How are body parts organised? 

Living organisms have life processes. Organisms need to carry out these life processes in order to be counted as being alive. These processes include:

  • Movement
  • Respiration
  • Sensitivity
  • Growth
  • Reproduction 
  • Excretion 
  • Nutrition

An easy way to remember the life processes is by using MRS GREN.

  • M ➜ Movement
  • R ➜ Respiration
  • S ➜ Sensitivity
  • G ➜ Growth
  • R ➜ Reproduction 
  • E ➜ Excretion 
  • N ➜ Nutrition


All living things are able to move in many different ways. A deer can run away from danger. Plants can move towards the sun to increase the amount of sunlight they receive. 


Respiration is the process of breathing. Animals use oxygen from the air to breathe through their mouth and nose. Plants take in carbon dioxide and give out oxygen. 


All living things are able to have an awareness and understanding of their surroundings. They are also able to change according to their environment. 


All living things grow. Organisms’ life cycles are different; some grow from seeds, eggs, babies, etc. For example, a chick hatches out of an egg, and the chick grows into an adult chicken. 


All living things reproduce. This means they make more of their own type. Organisms reproduce in many different ways. Plants produce seeds, some animals lay eggs, and humans and other animals have babies. For example, humans give birth to a live baby. 


All living things get rid of waste products. Plants use their leaves to get rid of any waste products. 


All living things need the energy to survive. Living things get their energy from different places. Eating food is how animals get energy. This food provides the organism with calories that it would otherwise not survive without. Some animals eat plants (herbivores), some eat animals (carnivores), and some eat both plants and animals (omnivores). Plants take in nutrients from the soil, and they create their own food using the sun’s energy through the process of photosynthesis.

Plants and animals consist of cells that work together. A cell is the basic building block of all living organisms. They are very small and are only seen using a microscope. Some organisms are unicellular – this means they have only one cell, for example, bacteria, protists and yeast. Some organisms are multicellular – this means that they have many cells for example animals and plants.

Animals and plants have different structures that make up the parts of animal cells and plant cells. Both animal and plant cells are eukaryotic cells. These are big and complex cells that have membrane-bound organelles. The genetic material is enclosed in a nucleus. Both animal and plant cells have organelles. Organelles are structures that perform different functions in the cell. 

Watch the video

Level of organisation: 

  • Similar cells form a tissue. 
  • Similar tissues form an organ.
  • Different organs interact to form systems. 
  • Different systems interact to form an organism.  

Watch the video

Animal level of organisation example:

Muscle cells work together to form muscle tissue, muscle tissue then combine to form an organ e.g. heart, stomach or liver. Different organs work together to make up systems e.g. cardiovascular system or the muscular system. A combination of these different systems in the body make up an organism.  

Plant level of organisation example: 

Root hair cells work together to form root tissue. Root tissue then combine to form roots of the plant. These then make up the transport system of a plant. The transport system makes up part of the organ system. The different systems work together to make up the plant.