Topic 3 - Organisms exchange substances with their environment Flashcards
What is the relationship between size of organism and its SA:V ratio
The larger the organism, the smaller the SA:V ratio
What do larger organisms require to obtain the substances they need
Specialised exchange systems eg, lungs
state the adaptations to increase the rate of exchange
Large SA:V ratio, short diffusion pathway to minimise, Movement of medium such as blood to maintain a concentration gradient, selectively permeable membranes
What do organisms with high metabolic rates require
A greater SA:V ratio to get more oxygen so more respiration can occur
What do multicellular organisms have to help aid diffusion
Tissue Fluid
What is the exchange system in insects
Spiracles, trachea and tracheoles surrounded by cells
What are the 3 ways in which insects have effective exchange
- Diffusion, o2 diffuses in from high to low and o2 is used in cells so constant gradient maintained
- The trachea expand and contract to move oxygen in
- Water in tracheaoles
Why is water in tracheoles important
During extensive exercise lactic acid builds up, there is a high water potential In the tracholes to water moves int cells. this decreases volume which decreases air pressure so the atmospheric pressure is greater and air moves in. Greater rate of diffusion since it occurs in the gas phase not liquid
What is the structure of the gas exchange in fish
lamellae running perpendicular to filaments with good water supply to maintain concentration gradient
What is parallel flow
The blood and water flow in the same direction so concentration gradient is not maintained
Explain how countercurrent flow maximise gas exchange in fish
-Blood and water flow in opposite directions
-So blood is constantly passing water with a higher concentration on o2
-so a concentration gradient is maintained
-along the whole length of the gill filament
What is the structure of a leaf from top to bottom
Waxy cuticle, upper epidermis, palisade mesophyll, spongey mesophyll, vascular bundle, lower epidermis, stomata and guard cells
function of the waxy cuticle
Reduces water loss
function of the upper epidermis
Transparent to let light through
function of the palisade mesophyll
Lots of chlorophyll so photosynthesis can occur
function of the spongey mesophyll
the site of gas exchange with lots of air spaces for a greater surface area
function of the vascular bundle
contains the xylem and phloem
function of the stomata
Pathway for gases to enter and exit the leaf
function of the guard cell
Open and close the stoma
What is a xerophyte
A plant which is adapted to live in conditions with little water
What are 3 adaptations of xerophytes
Rolled leaves, hairs and stomata located in pits
How do these adaptations of xerophytes help reduce water loss
The water vapour leaves via diffusion and is trapped this lowers the water vapour potential gradient between inside and outside of the leaf so less water is lost
What is the gas exchange system in humans
Mouth/nose, trachea, bronchi, bronchioles, alveoli, lungs, thorax, diaphragm
Explain how the lungs are adapted to allow rapid gas exchange
-Alveoli one cell thick so short diffusion pathway
-The RBC push against the capillary so shorter diffusion pathway
-constant heart beat so blood being pumped which maintains concentration gradient
- RBC slowed so more time for diffusion
-Lots of capillary’s so more diffusion at once
describe the process of inhalation in humans
- External intercostal muscles contract so internal intercostal muscles relax
- this pushes the ribs up and outwards
- diaphragm contracts and flattens
- so volume in the thorax increases
- So lower pressure in the lungs
- so pulmonary pressure is less than atmospheric pressure so air moves in
Describe the process of exhalation in humans
- Internal intercostal muscles contract and external intercostal muscles relax
- so ribs move inwards and down
- diaphragm relaxes so moves up
- volume of thorax decreases
- pressure in lungs increases
- so pulmonary pressure is greater than atmospheric pressure so sir moves out
What is physical digestion
Breaking down larger pieces of food into smaller pieces using the mouth and teeth so it is easier to swallow and provides a greater SA for enzymes
What is chemical digestion
Hydrolysing large insoluble molecules into smaller soluble molecules so the products of digestion can be absorbed into the bloodstream
What organs are involved in the digestion of carbohydrates
Mouth, stomach, pancreas, ileum
what happens in the mouth when digesting carbohydrates
Amylase is released by the salivary glands as well as mineral salts to maintain a ph of 7.
What does amylase break down starch into
Starch into maltose
What happens to amylase in the stomach
The stomach acid denatures the amylase
What does the pancreas secrete
Pancreatic juices containing amylase and alkaline salts to maintain a ph 7
What does the ileum do in the digestion of carbohydrates
Secretes maltase which is membrane bound
What is a disaccharidase and 3 examples
Breaks down disaccharides
-maltase
-sucrase
-lactase
What does maltase break maltose into
alpha glucose
What does sucrase break sucrose into
glucose and fructose
What does lactase break lactose into
glucose and galactose
What enzyme breaks down triglycerides
Lipase
What are triglycerides broken into by lipase
Monoglycerides and fatty acids
Where is lipase produces
Pancreas and small intestine
What is emulsification
Large lipid molecules being broken down into micelles by bile salts
Where is bile produces
Liver
Where is bile stored
Gal bladder
what three enzymes are involved in the digestion of proteins
Endopeptidase, exopeptidase and dipeptidase
What does exopeptidase do
Hydrolyses the peptide bonds on the outside of the smaller peptide chain forming amino acids and dipeptides
What does endopeptidase do
Hydrolyse the peptide bonds in the middle of the peptide chain forming smaller peptide chains
What does dipeptidase do
hydrolyses dipeptides into amino acids
What is different about endopeptidase and exopeptidase compared to dipeptidase
Dipeptidase is membrane bound
Explain how glucose is absorbed into the ileum
There is a higher concentration of glucose in the lumen of the ileum than the epithelial cells so glucose enters via facilitated diffusion. once the concentration of glucose is lower in the lumen of the ileum than not eh epithelial cell the glucose enters via co transport, against a concentration gradient
What system are lacteals part of
The lymphatic system
What is the process of absorption of triglycerides
There are epithelial cells adjacent to lacteals which drain into capillaries. Micelles contain bile salts, monoglycerides and fatty acids which burst when they come in contact with the epithelial cell. the monglycerides and fatty acids can enter the epithelial cell via simple diffusion since they are lipid soluble. Inside the epithelial cell the monoglycerides and fatty acids are reformed by the SER. these are packaged into vesicles which take them
