Biology Module 3: Miss Colenette

Question 1

What are Goblet cells?

Answer 1

Goblet cells are cells that are scattered throughout the ciliated epithelium along the trachea. They contain mucus glands that produce viscous mucus which is released into the trachea to trap pathogens and micro-organisms, before being swept into the throat by the cilia, and being swallowed and destroyed in the stomach.

Question 2

How do Ciliated and squamous epithelial cells, smooth muscle, goblet cells, cartilage capillaries and elastic fibres help maintain and run the mammalian gas exchange system?

Answer 2

-Ciliated epithelial cells are found along the trachea and bronchi, with small cilia projections to sweep mucus and dust up the throat and down the oesophagus
-Squamous epithelial cells allow for very thin alveoli walls, shortening the diffusion pathway and speeding up gas exchange
-Goblet cells secrete viscous mucus to trap pathogens and dust, stopping them from reaching the lungs
-Cartilage is present on the trachea in places called tracheal rings, which allow the trachea to stay open whilst still being able to flex
-Smooth muscles regulate airflow by dilating to increase airflow and contracting when less air is needed
-Capillaries surround alveoli and are especially thin to slow erythrocytes and allow gases to diffuse
-Elastic fibres allow lungs to stretch and recoil, causing expiration to be passive

Question 3

What is the structure of the trachea?

Answer 3

-It is channel shaped to allow air to enter the lungs, with C shaped rings of cartilage (tracheal rings, with gaps between them) to prevent it from closing, but allow it to flex
-This also prevents friction between the trachea and the oesophagus
-It is lined with goblet and ciliated epithelial cells, to trap dust and pathogens
-The walls contain smooth muscle and elastic fibres to allow the trachea to flex

Question 4

What is the structure of the bronchi?

Answer 4

-Similar structure to the trachea, but has thinner walls and a smaller diameter
-Cartilage can therefore form full rings and irregular blocks along the bronchi length

Question 5

What is the structure of bronchioles?

Answer 5

-Narrow tubes with thin walls, usually not containing cartilage
-They are lined with ciliated epithelium and get smaller closer to the alveoli
-They posses elastic fibres and smooth muscle to adjust size and regulate airflow, though this is not present in smaller bronchioles

Question 6

What is the structure of alveoli?

Answer 6

-Located at the end of small bronchioles
-Consists of a single layer of squamous epithelial cells
-Also contains elastic fibres in the extracellular matrix allowing expiration to be a passive process
-Have an extensive network of capillary beds over them to facilitate gas diffusion

Question 7

What are the muscles between the ribs called?

Answer 7

Intercostal muscles. These are examples of antagonistic muscles (muscles working in a pair) as they consist of both an external intercostal muscle and an internal intercostal muscle

Question 8

What makes an effective exchange surface?

Answer 8

-Large SA/V ratio - larger area for diffusion to occur
-Moist surface - gas can dissolve before diffusing
-Short diffusion pathway - less distance for gas to diffuse across
-Maintained concentration gradient
-Ventilated - helps maintain gradient
-Permeable membrane

Question 9

What is the process of exhalation and inhalation?

Answer 9

Exhalation:
EEE = Exhalation, External, rElax
1. The External intercostal muscles rElax (the internal contract)
2. The volume of the lungs decreases so the pressure inside the lungs increases to ~ atmospheric level
3. Air therefore rushes out the lungs
4. The diaphragm relaxes and becomes domed due to being displaced by the organs beneath it
Inhalation:
1.The Internal intercostal muscles relax (the external contract)
2. The volume of the lungs increases so the pressure decreases in relation to the atmosphere
3. Therefore air rushes into the lungs
4. The diaphragm contracts, becoming flat and displacing the organs beneath it

Question 10

What are the 4 different scientific methods of measuring breathing?

Answer 10

1. Vital capacity - the maximum volume of air that can inhaled/exhaled in one breath
2. Tidal volume - the volume of air exhaled/inhaled in a normal breath
3. Breathing rate - number breaths 1 mins
4. Oxygen uptake - O2 absorbed in a given time

Question 11

How do you calculate Minute ventilation?

