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Biology Paper 1 > Gas Exchange, Digestion & Absorption > Flashcards

Gas Exchange, Digestion & Absorption Flashcards

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1
Q
A
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2
Q

Why did elephants have large ears

A

An adaption to increase surface area for heat loss

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3
Q

What is the difference in a mouse and elephants surface area to volume ratio

A

mice - large
elephant - small

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4
Q

How much heat do mice lose?

A

The mice loses large amount of heat relative to its mass

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5
Q

Why do mice respire at a high rate?

A

Because of the large amount of heat loss.

•they respire at a high rate to maintain a constant body temp
• thus high uptake if oxygen

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6
Q

What is in the gas exchange system ?

A

• trachea
• bronchi
• bronchioles

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7
Q

Describe the gas exchange system

A

trachea supported by rings if cartilage to prevent it collapsing during pressure changes in ventilation

• trachea divides into 2 bronchi that repeatedly divide into bronchioles

• alveoli at end bronchioles provide large surface area for gaseous exchange

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8
Q

How are the alveoli adapted for gaseous exchange?

A

• shape and large number provide large surface area

• fluid lining alveolus allows gases to dissolve and diffuse across

• two cell layers= short diffusion pathway

• blood capillaries = large SA

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9
Q

Whats the function of the circulatory system?

A

maintain high concentration gradient for gas exchange by transporting deoxygenated blood to lungs and removing oxygenated blood from lungs

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10
Q

What is the function of the ventilation mechanism?

A

maintains high concentration gradient for gaseous exchange
• continuously provides air with high oxygen concentration and removes air with high carbon dioxide conc

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11
Q

What is the function of the fluid lining the epithelium of the alveolus?

A

oxygen in the alveolar air space dissolves in the fluid

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12
Q

What are the two cells separating blood and air in the alveoli?

A

flattened epithelial cells (alveolar wall)
endothelial cells (capillary wall)

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13
Q

What is inspiration

A

breathing in (INspiritation>

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14
Q

Describe inspiration.

A
  • external intercostal muscles contact
  • rib cage pulled up and out
  • diaphragm muscles contract
  • diaphragm flattens
  • thorax volume increases and pressure decreases
  • air enters area of low pressure IN LUNGS
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15
Q

Describe Expiration

A
  • external intercostal muscles relax
  • rib cage pulled down and in
  • diaphragm muscles relax
  • diaphragm moves up to dome shape
  • thorax volume decreases and pressure increases
  • air enters area of low pressure OUT LUNGS
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16
Q

What is the equation for pulmonary ventilation

A

pulmonary ventilation = tidal volume(dm3) x ventilation rate(min-1)

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17
Q

What is the ventilation rate?

A

number if breaths per minute (usually 12-20)

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18
Q

What is the tidal volume?

A

Volume if air normally taken in with each breath ( usually 0.5)

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19
Q

What are spiracles?

A
  • tiny holes on opening of tracheae
  • have valves that can close ti reduce water loss
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20
Q

What are tracheoles?

A
  • branches from the trachea
  • thin thus providing short diffusion distance for oxygen
  • many = large surface area
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21
Q

How dies oxygen enter the insects cell?

A
  • diffuses from air into spiracles along trachea and tracheoles into cells
  • CO2 leaves in the reverse path way
22
Q

What happenens during increased activity in insects?

A

anaerobic respiration creates lactic acid
- lowers WP of cells and water ends in tracheoles move into cells by osmosis

  • more air moves along tracheoles
23
Q

How are gills adapted for gas exchange?

A
  • large surface area
    provided by gill filaments which posesss lamellae
  • short diffusion pathway
    bc blood and water is separated by two cell layers
    • epithelial layer if lamellae
    • endothelial layer of capillaries
24
Q

Describe the countercurrent system?

A

blood and water flow in opposite directions

  • blood continuously meets water with a higher oxygen conversion
  • this maintains a high diffusion gradient along the length of the lamellae
25
Q

How does the ventilation system help gas exchange in fish?

A

provides continual flow of water over gills
- this brings more oxygen and removes CO2 thus maintaining high diffusion gradient

26
Q

How does the circulatory system hell gas exchange im fish?

