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Biology Y12 > Section 3:Exchange > Flashcards

Section 3:Exchange Flashcards

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1
Q

What is the purpose of digestion?

A

Hydrolyse large insoluble organic molecules into smaller soluble molecules that can be absorbed into the blood stream
Nutrients are then broken down into smaller units which can be absorbed and assimilated

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2
Q

What are the two stages of digestion?

A
  • Stage One:Mechanical breakdown
  • Stage Two:Chemical digestion
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3
Q

How does mechanical breakdown in digestion happen?

A

Chewing physically breaks down solid food into smaller pieces=increases SA for enzymes to work on
Stomach churning also breaks down food

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4
Q

Name the enzymes involved

How does chemical digestion occur?

A

Enzymes break down complex molecules into smaller molecules by hydrolysis
* Protease (pepsin)~protein~amino acids
* Lipase~lipids~fatty acids + glycerol
* Amylase~polysaccharide(starch)~maltose
* Carbohydrase~maltose~alpha glucose

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5
Q

What are the seven parts of the digestion system?

A
  1. Oesophagus
  2. Stomach
  3. Ileum
  4. Large intestines
  5. Rectum
  6. Salivary glands
  7. pancreas
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6
Q

What does the salivary glands and oesophagus do?

A
  • Salivary glands=Pass secretions containing the enzyme amylase via a duct to the mouth so starch is hydrolysed into maltose
  • Oesophagus=Carries food from the mouth to the stomach
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7
Q

What’s the function of the rectum?

A

faeces stored here before being removed by the anus by the process of egestion

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8
Q

What does the ileum and large intestines do?

A
  • Ileum=enzymes produced by walls & glands. Inner walls folded into villi increases SA. SA further increased by microvilli on the epithelial cells on villi. Products of digestion are absorbed into the blood here
  • Large intestines=absorbs water
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9
Q

What does the pancreas and stomach do?

A
  • Pancreas=Produces a secretion called pancreatic juice containing: protease, lipase and amylase
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10
Q

Six points

How does the structure of the ileum supports its function?

A
  • Increased SA=increased rate of diffusion
  • Thin walled (one cell thick)=short diffusion pathway
  • Good blood supply=maintain concentration gradient
  • Posses microvilli=increases SA more
  • Contains muscle so can move=which maintains a diffusion gradient
  • Enzymes allow intracellular digestion
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11
Q

How are monosaccharides and amino acids absorbed during digestion?

A

Diffusion and co-transport

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12
Q

Six points

Describe how glucose is absorbed during digestion

A
  1. Ileum absorbs glucose via FD and co-transport
  2. Co-transport proteins move glucose across the membrane in the presences of Na+
  3. Each time a glucose molecules is transported into the cell so it a Na+
  4. This will only work if there are sodium ions available to move down a concentration gradient
  5. The gradient is maintained via AT of Na+ out of the cell into the blood
  6. Glucose molecules move out of the cell via FD
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13
Q

What happens to the surface area:volume ratio when the size of the animal increases?

A

The larger the animal the smaller the surface area to volume ratio

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14
Q

Type of environment they would be in

Describe the characteristics of having a small or a large surface area to volume ratio

A
  • Big SA:V=easy to lose heat~good for hot environment~needs high metabolic rate to compensate
  • Small SA:V=hard to lose=good for cold environment~can have a low metabolic rate
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15
Q

How does the shape of an animal affect heat?

A
  • Irregular shape=Increases SA:V which increases heat loss
  • Round and compact shape=Decreases SA:V which decreases heat loss
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16
Q

Describe five features of gas exchange surfaces

A
  1. large SA:V
  2. Thin,flat shape=short diffusion pathway
  3. Selectively permeable
  4. Movement of the environment medium
  5. Transport system to ensure the movement of internal medium
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17
Q

Describe what Fick’s law is

A

Relation between three factors SA x Diff in conc/Thickness is surface

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18
Q

What factors affect diffusion rate and how do they increase rate

A
  • Temperature=High temp~faster rate
  • Diff in conc=Greater diff~faster rate
  • SA=Large SA~faster rate
  • Thickness of surface=Thinner~faster
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19
Q

Why is water a good conductor of heat and how does it affect heat loss by animals?

A

Water molecules are closer together than air
Animals lose heat at a faster rate in cold water than cool air

20
Q

Why do single celled organisms not need a specalised exchange system?