Answer 11

Minute ventilation = Tidal volume x Breathing rate

Question 12

How do you calculate Oxygen consumption over a period?

Answer 12

Oxygen consumed over a period = Oxygen consumed (dm^3) / Time (s)

Question 13

What is the opperculum?

Answer 13

-The opperculum is a bony plate that covers the gills in bony fish, eg, mackerel
-The opperculum both protects the delicate gills and moves outward to help draw water into the fish

Question 14

What is the structure of gills on bony fish?

Answer 14

-The gills, situated on either side of the head, is covered by the opperculum
-The gills consist of 2 rows of gills filaments attached to 1 bony gill arch
-There are a number of gills arches present in 1 gill
-Surface of gill filaments folded into secondary lamelae to provide an extremely large surface area for oxygen to diffuse on

Question 15

How does ventilation occur in bony fish?

Answer 15

1. Opperculum and mouth expand, drawing water into gills in similar way to lungs with air
2. Water runs over gill arches, gill filaments and gill lamelae/plates, which seems red due to rich blood supply
3. Capillaries run around the gill lamelae in a coutercurrent flow, to maximise the rate of oxygen diffusion
4. The water leaves the gills via the back of the opperculum

Question 16

What is couter-current flow?

Answer 16

-The flow of the blood is in the opposite direction to the flow of the water
-This means that a favourable concentration gradient is maintained, even though the concentration isn’t as large as if the flow was parallel

Question 17

How do insects ventilatory systems work?

Answer 17

1. Air enters the insect via holes in the chitin exoskeleton called spiracles, which may have muscular sphincters that can open or close depending on the air requirements of the insect
2. The air enters a trachea under the exoskeleton, which is supported by rings of chitin
3. This splits further into small trachioles that deliver O2 directly to respiring cells, that contain tracheal fluid, which can be withdrawn during high respiration periods
4. This means that gaseous exchange in insects is essentially passive as O2 diffuses from an area of high concentration in the air to the low concentration in the insect
5. The CO2 exchange occur in the opposite direction

Question 18

How does tracheal fluid regulate ventilation in insects?

Answer 18

-The tracheal fluid covers the end of the trachioles
-When the cells around them respire heavily/anarobically, eg whilst flying, they produce lactic acid as a waste product
-This lowers the psi of the cells and causes the tracheal fluid to move via osmosis into adjacent cells
-This exposes more trachiole area, and therefore the surface area available for gas exchange to occur on, so increase the rate of ventilation
-Some trachioles or tracheal have a more flexible wall and are called air sacs, which help increase the rate of flow of the gas through the insect, as more air makes up the residual volume

Question 19

Why has ventilation in insects evolved as it is?

Answer 19

1. It evolved due to the insects body being split into 3 very small sections, the head, the thorax and the abdomen, so there is little space for lungs
2. Insects have a open-circulatory system that allows O2 to be delivered straight to active tissues that are respiring, like flight muscles
3. O2 diffusion is quicker and more effective in air than in blood

Question 20

How are xylem and phloem tissues specialised for their function, and what is their structure?

Answer 20

Go to Hodges yr 12 and find the 2 cards before studying them after the next 10 cards

Question 21

What are the 3 ways H2O can move into the xylem vessels?

Answer 21

-Water has to move from the root hair cells, through the dermis (exodermis and then the endodermis) to reach the xylem
-It does this in 3 ways:
1. Apoplast pathway
2. Symplast pathway
3. Vacuolar pathway

Question 22

What is the apoplast pathway?

Answer 22

-The movement of water through the cortex cell walls and intercellular space
-Cohesive/tensive forces acting on cell walls pulls H2O up plant
-The fastest of the 3
1. Water moves into cell wall
2. Moves through cell wall
3. May move from cell wall to cell wall across intercellular space or just move to adjacent cell walls

Question 23

What is the symplast (+vacuolar) pathway?

Answer 23

-Movement of water through cell cytoplasm
-Moves between cells via plasmodesmata
-Each cell further from roots has lower psi, so water drawn up plant
1. Water enters cells across the plasma membrane
2. May move from cell to cell via plasmodesmata
3. May move from cell to cell across adjacent cell walls and plasma membranes
Vacuolar:
-Slowest
-Like symplast but moves from vacuole to vacuole

Question 24

What is the Casparian strip and what is its function?

