy storage; cellulose uses beta-glucose forming structural fibers that most
organisms cannot digest.
22.Q: What are lipids?
ANSWER Nonpolar, hydrophobic macromolecules including fats, oils, waxes, and
steroids, used for energy storage, insulation, and membrane structure.
23.Q: What is a triglyceride?
, ANSWER A fat molecule consisting of one glycerol bonded to three fatty acid
chains via ester bonds.
24.Q: What is the difference between saturated and unsaturated fats?
ANSWER Saturated fats have no double bonds between carbons (solid at room
temp); unsaturated fats have one or more double bonds (liquid at room temp).
25.Q: What is a phospholipid?
ANSWER A lipid with a glycerol, two fatty acid tails (hydrophobic), and a
phosphate group head (hydrophilic). They form the cell membrane bilayer.
26.Q: What are the monomers of proteins?
ANSWER Amino acids (there are 20 different standard amino acids).
27.Q: What is a peptide bond?
ANSWER The covalent bond formed between the carboxyl group of one amino acid
and the amino group of another during dehydration synthesis.
28.Q: What are the four levels of protein structure?
ANSWER Primary (amino acid sequence), secondary (alpha helices and beta
sheets), tertiary (3D folding), and quaternary (multiple polypeptide chains).
29.Q: What is the primary structure of a protein?
ANSWER The unique sequence of amino acids in the polypeptide chain.
30.Q: What is protein denaturation?
ANSWER The loss of a protein's native 3D shape due to heat, pH changes, or other
factors, causing loss of function.
31.Q: What are the monomers of nucleic acids?
ANSWER Nucleotides, each consisting of a sugar, a phosphate group, and a
nitrogenous base.
32.Q: What are the two types of nucleic acids?
ANSWER DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
33.Q: What are the nitrogenous bases in DNA?
ANSWER Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).
34.Q: What is Chargaff's rule?
ANSWER In DNA, A always pairs with T and G always pairs with C, so %A=%T
and %G=%C.
35.Q: What is the difference between DNA and RNA?
ANSWER DNA is double-stranded with deoxyribose sugar and thymine; RNA is
single-stranded with ribose sugar and uracil instead of thymine.
, 36.Q: What is the cell theory?
ANSWER All living things are made of cells; the cell is the basic unit of life; all
cells come from pre-existing cells.
37.Q: What is the difference between prokaryotic and eukaryotic cells?
ANSWER Prokaryotes lack a membrane-bound nucleus and organelles; eukaryotes
have a nucleus and membrane-bound organelles.
38.Q: What are examples of prokaryotes?
ANSWER Bacteria and archaea.
39.Q: What are examples of eukaryotes?
ANSWER Animals, plants, fungi, and protists.
40.Q: What is the function of the nucleus?
ANSWER Houses the cell's DNA and controls gene expression; the control center of
the cell.
41.Q: What is the function of the mitochondria?
ANSWER Site of cellular respiration; produces ATP (energy) for the cell; often
called the powerhouse of the cell.
42.Q: What is the function of the ribosome?
ANSWER Site of protein synthesis; translates mRNA into polypeptide chains.
43.Q: What is the function of the endoplasmic reticulum (ER)?
ANSWER Rough ER (with ribosomes) synthesizes and processes proteins; smooth
ER synthesizes lipids and detoxifies chemicals.
44.Q: What is the function of the Golgi apparatus?
ANSWER Modifies, packages, and ships proteins and lipids to their final
destinations inside or outside the cell.
45.Q: What is the function of lysosomes?
ANSWER Contain digestive enzymes that break down waste materials, cellular
debris, and foreign invaders.
46.Q: What is the function of the chloroplast?
ANSWER Site of photosynthesis in plant and algae cells; converts light energy into
chemical energy (glucose).
47.Q: What is the function of the cell membrane?
ANSWER Regulates what enters and exits the cell; maintains homeostasis;
composed of a phospholipid bilayer.
48.Q: What is the fluid mosaic model?
ANSWER Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N) — often
remembered as CHON.
2. Q: What is an atom?
ANSWER The smallest unit of an element that retains the chemical properties of
that element, composed of protons, neutrons, and electrons.
3. Q: What is a covalent bond?
ANSWER A chemical bond formed by the sharing of electron pairs between atoms,
producing molecules.
4. Q: What is an ionic bond?
ANSWER A chemical bond formed when one atom transfers electrons to another,
creating oppositely charged ions that attract each other.
5. Q: What is a hydrogen bond?
ANSWER A weak attraction between a slightly positive hydrogen atom and a
slightly negative atom (usually O or N) in another molecule or the same molecule.
6. Q: Why is water considered a polar molecule?
ANSWER Because the oxygen end carries a slight negative charge and the hydrogen
ends carry slight positive charges due to unequal electron sharing.
7. Q: What is cohesion in water?
ANSWER The tendency of water molecules to stick to each other due to hydrogen
bonding.
8. Q: What is adhesion in water?
ANSWER The tendency of water molecules to stick to other polar substances.
9. Q: What is specific heat capacity and why is water's high?
ANSWER The amount of energy needed to raise 1 g of a substance by 1°C. Water's
high specific heat is due to hydrogen bonds that must be broken before temperature
rises.
10.Q: What is the pH scale?
ANSWER A logarithmic scale from 0–14 measuring hydrogen ion (H⁺)
concentration; pH 7 is neutral, below 7 is acidic, above 7 is basic.
