Biology Eoc Review Packet Answer Key

Let's explore the concepts covered in a Biology End-of-Course (EOC) review packet, diving into key areas of study and providing insights to help you succeed. While an "answer key" provides quick solutions, a deeper understanding of the underlying principles is crucial for truly mastering biology.

The Building Blocks of Life: From Molecules to Cells

Biology, at its core, is the study of life. Life, in all its diversity, shares fundamental characteristics and is built upon a hierarchy of organization. We begin our review at the smallest level, the molecular level, and work our way up to the complexity of cells.

Chemical Basis of Life

All living organisms are composed of matter, which consists of chemical elements in pure form or combined into compounds. Key concepts include:

• Elements Essential for Life: Carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur (often remembered as CHNOPS) are the most abundant elements in living organisms.
• Macromolecules: These are large polymers assembled from smaller repeating monomers. The four major classes of macromolecules are:
  • Carbohydrates: Primarily used for energy storage and structural support. Monomer: monosaccharides (e.g., glucose, fructose).
  • Lipids: Diverse group including fats, oils, phospholipids, and steroids. Functions include energy storage, insulation, and forming cell membranes. Monomers: glycerol and fatty acids (though lipids are not true polymers).
  • Proteins: Perform a vast array of functions, including enzymatic catalysis, structural support, transport, defense, and signaling. Monomer: amino acids.
  • Nucleic Acids: Store and transmit genetic information. DNA and RNA are the two types. Monomer: nucleotides.
• Water: Its unique properties, such as high heat capacity, cohesion, adhesion, and its role as a versatile solvent, make it essential for life.
• Acids, Bases, and pH: Understanding the pH scale and the importance of buffers in maintaining cellular homeostasis.

Cell Structure and Function

The cell is the basic unit of life. All organisms are composed of one or more cells. Key concepts include:

• Cell Theory:
  • All living things are composed of cells.
  • The cell is the basic unit of structure and function in living things.
  • All cells arise from pre-existing cells.
• Prokaryotic vs. Eukaryotic Cells: Prokaryotic cells (bacteria and archaea) lack a nucleus and other membrane-bound organelles, while eukaryotic cells (protists, fungi, plants, and animals) possess a nucleus and complex internal organization.
• Organelles: Membrane-bound structures within eukaryotic cells that perform specific functions. Key organelles include:
  • Nucleus: Contains the cell's DNA and controls cellular activities.
  • Ribosomes: Synthesize proteins.
  • Endoplasmic Reticulum (ER): Involved in protein synthesis and lipid metabolism. Smooth ER lacks ribosomes; rough ER has ribosomes.
  • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.
  • Lysosomes: Contain enzymes for intracellular digestion.
  • Mitochondria: Site of cellular respiration, generating ATP.
  • Chloroplasts (in plant cells): Site of photosynthesis.
  • Cell Membrane: Selectively permeable barrier that controls the movement of substances into and out of the cell. Composed of a phospholipid bilayer with embedded proteins.
  • Cell Wall (in plant cells): Provides structural support and protection.

Cell Transport

Cells must exchange materials with their environment. This occurs through various mechanisms:

• Passive Transport: Does not require energy input from the cell.
  • Diffusion: Movement of molecules from an area of high concentration to an area of low concentration.
  • Osmosis: Movement of water across a selectively permeable membrane from an area of high water concentration to an area of low water concentration (or from an area of low solute concentration to an area of high solute concentration).
  • Facilitated Diffusion: Movement of molecules across a membrane with the help of transport proteins.
• Active Transport: Requires energy input (usually in the form of ATP) to move molecules against their concentration gradient.
  • Pumps: Transport proteins that use ATP to move specific ions or molecules across the membrane.
  • Endocytosis: Process by which the cell takes in macromolecules by forming vesicles from the plasma membrane.
  • Exocytosis: Process by which the cell releases macromolecules by fusing vesicles with the plasma membrane.

Energy and Life: Photosynthesis and Cellular Respiration

Living organisms require energy to carry out their functions. This energy is obtained through two major processes: photosynthesis and cellular respiration.

