2.50 understand the need for a transport system in multicellular organisms

Multicellular cells have large volume to surface area ration so diffusion happens too slowly for organism to sustain itself. Therefore, they have created transport systems to make diffusion happen quicker so the organism can sustain itself.  

2.49 understand why simple, unicellular organisms can rely on diffusion for movement of substances in and out of the cell

Unicellular cells have a small volume to surface area ratio making diffusion an effective way to get the substances they require.

2.48 describe experiments to investigate the effect of exercise on breathing in humans.

Experiment to investigate the effect of exercise on breathing in humans:

1)      Have someone do jumping jacks for a certain amount of time

2)      Count their breaths before during a after exercise

3)      Their breaths should increase while exercises because the body needs oxygen for cell respiration. After the exercise they will continue to breathe heavily due to oxygen debt.

2.47 understand the biological consequences of smoking in relation to the lungs and the circulatory system, including coronary heart disease

Consequences of smoking:

·         Blood clots

·         Cancer

·         Coronary artery disease

·         Decreased ability to taste or smell

·         Delayed wound healing

·         High blood pressure

·         Lung problems eg chronic bronchitis

·         Tooth and gum disease

·         The carbon monoxide combines with the hemoglobin in red blood cells to decrease the bloods ability to carry and transport oxygen

2.46 explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries

Alveoli adaptations:

·         Made of one cell layer: easy for gases to diffuse in and out

·         Spherical: more surface area

·         Good blood supply: easy access for gases to blood

Oxygen and carbon dioxide dissolve in mucus to be dissolved easier

2.45 understand the role of the intercostal muscles and the diaphragm in ventilation

Intercostal muscles:

Inspiration:

·         The external intercostal muscles contract

·         Causes the rib cage to be lifted up and out

·         This increases the thoracic volume and causes air to rush in filling the space

Expiration:

·         The internal intercostal muscles contract

·         Causes the ribs the be pulled down and in

·         This reduces the thoracic volume causing air to rush out

2.44 describe the structure of the thorax, including the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membrane

The Thorax:

·         Is incased by the rib cage which has intercostal muscles in between the ribs and the diaphragm underneath

·         Inside the ribcage are two lungs

·         The air is brought through the trachea to the bronchi

·         The air travels to the bronchioles until it reaches the alveoli where the capillaries in the pleural membrane exchange the carbon dioxide with oxygen to use for cell respiration