AP Biology Exam Preparation Notes

Overview of AP Biology Exam Preparation

Unit 1: Chemistry of Life

• Water: The polar molecule critical for life due to hydrogen bonding, leading to properties such as:

  • Adhesion

  • Cohesion

  • Surface tension

  • High specific heat

  • Universal solvent

• Biological Molecules:

  • Carbohydrates: Monomers end in -ose; energy sources and structural materials (1:2:1 ratio of C:H:O).

  • Types: Rings or chains, short and long-term energy sources.

  • Lipids: Non-polar molecules with a high H:O ratio; includes fatty acids (saturated vs. unsaturated).

  • Key in phospholipid bilayer fluidity.

  • Proteins: Polypeptides that perform diverse functions divided by structure and function.

  • Nucleic Acids: Made of nucleotide monomers; DNA and RNA functions to be detailed in Unit 5.

• Polymer formation: Dehydration synthesis; breakdown: hydrolysis.

Unit 2: Cell Structure and Function

• Cell Types: Prokaryotic (simple) vs. Eukaryotic (complex).

• Importance of size for surface area to volume ratio for efficient exchange of materials.

• Eukaryotic organelles: Majority are membrane-bound; includes:

  • Rough ER (RER)

  • Smooth ER (SER)

  • Golgi apparatus

• Ribosomes are not membrane-bound organelles.

• Transport Mechanisms:

  • Active transport: Requires ATP; moves substances against concentration gradient.

  • Passive transport: Moves molecules along concentration gradient (diffusion and osmosis).

  • Endo/Exocytosis: Mechanisms for large molecule transport across membranes.

Unit 3: Cellular Energetics

• Focus on the flow of energy in biochemical processes.

• Enzymes: Protein catalysts that lower activation energy; not consumed in reactions but subject to denaturation.

• Photosynthesis:

  • Light reactions in thylakoids; Calvin cycle in stroma.

• Cellular Respiration:

  • Glycolysis (cytoplasm), Krebs cycle (mitochondrial matrix), Electron Transport Chain (cristae); ATP produced through oxidative phosphorylation.

• Fitness: Concept that organisms with advantageous traits have improved survival and reproductive success.

Unit 4: Cell Communication and Cell Cycle

• Communication: Autocrine, paracrine, endocrine signaling; important for cellular response and homeostasis.

• Signal Transduction Pathway: Steps include reception, transduction (often involving phosphorylation), and response.

• Cell Cycle:

  • Interphase stages: G1, S (DNA synthesis), G2.

  • Mitosis stages: prophase, metaphase, anaphase, telophase followed by cytokinesis.

  • Checkpoints regulated by cyclins and CDKs.

Unit 5: Heredity

• Meiosis: Process for gamete formation; includes PMAT twice and leads to genetic diversity.

• Understanding Mendelian vs. Non-Mendelian genetics (e.g., independent assortment, codominance).

• Chromosomal Disorders: Caused by nondisjunction, deletion, inversion, translocation.

• Tools: Punnett squares, pedigrees, probability rules, Chi-square analysis for genetics.

Unit 6: Gene Expression and Regulation

• Nucleic Acids:

  • DNA (double-stranded) vs. RNA (single-stranded) structure and function.

• Central Dogma: DNA -> RNA -> Protein

  • Transcription in nucleus (via RNA polymerase), processing mRNA.

  • Translation at ribosome (tRNA brings amino acids based on mRNA codons).

• Regulation of gene expression; biotechnology techniques like PCR and gel electrophoresis.

Unit 7: Natural Selection

• Natural Selection: Requires variation, struggle for existence; environment drives hereditary trait success.

• Evolution: Change in allele frequency; mechanisms include natural selection, mutation, genetic drift, non-random mating.

• Hardy-Weinberg Equilibrium: Conditions for a stable population base.

• Evidence for evolution includes fossil records, biogeography, homologous structures.

• Processes of speciation and extinction; building phylogenetic trees and cladograms.

Unit 8: Ecology

• Organism-environment interactions, ecological niches, and community dynamics.

