Seven Life Processes

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The seven processes of life

The seven processes of life are the key to all living organisms: these processes consist of nutrition, growth, movement, respiration, reproduction, sensitivity and excretion. Although, they may be achieved in different ways depending on the organism. These processes happen with in both plants and animals; in each organ, cell and organelle. All these processes are interlinked and have a chain effect upon one another. Without one of them the others aren’t possible.

Movement
For living things to find energy/nutrients they have to interact with their surroundings, this is only possible if movement is able to happen. A plant will turn its leaves to the sun (phototropism): strands of xylem and phomen provide a skeleton like structure for the plant to grow towards the light source. Whilst a plant’s roots grow downward in response to the pull of gravity known as gravitropism.

Nastic movement in plants do not involve growth and do not depend on the direction of the stimulus. The leaflets of a Mimosa Pudica, after being exposed to thermal stimuli through touch react due to the change on turgor pressure within the base of each leaflet. It can take only a few seconds to cause a response. Another nastic response is sleepmovement, known as photonasticy, a plant’s response to night and day. This again is a reaction from the change of turgor pressure in motor cells.

Active transport is an example of movement on cellular level as only take place in a living system that is actively producing energy by respiration. Energy is needed for the molecules or ions to be carried against their concentration gradient. (M.B.V. Roberts, Biology a functional approach)

Animals have the ability to move from one place to another. This occurs in three different environments, water, land and air; in basic terms it enables them to move away from danger and find food.

In water, buoyancy reduces the influence of gravity. The primary force restricting forward movement is drag, so the body shape of the organism is important in order to reduce the friction and turbulence created through swimming. The sinuous undulation of an eel’s body propels it forward as each body segment pushes against the water and the moving wave forces the eel forward.

On land, vertebrates and arthropods have been able to develop the means of rapid locomotion across a surface. Both of these body groups are raised above the ground by a series of jointed appendages, the legs, and can move forward by pushing against the ground. Not only do the legs provide propulsion but also support for the body, providing it with stability, helping the body maintain its centre of gravity when moving.

In the air, flight is achieved by birds and insects by pushing down against the air with their wings. This raising and lowering of the wings happens due to the alternating contraction of the extensor muscles known as the elevators and the flexor muscles, the depressors. In flies and insects, the movement of their wings are too rapid for nerves to carry successive impulses. So in order for this to happen flight muscles are not attached to the wings, but to the stiff wall of the thorax, that becomes distorted in and out by the movement. The result of this distortion triggers its contraction in turn without the arrival of a nerve impulse. For example, a mosquito can beat its wings more than 1000 times per second.

Respiration
Respiration is a chemical change carried out in all living animals and plants, and is a continuous process. Not all animals respire in the same way, but in all cases they consist of numerous flat surfaces, sacs or tubes, with a large surface area. For instance earthworms exchange gases across the entire surface area of the body, flatworms are the same but through having a flattened body the surface area not only maximises respiration but also decreasing the distance in which diffusion has to occur within the body of the worm. External gills...
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