Unit 2 KA3 Flashcards
Metabolic rate
The speed of chemical reactions in an organism.
It is the quantity of energy used by the body in a given time, in kj or kcal.
Measured by measuring oxygen consumption, or production of carbon dioxide or heat.
Calorimeter
Used to measure the heat produced by an organism.
The organism is placed in a well insulated container, and the temperature difference between water flowing in and out is measured.
Respirometer
Used to measure oxygen uptake of an organism.
Carbon dioxide must be absorbed using soda lime/sodium hydroxide, so that the liquid moves along the scale.
Oxygen/carbon dioxide probes
Used to accurately measure oxygen uptake and carbon dioxide production over time.
Linked to computers to collect data over a longer time period.
BMR
Basal metabolic rate.
The minimum rate of energy release needed to maintain life.
Surface area : volume ratio
As volume (or body size) increases, the SA : volume ratio of an organism decreases.
It has a smaller surface area compared to its volume.
Tiny endothermic (warm blooded) organisms with a high SA : volume ratio tend to lose heat faster, so have a higher BMR.
Organisms with a low metabolic rate
Organisms that are sessile (don’t move), ectothermic (cold blooded) and aquatic (live in water) tend to have a lower BMR.
eg. fish, sea anemones.
Organisms with a high metabolic rate
Organisms that live on land (or fly), are endothermic, highly active and are tiny (high SA : volume ratio) tend to have a very high BMR.
eg. mice, bats, hummingbirds.
Circulatory system
Heart, blood vessels and blood.
Needed to deliver oxygen to respiring tissues.
Organisms with a high BMR need a more efficient circulatory system.
Single circulatory system
The blood passes through the heart once on each circuit of the body.
The heart has 2 chambers - one atrium, one ventricle.
Blood travels to the gills at high pressure, but then loses pressure in the permeable gill capillaries, and passes to the tissues at low pressure.
It is a primitive and inefficient system, but is adequate for fish which have a low BMR.
Double circulatory system
The blood passes through the heart twice on each circuit of the body.
There are 2 separate circuits - to the lungs (pulmonary circuit) and the body tissues (systemic circuit).
Blood is pumped to the lungs and body tissues at high pressure, making it a more efficient system for the delivery of oxygen.
Incomplete double circulation
Found in amphibians (which have no septum, and one ventricle) and reptiles (which have a partial septum).
The oxygenated and deoxygenated blood mix in the shared ventricle, making oxygen delivery less efficient than complete double circulation.
Septum
A strip of tissue separating the left and right sides of the heart.
Prevents oxygenated and deoxygenated blood from mixing.
Complete double circulation
The septum completely separates the left and right sides of the heart, preventing oxygenated and deoxygenated blood from mixing.
There are 2 separate atria and 2 separate ventricles.
This is much more efficient, and ensures that oxygen is supplied to respiring tissues rapidly.
Found in organisms with a high BMR - mammals and birds.
