Biology: Gas Exchange

Question 1

Insect - Gas Exchange

Answer 1

Spiracles in the thorax and or / abdomen. Can open and close. Prevent water loss, opens at high levels of Co2. Large gas exchange surface area many branches of the tracheoles. Close contract with tracheoles. One cell thin to give a short diffusion pathway. Steep concentration gradient - oxygen in the cells is used in respiration that lowers the concentration of oxygen in the cells than in the tracheoles. Discontinuous gas-exchange cycle.

Question 2

Fish - Gas EXchange

Answer 2

• Many Gill filaments give a large surface area for a faster rate of diffusion
• Many lamellae on each filament further increase surface area for a faster rate of diffusion
• Lamellae walls are one cell thick and the cells are flattened to provide a short diffusion pathway for a faster rate of diffusion
• Capillary wall is one cell thick and the cells are flattered to provide a short diffusion pathway for a faster rate of diffusion
• Capillary and lamellae walls are in close contact with each other which keeps the diffusion pathway short for a faster rate of diffusion
• The capillaries are narrow which slows down the speed of the blood and gives more time for diffusion
• Each lamellae contains a capillary bed which gives a good bl;pod flow and maintains the concentration gradient for a faster rate of diffusion by removing blood that is saturated with oxygen and replacing it with blood that has a low concentration of oxygen
• Ventilation mechanism to bring in water with a bigger concentration of oxygen and maintain a steep concentration gradient for a faster rate of diffusion
• Counter current flow / the blood and water flow in the opposite direction
• Maintain the contraction gradient over the whole length of the Gill filament / equilibrium is never reached
• So greater saturated of the blood with oxygen and higher rates of aerobic respiration can take place

Question 3

Surface of spongy mesophyll cell - Gas Exchange

Answer 3

Maintained at a lower concentration with the cell then within the intercellular airspace for diffusion. One cell thick. Air Scape gives a large surface area. Long and thin leaves gives a large SA.

Question 4

Human - Gas Exchange

Answer 4

• The gross structure of the human gas exchange system limited to the alveoli, bronchioles, bronchi, trachea and lungs.
• Ventilation and the exchange of gases in the lungs. The mechanism of breathing to include the role of the diaphragm and the antagonistic interaction between the external and internal intercostal muscles in bring about pressure changes in the thoracic cavity.
  Ventilation mechanism to maintain concentration gradient
  Capillary network around every alveoli which maintains good blood flow

Question 5

Lung disease

Answer 5

• Interpret information relating to the effects of lung disease on Gas Exchange and / or ventilation
• Interpret data relating to the effects of pollution and smoking on the incidence of lung disease
• Analyse and interpret data associated with specific risk factors and the incidence of lung disease
• Evaluate the way in which experimental data led to statutory restrictions on the sources of risk factors
• Recognise correlations and causal relationships