A
  • High SA:V
  • Use cell membrane as a gas exchange system
  • Can occur through the membrane as it is :moist,thin,permeable and has a short diffusion path
21
Q

How do insects reduce water loss?

A
  • Waterproof coverings(chitin) over body srufaces~Rigid outer skeleton covered with a waterproof cuticle
  • Small SA:V=minimise area of which can be last
22
Q

What is the purpose of spiracles on an insect?

A

Open and closed by the insect~when open water can evaporate (closed most of the time)
Opened periodically to allow gas exchange

23
Q

Why are there hairs on spiracles?

A

Increases humidity and to catch water vapour which decreases the concentration gradient

24
Q

Describe the tracheal system of an insect

A

Spiracle~Trachea~Air sac~Tracheoles~Muscle cell

25
Q

What are the three ways in which respiratory gases move in and out of an insect?

A
  1. Along a diffusion gradient
  2. By mass transport and ventilation
  3. By the end of the tracheoles filled with fluid
26
Q

Respiring Cells

Describe how respiratory gases move in and out of an insect along a diffusion gradient

A
  • Cells are respiring=Oxygen used and so the concentration towards the ends of the tracheoles fall
  • Creates a diffusion gradient=Oxygen diffuses from the atmosphere along the trachea and tracheoles to muscle cells
  • CO2 produced by respiring cells=Creates a diffusing gradient in the opposite direction to oxugen
27
Q

Describe how respiratory gases move in and out of insects by mass transport and ventilation

A
  • Spiracles close and muscles pull skeletal plates of the abdomen closer together
  • Squeezes tracheal system and pumps the air into the sacs=Speeds up the exchange of respiratory gases
28
Q

Six points

Describe the tracheal system of an active insect

A
  • Increased rate of metabolism within insect’s cells=Accumulation of lactic acid within cells as they anaerobically respire
  • Lactic acid reduces osmotic potential of cells & Fluid withdrawn from tracheoles via osmsis
  • Air moves in to replace the fluid lost & gas diffuse in~Filled tracheoles
29
Q

Five points

Describe how respiratory gases move in and out of insects faster when the ends of tracheoles fill with water

A
  • More oxygen in to muscles during periods of activity
  • Leaking water enters tracheoles when resting allows ends of tracheoles to fill with water
  • In flight,muscles respire anaerobically&produce lactate
  • Lactate is soluble&lowers WP of muscle cells=Water moves from tracheoles into cells via osmosis
  • Movement of water draws air closer into tracheoles so final diffusion pathway is in gas
30
Q

SIx points

Describe how oxygen enters the muscles cells in insects from the air

A
  1. Air enters via open spiracles=conc of O2 is outside>inside
  2. O2 moves through traceae and ends up in tracheoels which extend into muscle cells
  3. In muscle cells,O2 used in respiration=lowers O2 concin the cells
  4. O2 is replaced in the muscle cells from the tracheoles
  5. Lower O2 conc in tracheoles,replaced by O2 in the insects tracheol system
  6. Continues as O2 is always moving down its conc gradient
31
Q

Two section~Four points

An insect lives in the air. Describe how the insect is able to obtain oxygen and limit water loss

A

Obtain oxygen:Ventilation of the insect through spiracles~Diffusion gradient due to respiring cells~Diffusion pathway
Limit water loss:Waterproof coverings~Small SA:V ratio due to compact shape~Ability to close spiracles using valves~Hair on spiracles

32
Q

How is a small diffusion pathway maintained in an insect?

A

Every cell of an insect is only a short diffusion distance from one of the trachea so the diffusion pathway is short

33
Q

Suggest the function of the rigid rings in the walls of tracheae

A

To keep the trachease open, for example when muscles close to them contract or the internal pressure is lowered

34
Q

What is a spiracle?

