Biology, module 3

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What number should be 1 in a SA:V ratio?
Volume
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Why do multicellular organisms need exchange surfaces?
Cells are too deep in the body, low SA:V ratio and they have a high metabolic rate they need to keep up with
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Why do single cellular organisms not need exchange surfaces?
The diffusion rate is quick as the substances diffuse directly into the cell
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Why do exchange surfaces have a large surface area?
Increase the rate of absorption
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Why do exchange surfaces have thin walls?
To decrease the distance the substances have to diffuse over
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Why do exchange surfaces have good ventilation and blood supply?
Helps to maintain a strong concentration gradient between two substances
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Describe the layout and movement of air in mammalian gas exchange system
Air enters trachea which splits into two bronchi, one bronchus leading to each lung which splits into bronchioles which have alveoli on the end .
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What are three components with help inhaliation and exhalation?
Rib cage, intercostal muscles and the diaphragm
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What is the function of goblet cells?
To secrete mucus which traps microorganisms and dust particles to stop them from reaching the alveoli
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What is the function of cilia?
To move the mucus away from the alveoli to the throat where its swallowed to prevent infection
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What is the function of the elastic fibres?
Help breathing out by being found in the walls of the trachea, bronchi, bronchioles and alveoli where they’re stretched out then recoil
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What is the function of the smooth muscles?
Allows the diameter of the trachea, bronchi and bronchioles to be controlled so air flow can be controlled
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What is the function of the rings of cartilage in the trachea and bronchi?
To provide support to prevent them from collapsing
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What is the composition fo the trachea?
Has smooth muscles, elastic fibres, c-shaped cartilage, ciliates epithelium with large cartilage
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What cells do the trachea contain?
Smooth muscle cells, elastic fibres, goblet cells and collated epithelium
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What is the composition of the bronchi?
Smooth muscle, small pieces of cartillage, elastic fibres, ciliates epithelium
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What cells do the bronchi contain?
Smooth muscle, elastic fibres, goblet cells and ciliates epithelium
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What is the commotion of larger, smaller and smallest bronchiole?
Smooth muscles and elastic fibres, dilated epithelium
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What cells do the larger bronchiole contain?
Smooth muscle cells, elastic fibres cells, goblet cells and ciliates epithelium cells
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What cells do smaller bronchioles contain?
Smooth muscle cells, elastic fibre cells and ciliated epithelium cells
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What cells do the smallest bronchioles contain?
Elastic fibre cells
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What is the composition of the alveoli?
Just smooth elastic fibres
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What is the mechanics of inspiration?
External intercostal muscles and diaphragm contract moving rib cage up and out increasing the volume of the thorax decreasing lung pressure causing air to flow into the lungs
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What type of process is inspiration?
An active process
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Describe the mechanics of expiration
External intercostal muscles and diaphragm relax moving the rib cage down and in decreasing thorax volume so air is forced out of lungs die to increase in air pressure above atomospheric pressure
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Define tidal volume
The volume of air in each breath
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Define vital capacity
Maximum volume of air that can be breathed in or out
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Define breathing rate
How many breaths are taken per minute
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Define oxygen consumption (oxygen uptake)
That rate as which an organism uses up oxygen
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What readings does a spirometer take?
Tidal volume, vital capacity, breathing rate and oxygen uptake
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How does the spirometer work?
Person breathes through a tube connected to oxygen chamber which has a moveable lid which moves as the person breathes in and out. This writes on a rotating drum
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What is the soda lime for in the spirometer machine?
To absorb the carbon dioxide
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Why does the total volume of gas decrease over time?
Because air is breathed out is a mixture of oxygen and carbon dioxide and the carbon dioxide is absorbed by the soda lime so only oxygen is left which is used up by respiration
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What type of gas exchange system do fish use?
Counter current system
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Describe the structure of gills
Made of gill filaments which are covered in primary and secondary lamellae with each gill being supported by a gill arch
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What are the adaptations of fishes gills?
Have lots of blood capillaries, thin layer of cells and increased surface area from lamellae to speed up diffusion
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Why is the fish gills known as a counter current system?
Blood flows one way and water flows in the opposite direction
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Why is the fish gills system a counter current one?
To maintain a large contraction gradient
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How is water drawn into the fishes mouth?
Opens mouth lowering buccal cavity increasing volume and and decreasing pressure then water is sucked in
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How is water drawn out of the fish?
Closing the mouth decreases the buccal cavity volume and increases the pressure forcing the after out of the cavity across the gill filaments
