Exchange in organisms

Created by

Adam

Cards (45)

How do single-celled organisms exchange substances?
Substances diffuse directly through the membrane from its immediate environment
Why do multicellular organisms require transport systems?
Because most of their cells are not in direct contact with their immediate surroundings
The smaller the animal...
The greater the SA:V ratio
Describe the tracheal system of insects
Holes where gases diffuse - spiracles
Main tracheal tube - trachea
Smaller tracheal tubes - trachioles
How do insects maintain a steep rate of diffusion?
Trachioles are bathed in tracheal fluid that keep the tracheal system moist in order to maintain a steep concentration gradient
-Spiracles can close to prevent water loss
What adaptation do fish have to respire?
Gills
What process do fish use to maximise respiration by maintaining a concentration gradient?
Counter current flow mechanism
How does the countercurrent exchange system work?
The blood flows in the opposite direction to water passing the gills, which maintains a constant concentration of oxygen throughout
What are the layers of a leaf cell
Waxy cuticle, upper and lower epidermis, palisade mesophyll, spongy mesophyll, stomata and guard cells
How are stomata adapted for their function?
- More stomata on the base of the leaf which is cooler and shaded, minimising water loss
- Guard cells control the state of passage depending on water concentration, meaning water won't be lost to transpiration
- They are only open during the day as photosynthesis can only occur in the presence of sunlight
How is a leaf adapted for gas exchange?
- Air space to allow gas movement
- Short diffusion pathway
How do xerophytic plants reduce water loss?
Thick waxy cuticles, Extensive root systems and thin needle-like spines all act to reduce water loss through transpiration via surface area
What are the sections of the respiratory system?
The trachea, bronchi, lungs, bronchioles and alveoli
How is the trachea adapted?
Cartilage rings to keep airway open to maintain reliable gas source
How are the bronchioles adapted?
Lined with goblet cells that produce mucus to trap foreign particles
Ciliated epithelial cells waft mucus up to be coughed up as phlegm or swallowed and destroyed by stomach acid
How does inspiration occur?
-The diaphragm moves down
-external intercostal muscles contract
-internal intercostal muscles relax
-rib cage moves upward and outward
-increase in thoracic volume
-Atm. pressure > thoracic pressure causes air to rush in
How does expiration occur?
-The diaphragm moves up
-external intercostal muscles relax
-internal intercostal muscles contract
-rib cage moves downward and in
-decrease in thoracic volume
-Thoracic pressure > atm. pressure forcing air out
What is the equation for pulmonary ventilation rate?
Tidal volume x breathing rate
How are the alveoli adapted?
One cell thick - Short diffusion pathway
Moist- Allows gases to diffuse
Rich blood supply - Steep concentration gradient
What enzymes are involved in digestion?
Amylase, protease, lipase
Where is amylase produced?
The pancreas and salivary glands
Where is protease produced?
The pancreas and stomach
Where is lipase produced? 
The pancreas and small intestine
How are carbohydrates digested?
First by amylase produced in the salivary glands, then by maltase, sucrase, and lactase to break down disaccharides into their constituent monosaccharides
How are proteins digested?
-Endopeptidase hydrolyses bonds in the middle of the polypeptide to increase surface area and make exopeptidase more efficient
-Exopeptidase hydrolyses bonds at the end of the polypeptides
-Dipeptidase hydrolyses dipeptides into individual amino acids
How are lipids digested?
-Lipids = emulsified by bile • increases surface area produces micelles (lipid droplets)
-Micelles are broken down upon contact of the epithelial lining into monoglycerides and fatty acids, absorbed directly through the epithelial lining
-The ER recombines them into triglycerides
-The Golgi apparatus modifies them into chylomicrons
-exit via exocytosis into the lacteal/ the lymphatic system
Structure of haemoglobin
Quaternary polypeptide with 4 haem groups with Fe2+ to bind to oxygen
Haemoglobin with a high affinity to oxygen
Take up oxygen more readily but lose it less readily (left side of oxy. dis. curve)
Haemoglobin with a low affinity for oxygen 
Take up oxygen less readily but lose it more readily (right side of oxy. dis. curve)
Explain the shape of the oxygen dissociation curve
Positive correlation - each binding makes subsequent bindings easier
Curve plateaus when all four binding sites are full
What is the Bohr shift?
Shifts left for low concentration - low oxygen affinity
Shifts right for high concentration - high oxygen affinity
What does a double circulatory system refer to?
A double circuit system, where blood travels from the heart to the lungs, then back to the lungs to be pumped around the body
What are the four blood vessels of the heart?
Vena cava - Receives from the body
Pulmonary artery - Pumps to the lungs
Pulmonary vein - Receives from the lungs
Aorta - Pumps to the body
What are the four chambers of the heart?
Right and left atria, right and left ventricles
What are the names of the valves between atria and ventricles?
Atrioventricular (AV) valves
What are the names of the valves in the pulmonary artery and the aorta?
Semilunar valves
What are the three stages of the cardiac cycle?
Atrial systole, ventricular systole, diastole
What occurs during atrial systole?
-Blood flows into the right atrium from the vena cava • causes pressure to increase
-Buildup in pressure causes blood to flow through the right ventricle through the right AV valve
What occurs during ventricular systole?
-AV valves closes
-ventricles contract
-forces blood upward through the pulmonary artery and aorta
What happens during diastole?
-All chambers relax
-semilunar valves prevent backflow