High School Biology: Homework Help Resource

Course Summary

Work towards a better grade in biology class with our interactive, fun high school biology homework help course. Choose the short video lessons you need to review in order to complete your homework, and then test your skills using our multiple-choice quizzes.
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36 chapters in High School Biology: Homework Help Resource

Course Practice Test

Check your knowledge of this course with a 50-question practice test.
  • Comprehensive test covering all topics
  • Detailed video explanations for wrong answers
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Course Progress Best Score
Lesson 1 - How a Phospholipid Bilayer Is Both Hydrophobic and Hydrophilic  Take Quiz
Lesson 2 - The Fluid Mosaic Model of the Cell Membrane  Take Quiz
Lesson 3 - Passive Transport in Cells: Simple and Facilitated Diffusion & Osmosis  Take Quiz
Lesson 4 - Active Transport in Cells: Definition & Examples  Take Quiz
Lesson 5 - Endocytosis and Exocytosis Across the Cell Membrane  Take Quiz
Lesson 6 - Structure of the Nucleus: Nucleolus, Nuclear Membrane, and Nuclear Pores  Take Quiz
Lesson 7 - The Ribosome: Structure, Function and Location  Take Quiz
Lesson 8 - The Endomembrane System: Functions & Components  Take Quiz
Lesson 9 - The Cytoskeleton: Microtubules and Microfilaments  Take Quiz
Lesson 10 - Mitochondria Structure: Cristae, Matrix and Inner & Outer Membrane  Take Quiz
Lesson 11 - Chloroplast Structure: Chlorophyll, Stroma, Thylakoid, and Grana  Take Quiz
Lesson 12 - Plant Cell Structures: The Cell Wall and Central Vacuole  Take Quiz
Lesson 13 - Eukaryotic and Prokaryotic Cells: Similarities and Differences  Take Quiz
Lesson 14 - Selectively Permeable Membranes: Definition & Examples  Take Quiz
Lesson 15 - Membrane-Bound Organelles in Eukaryotic Cells  Take Quiz
Lesson 16 - Membrane Proteins: Functions, Types & Structure  Take Quiz
Lesson 17 - Smooth ER: Definition, Functions & Structure  Take Quiz
Lesson 18 - Eosinophils: Definition & Function  Take Quiz
Lesson 19 - Inner Cell Mass (ICM): Definition & Function  Take Quiz
Lesson 20 - Mitochondrial Cristae: Definition & Function  Take Quiz
Lesson 21 - Mitochondrial Inner Membrane: Definition & Overview  Take Quiz
Lesson 22 - Mitochondrial Matrix: Definition & Function  Take Quiz
Lesson 23 - Mitochondrial Outer Membrane: Definition & Overview  Take Quiz
Lesson 24 - Myosin: Definition, Function & Structure  Take Quiz
Lesson 25 - Pinocytosis: Definition & Examples  Take Quiz
Lesson 26 - Tropomyosin: Definition, Structure & Function  Take Quiz
Lesson 27 - What are Cells? - Overview  Take Quiz
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Course Progress Best Score
Lesson 1 - Theories of Evolution: Lamarck vs. Darwin  Take Quiz
Lesson 2 - Evidence for Evolution: Paleontology, Biogeography, Embryology, Comparative Anatomy & Molecular Biology  Take Quiz
Lesson 3 - Rates of Evolution: Punctuated Equilibrium & Molecular Clock Hypothesis  Take Quiz
Lesson 4 - Hardy-Weinberg Equilibrium I: Overview  Take Quiz
Lesson 5 - Hardy-Weinberg Equilibrium II: The Equation  Take Quiz
Lesson 6 - Hardy-Weinberg Equilibrium III: Evolutionary Agents  Take Quiz
Lesson 7 - Natural Selection & Adaptation: Definition, Theory & Examples  Take Quiz
Lesson 8 - Natural Selection: Definition, Types & Examples  Take Quiz
Lesson 9 - Speciation: Allopatric and Sympatric Speciation  Take Quiz
Lesson 10 - Prezygotic Reproductive Barriers & Speciation: Definition & Examples  Take Quiz
Lesson 11 - Postzygotic Reproductive Barriers: Definition & Examples  Take Quiz
Lesson 12 - Genetic Variability and Random Mutation  Take Quiz
