organisms exchanging substances Flashcards
What is the relationship between size of an organism and sa : v ratio
the smaller the organism, the larger the sa : v ratio
Describe the process on inspiration
external intercostal muscles contract causing ribcage to move up and out
diaphragm contracts and flattens moving down
volume of thoracic cavity increases and pressure decreases below atmospheric pressure so air rushes in
Describe the process of expiration
external intercostal muscles relax causing ribcage to move down and in
diaphragm relaxes and curevs moving up
volume of thoracic cavity decreases and pressure increases above atmospheric pressure so air rushes out
What is the spirometer?
a machine the doctor uses to measure lung volume
its consists of a chamber filled with oxygen
the lid moves up and down as person breathes
soda lime absorbs CO2 exhaled
What is forced expiration and what does it involve?
External intercostal muscles relax and internal contract moving ribcage further down and in
Explain gas exchange in insects
air-filled pipes called trachea have small pores called spiracles
each trachea branches off into trachioles which have thin permeable walls
CO2 moves in opposite direction and goes into atmosphere
oxygen travels down conentration gradient
How do insects prevent water loss?
exchanging gases results in loss of water vapour
if too much water is lost insect uses muscle to close spiracles
also covered with waterproof waxy cuticle and tiny hairs
Insection dissection method
place locust on back and pin onto dissection tray
make 4 cuts in shape of rectangle
gently peel exoskeleton
observe where trachea is
remove exchange surface area with tweezers and put onto glass slide
observe under microscope
Explain gas exchange in fish
Gills - water containing O2 passes across gills
each gill is made up of thin plates called gill fillaments attached to a gill arch
gill filaments have tiny structures called lamellae
Counter-current mechanism
Explain the counter-current mechanism in fish
blood and water flow in opposite direction
water has higher concentration of O2 than blood
steep concentration gradient created
O2 moves to lower concentration from water to blood
Explain the fish dissection
place fish on dissection tray and locate gills
use scissors to remove gill arch
wash gill fillaments with distilled water
use scalpel to cut off gill filament and view under microscope
Explain gas exchange in plants
gases enter/exit through stomata
stomata can open/close to prevent water loss - controlled by guard cells
during light hours CO2 enters for photosynthesis
when water enters guard cells it makes it turgid opening stomata
if plant is dehydrated guard cells become flaccid and close
What are xerophytes?
plants adapted to live in really warm windy or dry habitats
What are xerophyte adaptations?
Sunken stomata - allow moist air to be trapped
waxy cuticle - reduces water loss
hairy epidermis - traps moist air
fewer stomata - fewer areas of water loss
curled leaves - stomata protected from wind and water loss
Explain the role of the pulmonary artery
carries deoxygenated blood from heart to lungs
Explain the role of the pulmonary vein
carries oxygenated blood from lungs to heart
Explain the role of the vena cava
carries deoxygenated blood from heart to lungs
Explain the role of the aorta
carries oxygenated blood from heart to body
Explain the role of the renal artery
carry oxygenated blood from body to kidneys
Explain the role of the renal vein
carry deoxygenated blood from kidneys to heart
What are coronary arteries?
The blood vessels that supply the heart muscles with their own blood
What are the features of arteries?
Carry blood away from heart
thick muscular walls
folded and elastic endothelium
smaller lumen
carry blood at high pressure
What are the features of capillaries?
1 cell thick
large surface area
very small lumen
What are the features of veins?
carry deoxygenated blood back to the heart at low pressure
wide lumen
little elastic or muscular tissue
valves to prevent backflow
What is tissue fluid?
Fluid that surrounds cells in tissues
made up of small molecules that leave blood plasma
Explain how molecules move from blood into tissue fluid
there is difference in hydrostsatic pressure in capillaries and tissue fluid due to plasma proteins in blood
outward pressure forces fluid into spaces surrounding cells
high concentration of plasma in blood and lower water potential
water re-enters blood by osmosis
excess tissue fluid is drained into lymphatic system
Describe the role and structure of haemoglobin ?
carry oxygen around the body
protein quaternary structure made up of 4 polypeptide chains
each chain has haem group containing iron ion
Describe the features of heamoglobins role
Each haemoglobin carries 4 O2 molecules
when O2 joins haemoglobin it creates oxyhaemoglobin (called loading or association)
when oxygen leaves haemoglobin its called dissociation or unloading
What are the different types of haemoglobin and its properties?
