Unit 3 - exchanging substances Flashcards
(22 cards)
Describe the cohesion-tension theory of water transport in the xylem
-water lost from the leaf through transpiration
-lowers the water potential of leaf cells
-water pulled up the xylem, creating tension
-water molecules cohere (stick together) by hydrogen bonds
-forms a continuous column of water
-adhesion of water molecules to the walls of the xylem
Explain the movement of oxygen into the gas exchange system of an insect when it’s at rest
-oxygen used in aerobic respiration
-so oxygen concentration gradient established
-so oxygen moves in down the concentration gradient
Adaptations of the alveoli
-there are many alveoli so there’s a large surface area
-alveolar epithelium and capillary endothelium are just one cell thick, so there’s a short diffusion pathway between air and the blood.
-many capillaries which are close to the alveoli to maintain a good blood supply and a concentration gradient.
Describe features of an artery
-a thick muscular wall
-folded endothelium
-narrow lumen
-doesn’t have valves
Describe features of a vein
-thin wall
-a endothelium that isn’t folded
-wide lumen
-valves
Describe the role of antibodies in producing a positive result in an ELISA test
-antigen attached to test well
-first antibody attaches to antigen
-second antibody with enzyme attached is added
-well is washed
-second antibody attaches to antigen
-solution added and colour changes
what is a monoclonal antibody
-antibodies with the same tertiary structure
Describe an insects tracheae system and how it allows for fast gas exchange
-branched, chitin lined system with openings called spiracles
-diffusion distance small at tracheoles so fast gas exchange
-fluid in the end of tracheoles that moves into tissues during exercise so faster diffusion through the air to gas exchange surface
-muscles can move body to move air so maintains a concentration gradient for gases
Explain how insects can control water loss
-can close their spiracles using muscles
-have a waterproof waxy cuticle to reduce evaporation
-hairs around the spiracles to reduce evaporation
explain how water from tissue fluid is returned to the circulatory system
-plasma proteins remain
-reduces the water potential of the blood
-water returns to the blood by osmosis
-returns to the blood by the lymphatic system
Describe the formation of tissue fluid
-high hydrostatic pressure of blood at the arterial end due to the left ventricle contracting
-water and small soluble molecules forced out of the capillary - eg amino acids and glucose
-plasma proteins and large molecules remain
-this lowers the water potential of the blood
-water moves back into the venule end of the capillary
-lymph system collects any tissue fluid which returns to the blood at the superior vena cava
what is tidal volume
the volume of air in each breath
what is ventilation rate
breaths per minute
what is forced expiratory volume
the maximum volume of air that can be breathed out in 1 second
what is forced vital capacity
the maximum volume of air breathed out forcefully after a deep breath
Describe the full digestion of starch
-starch is hydrolysed into maltose by amylase
-amylase is produced by the salivary glands and released into the mouth
-amylase is produced by the pancreas and released into the duodenum
-membrane bound disaccharidases attached to the epithelial cells in the ileum eg maltase hydrolyse maltose into glucose
Adaptations of epithelial cells
-microvilli, folds in the cell membrane increasing the surface area
-more protein channels and carriers for more active transport, facilitated diffusion and co-transport
-more mitochondria to produce more ATP for more active transport and co-transport
-more ribosomes, RER’s and golgi body’s for proteins synthesis and modification to produce more membrane proteins
Describe how the structure of the ileum is adapted for better absoption
-the ileum is very long and folded into structures called villi, this increases surface area for absorption
-each villus has a good capillary network and a network of tubes called a lacteal (part of the lymph system), these rapidly remove absorbed molecules maintaining a steep concentration gradient
-the lining of the ileum is made of one layer of epithelial cells and the capillaries are one layer of endothelial cells, this ensures a short pathway for absorption
How is xylem tissue adapted for the transport of water
-consists of dead cells - this means the cells are hollow so no impeded flow
-cell walls - provides strength and preventing inward collaspe
-cell walls contain lignin - water can adhere to the lignin
-no end walls - allows for a continuous column of water
-pits in the cell wall - allows for horizontal movement of water between xylem vessels
Describe the processes involved in the transport of sugars in plant stems
at the source sucrose is actively loaded into the phloem by the companion cells
-this lowers the water potential in the phloem and water moves in from the xylem by osmosis
-this creates a high hydrostatic pressure
-then mass flow towards the sink
-at sink the sugars are unloaded and used in respiration/stored
describe how an atheroma builds up in the arteries and the potential side effects
-damage to endothelial cells, macrophages and lipids from the blood clump together to form fatty streaks
-white blood cells, lipids and connective tissue build up and harden which could develop into a atheroma
-side effects: blood flow can be restricted, increasing blood pressure and can cause a aneurysms or blood clots
describe how glucose is absorped through co-transport of sodium ions
-sodium ions are pumped out of the epithelial cell into the capillary by active transport using ATP
-this lowers the sodium ion concentration in the epithelial cell
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