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What do insects use to exchange gases?
Tracheae
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How does air move into the tracheae?
Through pores called spiracles
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How are gases exchanged in the tracheae?
Oxygen travels down conc gradient towards cells with carbon dioxide moving from the cells to wards spiracles to be released into the atmosphere
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What do tracheae branch off into?
Smaller tracheoles
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How does oxygen diffuse directly into cells in insects?
The oxygen dissolves in fluid and goes through the thin permeable walls
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How do insects change the volume of their bodies?
By using rhythmic abdominal movements
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What type of circulatory does a fish have?
Single circulatory system
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What is a single circulatory system?
When the blood only passes through the heart once
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What type of circulatory system do mamals have?
Double circulatory system
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What is a double circulatory system?
When the blood passes through the body twice
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Which side of the heart pumps blood to the lungs?
Right
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What side of the heart pumps blood to the body?
Left
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What is the main benefit of the double circulatory system and why is this?
The blood can travel faster as the blood is given an extra push between the lungs and the rest of the body
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What is a closed circulatory system?
When the blood is enclosed inside blood vessels at all times
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What is an open circulatory system?
When blood isn’t enclosed in blood vessels at all times instead flowing freely in the body cavity
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How does an open circulatory system work?
Heart contracts pumping the blood into a single artery, artery opens up into body cavity, blood gradually makes way back to heart through series of valves
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How does a closed circulatory system work?
Heart pumps blood into arteries which branch out into capillaries with oxygen and glucose diffusing from the blood into capillaries and the blood stays inside the vessels as it circulates with veins taking blood back to the heart
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What are the features of an artery?
Thick muscular elastic tissue walls to carry blood at high pressure, inner endothelium is folded with small lumen to carry blood at high pressure
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What are the features of a vein?
Thin muscle walls with a large lumen to carry blood at low pressure with valves to prevent the back flow of blood
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What are the features of arterioles?
Smaller versions of arteries which contract and relax to control blood flow
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What are the features of capillaries ?
Only one cell thick is make them efficient for diffusion
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What substance is tissue fluid made from and where is it found?
Blood and in between cells in tissues
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How do cells use tissue fluid?
They take in oxygen and nutrients from the fluid and release metabolic waste into it
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What is a capillary bed?
TThe network of capillaries in an area of tissue
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How do substances move out of capillaries?
Through pressure filtration
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Describe the process of pressure filtration
Hydrostatic pressure nearest arteries inside the capillary is greater than hydrostatic pressure in tissue fluid which forces fluid out of the capillary. As fluid leaves capillary hydrostatic pressure decreases in capillary so is lower at venule end where
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What is oncotic pressure generated by?
Plasma proteins in the capillaries which lower the water potential
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Where doe excess tissue fluid drain to?
Lymph vessels
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What is the lymphatic system?
A drainage system made up of lymph vessels
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Describe the movement of tissue fluid into the lymphatic system
Excess fluid passes into lymph vessel where valves stop the lymph going backwards where it gradually moves towards the main lymph vessel in the thorax where it’s returned to the blood near the heart
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What does blood contain?
Red blood cells, white blood cells, platelets, plasma, proteins, water, dissolved substances
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What does tissue fluid contain?
White blood cells, proteins, water and dissolved substances
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What does lymph contain?
White blood cells, antibodies
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What is the valve which links the atria to the ventricles called?
Atrioventricular valves
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What is the valve which links the ventricle to the pulmonary artery and aorta?
Semi lunar valve
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When does a valve open?
When they’re higher pressure behind it then in front
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What is the cardiac cycle?
The ongoing sequence of contraction and relaxation of the atria and ventricles which keeps the blood continuously circulating
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What are the three simplified stages of the cardiac cycle?
Ventricles relax and atria contract, ventricles contract and atria relax, ventricles react and atria relax
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What does cardiac muscle control?
Regulating the heart beat
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What does myogenic mean?
That the cells can contact and relax without receiving signals
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What is the sino-atrial nodes role?
Acts as a pacemaker in the wall of the right atrium
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What effect does the sino-atrial node have on the heart?
It makes the right and left atria contract at the same time
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What protects the rest of the heart from reacting to the electrical impulses?