Lesson 13 - An Example of Rapid Adaptation: The Peppered Moths  Take Quiz
Lesson 14 - Artificial Selection in Evolution  Take Quiz
Lesson 15 - Alfred Wallace: Theory of Evolution & Contribution  Take Quiz
Lesson 16 - Fossil: Definition, Types, Characteristics & Examples  Take Quiz
Lesson 17 - Inclusive Fitness: Definition & Theory  Take Quiz
Lesson 18 - Peppered Moths Simulation: Overview  Take Quiz
Lesson 19 - Relative Fitness: Definition & Equation  Take Quiz
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Course Progress Best Score
Lesson 1 - Classification of Vascular, Nonvascular, Monocot & Dicot Plants  Take Quiz
Lesson 2 - Structure of Plant Stems: Vascular and Ground Tissue  Take Quiz
Lesson 3 - Apical Meristem & Primary Shoot System Growth  Take Quiz
Lesson 4 - Lateral Meristem & Secondary Shoot System Growth  Take Quiz
Lesson 5 - Structure of Leaves: The Epidermis, Palisade and Spongy Layers  Take Quiz
Lesson 6 - Primary Root Tissue, Root Hairs and the Plant Vascular Cylinder  Take Quiz
Lesson 7 - Root System Growth: The Root Cap, Primary Roots & Lateral Roots  Take Quiz
Lesson 8 - Nitrogen Fixation: Significance to Plants and Humans  Take Quiz
Lesson 9 - Xylem: The Effect of Transpiration and Cohesion on Function  Take Quiz
Lesson 10 - Phloem: The Pressure Flow Hypothesis of Food Movement  Take Quiz
Lesson 11 - Flowers: Structure and Function of Male & Female Components  Take Quiz
Lesson 12 - Methods of Pollination and Flower-Pollinator Relationships  Take Quiz
Lesson 13 - Apical Meristem: Definition & Function  Take Quiz
Lesson 14 - Corolla of a Flower: Structure, Function & Definition  Take Quiz
Lesson 15 - Cotyledon: Definition & Function  Take Quiz
Lesson 16 - Cuticle Of The Leaf: Function & Concept  Take Quiz
Lesson 17 - Hybrid Plants: Definition & Examples  Take Quiz
Lesson 18 - Photosystem: Definition & Overview  Take Quiz
Lesson 19 - Plastids: Definition, Structure, Types & Functions  Take Quiz
Lesson 20 - Root Hairs in Plants: Function & Definition  Take Quiz
Lesson 21 - Spongy Layer of a Leaf: Function & Concept  Take Quiz
Lesson 22 - What Are Perennial Plants? - Examples & Types  Take Quiz
Lesson 23 - What are the Parts of a Plant?  Take Quiz
Lesson 24 - What is Agar?  Take Quiz
Lesson 25 - What Is Pollen? - Definition & Benefits  Take Quiz
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Course Progress Best Score
Lesson 1 - Homeostasis and Temperature Regulation in Humans  Take Quiz
Lesson 2 - Homeostasis of Glucose Levels: Hormonal Control and Diabetes  Take Quiz
Lesson 3 - Functions of the Nervous System  Take Quiz
Lesson 4 - The Structure and Function of Neurons  Take Quiz
Lesson 5 - The Central and Peripheral Nervous Systems  Take Quiz
Lesson 6 - The Sympathetic and Parasympathetic Nervous Systems  Take Quiz
Lesson 7 - Brain Structures and Functions Part I  Take Quiz
Lesson 8 - The Cerebral Cortex: Brain Structures and Functions Part II  Take Quiz
Lesson 9 - Innate Immunity: Inflammation, Neutrophils & Natural Killer Cells  Take Quiz
Lesson 10 - Acquired Immunity: T Cells, B Cells and Antibodies  Take Quiz
Lesson 11 - Antibiotics and Vaccines  Take Quiz
Lesson 12 - Pathogens: Antibiotic Resistance and Virulence  Take Quiz
Lesson 13 - Adipose Tissue: Function, Location & Definition  Take Quiz
Lesson 14 - Parasympathetic Nervous System: Definition, Function & Effects  Take Quiz
Lesson 15 - Somatic Nervous System: Definition, Function & Example  Take Quiz
Lesson 16 - What is the Limbic System in the Brain? - Definition, Functions & Parts  Take Quiz
Lesson 17 - Olfactory Nerve: Function, Disorders & Regeneration  Take Quiz
Lesson 18 - What is Immunity? - Definition & Types  Take Quiz
