Biology Master Study Guide: Cells, Genetics, Evolution, and Photosynthesis

Scientific Hypothesis

A hypothesis must be testable and falsifiable.

Independent Variable (IV)

Manipulated variable plotted on the x-axis.

Dependent Variable (DV)

Measured variable plotted on the y-axis.

Control Variables

Variables kept constant in an experiment.

Control Group

Baseline comparison group in an experiment.

Placebo

Substance that reduces bias in human trials.

Controlled Experiment

Researcher manipulates the independent variable.

Observational Study

No manipulation; shows correlation, not causation.

Good Science

Reproducibility, peer review, testability, avoids pseudoscience.

Characteristics of Life

Cells, homeostasis, metabolism, growth & reproduction, response to environment.

Levels of Organization

Atom → molecule → organelle → cell → tissue → organ → system → organism → population → community → ecosystem → biosphere.

Prokaryotes

No nucleus, circular DNA, includes bacteria and archaea.

Eukaryotes

Contains a nucleus, linear chromosomes, includes animals, plants, fungi, protists.

Mitosis

1 division resulting in 2 identical diploid cells.

Meiosis

2 divisions resulting in 4 unique haploid gametes.

Transcription

Process where DNA is converted to mRNA.

Translation

Process where mRNA is translated into amino acids.

Mutations

Changes in DNA sequence; types include silent, missense, nonsense, frameshift.

Glycolysis

Occurs in cytoplasm, splits glucose, produces 2 ATP, 2 NADH, 2 pyruvate.

Krebs Cycle

Occurs in mitochondrial matrix, produces NADH, FADH₂, ATP, CO₂.

Electron Transport Chain

Uses NADH/FADH₂ to produce ~30 ATP; O₂ is the final electron acceptor.

10% Rule

Only 10% of energy transfers between trophic levels.

Biomagnification

Toxins accumulate in fat and become more concentrated at higher trophic levels.

Eutrophication

Process triggered by fertilizer runoff leading to oxygen depletion in water bodies.

Carbon Cycle

Photosynthesis ↔ respiration.

Nitrogen Cycle

Nitrogen-fixing bacteria convert N₂ to nitrate, which is used by plants.

Phosphorus Cycle

Phosphorus comes from rocks and is often a limiting nutrient in freshwater.

Evolution

Change in allele frequencies in a population over time.

Natural Selection

Acts on phenotypes, requires variation, heritability, and differential survival/reproduction.

Speciation

Requires reproductive isolation: geographic, behavioral, or temporal.

Innate Immunity

Fast, general defense mechanisms including barriers and immune cells.

Adaptive Immunity

Specific immune response involving B cells and T cells.

Photosynthesis Overall Equation

6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂.

Calvin Cycle

Occurs in stroma; uses CO₂, ATP, and NADPH to produce G3P.