Biology 1 MCAS Model Midterm Study Guide (2024)

Biology 1 MCAS Model Midterm Study Guide (2024)

• Scientific Method

  • Observations lead to testable hypotheses.
  • Controlled experiments provide data.
  • Data analysis forms a conclusion.
  • Supported hypotheses may become theories.

• Characteristics of Living Things

  • Cellular organization, growth, reproduction, adaptation, metabolism, and response to stimuli (irritability).
  • Maintain homeostasis by fulfilling these characteristics.

Chemistry of Life

• Molecular Structure

  • Atoms (protons(+), neutrons (0), electrons(-)) are the basic unit of matter.
  • Protons and neutrons are in the nucleus, electrons in orbitals.
  • Elements are single-atom substances.
  • Compounds combine multiple elements in specific proportions.
  • CHNOPS (Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur) are common in living things.

• pH

  • The pH scale ranges from 1 to 14, measuring hydrogen ion (H+) concentration.
  • Acids have a pH of 6 or less.
  • Bases have a pH of 8 or more.
  • Neutral substances have a pH of 7.
  • Strong acids and bases can be harmful.

• Organic Molecules

  • Organic molecules are based on carbon skeletons.
  • Monomers build polymers.
  • Four main types:
    • Carbohydrates (sugars, starches): primary energy source.
    • Proteins (muscles, enzymes): various functions including building and regulating.
    • Lipids (fats, oils, waxes): long-term energy storage, waterproof coverings; phospholipids build cell membranes.
    • Nucleic Acids (DNA, RNA): store and transmit genetic information.
  • Enzymes (proteins) speed up reactions by lowering activation energy.
  • Organic molecules all contain carbon.

Cell Structure and Function

• Cell Theory

  • All living things are composed of cells.
  • Cells are the basic units of structure and function.
  • All cells come from pre-existing cells.

• Types of Cells

  • Prokaryotic cells (bacteria) lack a nucleus.
  • Eukaryotic cells (animals, plants, fungi, protists) have a nucleus.
  • All cells have cell membranes, cytoplasm, DNA, and ribosomes.
  • Cell walls are common in prokaryotes and some eukaryotes (Plants but not animals).

• Cell Organelles

  • Many structures within cells maintain homeostasis. Examples include mitochondria, chloroplasts, lysosomes, endoplasmic reticulum (rough and smooth), ribosomes, Golgi apparatus, cytoskeleton, and vacuoles.
  • Plant cells have chloroplasts, cell walls, and a large central vacuole. Animal cells have centrioles, cilia, flagella, and multiple smaller vacuoles.

• Cell Membrane

  • Phospholipid bilayer forms the cell membrane, making it semi-permeable.

• Cellular Transport

  • Diffusion: movement from high to low concentration.
  • Osmosis: water diffusion from high to low water concentration.
  • Facilitated diffusion: larger particles move through protein channels from high to low concentration.
  • Active transport: movement from low to high concentration, requires energy (endocytosis & exocytosis).
  • Hypertonic: higher solute concentration (cell shrinks).
  • Hypotonic: lower solute concentration (cell swells).
  • Isotonic: equal solute concentration (dynamic equilibrium).

Photosynthesis and Cellular Respiration

• Photosynthesis

  • Light reactions use chlorophyll to capture light energy, splitting water (O2 released), and producing ATP and NADPH.
  • Calvin cycle (light-independent reactions) uses ATP and NADPH, plus CO2, to produce glucose.
  • Equation: 6CO2 + 6H2O → C6H12O6 + 6O2.

• Cellular Respiration

  • Breaks down glucose (in presence of oxygen) releasing energy (ATP).
  • Stages:
    • Glycolysis: glucose → pyruvate, 2 ATP.
    • Krebs Cycle: pyruvate breakdown, CO2 released, NADH and FADH2 produced, 2 ATP.
    • Electron Transport Chain: NADH and FADH2 produce 32 ATP.
  • Overall equation: C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP (36-38 ATP per glucose).
  • Fermentation: energy production (2 ATP) in absence of oxygen (alcoholic/lactic acid).

Body Systems

• Digestive System

  • Converts food macromolecules into usable smaller molecules.
  • Alimentary canal (mouth to anus) and accessory organs (salivary glands, pancreas, gallbladder, liver).

• Nervous System

  • Collects, processes, and responds to information.
  • Central nervous system (brain and spinal cord) and peripheral nervous system (nerves & supporting cells).
  • Neurons are the basic units, consisting of cell bodies, dendrites, axons, and in some instances, myelin sheaths.
  • Sensory neurons detect information (photoreceptors, chemoreceptors, mechanoreceptors, thermoreceptors).
  • Motor neurons carry impulses away from the central nervous system to effectors (muscles & glands).

• Respiratory System - Exchanges gases (taking in oxygen, removing carbon dioxide). - Gas exchange occurs at alveoli (tiny air sacs) and capillaries.

• Circulatory System - Transports oxygen and nutrients throughout the body; also removes waste (e.g., carbon dioxide). - Heart pumps blood, oxygen-poor blood to lungs, oxygen-rich blood throughout the body.

Ecology

• Ecology
  • Food chains and food webs start with producers (autotrophs make own food).
  • Consumers (heterotrophs) eat to obtain energy.
  • Categories of consumers: herbivores, carnivores, omnivores, detritivores (decomposers).
  • Food chains: single energy pathway (Producer → Primary Consumer → Secondary Consumer → Tertiary Consumer).
  • Food webs: multiple food chains.
  • Energy transfer: 10% of energy is transferred to higher trophic levels (90% loss).