Photosynthesis

Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose. The overall equation for photosynthesis is:

6CO2 + 6H2O + Light Energy → C6H12O6 + 6O2

Key concepts include:

• Chloroplasts: The site of photosynthesis in plant cells.
• Light-Dependent Reactions: Occur in the thylakoid membranes of the chloroplasts. Light energy is absorbed by chlorophyll and used to split water molecules, releasing oxygen and generating ATP and NADPH.
• Calvin Cycle (Light-Independent Reactions): Occurs in the stroma of the chloroplasts. ATP and NADPH from the light-dependent reactions are used to fix carbon dioxide and produce glucose.
• Factors Affecting Photosynthesis: Light intensity, carbon dioxide concentration, and temperature.

Cellular Respiration

Cellular respiration is the process by which cells break down glucose to release energy in the form of ATP. The overall equation for cellular respiration is:

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

Key concepts include:

• Mitochondria: The site of cellular respiration in eukaryotic cells.
• Glycolysis: Occurs in the cytoplasm. Glucose is broken down into pyruvate, producing a small amount of ATP and NADH.
• Krebs Cycle (Citric Acid Cycle): Occurs in the mitochondrial matrix. Pyruvate is further broken down, releasing carbon dioxide and generating ATP, NADH, and FADH2.
• Electron Transport Chain: Occurs in the inner mitochondrial membrane. Electrons from NADH and FADH2 are passed along a series of protein complexes, releasing energy that is used to pump protons across the membrane, creating a proton gradient. The energy stored in this gradient is then used to produce ATP through chemiosmosis.
• Aerobic vs. Anaerobic Respiration: Aerobic respiration requires oxygen and produces a large amount of ATP. Anaerobic respiration (fermentation) does not require oxygen and produces a much smaller amount of ATP. Types of fermentation include alcoholic fermentation (in yeast) and lactic acid fermentation (in muscle cells).

Genetics and Heredity: The Blueprint of Life

Genetics is the study of heredity, the transmission of traits from parents to offspring. Key concepts include:

DNA Structure and Function

• Structure of DNA: DNA is a double helix composed of two strands of nucleotides. Each nucleotide consists of a deoxyribose sugar, a phosphate group, and a nitrogenous base. The nitrogenous bases are adenine (A), guanine (G), cytosine (C), and thymine (T). A pairs with T, and G pairs with C.
• DNA Replication: The process by which DNA is copied. DNA replication is semiconservative, meaning that each new DNA molecule consists of one original strand and one newly synthesized strand.
• Genes and Chromosomes: Genes are segments of DNA that code for specific proteins. Genes are located on chromosomes, which are structures made of DNA and protein that are found in the nucleus of eukaryotic cells.
• Central Dogma of Molecular Biology: DNA → RNA → Protein. This describes the flow of genetic information from DNA to RNA to protein.

RNA Structure and Function

• Structure of RNA: RNA is a single-stranded nucleic acid that is similar to DNA, but with a few key differences: the sugar is ribose instead of deoxyribose, and the nitrogenous base uracil (U) replaces thymine (T).
• Types of RNA:
  • Messenger RNA (mRNA): Carries genetic information from DNA to the ribosomes.
  • Transfer RNA (tRNA): Carries amino acids to the ribosomes during protein synthesis.
  • Ribosomal RNA (rRNA): A component of ribosomes.

Protein Synthesis

Protein synthesis involves two main processes: transcription and translation.

• Transcription: The process by which DNA is transcribed into mRNA. This occurs in the nucleus.
• Translation: The process by which mRNA is translated into a protein. This occurs in the ribosomes.

Genetic Variation

Genetic variation is essential for evolution. Key concepts include:

• Mutations: Changes in the DNA sequence. Mutations can be spontaneous or caused by environmental factors. Mutations can be harmful, beneficial, or neutral.
• Meiosis and Sexual Reproduction: Meiosis is a type of cell division that produces gametes (sperm and egg cells). Sexual reproduction involves the fusion of gametes, resulting in offspring with a unique combination of genes from both parents.
• Genetic Recombination: During meiosis, homologous chromosomes can exchange genetic material through a process called crossing over, which further increases genetic variation.