Answer 24

-Found in endodermis (inner cortex)
-Strip of waxy material called suberin that is impermeable to water
-Forces water and ions into cytoplasm, and into symplast pathway
-Means water and ions are under cellular control and can be moved into the xylem

Question 25

What processes drive Transpiration?

Answer 25

Root pressure: -Root cells around xylem move minerals into xylem, via active transport, causing water to move into xylem via osmosis and cause the movement of water up plant Cohesive-tension theory: -Forces in cohesion cause H2O molecules to adhere to xylem walls and cohere to each other, increasing hydrostatic pressure and moving H2O up vessel Capillary action: -Due to small xylem diameter, hydrostatic pressure increased, and water moved up vessel Osmosis: -Water movement passive as the roots have a high water potential and the leaves have a low water potential -Therefore water drawn upwards via osmosis

Question 26

What evidence is there for the cohesive-tension theory?

Answer 26

Diameter changes: -The diameter of a plant changes throughout the day -This is because tension and transpiration are at their greatest during the day, so the plant diameter decreases as xylem's cave slightly Broken Xylem vessels: -Pressure is lost when vessels are broken, and so cohesive forces are broken -This means H2O cannot be pulled up any longer and air replaces it, instead of H2O leaking out

Question 27

What factors affect transpiration?

Answer 27

Airflow: -Increases rate due to a good airflow removing H2O vapour , so maintaining a good concentration gradient for diffusion out of the leaf Humidity: -Measure of moisture in the air -Decreases rate as when air is saturated, concentration gradient is lost Light intensity: -Increases rate due to guard cells responding and opening stomata, increasing H2O loss Temperature: -Increases rate as at a higher temperature, molecules kinetic energy is increased and so diffusion rate increases

Question 28

What are sinks and sources, and what are some examples of them?

Answer 28

Sinks are tissues or cells that will use transported assimilates in metabolic processes, for example, roots or stems. Sources are tissues or cells that provide and synthesise assimilates for the rest of the plant, eg, leaves or storage organs.

Question 29

What are the 2 pathways assimilates can be loaded into the sieve tube elements?

Answer 29

The symplast pathway: -Assimilates stored in plant cell permanent vacuole -Moved passively into the sieve tube element via plasmodesmata -This is mainly driven by changes in the cells ψ The apoplast pathway: -Assimilates diffuse through cell walls and intermembrane spaces -When companion cells reached, assimilates actively loaded into sieve tube elements

Question 30

What is the process of active loading?

Answer 30

1. H^+ ions (acting as a co-transporter) will move via active transport outside of the plasma membrane 2. This will cause the concentration of H^+ ions inside the cell to decrease and they will diffuse (facilitated) back through the membrane, bringing with it sucrose through a co-transporter protein

Question 31

How does translocation between a source and sink occur?

Answer 31

1. Assimilates actively loaded into sieve tube elements, decreasing the element's water potential 2. This causes water (from the xylem or surrounding cells) to move into the sieve tube element via osmosis, increasing the hydrostatic pressure of the phloem at the source 3. This causes the water and assimilates to move down the pressure gradient, from an area of high pressure at the source to an area of low pressure at the sink 4. The assimilates are actively loaded into the companion cells, raising the water potential of the element's at the sink, causing water to move out via osmosis, and lowering the hydrostatic pressure of the phloem at the sink 5. This maintains a favourable pressure gradient for mass flow to continue to ocur

Question 32

What is some evidence for and against the mass flow hypothesis?

