Topic 2 - Gaseous Exchange Flashcards
What must the surface over which gas exchange takes place be
Permeable to oxygen and carbon dioxide
Moist, since gases must dissolve in water before diffusing into tissue cells
What is Ficks Law
Surface area x difference in concentration
Rate of diffusion = ——————————————————————-
Length of diffusion pathway
According to Fick’s Law, how is gas exchange increased
The exchange surface has a large surface area
There is a big difference in the concentration of gases on each side of the surface
The exchange surface is thin, with a short diffusion distance
What are the 2 processes in flowering plants that involve gas exchange
Respiration and photosynthesis
Where and when does Respiration take place
Where - in all times
When - all the time
Where and when does Photosynthesis take place
Where - in green tissues
When - only during the daylight hours
When does Maximum photosynthesis occur
When the light intensity is highest
What is the compensation point
The time of day when the rate of photosynthesis equals the rate of respiration, therefore the next exchange of oxygen is 0
What can increase the surface area-to-volume ratio in plants
The root hairs in epidermal cells
In plants, where does diffusion of respiratory gases take place
Through the cell wall and cell membrane of root hairs
Where are the most active cells in a plant cell
Those under the surface
In a stems outer covering, what is provided to increase diffusion
There are small pores to allow oxygen in and carbon dioxide out
Why do large plants lack specialised respiratory surfaces
They lack tissues with a high energy demand and so have low respiration rates
What is the major photosynthetic organ in a flowering plant
The leaf
Why do leaves need specialised gas exchange surfaces
A high rate of photosynthesis is generated
The concentration of carbon dioxide in air is low
Give the path of gaseous exchange, from Carbon Dioxide to Oxygen, in a leaf
Carbon dioxide is taken in by the opening of the stomata, by guard cells
The carbon dioxide is then diffused into the air space system in the spongy mesophyll
The spongy mesophyll cells then absorb the carbon dioxide, and is exchanged with oxygen
Oxygen produced is then diffused out the mesophyll cells into the air spaces and out through the stomata
What are some adaptations of hydrophytes in aquatic flowering plants that facilitates the uptake and movement of oxygen and carbon dioxide
Air spaces in the stem, so that it’s easier for oxygen to diffuse to all tissues, including the root
Air spaces in the leaf, so that it’s easier for diffusion of gases and aids the flotation of the leaf
Stoma on the upper epidermis, which allows gas exchange without the leaf becoming flooded, transpirational loss of water is not a problem
What is the difference between the inside of an animal cell and the outside, in terms of Carbon Dioxide and oxygen concentration
Outside- low CO2 concentration, high O2 concentration
Inside - high CO2 concentration, low O2 concentration
What are the 4 stages of movement of oxygen to cells, and of carbon dioxide out in mammals
Diffusion of gases between respiring tissues and blood
Transport of gases in blood
Diffusion of gases across the gas exchange surface between alveolar air and blood
Ventilation of the lungs with fresh air
What is the trachea
The place where air enters or leaves the lungs
What is the thorax
The place where the lungs are situated within
What is the bronchi
What the trachea is branched into
What are bronchioles
A fine series of cells within the bronchi that contain alveoli
Where are alveoli located
In the bronchioles
