A single organism in an ecosystem is called an

Cells

blue whale

amoeba Organisms come in a great variety of shapes and sizes, and can be found in all areas of the Earth. Some, like microscopic amoebas, are so small, we need to use a microscope to see them. Others, like the blue whale, can reach lengths of over 25 meters – that’s about as long as a basketball court! From microscopic amoebas to giant blue whales, all organisms are made of cells. Cells are the smallest units within an organism that can carry out life processes. They are often referred to as the ‘building blocks of life’. Some organisms, like parameciums, diatoms and bacteria, are made up of only a single cell. They are unicellular organisms. Others, like most of the plants and animals you are familiar with, are made up of many cells. They are called multicellular organisms. Humans are multicellular organisms. Scientists estimate that our bodies are made up of trillions of different cells that all play a role in helping our bodies function. Did You Know? Cells were first discovered in 1665 by the English scientist Robert Hooke. When observing cork under a microscope, he noticed a series of small boxes which he called ‘cells’. Activities 1.2 – 1.3AB Regal esses. esse uilding block ng blo s, like parameciums, e parameciu are made up of only made up of cellular organisms ular organis e plants and animals nts and anim made up of many c e up of many ellular organisms ar organisms. mans are multicellula mans are multice stimate that our bod stimate that ou of different cells tha of different cells es function. es fu educ pes of ebas, s, scope hale, can hale, can – that’s about hat’s about s to giant blue giant blue made of cells. e of cells C n organism organism are are ucatio 5