Answer 32

For: -Tracers and radioactive elements can be seen under microscopes supporting the mass flow hypothesis -Translocation occurs much faster than would be expected with just diffusion -Companion cells contain mitochondria, which when inhibited, can no longer produce ATP, and translocation stops -When a stem is cut, sap leaks out due to the loss of hydrostatic pressure Against: -Not all solutes move at the same speed, but sucrose does regardless of the concentration gradient -Sieve plates seem to be obstructive

Question 33

What are Xerophytes and how are they adapted? (marram grass + cacti)

Answer 33

-Plants with structural and physiological adaptations to aid their survival in hot, dry and arid conditions with little water -Fleshy succulent leaves allows H2O storage during arid periods -Hinge cells lose turgidity quickly and shrink, exposing the waxy cuticle to the air, and rolling the leaf, creating a humid space inside it -Reduced leaf size, reducing the SA/V ratio for transpiration to occur -Stomata open at night, which reduces the H2O loss and allows the plant to take in CO2 for photosynthesis during the day, stored as malic acid -Sunken stomata + spines/hairs, trap moist air around the stoma reducing the concentration gradient -Fewer stomata, fewer pores=less H2O loss, and found in upper epidermis -Thick waxy cuticle, stopping H2O loss from top of leaves

Question 34

What are Hydrophytes and how are they adapted?

Answer 34

Plants with physiological and structural adaptations that allow them to inhabit aquatic areas. -Floating leaves, leaves are thin and flat, containing Aerenchyma (large air spaces) for buoyancy, keeping them at the surface to allow for optimum light intensity for photosynthesis -Thin waxy cuticle, very thin as H2O loss not concern -Stomata on upper epidermis, allowing gas exchange in air, not water -Reduced roots and transport tissues, as nutrients and water can be absorbed by tissues and cells directly from the water

Question 35

What are the factors that affect an organisms need for a transport system?

Answer 35

There are 3 main factors that affect the need of an organism for a specially adapted transport system: -SA:V ratio - as an organisms SA:V ratio increases, its ability to exchange substances, eg, O2 and waste products, directly with it's environment is reduced, meaning it has to have a specifically designed transport system to move these substances around -Diffusion distance - as the distance that substances have to diffuse across increases, the ability of the organism to rely on diffusion to obtain biological molecules decreases, as it is too slow, and not efficient -Metabolic demand - larger organisms will have a higher metabolic demand than smaller organisms as more cells and tissues require substances to function, and so a transport system can deal with this increased need for certain molecules, eg, O2

Question 36

What are the advantages of a transport system?

Answer 36

-Brings substances quickly from one exchange site to another, faster than diffusion, as it moves molecules down a pressure gradient -It allows exchange sites to maintain concentration gradients for diffusion between the cells and their fluid environment -It also ensures effective cell function by keeping cells fluid environment, lymph, in an optimum metabolic range, eg, enough O2 or glucose dissolved in it

Question 37

What are the 2 different models of circulatory systems?

Answer 37

-The 2 models are single and double circulatory systems Single circulatory: -Blood passes through the heart once during a complete bodily circuit Double circulatory: -Blood passes through the heart twice during a complete bodily circuit, and is split into 2 sections, the systemic circuit and the pulmonary circuit

Question 38

What are the advantages of a double circulatory system?

Answer 38

-When blood enters capillaries BP (blood pressure) drops significantly -In a single circulatory system, blood has to pass through 2 capillary beds before returning to the heart, whereas in a double circulatory system, it only has to pass through 1 -This means that a double system maintains a higher overall BP and speed of blood-flow, making it more efficient -Also helps maintain a steeper concentration gradient, allowing for a more efficient exchange of nutrients/waste with the surrounding tissues

Question 39

What are the 2 types of circulatory system?

Answer 39

-The 2 different types of system are open or closed circulatory systems -In a closed system, blood is always contained within blood vessels adapted specifically for that purpose -In an open system, blood is not contained within blood vessels, instead being pumped directly into body cavities

Question 40

What is the fish circulatory system?

Answer 40

-Fish have a closed-single circulatory system -This means deoxygenated blood is pumped to the gills from the hear, consisting of 1 atria and ventricle, where it is oxygenated -The oxygenated blood passes from the gills to the rest of the fishes body, before returning to the heart deoxygenated -Fish can have a much less efficient circulatory system as they are much smaller organisms than others, eg, mammals

Question 41

What is the mammalian circulatory system?