• Energy flow: from autotrophs to heterotrophs (food web dynamics).

• Population Growth Factors: Resource availability, carrying capacity.

  • Review relevant equations and graphical interpretations.

• Relationships within communities: predation, competition, symbiosis.

• Human impact on ecosystems: ecosystem disruption and biodiversity loss.

More Detailed:

Unit 1: Chemistry of Life

• Water: The polar molecule critical for supporting life due to its hydrogen bonding capabilities, leading to essential properties:

  • Adhesion: The ability of water to stick to other substances, crucial for processes like capillary action in plants.

  • Cohesion: Water molecules attracting each other, resulting in surface tension that affects organisms in aquatic environments.

  • High specific heat: The capacity of water to absorb and retain heat, which helps regulate temperature in organisms and environments.

  • Universal solvent: Water's ability to dissolve a wide range of substances, facilitating biochemical reactions within cells.

• Biological Molecules:

  • Carbohydrates: Monomer units typically ending in -ose, serving as key energy sources and structural materials with a stoichiometric ratio of 1:2:1 for carbon, hydrogen, and oxygen.

  • Types: Exist as rings or chains, functioning as short-term energy sources (e.g., glucose) or structural components (e.g., cellulose in plant cell walls).

  • Lipids: Non-polar molecules with a high hydrogen to oxygen ratio; these include fatty acids that may be saturated (single bonds) or unsaturated (double bonds).

  • Function: Essential for forming the phospholipid bilayer of cell membranes, impacting fluidity and permeability.

  • Proteins: Composed of polypeptides that carry out diverse biological functions; their structure and function are closely linked, influenced by amino acid sequence.

  • Function types: Enzymatic, structural, transport, and signaling roles among others.

  • Nucleic Acids: Comprised of nucleotide monomers, serving as the blueprint for life; DNA involves double-helix structure, while RNA plays various roles including mRNA, tRNA, and rRNA, which will be detailed in Unit 5.

• Polymer formation: Involves processes of dehydration synthesis to create larger macromolecules and hydrolysis for their breakdown.

Unit 2: Cell Structure and Function

• Cell Types: Comparison between Prokaryotic (simple, no nucleus, e.g., bacteria) and Eukaryotic (complex, with membrane-bound organelles, e.g., plant and animal cells).

• Importance of Size: The significance of maintaining a favorable surface area to volume ratio to maximize efficiency in the exchange of materials, vital for metabolic processes.

• Eukaryotic Organelles: Majority are membrane-bound and perform specific functions:

  • Rough ER (RER): Studded with ribosomes, involved in protein synthesis and modification.

  • Smooth ER (SER): Lacks ribosomes, associated with lipid synthesis and detoxification processes.

  • Golgi Apparatus: The site for processing and packaging proteins and lipids before distribution.

  • Ribosomes: Non-membrane-bound organelles essential for protein synthesis, found free-floating in the cytoplasm or attached to the rough ER.

• Transport Mechanisms:

  • Active Transport: Requires energy (ATP) to move substances against their concentration gradient, crucial for maintaining cellular homeostasis.

  • Passive Transport: Facilitates movement of molecules along concentration gradients through processes such as diffusion and osmosis.

  • Endo/Exocytosis: Mechanisms for the transport of large molecules across cellular membranes, essential for nutrient uptake and waste removal.

Unit 3: Cellular Energetics

• Focus: The flow of energy in biochemical processes, emphasizing the transformation of energy through metabolic pathways.

• Enzymes: Proteins that act as catalysts in biochemical reactions, lowering the activation energy needed; they remain unchanged after reactions but can be denatured by extreme conditions.

  • Photosynthesis:

  • Light Reactions: Occur in thylakoids, converting solar energy to chemical energy (ATP and NADPH).

  • Calvin Cycle: Takes place in the stroma, synthesizing glucose from carbon dioxide using energy carriers from the light reactions.

  • Cellular Respiration: Series of metabolic processes that convert biochemical energy from nutrients into ATP, including:

  • Glycolysis: Occurs in the cytoplasm and breaks down glucose into pyruvate, generating small amounts of ATP and NADH.

