Summary

• What are the basic units of life?

  Cells
• What do all living organisms consist of?

  Cells
• Why do we need magnifying instruments to view cells?

  Because cells are very small
• What type of microscope uses a beam of light focused by glass lenses?

  Light microscope
• How do electron microscopes differ from light microscopes?

  Electron microscopes have a much higher magnifying power
• What did Robert Hooke examine in 1665 using a light microscope?

  Non-living cork cells
• Who was the first person to observe living cells using a microscope?

  Antonie van Leeuwenhoek
• What is cell theory based on?

  Microscopic studies of cells
• What are the basic components of all cells?

  • Surrounded by a cell membrane
  • Contains cytoplasm
  • Contains organelles
• How do cells differ from one another?

  Cells differ in size, shape, and structure to carry out specialized functions
• What is the composition of the cell membrane?

  Proteins and phospholipids
• What model explains the structure of cell membranes?

  The fluid mosaic model
• What does the nucleus control?

  All the activities of the cell
• What is the function of mitochondria?

  Releases energy for the cell during respiration
• What is the role of ribosomes in a cell?

  Important in protein production
• What is the function of cytoplasm?

  Stores and circulates materials
• What is the role of the endoplasmic reticulum?

  Transports substances from one part of the cell to another
• What does the Golgi body do?

  Secretes, packages, and distributes materials around and between cells
• What is the primary function of vacuoles?

  Mainly for storage
• How do plant and animal cell vacuoles differ?

  Plant cell vacuoles are large, while animal cell vacuoles are small
• What are lysosomes and where are they found?

  Found only in animal cells, they destroy damaged, dead, and foreign cells
• What is the composition of cell walls in plant cells?

  Mainly made of cellulose
• What is the function of the cell wall?

  Gives cells their shape, supports, and protects cells
• What are plastids and where are they found?

  Found only in plant cells
• What are the three types of plastids?

  Chloroplasts, chromoplasts, and leucoplasts
• What is the function of chloroplasts?

  Production of food by photosynthesis
• What do chromoplasts do?

  Give colour to fruits and flowers
• What is the main function of leucoplasts?

  Mainly used for food storage
• How do substances pass across cell membranes?

  • Diffusion
  • Osmosis
  • Active transport
• What is diffusion?

  Movement of molecules from high to low concentration until equal
• What is osmosis?

  Movement of water molecules from high to low concentration across a membrane
• What is active transport?

  Process that uses energy to transport molecules against a concentration gradient
• How does the mitochondria contribute to active transport?

  It provides energy for the transport of large molecules
• How do diffusion, osmosis, and active transport differ in terms of energy usage?

  Diffusion and osmosis do not use energy, while active transport does