A frog is an animal. The skin of a frog is permeable to oxygen and carbon dioxide. Which directions will have a net diffusion of oxygen and carbon dioxide when a frog swims in pond water?

11.1.1 List the features of gas exchange surfaces in humans, limited to large surface area, thin surface, good blood supply and good ventilation with air

11.1.10 Explain the role of goblet cells, mucus and ciliated cells in protecting the gas exchange system from pathogens and particles

11.1.2 Name and identify the lungs, diaphragm, ribs, intercostal muscles, larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries

11.1.3 State the differences in composition between inspired and expired air, limited to oxygen, carbon dioxide and water vapour  Use limewater as a test for carbon dioxide to investigate the differences in composition between inspired and expired air

11.1.4 Investigate and describe the effects of physical activity on rate and depth of breathing

11.1.5 Name and identify the internal and external intercostal muscles

11.1.6 State the functions of the cartilage in the trachea

11.1.7 Explain the role of the ribs, the internal and external intercostal muscles and the diaphragm in producing volume and pressure changes in the thorax leading to the ventilation of the lungs

11.1.8 Explain the differences in composition between inspired and expired air

11.1.9 Explain the link between physical activity and rate and depth of breathing in terms of the increased carbon dioxide concentration in the blood, detected by the brain, causing an increased rate of breathing