Exam 1

What do statistical tests calculate in experiments?
Choices:
a) How well the experiment was designed
b) The probability that observed differences are due to chance
c) Whether a hypothesis is correct
d) Sample size of the study
Back:
Correct Answer: b

Statistical tests help determine if an observed result could have occurred by random variation alone.

Which protein structures are disrupted by denaturation?
Choices:
a) Primary only
b) Secondary only
c) Tertiary only
d) Secondary and tertiary
Back:
Correct Answer: d

Denaturation affects hydrogen bonds and weak interactions in secondary and tertiary structures, not peptide bonds.

Two species in the same genus must also belong to the same…
Choices:
a) Order
b) Phylum
c) Family
d) All of the above
Back:
Correct Answer: d

Taxonomic hierarchy means species in the same genus share family, order, and phylum.

What bond forms during a condensation reaction in protein synthesis?
Choices:
a) Hydrogen bond
b) Peptide bond
c) Ionic bond
d) Disulfide bridge
Back:
Correct Answer: b

A peptide bond is formed when two amino acids are joined by removing a water molecule.

What does the triple bond between two nitrogen atoms share?
Choices:
a) Two electrons
b) Four electrons
c) Six electrons
d) Eight electrons
Back:
Correct Answer: c

Each covalent bond shares 2 electrons, so a triple bond shares 6.

When did the first life forms evolve on Earth?
Choices:
a) 6 billion years ago
b) 40 million years ago
c) 2 million years ago
d) 4 billion years ago
Back:
Correct Answer: d

The earliest life forms are estimated to have appeared about 4 billion years ago.

How many valence electrons does carbon have?
Choices:
a) 2
b) 4
c) 6
d) 8
Back:
Correct Answer: b

Carbon has 4 electrons in its outer shell and can form 4 covalent bonds.

What happens if blood pH rises (H⁺ drops) in the carbonic acid buffer system?
Choices:
a) Reaction shifts left
b) Reaction shifts right
c) pH drops to 7
d) Buffer becomes basic
Back:
Correct Answer: b

The system shifts right to release more H⁺ and stabilize pH.

Which statement about cell membranes is false?
Choices:
a) All cells have a membrane
b) Eukaryotic cells have membranes
c) Only eukaryotic cells have membranes
d) Prokaryotic cells also have membranes
Back:
Correct Answer: c

Cell membranes are found in all cells, including prokaryotes.

What is the correct order of increasing complexity?
Choices:
a) Cell → molecule → tissue → organ
b) Molecule → tissue → cell → organ
c) Molecule → cell → tissue → organ → organ system
d) Tissue → cell → organ system → molecule
Back:
Correct Answer: c

The biological hierarchy goes from small to complex: molecule → cell → tissue → organ → organ system.

How are atoms bonded in a hydrogen (H₂) molecule?
Choices:
a) Hydrogen bonds
b) Ionic attraction
c) Shared pair of electrons
d) Van der Waals forces
Back:
Correct Answer: c

A covalent bond is formed by sharing a pair of electrons.

Which ecological statement is NOT true?
Choices:
a) All organisms in a rainforest = population
b) Biomes = large geographic areas
c) Biomes make up the biosphere
d) Ecosystems include communities
Back:
Correct Answer: a

A population is a group of one species; all organisms = a community.

What is the valence (bonding capacity) of oxygen?
Choices:
a) 1
b) 2
c) 4
d) 6
Back:
Correct Answer: b

Oxygen has 6 electrons in the outer shell and typically forms 2 bonds.

Which macromolecule functions are related to their 3D shape and monomer sequence?
Choices:
a) Proteins
b) Carbohydrates
c) Lipids
d) Nucleic acids
Back:
Correct Answer: a

Protein function depends on the sequence of amino acids and its 3D structure.

Which compound helps stabilize blood pH as a buffer?
Choices:
a) Sodium hydroxide
b) Carbonic acid
c) Nitric acid
d) Hydrochloric acid
Back:
Correct Answer: b

Carbonic acid can donate or absorb H⁺ to resist changes in blood pH.

Which is NOT a universal characteristic of life?
Choices:
a) Cell membrane
b) Genetic material
c) Transformation of sunlight into energy
d) Internal regulation
Back:
Correct Answer: c

Some lifeforms do not use sunlight, e.g., chemosynthetic organisms.

