Please enable JavaScript.
Coggle requires JavaScript to display documents.
Gas exchange - Coggle Diagram
Gas exchange
leaf structure
-
different cell types and tissues are arranged in a specific way to allow for photosynthesis to occur
-
-
-
the close contact between the cells and air spaces allows efficient gas exchange for photosynthesis and respiration
-
adaptations of the leaf
thin, meaning a short diffusion distance
flat, providing a large SA:vol ration
many stomata which allow movement of gases in and out of the leaf, allowing the leaf to maintain a steep concentration gradient
stomata
found between two guard cells, normally on the lower epidermis of the leaf
guard cells open or close the stomata which controls gas exchange and water loss, and are normally open when these is plenty of sunlight and water
stomata open when water moves by osmosis into the guard cells causing them to become turgid, allowing gases to diffuse in and out. they close when water moves out of the guard cells, making them flaccid
-
alveoli
-
thin, single celled walls to minimise diffusion distance
-
-
day and night
Plants can only photosynthesize when they have access to light, however, cells respire all the time, meaning that gas exchange in plants varies throughout a 24 hour period
The rate of photosynthesis tends to be higher than the rate of respiration (unless there is a low light intensity) Therefore there is net diffusion of carbon dioxide into the plant and net diffusion of oxygen out of the plant during the day
At low light intensities, the rate of photosynthesis is equal to the rate of respiration meaning that there is no net movement of oxygen or carbon dioxide in either direction
diffusion
diffusion is why gas exchange occurs. single celled organisms, such as amoeba, can exchange gases sufficiently by simple diffusion through the cell membrane
multicellular organisms have exchange surfaces and organ systems that maximise the exchange of material (e.g gills) which increase the efficiency of exchange in a number of ways
-
-
-
-
-
lungs
all gas exchange surfaces have features in common allowing the maximum amount of gases top be3 exchanged in the smallest amount of time
-
-
well ventilated with air, allowing diffusion gradients to be maintained
-
structures in the lungs
-
-
diaphram
sheet of tissue and muscles at the bottom of the thorax that helps change the volume of the thorax, allowing for inhalation and exhalation,
-
-
-
-
pleural cavity
the fluid filled space between the pleural membrane which reduces friction and allows the lungs to move freely
smoking
smoking causes COPD, coronary heart disease, as well as cancer.
-
breathing practical
Exercise causes the frequency of breathing to increase in order to provide more oxygen for respiration and to pay off any subsequent oxygen debt
CORMS
-
Organisms – The students should be of the same age, gender, size and general fitness
-
-
-
Same – We will control the type of exercise carried out, the temperature of the environment, the food intake of the students prior to the investigation