A

A pore in the exoskeleton which can be opened and closed

35
Q

Describe the movement of water into a fish

A
  1. Operculum is closed
  2. Mouth is opened
  3. Floor of mouth is lowered=Bucal cavity becomes larger
  4. Low pressure created due to larger volume
  5. Water enters fish’s mouth=Opercular cavity bulges
  6. Causes a slight drop in pressure as water forced over gills=Water enters opercular cavity from mouth
36
Q

Six points

Describe howe the ventilation mechanism and structure of the gills result in the efficent uptake of oxygen from water

A
  1. Gill fillaments=Increase uptake of O2
  2. Gill fillaments have lamellae=further increases SA~increasing the uptake of O2
  3. Gill surrounded by capillaries and have a good flow of blood=Ensures conc gradient is maintained
  4. Countercurrent exchange system=maintains a conc gradient along the whole length of the gill
  5. Pressure changes=allow more water to be brought in
  6. Thin epithelium=short diffusion pathway
37
Q

What is meant by a countercurrent flow system?

A

The flow of blood within the gill lamellae and the flow of blood within them travel in opposite directions

38
Q

Why is there a constant conc gradient between blood and water?

A

Oxygen can diffuse down its conc gradient and is removed by blood in capillaries
CO2 diffuses the opposite way down its conc gradient

39
Q

Describe the structure of the trachea and bronchi

A

Trachea=Muscular tube line with ciliated epithelial cells supported by rings of cartilage
Bronchi=Smooth muscle in wall lined with ciliated muscle cells

Bronchi produces mucus to trapdirt particles and cillia move dirt laden

40
Q

Describe the function and structure if the alveoli and ribcage

A
  • Alveoli=Surrounded by a capillary netwoke. Between alveoli are some collagen and fibres~Elastic fibres allow alveoli to strech as they fill with air
  • Ribcage=aid in inspiration and expiration by allowing chest cavity to change in size & thus change pressure~Move by intercostal muscle contracting&relaxing
41
Q

Breathing in

Describe the process of inspiration

A
  1. External intercostal muscles contracts & internal relaxes
  2. Diaphgram contracts~Pulling it from domed shape to a flattened shape
  3. Ribs are pulled and out
  4. Volume of thorax and lungs increased causing pressure to decrease
  5. Atmospheric pressure>Pulmonary pressure=air moves in down a pressure gradient
  6. Active process as it involves energy

During expiration the elastic lung tissue recoils,ribcage falls under ow

42
Q

What is pulmonary ventlation and how is it calculated?

A

Total volume of air that is moved into the lungs in one minute
tidal volume x breathing rate

43
Q

How are the alveoli adapted for gas exchange?

A
  • Increased surface area~covered with a network of blood capillaries
  • Distance for diffusion=walls are flattened and very thin layer of cytoplasm between their cell surface membranes
  • Capillary walls are narrow=Minimises diffusion distance
  • Concentration gradient=maintained by ventilation of lungs along with continual blood flow
44
Q

Describe how a diffusion gradient controls air flow into RBCs

A
  1. Oxygen dissolves then diffuse down the gradient
  2. O2 molecules must diffuse through the lining of the alveolus and the lining of the blood capillary
  3. Then picked up by the haem group in a red blood cell
45
Q

What and the three different types of proteases and describe their function

A
  • Endopeptidases=Hydrolyses peptide bonds between AA in the central region
  • Exopeptidases=Hydrolyses peptide bonds on the terminal AA
  • Dipeptidases=Hydrolyses the bond between 2 AA of a dipeptide (membrane-bound)
46
Q

Six points

How do villi increase the rate of absorption in the ileum?

A
  • Large SA=for diffusion
  • Thin walls lined with epithelial cells=Reducing diffusion pathway
  • Contains muscle=Helps maintain diffusion gradients and help food move (as they can contract)
  • Network of blood capillaries surrounding them=Can carry blood with absorbed products~maintain conc gradient
  • Epithelial cells of villi have microvilli=Further increase SA
  • Situated between the lumen of intestines and the blood/other body tissues
47
Q

Six points

Describe the process of co-transport

A
  1. Bile emulsifies lipid droplets to form micelles
  2. Micelles contact epithelial cells lining villi~breakdown forming monoglycerides,fatty acids and bile salts
  3. These diffuse into epithelial cells via membrane as they’re non polar and are transported to ER~recombined to form triglycerides
  4. Triglycerids move from ER to golgi apparatus~Chylomicrons formed when triglycerides combine with cholesterol&lipoproteins
  5. Chylomicrons move out epithelial cells by exoctosis enter lacteats
  6. From lactates,chylomicrons passed into blood capillaries~triglycerides hydrolysed-diffuse into cells

Biology Y12 (10 decks)

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