South Carolina EOCEP Biology 1

Which organelle contains the cell's genetic material and controls cellular activities by regulating gene expression?

• AMitochondrion
• BRibosome
• CNucleus
• DGolgi apparatus

Muscle cells require large amounts of energy to contract continuously. Which cellular organelle is expected to be present in high density within muscle tissue?

• AChloroplast
• BMitochondrion
• CLysosome
• DVacuole

Proteins are macromolecules essential for cell structure, enzyme catalysis, and transport. What are the fundamental monomer subunits that link together to form polypeptides?

• AMonosaccharides
• BFatty acids
• CNucleotides
• DAmino acids

The cell membrane is composed of a phospholipid bilayer with embedded proteins. How are individual phospholipid molecules oriented within this bilayer?

• AHydrophilic heads face outward toward water, while hydrophobic tails face inward away fro…
• BHydrophobic heads face outward toward water, while hydrophilic tails face inward away fro…
• CBoth heads and tails face outward toward the intracellular fluid.
• DPhospholipids assemble in single-layer spheres with nonpolar heads touching water.

A model of photosynthesis shows arrows for the matter entering and leaving a leaf. Which set of inputs and outputs correctly represents photosynthesis?

• AInputs: oxygen and sugar; Outputs: carbon dioxide and water
• BInputs: carbon dioxide and water, using light energy; Outputs: sugar and oxygen
• CInputs: nitrogen and water; Outputs: protein and carbon dioxide
• DInputs: sugar and light energy; Outputs: carbon dioxide and oxygen

Mitosis is a vital process in somatic cell division. What is the primary outcome of mitotic cell division in multicellular organisms?

• AProduction of four genetically diverse haploid daughter cells
• BProduction of two genetically identical diploid daughter cells
• CReduction of chromosome number by half for gamete formation
• DRandom distribution of mutated chromosomes into reproductive cells

A cell synthesizes digestive enzymes destined for secretion outside the cell. Which sequence correctly traces the path of these proteins from synthesis to secretion?

• ASmooth ER → Nucleus → Ribosome → Cell Membrane
• BRibosome on Rough ER → Golgi Apparatus → Transport Vesicle → Cell Membrane
• CGolgi Apparatus → Ribosome → Mitochondria → Lysosome
• DNucleolus → Lysosome → Rough ER → Plasma Membrane

A student claims that the light energy absorbed by a plant is destroyed once the plant makes sugar. How should the claim be corrected using a model of photosynthesis?

• AThe claim is correct, because light energy disappears when it is absorbed by chlorophyll.
• BLight energy is not destroyed; it is transformed into chemical energy stored in the bonds…
• CLight energy is converted directly into the mass of the plant's water molecules.
• DLight energy is stored unchanged inside the chloroplast and released later as light.

A model of aerobic cellular respiration in a muscle cell should show which inputs and outputs?

• AInputs: carbon dioxide and water; Outputs: sugar and oxygen
• BInputs: sugar and oxygen; Outputs: carbon dioxide, water, and transferred energy
• CInputs: sugar and nitrogen; Outputs: protein and oxygen
• DInputs: oxygen and light; Outputs: sugar and carbon dioxide

A sprinter's leg muscles keep working after the oxygen supply cannot keep up with demand. What does comparing anaerobic with aerobic cellular respiration show about this situation?

• AAnaerobic respiration transfers much less usable energy per sugar molecule than aerobic r…
• BAnaerobic respiration transfers more usable energy per sugar molecule because no oxygen i…
• CAnaerobic respiration transfers exactly the same amount of energy, just more slowly.
• DAnaerobic respiration stores energy in sugar rather than releasing it.

Both carbohydrates and lipids store chemical energy in biological organisms. How do these two macromolecule classes differ in energy storage efficiency and cellular role?

• ACarbohydrates provide long-term energy storage, while lipids provide immediate, easily ac…
• BCarbohydrates store twice as much energy per gram as lipids due to heavy nitrogen bonding.
• CLipids yield more energy per gram than carbohydrates and provide long-term energy storage…
• DLipids are soluble in water and act as fast-acting energy sources during rapid exercise.