  • Krebs cycle: Occurs in the mitochondrial matrix, further breaking down pyruvate to produce NADH and FADH₂.

  • Electron Transport Chain: Located in the cristae of the mitochondria, this stage creates a large amount of ATP through oxidative phosphorylation utilizing oxygen as the final electron acceptor.

  • Fitness: The concept that organisms with advantageous traits have higher survival and reproductive success within their environments, driving natural selection.

Unit 4: Cell Communication and the Cell Cycle

• Communication: Mechanisms including autocrine, paracrine, and endocrine signaling that facilitate cellular response and maintain homeostasis within organisms.

• Signal Transduction Pathway: Comprises the stages of reception, transduction (often involving phosphorylation cascades), and response, allowing cells to respond to external signals.

• Cell Cycle:

  • Interphase Stages: G1 (cell growth), S (DNA synthesis), and G2 (preparation for mitosis).

  • Stages of Mitosis: Prophase, metaphase, anaphase, telophase, followed by cytokinesis which divides the cytoplasm.

  • Checkpoints: Regulated by proteins such as cyclins and cyclin-dependent kinases (CDKs) to ensure proper cell cycle progression and prevent errors.

Unit 5: Heredity

• Meiosis: The specialized division process for gamete formation, consisting of two rounds of PMAT that lead to genetic diversity among offspring.

• Mendelian vs. Non-Mendelian Genetics: Understanding inheritance patterns; Mendelian genetics involves simple dominant and recessive traits, while non-Mendelian covers variations such as codominance and incomplete dominance.

• Chromosomal Disorders: Result from errors in chromosome segregation including nondisjunction, deletion, inversion, and translocation events.

• Tools: Understanding genetic concepts through Punnett squares, pedigrees, probability rules, and Chi-square analysis for genetics assessments.

Unit 6: Gene Expression and Regulation

• Nucleic Acids:

  • Structure and Function: Differences between DNA (double-stranded) and RNA (single-stranded), with DNA storing genetic information and RNA playing roles in protein synthesis.

  • Central Dogma: The flow of genetic information illustrated as DNA -> RNA -> Protein, critical for understanding molecular biology.

  • Transcription: Occurs in the nucleus using RNA polymerase to synthesize mRNA from a DNA template.

  • Translation: Occurs at the ribosome where tRNA brings appropriate amino acids based on mRNA codons to form polypeptides.

  • Regulation of gene expression: Includes mechanisms controlling when and how genes are expressed, utilizing techniques such as PCR and gel electrophoresis for analysis.

Unit 7: Natural Selection

• Natural Selection: A process requiring variation within a population and competition for resources, where certain hereditary traits enhance an organism's fitness and thus are passed on.

• Evolution: Defined as changes in allele frequencies within a population over time, facilitated by mechanisms including natural selection, mutation rates, genetic drift, and non-random mating strategies.

• Hardy-Weinberg Equilibrium: Conditions necessary for a stable population, serving as a baseline for measuring evolutionary change.

• Evidence for Evolution: Includes fossil records, biogeographical patterns, homologous structures, and molecular comparisons that establish evolutionary links.

• Speciation and Extinction: The processes leading to the formation of new species or the loss of species, emphasizing the importance of evolutionary dynamics, including how to construct phylogenetic trees and cladograms to represent evolutionary relationships.

Unit 8: Ecology

• Organism-Environment Interactions: Examination of how organisms interact with their environments and each other, emphasizing ecological niches and community dynamics.

• Energy Flow: The transfer of energy through ecosystems, highlighting the role of autotrophs and heterotrophs within food web dynamics.

• Population Growth Factors: Influences such as resource availability and carrying capacity that affect population sizes over time; important graphs and equations should be reviewed to analyze trends.

• Community Relationships: Types of biological interactions including predation, competition, and symbiotic relationships, revealing the complexity of ecological interactions.

• Human Impact: The effects of human activities on ecosystems, showcasing issues like ecosystem disruption, habitat loss, and biodiversity decline due to industrialization and climate change.

Conclusion