Cells to Systems

OB43 draw one example each of an animal cell and a plant cell, identifying the nucleus, cytoplasm and cell wall (plant cell), and indicate the position of the cell membrane


Nucleus Contains chromosomes which control the cell

Cytoplasm A liquid in which many cell reactions take place

Cell Membrane Holds the cytoplasm in place and allows certain substances into and out of the cell


Chloroplasts Carries out photosynthesis*

Vacuole Stores materials in water and supports the cell, animal cells can have vacuoles too, but they are less common and much smaller

Cell Wall Provides strength and support

*Photosynthesis is when a plant makes food from Carbon Dioxide in light.

All living organisms (the official way to say living things) are made up of cells. The most basic organisms have only one cell but most of the organisms you know are multicelled (they have more than one cell).

So you should notice that all cells have

  1. a nucleus, this contains genes and DNA
  2. a cell membrane
  3. cytoplasm

they all carry out the processes of living things such as

  1. respiration
  2. growth

Cells are very small, many times smaller than a grain of sand....

how many grains of sand would you need to make a model of a human

so you would need many more cells to make you

OB41 living things are made up of

cells, tissues, organs and systems,

relationship between cells, tissues, organs and systems

There are many different types of cells in living things, there are skin cells, blood cells, muscle cells ......

When the cells act together they are called a tissue

We are made up of billions of cells, as one cell is so small that we need a microscope to see it you can see that these cells must work together. Similiar cells all join to form tissue.

For example we are covered in skin, this skin is made up of billions of cells but all these cells are similiar to each other.

Under the skin, we have blood, bones and muscles these are all different substances, they too are made from cells, but the cells in bone and muscle are different.

When cells work together we call this tissue.

Each type of cell has its own function (job) in large multicelled organisms, here are a few examples of

the functions that cells carry out,

When different sets of tissues act together they are called an Organ

examples include

Kidney, Heart, Lungs, Skin, Brain, Intestines, Liver, Bladder, Stomach, Spleen, Appendix, Eyes.

When different Organs, Tissues and Cells work together they are called Systems.

examples include

  • Respiratory System
  • Circulatory System
  • Urinary System
  • Sensory System
  • Digestive System
  • Reproductive System

In this course we will deal with many different types of systems. Check the biology index page for examples of the different systems that the body needs to survive.

and when different systems work together it is an organism

and understand that growth results from cell division

You can see examples of organs and systems on the BBC site.

Test yourself again, probably more in keeping with your JC course


The details of what happens inside the nucleus come later in the section on genetics