Mendelian Genetics

• Mendel's Laws:
  • Law of Segregation: Each individual has two alleles for each gene, and these alleles separate during gamete formation.
  • Law of Independent Assortment: The alleles of different genes assort independently of one another during gamete formation.
• Dominant and Recessive Alleles: Dominant alleles are expressed even when only one copy is present, while recessive alleles are only expressed when two copies are present.
• Genotype and Phenotype: Genotype refers to the genetic makeup of an individual, while phenotype refers to the observable characteristics of an individual.
• Punnett Squares: Used to predict the genotypes and phenotypes of offspring from a cross between two parents.
• Monohybrid and Dihybrid Crosses: Monohybrid crosses involve one gene, while dihybrid crosses involve two genes.

Beyond Mendelian Genetics

• Incomplete Dominance: Neither allele is completely dominant, resulting in a blended phenotype.
• Codominance: Both alleles are expressed equally.
• Multiple Alleles: More than two alleles exist for a particular gene.
• Sex-Linked Traits: Genes located on the sex chromosomes (X and Y).
• Polygenic Traits: Traits controlled by multiple genes.
• Epistasis: One gene affects the expression of another gene.

Evolution and Diversity: The Tree of Life

Evolution is the process by which populations of organisms change over time. It's the unifying theme of biology, explaining the diversity and unity of life.

Evidence for Evolution

• Fossil Record: Provides evidence of extinct organisms and the changes that have occurred in life over time.
• Comparative Anatomy: Similarities in the anatomy of different organisms suggest common ancestry.
  • Homologous Structures: Structures that have a similar underlying anatomy but different functions, indicating common ancestry.
  • Analogous Structures: Structures that have similar functions but different underlying anatomy, indicating convergent evolution.
  • Vestigial Structures: Structures that have no apparent function but are remnants of structures that were functional in ancestral organisms.
• Comparative Embryology: Similarities in the embryonic development of different organisms suggest common ancestry.
• Molecular Biology: Similarities in the DNA and protein sequences of different organisms suggest common ancestry.
• Biogeography: The geographic distribution of organisms.

Mechanisms of Evolution

• Natural Selection: The process by which individuals with traits that are better suited to their environment survive and reproduce at a higher rate than individuals with less favorable traits.
  • Variation: Individuals within a population vary in their traits.
  • Inheritance: Traits are passed from parents to offspring.
  • Differential Survival and Reproduction: Individuals with certain traits are more likely to survive and reproduce than individuals with other traits.
  • Adaptation: Over time, the population becomes better adapted to its environment.
• Genetic Drift: Random changes in the allele frequencies of a population. Genetic drift is more likely to occur in small populations.
  • Bottleneck Effect: A sudden reduction in population size due to a chance event.
  • Founder Effect: A small group of individuals colonizes a new area.
• Gene Flow: The transfer of genes between populations.
• Mutation: The ultimate source of new genetic variation.
• Non-random Mating: Mating that is not random can alter allele frequencies in a population. Examples include assortative mating (mating with individuals that are similar to oneself) and sexual selection (mating based on certain traits).

Speciation

Speciation is the process by which new species arise. Key concepts include:

• Species Concepts:
  • Biological Species Concept: A species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but do not interbreed with other such groups.
  • Morphological Species Concept: A species is a group of individuals that share similar physical characteristics.
  • Ecological Species Concept: A species is a group of individuals that occupy the same ecological niche.
  • Phylogenetic Species Concept: A species is a group of individuals that share a unique evolutionary history.
• Reproductive Isolation: The existence of biological factors (barriers) that impede members of two species from interbreeding and producing viable, fertile offspring.
  • Prezygotic Barriers: Barriers that prevent mating or fertilization. Examples include habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, and gametic isolation.
  • Postzygotic Barriers: Barriers that occur after the formation of a hybrid zygote. Examples include reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown.
• Allopatric Speciation: Speciation that occurs when populations are geographically isolated from one another.
• Sympatric Speciation: Speciation that occurs in the same geographic area.

