🎀⋆ ˚｡⋆ 3 - substance exchange

3.2 (red), 3.3 human (purple) and 3.3 plant (green)

what is hydrolysis?

when a water molecule is needed to break down a larger molecule

why is hydrolysis used in digestion?

to make the larger molecules small enough so they can diffuse into cells

what does the hydrolysis of proteins create?

amino acids

what does the hydrolysis carbohydrates of create?

monosaccharides and disaccharides

what does the hydrolysis lipids of create?

fatty acids and monoglycerides

what does amylase do?

hydrolyses starch into maltose

what bond is broken in the hydrolysis of carbohydrates?

glycosidic bonds

where can the membrane-bound disaccharidases be found?

in the epithelial cells in the ileum

what do membrane-bound disachharidases hydrolyse?

disachharides

how is glucose and galactose transported into the epithelial cells?

via co-transport proteins

how is fructose transported into the epithelial cells?

facilitated diffusion

where is amylase produced?

salivary glands and pancreas

where is lipase produced?

pancreas

where does lipase work?

small intestine

what enzyme is used for lipid digestion?

lipase

what bond does lipase hydrolyse?

ester bonds

where are bile salts produced?

liver

what do bile salts do?

forms small droplets called micelles by emulsifying the lipids

what do micelles do?

create a larger surface area for lipase to work on

how are mologlycerides and fatty acids absorbed into the epithelial cells?

simple diffusion

what does endopeptidase do?

hydrolyses the peptide bond WITHIN a protein

what does exopeptidase do?

hydrolyses the peptide bond AT THE END of a protein

how are amino acids absorbed into the blood?

co-transport

describe the process of co-transport?

1. sodium ions are actively transported out of the cell, causing a concentration gradient to form

2. this allows for sodium ions to diffuse into the cell within a co-transported alongside glucose/amino acids

3. then the cell either uses the monomer or it is absorbed into the blooidstream

what type of protein is haemoglobin?

globular

how does haemoglobin have a quarternary structure?

made of four polypeptide chains

what is called when haemoglobin binds to oxygen?

oxyhaemoglobin

how many oxygen molecules bind to one haemoglobin?

four

what does the oxygen do when it reaches the muscle cells?

it dissociates

how is haemoglobin red?

iron in the haem group

what is the partial pressure of oxygen?

concentration of oxygen within the cells

what is the partial pressure of carbon dioxide?

concentration of carbon dioxide within the cells

when does oxygen bind to haemoglobin?

when the pO₂ is high

when does the oxygen dissociate from the haemoglobin?

when the pO₂ is low

when is there a high affinity of oxygen?

when the pO₂ is high

when is there is low affinity of oxygen?

when the pO₂ is low

why do animals who live in higher altitudes have higher affinity of haemoglobin?

the air has a lower when pO₂ than the sea level

why do animals with a high metabolic rate have oxygen which dissociates easily?

oxygen is easily supplied to respiring cells

what happens when there is a low pO₂?

oxygen dissociates/low % of haem groups full

what shape is the oxygen dissociation curve?

s-shaped

what is the bohr effect?

a shift in the oxygen dissociation curve to the right due to carbon dioxide

what type of circulation do mammals have?

double-circulation

what blood vessel pumps deoxygenated blood from the heart to the lungs?

pulmonary artery

what blood vessel pumps oxygenated blood from the lungs to the heart?

pulmonary vein

what blood vessel pumps oxygenated blood from the heart to the body?

aorta

what blood vessel pumps deoxygenated blood from the body to the heart?

vena cava

which blood vessel supplies oxygenated blood to the heart?

coronary artery

which chamber the heart does deoxygenated blood flow in from the body?

right atrium

which chamber the heart does deoxygenated blood flow in from the right atrium?

right ventricle

which chamber the heart does oxygenated blood flow in from the lungs?

left atrium

which chamber the heart does oxygenated blood flow in from the left atrium?

left ventricle

what do the atrioventricular valves do?

prevent blood from flowing back into the atria

where are the atrioventricular valves located?

between the atria and ventricles

where are the semi-lunar valves located?

between the ventricles and blood vessel

what do the semi-lunar valves do?

prevent the back flow of blood between the ventricles and blood vessel

what are the stages of cardiac cycle?