A band of non conducting collagen tissue
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Where are the waves from the SAN transported to?
Atrioventricular node
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What does the atrioventricular node stimulate?
Passes the waves to the bundle of his
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What does the bundle of his control?
Group of muscles fibres responsible for contracting the ventricle walls
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Why is there a delay produced by the AVN?
To allow time for the atria to empty
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What is purkyne tissue?
Finer muscle fibres in the left and right ventricle walls
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What do doctors use ECGs for?
To monitor someone’s heart function and check for abnormalities
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What is the term for a heart beat which is too fast?
Tachycardia
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What is the term for a heart beat which has an extra heart beat?
Ectopic heart beat
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What is ectopic heart beat caused by?
An extra earlier contraction of the atria or ventricle
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What is the term for when a heart beat is too slow?
Bradycardia
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What is the term for an irregular heartbeat?
Fibrillation
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What are the effects of fibrillation?
Lack of pulse, death, chest pain, fainting
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How many molecules of oxygen can each haemoglobin molecule contain?
Four
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How can haemoglobin bind to so many oxygen?
Because haemoglobin has a high affinity for oxygen
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What is the structure of haemoglobin?
Large protein with a quaternary structure
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What does haemoglobin saturation depend on?
The partial pressure of oxygen
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What is the partial pressure of oxygen?
Measure of oxygen concentration
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When does maximum amount of oxygen bind or haemoglobin?
When the partial pressure of oxygen is high
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When does oxygen offload of haemoglobin?
When the partial pressure of oxygen is low
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What lowers the partial pressure of oxygen in the cell?
Respiration as oxygen is used up
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Why is an oxygen dissociation curve an s shape?
Because the first oxygen is hard to bind to the haemoglobin, then it undergoes a conformational change making the next two oxygens easier to bind then as more oxygen binds it becomes more saturated and harder for oxygen to bind
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What is the difference between adult haemoglobin and fetal haemoglobin?
Fetal haemoglobin has a higher affinity than adult haemoglobin
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Why does fetal haemoglobin have to have a greater affinity?
Because by the time the blood reaches the placenta the oxygen saturation has decreased so for the foetus to get enough oxygen it has to have a higher affinity to be able to load oxygen
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How does carbon dioxide levels affect oxygen unloading?
At greater particular pressures of carbon dioxide the oxygen is unloaded quicker
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What does the carbon dioxide react with to form in the red blood cells and what enzyme catalyses the reaction?
Reacts with water to from carbonic acid and carbonic anahydrase catalyses this reaction
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What does carbonic anahydrase dissociate into?
H+ ions and hydrogencarbonate ions
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How do the H+ ions effect the oxyhaemoglobin?
Causes the oxygen to unload so the haemoglobin can take up the H+ ions to form haemoglobin acid
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What is the positive about haemoglobinic acid forming?
Stops hydrogen ions increasing the cells activity
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Where does the carbonic acid go after leaving the red blood cell?
Transported in the blood plasma
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What happens to compensate for the loss of carbonic acid ions in the red blood cell ?
Cl- ions diffuse into red blood cell, this is called the chlorine shift
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Why do the chlorine ions diffuse into the cell?
To prevent any change in the pH that could affect the cells
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What happens to the carbonic acid and h+ ions when they reach the lungs and why?
They recombine due to the low partial pressure of carbon dioxide to form carbon dioxide and water
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Why do multicellular plants need transport systems?
Get rid of waste substances, high metabolic rate, small SA:V ratio, need to diffuse substances quickly
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What does xylem tissue transport?
Water and mineral ions in solution
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Which way does xylem transport substances?
Only up
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What does phloem transport?
Sugars
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Which way does the phloem transport substances?
Up and down
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What is the layout of xylem and phloem in the roots?
Xylem is in the centre surrounded by phloem to provide support
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What is the layout of xylem and phloem in stems?
Xylem and phloem are near the outside, xylem on the inner
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What is the layout of xylem and phloem in a leaf ?
Both make up a network of veins
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How are xylem vessels adapted to transport minerals and water?
Long tubelike with no end walls, they are dead with their walls being thickened by lignin deposited in either spirals or thick rings
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How does the water move in and out of the xylem?
Move in and out through small pits where there’s no lignin
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How is the phloem adapted?
Have tubes with phloem fibres, phloem parenchyma, sieve tube elements and companion cells
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What is the structure of sieve tube element in the phloem?
They’re living cells which join end to end what have sieve places between. They have no nucleus a very thin layer and few organelles