Classification and Phylogeny

• Taxonomy: The science of classifying organisms.
• Phylogeny: The evolutionary history of a species or group of species.
• Taxonomic Hierarchy: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
• Phylogenetic Trees: Visual representations of the evolutionary relationships among organisms.

Ecology: Interactions in the Biosphere

Ecology is the study of the interactions between organisms and their environment.

Levels of Ecological Study

• Organismal Ecology: Studies how an organism's structure, physiology, and behavior meet the challenges posed by its environment.
• Population Ecology: Studies the factors that affect population size and density.
• Community Ecology: Studies the interactions between different species in a community.
• Ecosystem Ecology: Studies the flow of energy and the cycling of nutrients in an ecosystem.
• Landscape Ecology: Studies the interactions between different ecosystems.
• Global Ecology: Studies the interactions between the Earth's ecosystems and the atmosphere, land, and oceans.

Population Ecology

• Population Density: The number of individuals per unit area or volume.
• Population Dispersion: The pattern of spacing among individuals within the boundaries of a population. Types of dispersion include clumped, uniform, and random.
• Population Growth: Factors that affect population growth include birth rate, death rate, immigration, and emigration.
• Exponential Growth: Population growth under ideal conditions.
• Logistic Growth: Population growth that is limited by carrying capacity (the maximum population size that an environment can support).
• Life History: The traits that affect an organism's schedule of reproduction and survival.

Community Ecology

• Interspecific Interactions: Interactions between different species.
  • Competition: (-/- interaction) When two or more species require the same limited resource.
  • Predation: (+/- interaction) One species (the predator) kills and eats the other species (the prey).
  • Herbivory: (+/- interaction) One species (the herbivore) eats parts of a plant or alga.
  • Symbiosis: A close relationship between two species. Types of symbiosis include:
    • Parasitism: (+/- interaction) One species (the parasite) benefits at the expense of the other species (the host).
    • Mutualism: (+/+ interaction) Both species benefit.
    • Commensalism: (+/0 interaction) One species benefits and the other species is neither harmed nor helped.
• Trophic Structure: The feeding relationships between organisms in a community.
• Food Chains and Food Webs: Visual representations of the flow of energy and nutrients through a community.
• Ecological Succession: The gradual process of change in the species structure of an ecological community over time.
  • Primary Succession: Occurs in an area where no soil exists.
  • Secondary Succession: Occurs in an area where soil exists.

Ecosystem Ecology

• Energy Flow: The movement of energy through an ecosystem. Energy flows from the sun to producers (plants), then to consumers (herbivores and carnivores), and eventually to decomposers (bacteria and fungi).
• Nutrient Cycling: The movement of nutrients through an ecosystem. Nutrients are recycled between the biotic (living) and abiotic (non-living) components of the ecosystem.
• Primary Production: The amount of light energy converted to chemical energy by autotrophs during a given time period.
• Trophic Efficiency: The percentage of energy transferred from one trophic level to the next. Typically around 10%.
• Biogeochemical Cycles: The cycling of nutrients through ecosystems. Examples include the water cycle, the carbon cycle, the nitrogen cycle, and the phosphorus cycle.

Conservation Biology

• Biodiversity: The variety of life in the world or in a particular habitat or ecosystem.
• Threats to Biodiversity: Habitat loss, invasive species, overexploitation, pollution, and climate change.
• Conservation Strategies: Protecting endangered species, restoring ecosystems, and promoting sustainable practices.

Mastering the Biology EOC

While this review covers many key concepts, remember that truly mastering biology requires more than just memorizing facts. Focus on understanding the underlying principles, making connections between different topics, and applying your knowledge to solve problems. Good luck with your Biology EOC! The key to success lies in diligent study and a genuine curiosity about the amazing world of biology.