Haemoglobins with a high affinity for oxygen- Take up oxygen more easily but release it less readily
Haemoglobin with a low affinity for oxygen- Take up oxygen less
easily but release it more readily
What does affinity for oxygen mean?
the tendency a molecule has to bind with oxygen
What is the Bohr effect?
shift in the oxygen dissociation curve caused by changes in the concentration of carbon dioxide or the pH of the environment
what is the relationship between partial pressure of O2 and affinity?
as partial pressure increases so does affinity
What do dissociation curves show ?
how saturated haemoglobin is with O2 at different partial pressure
What are different types of haemoglobin that cause the curve to shift ?
Low O2 environments - move to left
foetal - move to left
high activity levels - move to right
smaller organism - move to right
What is the structure of the heart?
2 atria
2 ventricles
Septum sepereting left and right side of heart
What are the differences between the atria and ventricles?
walls of atria are thin and less muscular as blood is pumped at low pressure
walls of ventricles are thicker and more muscular due to high pressure
left ventrile is thicker than right as it has to pump blood to rest of body - more powerful contractions
What are AV valves and where are they found?
Atrioventricular valves found between atria and ventricles. Attached to cords that prevent backflow of blood into atria when ventricles contract
What are SL valves and where are they found?
semi lunar valves found between ventricles, pulmonary artery and aorta
prevent backflow of blood into atria when ventricles relax
What is the cardiac cycle?
the continous sequence of contraction and relaxing of atria and ventricles
Describe the stages of the cardiac cycle
1- ventricles relax, atria contract
decrease volume , increase pressure
AV valves open
2- ventricles contract, atria relax
decrease volume, increase pressure
AV valves close
pressure is higher in ventricles than aorta and pulmonary artery so SL valves open
3- ventricles and atria relax
SL valves shut as pressure in pulmonary artery and aorta is higher than ventricles so SL valves shut
blood returns to heart via vena cava and pulmonary vein
What is amylase and what does it do?
a digestive enzyme produced in salivary glands and pancreas
it catalyses the hydrolysis reaction of starch to produce maltose (disaccharide)
What are membrane bound disaccharides and what do they do?
enzymes attached to the cell membrane of epithelial cells that line the ileum
they break down disaccharides into monosaccharides (maltose into 2 alpha glucose)
What are the 3 disaccharidases?
maltase
sucrase
lactase
How are monosaccharides absorbed?
Glucose and galactose are absorbed by active transport alongside sodium ions by co-transporter proteins
Fructose is absorbed from the lumen of the ileum into the blood by faciltated diffusion through a different transporter protein.
How are lipids absorbed?
broken down by the enzyme lipase
into monoglycerides by hydrolising ester bonds
bile salts- split lipids into smaller droplets- called micelles this is called emulsification
What is the role of micelles in absorption of lipids?
allow the monoglycerides and fatty acids to be absorbed by the epithelial cells in the ileum
What are the 3 peptidases and their roles?
endopeptidases - hydrolyse peptide bonds within the protein
exopeptidases - hydrolyse peptide bonds at the ends of the protein
dipeptidases - sepreate dipeptides
How are amino acids absorbed ?
Sodium ions are actively transported out of the epithelial cells of the ileum
sodium ions then diffuse back into the epithelial cells through transporter proteins, and as they do the amino acids also move in with them
What is the role of the xylem?
Transports water and mineral ions from the roots to the leaves
What is the role of the phloem?
Transports sugars in a solution
up and down the plant
What is the structure of xylem?
long tube like strctures joined end to end made up of dead xylem
What is the structure of phloem?
long tubes with sieve tube elements and companion cells
living cells
What is translocation?
an active process that moves sucrose to parts of plant that need it
Describe the process of translocation
-sucrose is produced in the source
-moves by facilitated diffusion into compaion cells
-H+ ions are pumped from the companion cells into the cell walls, which co-transport
sucrose
-water moves by osmosis from the xylem into the phloem creating high hydrostatic pressure
-At the sinks, the sucrose is transported from the phloem into the cells
- mass flow of substances in the plant
What evidence is there for mass flow?
removing a ring of bark - bulge forms
using asphids - sap flows out of mouthpiece quicker at the source
radioactive tracers in plants