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What is the structure of companion cells and function of them?
Compensates for lack of nucleus and other organelles in sieve tube elements, they array out living functions for both themselves and sieve cells
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How does water enter the root hair cells?
Through the root cortex
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How does water enter the root hair cells?
By osmosis
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What is the symplast pathway?
When substances go trough the living parts of the cell connecting via plasmodesmata
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What is plasmodesmata?
Small gaps in the cell wall
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What is the apoplast route?
When it goes through non living parts of the cell such as the cell wall via diffusion
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What is the water blocked by in the apoplast route?
A waxy ***** in the cell walls called the caspairian *****
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How does the issue of the casparian ***** combatted?
The symplast route is taken
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What type of cells is the casparian ***** in?
In the endodermis cell layer
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What pathway is most commonly used to transport water?
Apoplast pathway
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How does the water leave the plant?
Evaporates from cell walls into spaces between the cells so when the stomata opens the water diffuses out of the leaf into the opening air down the conc gradient
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How does water move up the plant against gravity?
Using cohesion and adhesion
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How does cohesion and adhesion work?
The water evaporating from the leaf creates tension with pulls more water into the leaf and where water molecules are cohesive they’re all pulled up
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How else does adhesion help the net movement of water as well as being attracted to each other?
They are attracted to the wall of xylem vessels to help water rise up
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What is transpiration?
The evaporation of water from a plants surface
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What four main factors affect transpiration?
Light, temperature, humidity, wind
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How does light affect transpiration?
Lighter= faster because stomata is more open when its light
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How does temperature effect the rate of transpiration?
Higher= faster, more kinetic energy to evaporate and leave leaf
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How does humidity affect transpiration?
Lower= faster because there’s a steeper concentration gradient
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How does wind affect transpiration?
Windier= faster as water molecules are blown away increasing the water potential gradient
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How is Marram grass adapted to reduce water loss?
Stomata sunk in pits= sheltered from wind, have hairs to trap moist air to reduce water potential gradient, reduces exposed surface area, thick waxy layer to reduce water loss
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How are cacti adapted to reduce water loss?
Has thick waxy layer to reduce water loss, have spines instead of leaves to reduce SA, close stomata at hottest time of day
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How are hydrophytes adapted to survive in water?
Have air spaces so they can float, stomata open on upper surfaces to maximise gas exchange, have flexible leaves and stem as to prevent damage by water currents
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What is translocation?
The movement of dissolved substances to where theyre needed in the plant
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Where does translocation move substances from and to?
They move from sources to sinks
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What is a source?
A place where the substance is made
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What is a sink?
Is the area where the substance is used up
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How do enzymes maintain a concentration gradient from the source to the sink?
By changing the dissolved substance at the sink into something else
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What is the first stage of the mass flow hypothesis?
That active transport is used to actively load solutes into sieve tubes of the phloem at the source, lowering the water potential in sieve tube so water enters tubes by osmosis from xylem and companion cells,
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What is the second stage of the mass flow hypothesis?
At the sink end solutes are removed which increases the water potential inside sieve tube so water also leaves by osmosis
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What is the the outcome of the mass flow hypothesis?
There becomes a pressure gradient from the source end to the sink end where the gradient pushes solutes along the sieve tubes to where theyre needed
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What is the process called that substance enter the phloem by?
By active loading
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What is the process of active loading?
Moving substances into the companion cells from surrounding tissues, then moving the substances into sieve tubes against the concentration gradient
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How is sucrose moved into the companion cell?
Companion cell uses ATP to move H+ ions out of cell, setting up conc gradient where there’s more H+ in the surrounding tissue, H+ binds to a co transport protein which at the same time sucrose does, movement of H+ ions moves sucrose at the same time
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How is sucrose moved into sieve tubes?
By the same process as theyre moved into companion cells
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The breakdown of which substance provides the energy for this ?
ATP
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Other cards in this set

Card 2

Front

Why do multicellular organisms need exchange surfaces?

Back

Cells are too deep in the body, low SA:V ratio and they have a high metabolic rate they need to keep up with

Card 3

Front

Why do single cellular organisms not need exchange surfaces?

Back

Preview of the front of card 3

Card 4

Front

Why do exchange surfaces have a large surface area?

Back

Preview of the front of card 4

Card 5

Front

Why do exchange surfaces have thin walls?

Back

Preview of the front of card 5
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