Why does ice float on water?
Choices:
a) Ice is denser than water
b) Ice has strong ionic bonds
c) Ice molecules pack less tightly
d) Ice has more hydrogen ions
Back:
Correct Answer: c

Ice forms a crystal lattice with fewer molecules per volume than water.

What allows hemoglobin to refold properly after heat exposure?
Choices:
a) Ions
b) Peptides
c) Chaperone proteins
d) Water
Back:
Correct Answer: c

Chaperones prevent misfolding and help polypeptides refold correctly.

What group of organisms first produced oxygen?
Choices:
a) Plants
b) Fungi
c) Photosynthetic prokaryotes
d) Eukaryotic algae
Back:
Correct Answer: c

Cyanobacteria were the first to release oxygen via photosynthesis.

Which molecule stores information for protein production?
Choices:
a) DNA
b) Enzyme
c) Glucose
d) Lipid
Back:
Correct Answer: a

DNA contains genes that encode protein sequences.

Which property of water helps regulate Earth's temperature?
Choices:
a) Cohesion
b) High specific heat
c) Adhesion
d) Ionization
Back:
Correct Answer: b

Water’s high specific heat allows it to absorb heat with minimal temperature change.

Which macromolecule is least involved in information storage?
Choices:
a) RNA
b) DNA
c) Protein
d) Lipid
Back:
Correct Answer: d

Lipids store energy and form membranes but do not store genetic information.

Which bond is responsible for maintaining tertiary protein structure?
Choices:
a) Peptide bonds
b) Hydrogen bonds
c) Ionic bonds
d) Disulfide bridges
Back:
Correct Answer: d

Disulfide bridges between cysteines stabilize the folded structure of proteins.

What makes scientific hypotheses testable?
Choices:
a) They must be observable
b) They can be proven
c) They can be rejected
d) They are published
Back:
Correct Answer: c

A hypothesis is testable if it can be supported or refuted through evidence.

What is the pH of a solution with H⁺ concentration of 10⁻¹²?
Choices:
a) 2
b) 5
c) 10
d) 12
Back:
Correct Answer: d

pH = -log[H⁺] = -log(10⁻¹²) = 12.

Which amino acid lacks chirality (symmetry)?
Choices:
a) Alanine
b) Glycine
c) Proline
d) Leucine
Back:
Correct Answer: b

Glycine has two hydrogen atoms on the alpha carbon, making it achiral.

Which is true about isomers?
Choices:
a) Only optical isomers affect biology
b) Cis-trans isomers have the same properties
c) Structural isomers behave the same
d) Different isomers may have different biological effects
Back:
Correct Answer: d

The shape of isomers can dramatically influence their biological activity.

Which macromolecule is most directly responsible for encoding genetic information?
Choices:
a) Carbohydrates
b) Lipids
c) Nucleic acids
d) Proteins
Back:
Correct Answer: c

Nucleic acids like DNA and RNA store and transmit genetic information in all living organisms.

Why does ice float on water?
Choices:
a) Ice has more mass
b) Ice has more hydrogen bonds
c) Ice is denser than water
d) Ice forms a crystalline structure with lower density
Back:
Correct Answer: d

Hydrogen bonding causes ice to form a structured lattice that takes up more space, making it less dense.

What is the role of enzymes in chemical reactions?
Choices:
a) Decrease energy release
b) Increase product concentration
c) Lower activation energy
d) Alter equilibrium point
Back:
Correct Answer: c

Enzymes speed up reactions by lowering the activation energy required for a reaction to proceed.

Which bond is most stable under physiological (cellular) conditions?
Choices:
a) Hydrogen bond
b) Ionic bond
c) Covalent bond
d) Van der Waals interaction
Back:
Correct Answer: c

Covalent bonds are the strongest and most stable bonds under biological conditions.

Which of the following best describes a condensation reaction?
Choices:
a) Splitting molecules with water
b) Releasing energy
c) Forming bonds and releasing water
d) Creating ions from molecules
Back:
Correct Answer: c

Condensation reactions join two molecules together with the removal of a water molecule.

Which of the following best explains the function of a buffer in biological systems?
Choices:
a) Speeds up chemical reactions
b) Maintains a constant pH
c) Acts as a structural protein
d) Transports oxygen
Back:
Correct Answer: b

Buffers help maintain a relatively stable pH despite the addition of acids or bases.

