Cells, Organs & Living Systems

Year 9 Biology Understanding Life's Building Blocks From Single Cells to Complex Organisms

What Makes Something Alive?

Think about a bacterium, a plant, and a human What do they all have in common? What are the characteristics of living things?

The Building Blocks of Life

All living things are made of cells Cells are the smallest unit of life Some organisms have just one cell Others have trillions of cells working together

Single-Celled Organisms

Bacteria and archaea are single-celled They carry out all life functions in one cell Examples: E. coli, cyanobacteria Found everywhere on Earth

Cell Observation Activity

Imagine you're looking through a microscope Draw what you think a bacterial cell looks like Label: cell membrane, genetic material, cytoplasm Compare with your partner's drawing

Multicellular Organisms

Made up of many cells working together Cells can specialize for different jobs Examples: plants, animals, fungi Cells organize into tissues and organs

From Cells to Organs

Specialized Cells in Action

Red blood cells - carry oxygen Nerve cells - send electrical signals Muscle cells - contract for movement Guard cells - control gas exchange in plants

Plant vs Animal Cells

{"left":"Plant cells have cell walls\nAnimal cells have flexible membranes\nPlant cells contain chloroplasts","right":"Animal cells have centrioles\nBoth have nucleus and mitochondria\nBoth have ribosomes and cytoplasm"}

Cell Detective Challenge

You find a cell with a thick wall and green structures What type of cell is it? What specialized function might it have? Where in the organism would you find it?

Organs and Their Functions

Heart - pumps blood throughout the body Lungs - exchange oxygen and carbon dioxide Liver - processes nutrients and toxins Kidneys - filter waste from blood

How Organ Systems Work Together

Circulatory system delivers nutrients and oxygen Respiratory system provides oxygen to blood Digestive system breaks down food Nervous system coordinates all activities