Biology Exam Review – Experimental Design, Enzymes, Respiration, Cell Division & Genetics

46 vocabulary flashcards summarizing key experimental design concepts, enzyme function, respiration, cell division, and genetics to support exam preparation.

Independent Variable (IV)

The factor the experimenter intentionally changes to test its effect.

Dependent Variable (DV)

The factor that is measured or observed; the data collected in an experiment.

Controlled Variable (CV)

Any factor kept constant to ensure that results are due only to the independent variable.

Null Hypothesis

A prediction that states there is no effect or difference between variables (e.g., ‘Substance X does not affect growth’).

Enzyme

A protein catalyst that speeds up biochemical reactions by lowering activation energy and is reusable.

Catalyst

A substance that increases the rate of a chemical reaction without being consumed; all enzymes are biological catalysts.

Activation Energy

The minimum amount of energy required to start a chemical reaction.

Active Site

The specific region on an enzyme where the substrate binds and the reaction occurs.

Substrate

The reactant molecule(s) upon which an enzyme acts.

Denaturation

Loss of an enzyme’s shape (and function) due to extreme temperature or pH.

Bromelain

Protease enzyme in fresh pineapple that breaks down gelatin protein, preventing JELL-O from setting.

Endotherm

Organism that generates body heat internally; maintains constant body temperature (e.g., humans).

Ectotherm

Organism whose body temperature depends on external environmental heat (e.g., snakes, goldfish).

Metabolic Rate

Speed of chemical reactions in an organism; increases with temperature in ectotherms.

Aerobic Cellular Respiration

Oxygen-requiring process that breaks down glucose to produce ATP, CO₂, and H₂O.

Cytoplasm (in respiration)

Site of glycolysis, the first stage of aerobic respiration.

Mitochondria

Organelle where the Krebs cycle and oxidative phosphorylation occur during aerobic respiration.

Gas Exchange

Breathing process that supplies O₂ for and removes CO₂ from cellular respiration.

ATP (Adenosine Triphosphate)

The primary energy currency produced by cellular respiration.

Mitosis

Nuclear division that produces two identical diploid somatic cells for growth and repair.

Somatic Cell

Any body cell other than sperm or egg; divides by mitosis and is diploid.

Cell Cycle

Ordered sequence of events: Interphase (G₁, S, G₂), Mitosis, and Cytokinesis.

Interphase

Longest cell-cycle phase where the cell grows, replicates DNA, and prepares for division.

Prophase

First mitotic stage: chromosomes condense, nuclear envelope breaks, spindle forms.

Metaphase

Mitotic stage where chromosomes line up at the cell’s equatorial metaphase plate.

Anaphase

Mitotic stage where sister chromatids separate and move toward opposite poles.

Telophase

Mitotic stage where nuclear envelopes reform around chromosomes at each pole.

Cytokinesis

Division of the cytoplasm, producing two separate daughter cells.

Meiosis

Two-division process that produces four genetically diverse haploid gametes.

Homologous Chromosome

Pair of chromosomes with the same genes but possibly different alleles; one from each parent.

Sister Chromatids

Identical copies of a chromosome connected at the centromere after DNA replication.

Haploid (n)

Cell containing one complete set of chromosomes; found in gametes.

Diploid (2n)

Cell containing two sets of chromosomes; characteristic of most body cells.

Gamete

Haploid reproductive cell (sperm or egg) formed by meiosis.

Spindle Fibers

Microtubules that attach to chromosomes and move them during cell division.

Nuclear Envelope

Double membrane surrounding the nucleus; disassembles during prophase and reforms in telophase.

Metaphase Plate

Imaginary plane in the cell where chromosomes align during metaphase.

Tetrad

Group of four chromatids formed by homologous chromosome pairing in Prophase I of meiosis.

Crossing Over

Exchange of DNA segments between homologous chromatids during Prophase I, increasing genetic diversity.

Independent Assortment

Random orientation of homologous pairs during Metaphase I, producing varied gamete combinations.

Law of Segregation

Mendel’s principle that alleles separate during gamete formation so each gamete carries one allele per gene.

Law of Independent Assortment

Mendel’s principle that alleles of different genes segregate into gametes independently of each other.

Polygenic Trait

Trait controlled by several genes, showing a wide range of phenotypes (e.g., human skin color).

Incomplete Dominance

Inheritance where heterozygotes display an intermediate phenotype (e.g., red × white flowers → pink).

Codominance

Inheritance where two dominant alleles are both fully expressed in heterozygotes (e.g., AB blood type).

Punnett Square

Diagram that predicts offspring genotype and phenotype ratios based on parental alleles.

Random Fertilization

Chance union of any sperm with any egg, adding to genetic variability in offspring.

Crossing Over, Independent Assortment & Random Fertilization

The three main sources of genetic diversity generated during meiosis and sexual reproduction.