Biology

• Seven characteristics that an organism must have to be recognized as a living thing:

  • Movement
  • Respiration
  • Sensitivity
  • Growth
  • Reproduction
  • Excretion
  • Nutrition
• Movement is an action causing a change of position or place

  • Respiration is chemical reactions in cells breaking down nutrient molecules and releasing energy
  • Sensitivity is the ability to detect and respond to changes in the environment
  • Growth is a permanent increase in size and dry mass
  • Reproduction processes make more of the same kind of organism
  • Excretion is the removal of waste products of metabolism and substances in excess
  • Nutrition is the taking in of materials for energy, growth, and development
• Binomial system of naming species:

  • Consists of two parts showing the genus and the species
  • Genus is a group of related species
  • Scientific names are in italics and start with a capital letter for the genus and a simple letter for the species
  • Example: Homo sapien
• Dichotomous keys:

  • Used to identify organisms based on a series of questions about their features
  • Branching into two descriptions at a time to lead to the name of the organism
• Classification of living things:

  • Organisms classified into five kingdoms: animals, plants, fungi, protists, and prokaryotes
  • Animals are multicellular, have a nucleus, no cell walls or chloroplasts, and get nutrition by eating other living things
  • Plants are multicellular, have a nucleus, chloroplasts, cell walls made of cellulose, and get nutrition through photosynthesis
  • Fungi are multicellular, have nuclei, cell walls not made of cellulose, and feed by saprophytic or parasitic nutrition
• • Protists may be unicellular or multicellular, have a nucleus, some have cell walls and chloroplasts, and get nutrition through photosynthesis or eating other living things
  • Prokaryotes are often unicellular, have cell walls not made of cellulose, no nucleus or mitochondria
• Vertebrates and invertebrates within the animal kingdom:

  • Vertebrates have a backbone, divided into mammals, birds, reptiles, amphibians, and fish
  • Invertebrates are animals without a backbone, classified into arthropods: myriapods, insects, arachnids, and crustaceans
• Ferns and flowering plants within the plant kingdom:

  • Ferns reproduce by spores and do not produce flowers
  • Flowering plants reproduce by flowers and seeds, divided into monocotyledons and dicotyledons
  • Monocots have a branching root system, parallel veins in leaves, and flowers with petals in multiples of three
  • Dicots have a Taproot system, broader leaves with branching veins, and flowers with petals in multiples of four or five
• Viruses:

  • Not considered living things as they cannot carry out life processes on their own
  • Made of genetic material surrounded by a protein coat
• A cell is the basic unit of life
• Structure of an animal cell:

  • Nucleus: control unit of a cell
  • Mitochondria: PowerHouse of the cell where aerobic respiration takes place
  • Cell membrane: controls what substances enter or leave the cell
  • Cytoplasm: jelly-like substance where cell organelles are present
  • Ribosomes: where proteins are made (protein synthesis)
• Structure of a plant cell:

  • Contains nucleus, mitochondria, cell membrane, cytoplasm, and ribosomes
  • Additional organelles in plant cell:
  • Cell wall: made of cellulose, provides structural strength and support
  • Chloroplasts: contain chlorophyll for photosynthesis
  • Vacuole: contains cell sap for storage and helps support cell shape
• Functions of cell parts:

  • Nucleus: contains genetic material, stores DNA, and coordinates cell activities
  • Mitochondria: site of aerobic respiration, provides energy for cell survival
  • Cytoplasm: where chemical reactions occur, supports cell organelles
  • Ribosomes: site of protein synthesis
  • Cell membrane: controls what goes in and out of the cell, provides protection
• Functions of plant cell structures:

  • Cell wall: made of cellulose, gives structural strength and support, protects the cell
  • Chloroplasts: contain chlorophyll for photosynthesis, converts light energy into food
  • Vacuole: contains cell sap for storage, helps support cell shape
• Structure of a bacterial cell:

  • Similar organelles to animal cell
  • Circular DNA and plasmids for genetic information exchange
• Cell division:

  • New cells are produced by the division of existing cells
  • Cells -> tissues -> organs -> organ systems -> multicellular organism
• Specialized cells:

  • Ciliated cells: have cilia for moving mucus
  • Root hair cells: help in mineral and water absorption
  • Palisade mesophyll cells: contain chloroplasts for photosynthesis
  • Neurons: nerve cells for carrying electrical impulses
  • Red blood cells: contain hemoglobin for oxygen transport
  • Sperm and egg cells (gametes): responsible for reproduction
• Magnification formula:

  • Magnification = image size / actual size
  • Convert sizes to millimeters if given in other units
• Unit conversion:

  • Millimeters to micrometers: multiply by 1000
  • Micrometers to millimeters: divide by 1000
• Diffusion, osmosis, and active transport are the three main ways substances move into and out of cells
• Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient
• Factors influencing diffusion:

  • Surface area: larger surface area leads to higher diffusion rate
  • Temperature: higher temperature increases diffusion rate
  • Concentration gradient: greater difference in concentrations leads to faster diffusion
  • Distance: shorter distance results in higher diffusion rate
• Osmosis is the net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane
• Water potential is used instead of concentration in osmosis
• Effects of osmosis on plant tissues:

  • In dilute solution, cells become turgid
  • In concentrated solution, cells become flaccid or plasmolyzed
• Active transport is the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration against a concentration gradient using energy from respiration
• Protein carriers in cell membranes facilitate active transport by capturing and transporting molecules using energy from respiration
• Comparison between diffusion, osmosis, and active transport:

  • Diffusion and active transport involve particle movement, while osmosis involves water molecule movement
  • Diffusion occurs down a concentration gradient, active transport against it, and osmosis from high to low water potential
  • Diffusion uses kinetic energy, active transport uses energy from respiration