A

Provides continual flow of blood through respiratory surface to absorb oxygen and remove CO2
- maintaining high diffusion gradient

27
Q

Which structures are involved in gas exchange in plants?

A

stomata and mesophyll cells and air spaces between them

28
Q

What are stomata?

A

pores in the epidermis of leaves that surrounded by guard cells
- gases diffuse in and out the stomata
- leaves are thin = short diffusion pathway

29
Q

whats the function of mesophyll cells?

A

provide large surface area for gas exchange

30
Q

Whats the function of amylase?

A

hydrolyses starch into maltose

31
Q

How is food broken down during chewing?

A

saliva contains salivary amylase which breaks down starch
- only a small amount is broken down as chewing is a short process

32
Q

How dies chewing speed up hydrolysis if starch?

A

breaks down food to smaller pieces which increases the surface area

33
Q

How dies the pancreas aid in breaking down the remainder if the starch?

A
  • releases pancreatic juice into small intestine which contains enzymes pancreatic amylase

this hydrolyses the remaining starch

34
Q

Where does the complete hydrolsis of starch occur?

A

In the ileum

35
Q

What do membrane bound disaccharidesdo ?

A

Maltase and other disaccharides
form the cell membrane of epithelial cells that line the ileum

36
Q

Which enzyme hydrolyses lipids?

A

lipase (hydrolyse the ester bonds in lipids)

37
Q

Where is lipase secreted from?

A

The pancreas into the small intestine

38
Q

How do bile salts increase the rate of hydrolysis of lipids?

A
  • they emulsify lipids causing them to form droplets
  • this increases surface area for hydrolysis
39
Q

What hydrolyses proteins?

A

endopeptides
exopeptides
dipeptidases

40
Q

How do Endopeptidases work?

A

They hydrolyse the INTERNAL peptide bonds between amino acids to form short amino acid chains

41
Q

How do exopeptidase work?

A
  • they hydrolyse peptide bonds at either end if a polypeptide so individual amino acids are removed
42
Q

What is the final stage of protein digestion

A

Breaking down dipeptides to single amino acids
- enzyme dipeptidase found in epithelial cells of the ileum
- hydrolyse dipeptide

43
Q

How is the ileum adapted for absorption?

A
  • large surface area due to long length villi and microvilli
  • villi contain blood capillaries that absorb
    monosaccharides and aminos, this maintains high diffusion gradient
  • lacteals in villi absorb digested lipids that also maintain high diffusion gradient for absorption
  • many mitochondria to provide ATP for active transport
44
Q

How do villi increase absorption?

A

Villus wall contain a single layer of epithelia cells providing short diffusion pathway

45
Q

What happenes during absorption digested of lipids?

A
  • bile salts emulsify lipids droplets
  • bile salts combine with monoglycerides and fatty acids to firm micelles
  • micelles transport MG and FA to surface of epithelial cell
  • micelles break down and release FA and MG and they diffuse thru epithelial cell
  • FA and MG recombine in smooth ER
  • packaged in protein and phospholipid by golgi and form CHYLOMICRONS
  • Chylomicrons absorbed into lacteals which drain into blood
46
Q

How are monosaccharides and aminos absorbed?

A

•they’re at a high concentration in lumen of ileum

so they will be absorbed down a concentration gradient by facilitated diffusion

47
Q

How are monosaccharides and aminos transported?

A

by co-transport against a concentration gradient

48
Q

How is glucose taken up by co-transport?

A
  • sodium ions actively transported out epithelial cells inti blood to ensure low conc of sodium in epithelial cell
  • high conc of sodium will be in lumen
  • so there will be a conc gradient for sodium ions to diffuse into cell from lumen via co-transport protein
  • glucose moves out cell to blood capillary by facilitated diffusion
49
Q

Define digestion

A

process where large molecules are hydrolysed by enzymes to produce small molecules that can be absorbed

50
Q

Where is the endopeptidase Pepsin secreted from?

A

cells lining the stomach

51
Q

Where are exopeptidases secreted from?

A

pancreas

Biology Paper 1 (8 decks)

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