From Cells to Complex Living Systems
Year 11 Biology Understanding the hierarchy of life From unicellular to multicellular organisms
What Are We Learning Today?
Unicellular eukaryotes and their characteristics Colonial organisms as transitional forms Multicellular organisms and their advantages Cell specialization in plants and animals The hierarchy of life from cells to organ systems
Think About This...
What makes a living thing 'alive'? How do you think single cells can survive on their own? What advantages might there be to having many cells working together?
Characteristics of Life
Growth and reproduction Response to environment Metabolism (energy use) Homeostasis (maintaining balance) Cellular organization Evolution and adaptation
What Are Eukaryotic Cells?
Cells with a membrane-bound nucleus Contains organelles with specific functions DNA is organized in chromosomes More complex than prokaryotic cells Found in plants, animals, fungi, and protists
Unicellular Eukaryotes
Single-celled organisms Complete all life functions in one cell Examples: Amoeba, Paramecium, Euglena Can be found in various environments Some can photosynthesize, others consume food
Spot the Unicellular Eukaryote
Look at the microscope images provided Identify key features: nucleus, organelles, movement structures Guess which organism each image shows Discuss what each organism needs to survive
How Do Unicellular Organisms Survive?
Obtain nutrients from their environment Remove waste products through cell membrane Reproduce by cell division Respond to environmental changes Maintain water balance (osmoregulation)
Colonial Organisms: The Bridge
Groups of similar cells living together Each cell can still survive independently Some coordination between cells Examples: Volvox, some algae Stepping stone to true multicellularity
Unicellular vs Colonial Organisms
{"left":"Single cell performs all functions\nComplete independence\nLimited size due to surface area constraints\nSimple reproduction by division","right":"Multiple cells working together\nSome coordination and communication\nLarger size possible\nBeginning of specialization"}
True Multicellular Organisms
Cells cannot survive independently Specialized cells for different functions Complex communication between cells Tissues, organs, and organ systems Examples: plants, animals, fungi
Why Go Multicellular?
What advantages might multicellular organisms have over unicellular ones? Think about size, efficiency, and survival What challenges might arise from being multicellular?
20 more slides available after you open the deck.
Download all 32 slides