Nucleic acids such as DNA and RNA are polymers formed from nucleotide monomers. What three structural components make up every single nucleotide?

• AA nitrogenous base, a 5-carbon sugar, and a phosphate group
• BAn amino acid, a glycerol backbone, and three fatty acids
• CA monosaccharide, a peptide bond, and a lipid tail
• DA purine base, a carbon ring, and a protein subunit

An oak tree gains hundreds of kilograms of mass as it grows. Where does most of the carbon in that added mass originally come from?

• AMinerals absorbed from the soil by the roots
• BCarbon dioxide taken from the air and built into sugars during photosynthesis
• CWater absorbed from the soil and stored in the trunk
• DNitrogen gas absorbed directly from the atmosphere by the leaves

A human begins as a single fertilized egg but ends up with muscle cells, nerve cells, and skin cells that look and behave very differently. How is this possible if mitosis passes identical genetic material to every daughter cell?

• AEach cell type deletes the genes it does not need during mitosis.
• BThe cells keep the same genetic information but differentiate, using different parts of i…
• CMitosis gives each daughter cell a random half of the chromosomes.
• DNerve and muscle cells are produced by meiosis instead of mitosis.

During which phase of mitosis do duplicated chromosomes align in a single row along the equatorial plane of the cell?

• AProphase
• BMetaphase
• CAnaphase
• DTelophase

If a toxin inhibits the shortening of kinetochore microtubules during mitosis, which specific stage of cell division will be blocked?

• ATelophase
• BAnaphase
• CProphase
• DInterphase

Prior to undergoing mitosis, a cell must replicate its entire genome. During which subphase of interphase does DNA synthesis occur?

• AG1 phase (Gap 1)
• BS phase (Synthesis)
• CG2 phase (Gap 2)
• DM phase (Mitotic)

How does cytokinesis differ between dividing animal cells and plant cells?

• AAnimal cells construct a cell plate, whereas plant cells form a cleavage furrow.
• BAnimal cells pinch inward using an actin contractile ring (cleavage furrow), while plant…
• CPlant cells divide by binary fission, whereas animal cells divide by budding.
• DPlant cells undergo cytokinesis during G1 phase, while animal cells do so in S phase.

A genetic mutation causes lysosomes within a cell to lack acid hydrolase enzymes. What direct cellular consequence will occur?

• AThe cell will be unable to synthesize ATP during glycolysis.
• BUndigested cellular waste and damaged organelles will accumulate inside the cell.
• CDNA replication will cease during interphase.
• DSecretory vesicles will fail to fuse with the cell membrane.

A sealed terrarium containing only a green plant, soil, and air is placed in sunlight and stays alive for months. Which model best explains how matter keeps cycling inside the sealed container?

• AThe plant uses photosynthesis to build sugar and release oxygen, and cellular respiration…
• BThe plant only performs photosynthesis, so carbon dioxide is permanently removed and neve…
• CSunlight continuously creates new carbon atoms inside the sealed container.
• DThe soil converts oxygen directly into sugar without any biological process.

The sodium-potassium pump (Na+/K+-ATPase) maintains resting membrane potentials in animal cells. For each molecule of ATP hydrolyzed, what ions are transported and in which direction?

• A2 Na+ ions pumped out of the cell and 3 K+ ions pumped into the cell
• B3 Na+ ions pumped out of the cell and 2 K+ ions pumped into the cell
• C3 Na+ ions pumped into the cell and 3 K+ ions pumped out of the cell
• D1 Na+ ion and 1 K+ ion pumped out of the cell simultaneously

Disulfide bridges, ionic interactions, hydrogen bonds, and hydrophobic interactions between amino acid R-groups stabilize which specific level of protein structure?

• APrimary structure
• BSecondary structure
• CTertiary structure
• DQuaternary structure

Which statement best explains, in terms of matter flowing between organisms, how a consumer builds its own body from the food it eats?