,11.Q: What is an acid?
ANSWER A substance that donates H⁺ ions (protons) in solution, lowering pH.
12.Q: What is a base?
ANSWER A substance that accepts H⁺ ions or releases OH⁻ ions in solution, raising
pH.
13.Q: What is a buffer?
ANSWER A solution that resists changes in pH by absorbing or releasing H⁺ ions.
14.Q: What are the four major macromolecules of life?
ANSWER Carbohydrates, lipids, proteins, and nucleic acids.
15.Q: What is a monomer?
ANSWER The small subunit that is the building block of a larger polymer.
16.Q: What is a polymer?
ANSWER A large molecule composed of many repeating monomer units joined by
covalent bonds.
17.Q: What is dehydration synthesis (condensation)?
ANSWER A reaction that joins monomers by removing a water molecule to form a
covalent bond.
18.Q: What is hydrolysis?
ANSWER A reaction that breaks polymers apart by adding water to break covalent
bonds.
19.Q: What are the monomers of carbohydrates?
ANSWER Monosaccharides (simple sugars) such as glucose and fructose.
20.Q: What is the function of carbohydrates?
ANSWER Primary energy source for cells; structural support (cellulose in plants);
energy storage (starch, glycogen).
21.Q: What is the difference between starch and cellulose?
ANSWER Both are glucose polymers; starch uses alpha-glucose and is digestible for
energy storage; cellulose uses beta-glucose forming structural fibers that most
organisms cannot digest.
22.Q: What are lipids?
ANSWER Nonpolar, hydrophobic macromolecules including fats, oils, waxes, and
steroids, used for energy storage, insulation, and membrane structure.
23.Q: What is a triglyceride?
, ANSWER A fat molecule consisting of one glycerol bonded to three fatty acid
chains via ester bonds.
24.Q: What is the difference between saturated and unsaturated fats?
ANSWER Saturated fats have no double bonds between carbons (solid at room
temp); unsaturated fats have one or more double bonds (liquid at room temp).
25.Q: What is a phospholipid?
ANSWER A lipid with a glycerol, two fatty acid tails (hydrophobic), and a
phosphate group head (hydrophilic). They form the cell membrane bilayer.
26.Q: What are the monomers of proteins?
ANSWER Amino acids (there are 20 different standard amino acids).
27.Q: What is a peptide bond?
ANSWER The covalent bond formed between the carboxyl group of one amino acid
and the amino group of another during dehydration synthesis.
28.Q: What are the four levels of protein structure?
ANSWER Primary (amino acid sequence), secondary (alpha helices and beta
sheets), tertiary (3D folding), and quaternary (multiple polypeptide chains).
29.Q: What is the primary structure of a protein?
ANSWER The unique sequence of amino acids in the polypeptide chain.
30.Q: What is protein denaturation?
ANSWER The loss of a protein's native 3D shape due to heat, pH changes, or other
factors, causing loss of function.
31.Q: What are the monomers of nucleic acids?
ANSWER Nucleotides, each consisting of a sugar, a phosphate group, and a
nitrogenous base.
32.Q: What are the two types of nucleic acids?
ANSWER DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
33.Q: What are the nitrogenous bases in DNA?
ANSWER Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).
34.Q: What is Chargaff's rule?
ANSWER In DNA, A always pairs with T and G always pairs with C, so %A=%T
and %G=%C.
35.Q: What is the difference between DNA and RNA?
ANSWER DNA is double-stranded with deoxyribose sugar and thymine; RNA is
single-stranded with ribose sugar and uracil instead of thymine.
, 36.Q: What is the cell theory?
ANSWER All living things are made of cells; the cell is the basic unit of life; all
cells come from pre-existing cells.
37.Q: What is the difference between prokaryotic and eukaryotic cells?
ANSWER Prokaryotes lack a membrane-bound nucleus and organelles; eukaryotes
have a nucleus and membrane-bound organelles.
38.Q: What are examples of prokaryotes?
ANSWER Bacteria and archaea.
39.Q: What are examples of eukaryotes?
ANSWER Animals, plants, fungi, and protists.
40.Q: What is the function of the nucleus?
ANSWER Houses the cell's DNA and controls gene expression; the control center of
the cell.
41.Q: What is the function of the mitochondria?
ANSWER Site of cellular respiration; produces ATP (energy) for the cell; often
called the powerhouse of the cell.
42.Q: What is the function of the ribosome?
ANSWER Site of protein synthesis; translates mRNA into polypeptide chains.
43.Q: What is the function of the endoplasmic reticulum (ER)?
ANSWER Rough ER (with ribosomes) synthesizes and processes proteins; smooth
ER synthesizes lipids and detoxifies chemicals.
44.Q: What is the function of the Golgi apparatus?
ANSWER Modifies, packages, and ships proteins and lipids to their final
destinations inside or outside the cell.
45.Q: What is the function of lysosomes?
ANSWER Contain digestive enzymes that break down waste materials, cellular
debris, and foreign invaders.
46.Q: What is the function of the chloroplast?
ANSWER Site of photosynthesis in plant and algae cells; converts light energy into
chemical energy (glucose).
47.Q: What is the function of the cell membrane?
ANSWER Regulates what enters and exits the cell; maintains homeostasis;
composed of a phospholipid bilayer.
48.Q: What is the fluid mosaic model?
