Edexcel Salter’s -Nuffield A Level
Biology: Topic 2 Complete 2024 Exam
quiz Study Guide
What three things affect the rate of diffusion? -
Answer>>Surface area to volume ratio, distance and
concentration gradient..
Describe the process of breathing. - Answer>>Air drawn into
lungs via trachea due to low pressure in lungs, create by increase
of volume in thorax as ribs move up and diaphragm moves down.
, How are the alveoli adapted to their function? -
Answer>>Surface area and the concentration gradient is
directly proportional to the rate of diffusion. The alveoli wall is one
cell thick and the steep concentration gradient between the
alveolar air and the blood is maintained by ventilation of the
alveoli and the continuous flow of blood through the lungs. Every
alveolus is covered in capillaries so that there is never a shortage
of blood. Thickness of gas exchange surface is inversely
proportional to the rate of diffusion, so the short distance between
the blood and the alveolus means that oxygen can rapidly diffuse
into the blood as CO2 diffuses out and is expelled from the body.
Biology: Topic 2 Complete 2024 Exam
quiz Study Guide
What three things affect the rate of diffusion? -
Answer>>Surface area to volume ratio, distance and
concentration gradient..
Describe the process of breathing. - Answer>>Air drawn into
lungs via trachea due to low pressure in lungs, create by increase
of volume in thorax as ribs move up and diaphragm moves down.
, How are the alveoli adapted to their function? -
Answer>>Surface area and the concentration gradient is
directly proportional to the rate of diffusion. The alveoli wall is one
cell thick and the steep concentration gradient between the
alveolar air and the blood is maintained by ventilation of the
alveoli and the continuous flow of blood through the lungs. Every
alveolus is covered in capillaries so that there is never a shortage
of blood. Thickness of gas exchange surface is inversely
proportional to the rate of diffusion, so the short distance between
the blood and the alveolus means that oxygen can rapidly diffuse
into the blood as CO2 diffuses out and is expelled from the body.