• AA cow eats grass and gains mass, because the sugar built by the grass supplies carbon bac…
• BA cow eats grass and gains mass, because the cow performs photosynthesis inside its diges…
• CA cow gains mass mainly from the minerals dissolved in the water it drinks.
• DA cow gains mass because sunlight striking its hide is converted directly into body tissu…

Normal cells halt division at the G1 checkpoint if DNA damage is detected. If tumor suppressor protein p53 becomes nonfunctional due to a loss-of-function mutation, what will most likely occur?

• AThe cell will immediately enter G0 phase and stop dividing permanently.
• BThe cell will bypass DNA repair checkpoints, divide uncontrollably, and potentially accum…
• CThe cell will double its chromosome count in every subsequent mitosis without replicating…
• DThe cell will undergo rapid apoptosis before reaching metaphase.

According to Erwin Chargaff's rules of base pairing in double-stranded DNA, if a sample of DNA consists of 30% adenine (A), what percentage of the sample is cytosine (C)?

• A30%
• B20%
• C40%
• D60%

What type of chemical bonds hold the complementary nitrogenous base pairs together between the two opposing strands of a DNA double helix?

• ACovalent peptide bonds
• BIonic bonds
• CHydrogen bonds
• DPhosphodiester bonds

Where do transcription and translation take place within a eukaryotic cell?

• ATranscription occurs in the cytoplasm; translation occurs in the nucleus.
• BTranscription occurs in the nucleus; translation occurs in the cytoplasm at ribosomes.
• CBoth transcription and translation occur inside the mitochondria.
• DTranscription occurs at the cell membrane; translation occurs in the nucleolus.

What is the primary function of messenger RNA (mRNA) in protein synthesis?

• ATo transfer specific amino acids from the cytoplasm to the growing polypeptide chain
• BTo carry transcribed genetic instructions from nuclear DNA to the ribosome
• CTo form the structural core and enzymatic catalytic site of the ribosome
• DTo unwind double-stranded DNA during replication

Human somatic (body) cells contain 46 chromosomes (2n = 46). How many chromosomes are present in a human sperm or egg gamete produced via meiosis?

• A46 chromosomes
• B23 chromosomes
• C92 chromosomes
• D12 chromosomes

In pea plants, tall height (T) is dominant over short height (t). If two heterozygous tall pea plants (Tt × Tt) are crossed, what is the expected phenotypic ratio of their offspring?

• A100% tall
• B3 tall : 1 short
• C1 tall : 1 short
• D1 tall : 2 medium : 1 short

Which term describes the physical appearance or observable physiological trait of an organism resulting from its genetic inheritance?

• AGenotype
• BPhenotype
• CKaryotype
• DAllele

What is a mutation?

• AThe normal folding of a protein into its tertiary structure
• BA permanent change in the nucleotide sequence of an organism's DNA
• CThe movement of water across a selectively permeable membrane
• DThe breakdown of glucose during cellular respiration

DNA replication is described as semi-conservative. What does this mean regarding the composition of newly synthesized double-stranded DNA molecules?

• ABoth strands of the new DNA molecule are completely synthesized from scratch.
• BEach newly synthesized DNA molecule contains one original template strand and one newly c…
• CThe original DNA double helix remains intact, while an entirely new double helix is forme…
• DRandom segments of original and new DNA are spliced together on both strands.

Which enzyme is primarily responsible for adding complementary nucleotides to the growing DNA strand during DNA replication and proofreading for errors?

• ARNA polymerase
• BDNA polymerase
• CDNA ligase
• DHelicase

During DNA replication, what role is performed by the enzyme helicase?

• ASynthesizing short RNA primers on the lagging strand
• BUnwinding the double helix and separating complementary base pairs at the replication fork
• CAttaching amino acids to corresponding tRNA molecules
• DSealing single-strand breaks in the sugar-phosphate backbone

A mRNA codon reads 5'-AUG-3'. What is the corresponding anticodon sequence present on the matching tRNA molecule that delivers methionine?