What makes water an excellent solvent for biological molecules?
Choices:
a) It's a gas at room temperature
b) It’s nonpolar
c) It forms hydrogen bonds
d) It has high density
Back:
Correct Answer: c

Water’s polarity and ability to form hydrogen bonds make it a great solvent for polar molecules and ions.

Which macromolecule primarily provides energy for cellular processes?
Choices:
a) Proteins
b) Nucleic acids
c) Lipids
d) Carbohydrates
Back:
Correct Answer: d

Carbohydrates, like glucose, are the main source of quick energy for cells.

Which functional group makes amino acids behave as acids?
Choices:
a) Amino group
b) Carboxyl group
c) Hydroxyl group
d) Sulfhydryl group
Back:
Correct Answer: b

The carboxyl group (-COOH) donates H⁺ ions, giving amino acids their acidic behavior.

What causes isomers to have different biological functions?
Choices:
a) They have different molecular weights
b) They vary in hydrogen bonding
c) They have different 3D shapes
d) They dissolve differently
Back:
Correct Answer: c

Isomers can have different spatial arrangements, leading to different biological activities.

What type of reaction breaks polymers into monomers?
Choices:
a) Condensation
b) Hydrolysis
c) Isomerization
d) Neutralization
Back:
Correct Answer: b

Hydrolysis uses water to break covalent bonds between monomers in polymers.

Which of the following stores genetic information?
Choices:
a) Proteins
b) RNA
c) Phospholipids
d) Glucose
Back:
Correct Answer: b

RNA and DNA are nucleic acids responsible for storing and transmitting genetic information.

Which of the following is NOT part of the scientific method?
Choices:
a) Observation
b) Hypothesis formation
c) Religious belief
d) Experimentation
Back:
Correct Answer: c

The scientific method is based on testable and falsifiable evidence, unlike religious beliefs.

Which element does NOT follow the octet rule?
Choices:
a) Oxygen
b) Hydrogen
c) Nitrogen
d) Carbon
Back:
Correct Answer: b

Hydrogen only requires 2 electrons in its outer shell, so the octet rule doesn’t apply.

Which is false about protein structure?
Choices:
a) Tertiary structure uses hydrogen bonds
b) Shape determines function
c) Only ionic bonds hold shape
d) Denaturation affects shape
Back:
Correct Answer: c

Tertiary and quaternary protein structures are maintained by various interactions—not just ionic bonds.

Which of the following is a strong acid?
Choices:
a) HCl
b) Acetic acid
c) H₂SO₄
d) Carbonic acid
Back:
Correct Answer: c

Sulfuric acid (H₂SO₄) completely ionizes in water and is classified as a strong acid.

What is the pH of a solution with [H⁺] = 10⁻¹²?
Choices:
a) 2
b) 7
c) 12
d) 10
Back:
Correct Answer: c

pH = -log[H⁺] → pH = -log(10⁻¹²) = 12.

Which amino acid has a unique R group that forms a disulfide bridge?
Choices:
a) Glycine
b) Proline
c) Cysteine
d) Alanine
Back:
Correct Answer: c

Cysteine contains a sulfhydryl (-SH) group that can form disulfide bonds with another cysteine.

Which is responsible for cooling through evaporation?
Choices:
a) Water’s density
b) High specific heat
c) High heat of vaporization
d) Surface tension
Back:
Correct Answer: c

Water absorbs a large amount of heat when it evaporates, helping organisms regulate temperature.

What helps refold denatured proteins in cells?
Choices:
a) Kinases
b) Proteases
c) Chaperone proteins
d) Ligases
Back:
Correct Answer: c

Chaperones assist proteins in achieving proper folding after stress like heat shock.

Which organism first released oxygen into Earth’s atmosphere?
Choices:
a) Plants
b) Protists
c) Photosynthetic prokaryotes
d) Eukaryotes
Back:
Correct Answer: c

Cyanobacteria, a type of photosynthetic prokaryote, were the first organisms to produce oxygen.

Which trait is NOT shared by all living things?
Choices:
a) Regulation
b) Genetic material
c) Use of oxygen
d) Metabolism
Back

Not all living organisms require oxygen; some use anaerobic respiration or fermentation.