1. atrial contraction

2. ventricular contraction

3. relaxation

4. repeat

what is atrial contraction?

when the atria contracts and due to a pressure increase, the blood flows down into the ventricles

what is ventricular contraction?

when the ventricle contracts and due to a pressure increase, the blood flows up into the blood vessels

what are arterioles?

smaller artery vessels

how do arterioles control the direction of blood?

contraction and relaxation of the walls

what is the structure of an artery?

• thick muscle layer

• contains elastic fibres

• folded endothelium

what type of blood vessel carries blood away from the heart to the organs?

arteries

what is the structure of a vein?

• wide lumen

• thin muscle wall

• valves

what type of blood vessel carries blood back to the heart?

veins

why do veins have valves?

to ensure the deoxygenated blood reaches the heart

why do veins have a wide lumen?

so the blood flows at a lower pressure

where are capillaries located?

close to the cells

why is the short diffusion distance between capillaries and the cells useful?

exchange between the blood and cells is rapid

why are capillary beds useful?

they have a large surface area for diffusion

what part of the capillary structure makes them useful for exchange?

muscle walls are one cell thick

how do substances move into the tissue fluid from the capillaries?

pressure filtration

what type of pressure is at the start of the capillary bed?

high

what is pressure filtration?

when the fluid in the capillaries flows down the pressure gradient into the surrounding space

what does tissue fluid do?

substances in fluid can be transported to the cells

when does the tissue fluid return the capillary?

when the pressure in the capillary is lower than the tissue fluid

where does the excess tissue fluid go?

the lymphatic system

what is an atheroma?

the deposition of materials in the arteries causing a blockage

what happens when white blood cells are deposited into the arteries?

a fibrous plaque will form

why do atheromas increase blood pressure?

they make the narrow lumen of the arteries even more narrow

what is an aneurysm?

when an atheroma increases the blood pressure causing the artery wall to swell

what is thrombosis?

when an artery bursts and platelets accumulate and form a clot

why is a thrombus dangerous?

they block the flow of blood in the artery

what are the risk factors of contracting cardiovascular disease?

• high blood pressure

• smoking

• diet

what is the structure of the xylem?

a long tubes of vessel elements

are the cells in the xylem alive or dead?

dead

how does the xylem’s structure allow for a continuous tube of water to flow though?

the vessel elements have no cell walls

how is lignin important in xylem cells?

• allows for it to be waterproof

• provide structural support

what is transpiration?

when some of the water produced in photosynthesis evaporates out of the stomata

how is tension created in the xylem?

transpiration

which direction does the tension in the xylem pull the water?

upwards - to the leaves

how does cohesion pull the water up the xylem?

the water molecules are stuck together so when one molecule is pulled up, it pulls up those around it due to the hydrogen bonds

what does the combination of tension and cohesion in the xylem allow for?

water to be pulled upwards to replace that lost in transpiration

why does water enter the roots via osmosis?

the roots have a lower water potential due to water being pulled upwards

what are the four stages of the cohesion tension theory?

• transpiration

• tension

• cohesion

• diffusion into the roots

what piece of equipment is used to investigate the transpiration rate?

potometer

why when using a potometer should the plant be cut underwater?

to ensure no air enters the system

what is the structure of the phloem?

• sieve tube elements

• companion cells

• sieve plates

what is the structure of the sieve tube elements?

living cells made of cellulose containing the cytoplasm and a nucleus

how are the companion cells and sieve tube elements connected?

plasmodesmata - allows them to share a cytoplasm

what are sieve plates?

plates with large pores which allow sap to move through the sieve tube elements