Topic 3A- Exchange and Transport Systems + RP5 Flashcards
What is the rate of exchange effected by?
SA:V
What kind of surface area to volume ratio do small animals have?
High surface area to volume ratio
What kind of surface area to volume ratio do large animals have?
Low surface area to volume ratio
What 2 things do multicellular organisms need to be able to exchange substances?
- exchange organs
- mass transport systems
Why is the diffusion rate quick in single celled organisms?
In single celled organisms the substances are able to diffuse directly across the cell-surface membrane. The rate is quick because of the short distance the substances have to travel.
Why is diffusion across the outer membrane slower in multicellular organisms?
- some cells are deep within the body (there’s a big distance to travel)
- larger animals have a low SA:V ratio
Describe ‘mass transport’ in animals and plants
In mammals, usually the circulatory system which uses blood to carry glucose and oxygen around the body. It also carries hormones, antibodies and waste like CO2.
In plants, it involves the transport of water and solutes in the xylem and phloem.
What effects heat exchange?
Body size and shape
How does size effect the rate of heat loss?
smaller the animal, the more heat loss
Why do small organisms have a high metabolic rate?
Because small organisms loose a lot of heat due to their SA:V ratio, a high metabolic rate is needed in order to generate enough energy to stay warm.
How does the shape of an animal affect heat exchange?
Animals with a compact shape have a small surface area to volume ratio- minimising heat loss from their surface.
Animals with a larger surface area ratio (less compact) have an increased rate of heat loss from their surface
What does whether an animal is compact or not depend upon?
Whether an animal is compact or not depends on the temperature of its environment.
What do organisms do if they don’t have the body or shape to suit their climate?
They have behavioural and physiological adaptions.
What adaptions may small desert mammals have?
Kidney structure adaptions so that they produce less urine to compensate for the high SA:V ratio that means they loose more water.
What adaptions may small mammals living in cold regions have? (3)
- They need lots of energy so eat large amounts of higher energy foods such as seeds and nuts.
- They may have thick layers of fur.
- They may hibernate when the weather gets really cold.
What are the two main adaptions for gas exchange surfaces?
- large surface area
- they’re thin (short diffusion pathway)
also the organism maintains a steep concentration gradient of gases across the exchange surface
Describe how single-celled organisms exchange gases
Single celled organisms absorb and release gases by diffusion through their outer surface.
Name as many of the structures in the lungs (9)
- trachea (windpipe)
- bronchi (2 bronchus’)
- bronchioles
- alveoli
- ribcage
- lung
- diaphragm
- internal intercostal muscles
- external intercostal muscles
What type of process is inspiration?
Active
Which muscles contract during inspiration?
- external intercostal
- diaphragm
What happens to the diaphragm during inspiration?
It flattens
Why does the lung pressure decrease during inspiration?
Because the volume of the thoracic cavity increases, so the lung pressure decreases
What happens to the muscles during expiration?
They relax
How does the ribcage move during expiration?
It moves downwards and inwards, and the diaphragm becomes more curved.
What happens to the air pressure of the lungs during expiration?
It increases, as the thoracic cavity decreases
What type of process is normal expiration?
Passive