Give 5 reasons why specialist transport systems are needed
- metabolic demands of most animals is high
- SA:V decreases as animal size increases so diffusion distances increase whilst SA avaliable becomes relatively smaller
- molecules are made in one place but needed in another
- food will be digested in one organ system but needs to be transported to every cell
- waste products of metabolism need to be removed from cells and transported to excretory systems
As an organism gets larger what happens to the diffusion distance?
It gets larger
Why does a greater level of activity in an organism increase demand for glucose and oxygen?
- more activity requires more energy
- more energy requires more aerobic respiration
- which requires more reactants (oxygen and glucose)
Why does a greater volume of an organism mean a greater demand?
- greater volume means greater number of cells
- each cell requires energy
- so demand for energy/glucose/oxygen increases
Define mass flow
the movement of fluids down a pressure or concentration gradient
Define circulatory system
the transport system of an organism
Define open circulatory system
a transport system with a heart but with few vessels to contain the transport medium
Define closed circulatory system
the transport medium is enclosed in vessels and does not come into contact with the cells of the body
Define haemolymph
the blood like fluid contained in insects
Define single circulatory system
a circulatory system where the blood flows through the heart once during a complete circuit of the body
Define double circulatory system
a circulatory system where the blood flows through the heart twice during a complete circuit of the body
Define pulmonary circulation
The portion of the circulatory system which carries deoxygenated blood away from the right ventricle of the heart to the lungs and returns oxygenated blood to the left atrium and ventricle
Define systemic circulation
The part of the cardiovascular system which carries oxygenated blood away from the heart to the body and returns deoxygenated blood back to the heart
Give examples of organisms with a single closed circulatory system
Fish and annelid worms
Give examples of organisms with a double closed circulatory system
Birds and most mammals
Give an example of an organism with an open circulatory system
Insects
Why are fish able to be highly active despite having a single closed circulatory system?
- the countercurrent exchange mechanism means they can take up a lot of O2 from water
- their body weight is supported by the water
- they do not maintain their own body temperatures
Why are single closed circulatory systems not very efficient?
Blood pressure drops considerably
so blood flows slowly back to the heart
Why are double closed circulatory systems very efficient?
- each circuit passes through only one capillary network
- this maintains relatively high blood pressure
- so fast flow of blood back to the heart is maintained
What are the general features of circulatory systems?
- fluid to transport dissolved gases, nutrients, and waste
- a pumping mechanism to move fluid
- sometimes vessels to carry the fluid
How are open and closed circulatory systems different?
- blood enclosed in vessels in closed but not in open
- in open circulatory systems the fluid fills body cavities
- open less efficient
What is an advantage of having an open circulatory system?
less vulnerable to pressure
What is an advantage of closed circulatory systems?
more efficient
What is a disadvantage of open circulatory systems?
requires low metabolic rate so does not work for larger animals
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Unit 2: Microscopy20
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Unit 2 - Cells and Organelles20
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Unit 2 - Cells and Organelles 220
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Unit 2 - Biological Elements & Water20
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Unit 2 - Carbohydrates20
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Unit 2 - Testing for biological molecules20
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Unit 2 - Lipids33
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Unit 2 - Proteins73
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Unit 2 - Nucleic acids & DNA replication73
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Unit 2 - Enzymes35
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Unit 2 - Plasma membranes34
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Unit 2 - Diffusion/osmosis/active transport66
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Unit 2 - The cell cycle, mitosis, meiosis86
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Unit 2 - Cell organisation and stem cells29
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Unit 3 - Mammalian gas exchange and ventilation24
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Unit 3 - Gas exchange and ventilation in bony fish and insects10
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Unit 3 - Circulatory systems27
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Unit 3 - Blood and blood vessels46
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Unit 3 - Tissue fluid17
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Unit 3 - Structure and anatomy of the heart23
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Unit 3 - The cardiac cycle, heart action coordination, and ECGs38
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Unit 3 - Transport of oxygen and carbon dioxide41
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Unit 3 - Transport in plants94
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Unit 4 - Classification35
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Unit 4 - Variation and Evolution69
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Unit 4 - Biodiversity124
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Unit 4 - Communicable disease, disease prevention and the immune system161
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Unit 4 - Pathogens that cause disease in plants and animals28
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Unit 4 - Specific immune response27
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Unit 5 - Neuronal Communication62
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Unit 5 - Hormonal Communication55
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Unit 5 - Communication and Homeostasis45
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Unit 5 - Excretion, homeostasis and the liver86
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Unit 5 - Plant & Animal Responses142
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Unit 5 - Photosynthesis60
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Unit 5 - Respiration48
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Unit 6 - Genetics of living systems81
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Unit 6 - Patterns of Inheritance85
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Unit 6 - Manipulating genomes85
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Unit 6 - Cloning and biotechnology91
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Unit 6 - Ecosystems90
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Unit 6 - Population and Sustainability54
