Gas exchange in all cells involves the movement of gasesMultiple choice question.directly from the atmosphere into the cell.with the help of hemoglobin.with the help of a specialized protein (not necessarily always hemoglobin).across cellular membranes.

During gas exchange:Oxygen moves up a concentration gradient from the air in the alveoli to the bloodOxygen moves down a concentration gradient from the blood to the air in the alveoliOxygen moves down a concentration gradient from the air in the alveoli to the bloodOxygen moves up a concentration gradient from the blood to the air in the alveoliCHECK YOUR ANSWERS

Internal gas exchange:Question 26Select one:a.Exchange between the blood and tissuesb.Exchange between alvioli and the bloodc.Exchange between atmosphere and lungs (breathing in and out)d.Transport of gases around the body.

How do gases move across the plasma membrane and other cellular membranes?Multiple choice question.By facilitated diffusionBy passive diffusionThrough specialized gas channelsBy active transport

Gas exchange takes place in the lungs. The diagram shows an alveolus next to a blood capillary in a lung. The arrows show the movement of two gases, A and B.3. (a) (i) Draw a ring around the correct answer to complete the sentence.Gases A and B move by diffusion. osmosis. respiration. (1) Page 7 of 18Ebroyonic cells have ethical dialemas as it involves the destruction of human embros wheras using your own bone marrow does not harm the patient It is more compatable so there is a less risk of rejection by the immune system as embroyinstem cells may not be compatable with the patientBone marrow cells are more available as they can be harvested from the patient at any given timewheras embryonic cells need a donor embryo which isnt always available(ii) Gas A moves from the blood to the air in the lungs. Gas A is then breathed out. Name Gas A. ______________________________________________________________ (1) (iii) Which cells in the blood carry Gas B? Draw a ring around the correct answer. platelets red blood cells white blood cells (1) (b) The average number of alveoli in each human lung is 280 million. The average surface area of 1 million alveoli is 0.25 m 2 . Calculate the total surface area of a human lung. ___________________________________________________________________ Answer ___________________________________ m 2 (2) (c) An athlete trains to run a marathon. The surface area of each of the athlete’s lungs has increased to 80 m 2 . Give one way in which this increase will help the athlete. ___________________________________________________________________ ___________________________________________________________________

1. How do the respiratory and circulatory systems work together in exchanging and transporting gases in our body?