Answer 41

-Mammals have a closed-double circulatory system -Therefore the mammalian heart has 2 sides, one in which deoxygenated blood enters via the vena cava, entering the right atria and travelling through the tricuspid valve into the right ventricle leaving via the pulmonary artery, through the pulmonary valve to the lungs -Oxygenated blood enters via the pulmonary vein in the left atria, travelling through the bicuspid valve into the left ventricle, leaving to the body via the aorta, via the aortic valve -Some blood travels via the coronary arteries to supply the heart muscle with blood -The 2 sides are divided down the middle by a wall called the septum, split into the atrial and ventricular spetum -The tissue that covers the heart in the chest is called the pericardium

Question 42

What is the insect circulatory system?

Answer 42

-Insects have an open-single circulatory system -Have 1 main blood vessel, called the dorsal vessel -They also have a tubular heart in the abdomen pumps haemolymph into the dorsal vessel, which delivers it into the haemocoel (body cavity) -The haemolymph surrounds organs, re-entering the heart via one-way valves called ostia, so it is not directed like in mammals -This less efficient system is an option for insects as they have a separate ventilation system delivering O2 directly to respiring cells

Question 43

What are the 5 different types of blood vessels, and what are the 3 layers of structure for blood vessels?

Answer 43

The 5 different vessels are: -Arteries -Veins -Arterioles -Venules -Capillaries The layers for a blood vessel are: -Tunica adventitia/externa - the outermost layer -Tunica media - the thicker middle layer -Tunica intima - the layer closest to the lumen

Question 44

What is the structure of arteries?

Answer 44

-The tunica intima is made up of a layer of connective tissue, an endothelium and a layer of elastic fibres -Endothelium is 1 cell thick and lines the lumen of the blood vessel, reducing the friction for blood flow -Arteries have a very thick tunica media, consisting of smooth muscle and a thick layer of elastic fibres -Muscle cells strengthen arteries, allowing them to withstand high hydrostatic pressures, and allows them to contract and narrow the lumen, reducing blood flow -Elastic fibres help maintain BP , stretching and relaxing to even out pressure fluctuations -Tunica adventitia covers the artery exterior and made of collagen, stopping arteries from damaging due to over-elasticity -Arteries have a narrow lumen to maintain BP and have a pulse

Question 45

What are the structures of arterioles and venules?

Answer 45

Arterioles: -Posses a muscular layer, allowing them to contract and partially cut off blood-flow to specific organs, eg, the GI system during exercise -Have a lower proportion of elastic fibres and many muscle cells, allowing them to regulate the blood-flow Venules: -Have few to no elastic fibres and a large lumen -No muscular layer as blood is at a low BP

Question 46

What is the structure of veins?

Answer 46

-Receives low BP blood from capillaries -The tunica media is very thin, as high BP does not have to be withstood -Has large lumen, so blood is returned to the heart quickly, whilst reducing the friction between the blood and venal endothelium -Also balances out slow blood flow as more blood can be delivered at once, meaning the volume of blood delivered per unit of time is the same as arteries -Has valves to prevent the backflow of blood, and has no pulse -Has thin tunica adventitia, with many elastic fibres to allow the vein to stretch

Question 47

What is the structure of capillaries?

Answer 47

-Have thin, permeable walls made of 1 cell thick endothelium, allowing substances to leave to surrounding tissues -Have a very thin lumen, slowing erythrocytes to allow maximum time for gas exchange to occur -Large capillary beds branch between cells, so substances can diffuse very quickly due to a shortened diffusion distance -Cells in the walls have pores, allowing blood plasma o leak out and form tissue fluid, eg, phagocytes through the intra-cellular spaces

Question 48

What is Hydrostatic pressure?

Answer 48

-Hydrostatic pressure refers to the pressure of the blood against the walls of the blood vessels, eg, capillaries -This is higher at the arterial end of the capillaries, causing blood plasma to leak out of the blood to form tissue lymph

Question 49

What is Oncotic pressure?

Answer 49

-Oncotic pressure refers to pressure caused by the lower psi in the blood, causing water to be drawn back into the blood from the tissue lymph, due to the difference in pressure -This is higher at venal end of the capillaries, and appears mainly due to the high concentration of plasma proteins left in the blood when the H2O leaves