Cell Theory & Microscopes
Who first observed cells under the microscope, and what was he looking at?
Robert Hooke; he viewed cork.
The portion of the cell outside the nucleus is called what?
Cytoplasm.
What term describes the state of maintaining stable internal conditions?
Homeostasis.
What type of organisms dominate life on Earth?
Unicellular organisms.
What do solar panels convert sunlight into?
Electrical energy.
What did Anton van Leeuwenhoek view under the microscope?
Living microorganisms in pond water.
What structures carry genetic information inside the nucleus?
Chromosomes.
What is diffusion?
Movement of particles from high concentration to low concentration.
What do unicellular organisms do to maintain homeostasis?
Grow, respond to environment, transform energy, and reproduce.
What are pigments, and what is the principal pigment in green plants?
Light-absorbing molecules; chlorophyll.
State the three parts of the cell theory.
All living things are made of cells;
Cells are the basic unit of structure and function;
New cells come from existing cells.
Where are proteins assembled, and where are lipids synthesized?
Proteins: ribosomes; lipids: smooth ER.
What is osmosis, and what protein helps water move across membranes?
Osmosis is the diffusion of water; aquaporins help move water.
What type of cells carry gases like oxygen and carbon dioxide in the body?
Red blood cells.
Write the formula for photosynthesis.
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
What are the two types of electron microscopes, and which one produces 3-D images?
Transmission and scanning; scanning electron microscopes produce 3-D images.
What organelles break down lipids, carbohydrates, and proteins so they can be used by the cell?
Lysosomes.
What is facilitated diffusion, and why does it not require energy?
Movement through channels or carriers down the concentration gradient; no energy is required because it moves from high to low concentration.
Which organ contains the most mitochondria, and why is this useful?
The heart; it requires constant energy for continuous contraction.
What is the main purpose of cellular respiration, and in which organelle does it occur?
To convert chemical energy in food (glucose) into ATP; it occurs in the mitochondria.
What is the major difference between what light microscopes and electron microscopes use to form images, and why does this matter for resolution?
Light microscopes use light; electron microscopes use electron beams.
Electron beams provide much higher resolution because they have shorter wavelengths.
Explain the observation that led scientists to propose the endosymbiotic theory.
Mitochondria and chloroplasts contain their own DNA and resemble independent prokaryotes, suggesting they were once free-living bacteria engulfed by larger cells.
Name and describe two types of active transport shown in the chapter.
Endocytosis: Cell membrane folds inward to bring materials into the cell.
Exocytosis: Vesicles fuse with the membrane to release materials outside the cell.
How does defective mitochondrial DNA explain the symptoms of LHON?
Mitochondria cannot supply enough energy to nerve cells in the eyes, causing vision loss.
Explain the relationship between mitochondria and ATP production, and why cells like muscle cells have more mitochondria than others.
Mitochondria break down glucose to produce ATP through cellular respiration.
Muscle cells have more mitochondria because they need large amounts of ATP for constant movement and contraction.