Cell Theory
State one of the three tenets of the cell theory.
All living things are made of cells
Define a unicellular organism and give one example.
Unicellular = one cell; example: bacteria or protists.
Name the organelle often called the "control center" of the cell.
Nucleus
Name two organelles found in plant cells that are NOT found in most animal cells.
Chloroplasts and cell wall.
List the three main functions of the cell membrane described in the text.
Protects contents/acts as barrier; controls what enters/exits (selective permeability); cell signaling/communication.
Explain why cells do NOT arise spontaneously according to the cell theory.
Cells arise from pre-existing cells; spontaneous generation is not supported.
Define a multicellular organism and name two organ systems that help perform life functions.
Multicellular = many cells; organ systems: digestive, respiratory, circulatory, excretory, skeletal/muscular.
What organelle produces ATP, and why is ATP important?
Mitochondria produce ATP, which is usable energy for the cell.
What is the function of chloroplasts, and what pigment do they contain?
Chloroplasts perform photosynthesis; contain chlorophyll.
Explain the structure of the phospholipid bilayer, using the terms hydrophilic and hydrophobic.
Phospholipid bilayer: hydrophilic (water-loving) phosphate heads face outward/inward; hydrophobic (water-fearing) tails face inward toward each other.
Describe how the cell theory supports the idea that tissues are made of cells.
Cells are basic units; tissues are composed of many cells working together.
List two major differences between prokaryotes and eukaryotes.
Prokaryotes: no nucleus, no membrane-bound organelles, DNA in nucleoid. Eukaryotes: nucleus, membrane-bound organelles, DNA in nucleus.
Describe the difference between rough ER and smooth ER, and give a function for each.
Rough ER has ribosomes and makes proteins; Smooth ER makes lipids and transports materials.
Describe the role of the contractile vacuole in many protists and explain why it is necessary.
The contractile vacuole collects excess water and pumps it out to prevent bursting.
Distinguish between diffusion and facilitated diffusion and give an example substance for each.
Diffusion = direct passage through bilayer (e.g., O2, CO2). Facilitated diffusion = via channel or carrier proteins (e.g., ions through channel proteins, glucose via carrier proteins).
A scientist finds a new organism. What observation(s) would be required to confirm the organism follows the cell theory?
Observations: organism made of cells; cells contain DNA; cells divide to produce new cells.
Explain why protists are classified as eukaryotes and give one structural feature unique to many protists.
Protists are eukaryotes because they have a nucleus and membrane-bound organelles; many protists have cilia and contractile vacuoles.
Explain how lysosomes and vacuoles work together in an animal cell to digest food.
Food vacuole fuses with lysosome; lysosomal enzymes digest contents; vacuoles store/deliver.
Explain how the large central vacuole helps maintain plant cell shape (include the term turgor pressure).
The central vacuole fills with water; turgor pressure pushes against the cell wall to maintain rigidity and shape.
Define active transport and explain why ATP is required; include how pumps work.
Active transport moves substances from low to high concentration, requires ATP; pumps (transmembrane proteins) hydrolyze ATP to move substances.
Provide a one-sentence synthesis that connects all three tenets of the cell theory and explains their importance to biology.
Synthesis: "All organisms are built of cells, each cell is the basic functional unit, and all cells come from pre-existing cells, which together explain growth, reproduction, and heredity."
Compare and contrast bacteria and protists in terms of cell structure, organelles, and typical habitats (use details from the provided content).
Bacteria: prokaryotic, nucleoid, plasmids, cell wall, sometimes capsule, small, often unicellular. Protists: eukaryotic, nucleus, membrane-bound organelles (e.g., contractile vacuole, cilia), mostly in aquatic environments; some are photosynthetic (algae).
A nerve cell needs to produce and release neurotransmitters quickly. Identify three organelles involved in producing, packaging, and releasing these molecules and describe each organelle's role.
Ribosomes (make proteins), rough ER (fold/modify proteins), Golgi bodies (package into vesicles), vesicles + cell membrane for release.
Some protists can perform photosynthesis, while others cannot. Describe two organelle-based differences between a photosynthetic protist (like many algae) and a non-photosynthetic protist (like a paramecium), using the organelles mentioned in the document.
Photosynthetic protist: chloroplasts, can make food; non-photosynthetic protist: contractile vacuole, cilia, food vacuoles, macronucleus/micronucleus.
Osmosis problem: Describe what happens to a typical animal cell when placed in a solution that is (a) hypertonic, (b) hypotonic, and (c) isotonic — include the direction of water movement and the resulting cell shape.
Osmosis answers — (a) hypertonic: water moves out of the cell, cell shrinks (crenation in animal cells). (b) hypotonic: water moves into the cell, animal cell swells and may burst; plant cell gains turgor pressure, but the cell wall prevents bursting. (c) isotonic: no net water movement; cell stays normal.