Lesson 19 - Anticholinergics: Definition, Examples & Side Effects  Take Quiz
Lesson 20 - Asthenia: Definition, Symptoms & Treatment  Take Quiz
Lesson 21 - What Is Lymphadenitis? - Definition, Symptoms & Treatment  Take Quiz
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Course Progress Best Score
Lesson 1 - Male Reproductive System: Functions, Organs & Anatomy  Take Quiz
Lesson 2 - Male Reproductive System: Accessory Gland Functions  Take Quiz
Lesson 3 - Testicular Anatomy: Structure, Terms & Diagrams  Take Quiz
Lesson 4 - Male Reproductive System: External Anatomy  Take Quiz
Lesson 5 - Sperm's Journey from the Testes to Urethral Orifice  Take Quiz
Lesson 6 - The HPG Axis: Hormones of Male Reproduction  Take Quiz
Lesson 7 - Female Reproductive System: Internal Anatomy  Take Quiz
Lesson 8 - The Uterus and Uterine Wall: Structure and Parts  Take Quiz
Lesson 9 - External Anatomy of the Female Reproductive System  Take Quiz
Lesson 10 - HPG Axis: Hormonal Control of the Ovarian Cycle  Take Quiz
Lesson 11 - Phases of The Ovarian Cycle: Overview from Puberty to Menopause  Take Quiz
Lesson 12 - Follicular Phase of the Ovarian Cycle  Take Quiz
Lesson 13 - Luteal Phase of the Ovarian Cycle  Take Quiz
Lesson 14 - The Uterine Cycle: Phases and Endometrial Changes  Take Quiz
Lesson 15 - The Uterine Cycle: Menses  Take Quiz
Lesson 16 - The Uterine Cycle: Proliferative Phase  Take Quiz
Lesson 17 - The Uterine Cycle: Secretory Phase  Take Quiz
Lesson 18 - The Female Reproductive Axis: Coordination of the Brain, Ovaries & Uterus  Take Quiz
Lesson 19 - Ovulation to Implantation: Oocyte's Path through Uterine Tubes  Take Quiz
Lesson 20 - What is Human Fertilization? - Process, Definition & Symptoms  Take Quiz
Lesson 21 - Organogenesis in Humans: Definition & Concept  Take Quiz
Lesson 22 - What Is Menstruation? - Definition & Cycle  Take Quiz
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Course Progress Best Score
Lesson 1 - The Environment, Levels of Ecology and Ecosystems  Take Quiz
Lesson 2 - Ecosystems, Habitats and Ecological Niches  Take Quiz
Lesson 3 - Food Chains, Trophic Levels and Energy Flow in an Ecosystem  Take Quiz
Lesson 4 - Interspecific Competition, Competitive Exclusion & Niche Differentiation  Take Quiz
Lesson 5 - Predator/Prey Interactions, Camouflage, Mimicry & Warning Coloration  Take Quiz
Lesson 6 - Symbiotic Relationships: Mutualism, Commensalism & Parasitism  Take Quiz
Lesson 7 - Populations: Density, Survivorship and Life Histories  Take Quiz
Lesson 8 - Carrying Capacity, Migration & Dispersion  Take Quiz
Lesson 9 - Dispersal, Colonization, and Island Biogeography  Take Quiz
Lesson 10 - Conservation Biology, Habitat Fragmentation, and Metapopulations  Take Quiz
Lesson 11 - Ecological Succession: From Pioneer to Climax Communities  Take Quiz
Lesson 12 - How Introduced and Invasive Species Alter Ecological Balance  Take Quiz
Lesson 13 - Biomes: Desert, Tropical Rainforest, Savanna, Coral Reefs & More  Take Quiz
Lesson 14 - Biomes: Tundra, Taiga, Temperate Grassland, and Coastlines  Take Quiz
Lesson 15 - Biogeochemical Cycling and the Phosphorus Cycle  Take Quiz
Lesson 16 - Tundra Biome: Climate, Locations, Plants & Animals  Take Quiz
Lesson 17 - Endemic Plants and Animals: Definition & Examples  Take Quiz
Lesson 18 - Secondary Consumers: Definition & Examples  Take Quiz
Lesson 19 - What Are Herbivores? - Examples & Definition  Take Quiz
Lesson 20 - What Are Tropical Rainforests? - Definition, Plants & Animals  Take Quiz
Lesson 21 - What Is a Biome? - Definition & Types  Take Quiz
Lesson 22 - Population Biology: Definition & Example  Take Quiz
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