Cells and Systems Cells and Systems Topic 1: Characteristics of Life Processes of living organisms
Main question: What are the basic needs of all living things?
Source of Energy
Nutrients
Water
Gas Exchange
Suitable Habitat
All of the information in this topic you've learnt somewhere near Grade 7!
Main question: What are the 7 processes of all living things?
Excretion: All living things generate and expel waste
Nutrition: Taking in nutrients helps organisms grow
Sensitivity/Response to Stimuli: Reacting to their enviroment
Growth: Living things undergo life cycles
Reproduction: Reproduction is needed for species to survive
Movement: Living things move in a direct and controlled way
Respiration: Gas exchange
A specimen must carry out all living processes to be a living thing. Topic 2: Cell Theory
Well, what would be the most basic unit of life? Cells.
Cells are the most basic unit of life. There are 2 types of cells
Unicellular: Organisms made up of only one cell (Single-Celled)
Multicellular: Organisms made up of more than one cell
Cells are like building blocks. You and everything that exists is made up of small cells all working together. If you magnified an object, you could see all the cells that make up it.
Cells are invisible to the human eye, you need a microscope to see them, Cell theory states 3 things.
All living things are made up of cells
Cells perform all 7 life processes
Cells come from other cells
The components that make up a cell is called an organelle.
Cell Theory 1: All living things are made up of cells
Every single thing that exists is composed of many tiny cells, except for unicellular organisms
Cell Theory 2: Cells perform all 7 life processes
The existence of unicellular organisms mean that even single cells need to perform all life processes. Just like humans have organs, cells have organelles.
Cell Theory 3: Cells come from other cells
Cells reproduce by simply Dividing themselves, this is how organisms grow.
Cell Organization
Cell -> Tissue -> Organ -> System -> Organism Animal vs Plant Cells, Parts of a Cell
Organelles that both Plant and Animal Cells have:
Cell Membrane: Surrounds the cell and acts as a barier, controls what materials can enter and exit out the cell. Think of it as a security guard.
Cytoplasm: Jelly-like substance which keeps all organelles in place.
Nucleus: The nucleus controlls all activities of the cell, contains the cell's DNA.
Mitochondria: Power house, generates a cell's energy.
Vacoule: Stores nutrients.
Lysosome: Digests chemicals, breaks down bad stuff.
Organelles exclusive to Plant Cells:
Cell Wall: External structure, providing moer support protecting the cell.
Chloroplast: Contains chlorophyll, a pigment that makes plants green.
Cell Transport
Concentration: How much substance is in one specific area.
Diffusion: Particles going from high concentration to low concentration.
Permable is when liquids or gases are able to flow through, like soil or a sponge.
Impermable is when liquids cannot go through, like an umbrella.
Cell Memberanes are SEMI-permable, certain things can cross but others can't. Cell membranes are permable to water, this means they can diffuse across easily. Larger particles are impermable. See; gummy bear experiment.