• A3'-UAC-5'
• B3'-TAC-5'
• C3'-CAU-5'
• D3'-GUA-5'

How do DNA and RNA molecules differ in their sugar composition, nitrogenous bases, and strandedness?

• ADNA contains ribose, uracil, and is single-stranded; RNA contains deoxyribose, thymine, a…
• BDNA contains deoxyribose, thymine, and is typically double-stranded; RNA contains ribose,…
• CDNA contains adenine and guanine; RNA lacks purine bases entirely.
• DDNA is synthesized in the cytoplasm; RNA is synthesized exclusively in lysosomes.

During Prophase I of meiosis, nonsister chromatids of homologous chromosomes pair up to form tetrads and exchange genetic material. What is this process called and what is its biological significance?

• ANondisjunction; it leads to missing chromosomes in all offspring.
• BCrossing over (recombination); it increases genetic diversity in gametes.
• CCytokinesis; it splits the cell into four identical somatic units.
• DTranscription; it doubles the amount of mRNA available for translation.

Independent assortment during Metaphase I of meiosis generates genetic variation because homologous chromosome pairs align randomly at the cell equator. How many unique chromosome combinations can human gametes form from independent assortment alone (2^n, where n = 23)?

• A46 combinations
• B460 combinations
• COver 8 million combinations (2^23)
• D23 combinations

Cystic fibrosis is an autosomal recessive genetic disorder (f). Two parents who are both asymptomatic carriers (Ff) plan to have a child. What is the probability that their child will inherit cystic fibrosis?

• A0% (0/4)
• B25% (1/4)
• C50% (2/4)
• D75% (3/4)

A dihybrid cross is performed between two pea plants heterozygous for seed color and seed shape (YyRr × YyRr). Assuming independent assortment and complete dominance, what phenotypic ratio is expected in the F1 generation?

• A3 : 1
• B1 : 2 : 1
• C9 : 3 : 3 : 1
• D9 : 6 : 1

A mother with blood type A (genotype IAi) and a father with blood type B (genotype IBi) have a child. Which of the following blood types could their child potentially inherit?

• AOnly Type AB
• BOnly Type A or Type B
• CTypes A, B, AB, or O
• DOnly Type O

When a true-breeding red snapdragon (CRCR) is crossed with a true-breeding white snapdragon (CWCW), all F1 offspring have pink flowers (CRCW). What inheritance pattern does flower color display in snapdragons?

• AComplete dominance
• BIncomplete dominance
• CCodominance
• DSex-linked inheritance

Red-green colorblindness is an X-linked recessive trait (Xb). A female carrier for colorblindness (XBXb) marries a male with normal vision (XBY). What is the probability that their sons will be colorblind?

• A0%
• B25%
• C50%
• D100%

A point mutation changes a codon in mRNA from 5'-GAA-3' to 5'-GAG-3'. Both codons code for the amino acid glutamic acid. What type of mutation occurred?

• AMissense mutation
• BNonsense mutation
• CSilent mutation
• DFrameshift mutation

A single nucleotide insertion occurs early in the coding region of a gene. Why does a frameshift mutation generally result in a completely nonfunctional protein?

• AIt alters every codon downstream of the insertion, completely changing the amino acid seq…
• BIt prevents DNA polymerase from binding to the promoter region.
• CIt converts all purine bases into pyrimidine bases throughout the chromosome.
• DIt forces the ribosome to synthesize lipids instead of polypeptides.

A DNA template strand reads: 3'-TAC-TGA-TGG-ACT-5'. What is the amino acid sequence encoded after transcription to mRNA and translation? (Codons: AUG = Met, ACU = Thr, ACC = Thr, UGA = Stop)

• AMet - Thr - Thr - Stop
• BMet - Stop - Thr - Thr
• CTyr - Stop - Trp - Thr
• DMet - Thr - Trp - Stop