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biology paper 1 > 3. Exchange > Flashcards

3. Exchange Flashcards

1
Q

What is the relationship between the size of the organism and sa:v ratio?

A

The smaller the organism, the larger the sa: v ratio

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2
Q

What are the features of specialised exchange surfaces?

A
  • large sa to v ratio increases the rate of exchange
  • very thin = diffusion pathway is short
  • selectively permeable to allow selected materials to cross
  • movement of environmental medium to maintain diffusion gradient
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3
Q

What is Ficks law?

A

Rate of diffusion= surface area x concentration difference/ diffusion distance

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4
Q

What is the relationship between surface area to volume ratio and metabolic rate?

A

Smaller organisms have a larger surface area to volume ratio which means they lose heat quicker

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5
Q

How do single celles organisms exchange substances?

A

They are small and have a large sa: v ratio
Oxygen is absorbed by diffusion across body surface
CO2 diffuses out across the body surface

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6
Q

How are insects adapted for efficient gas exchange?

A
  • contain tracheae
  • divide into tracheoles, it brings oxygen directly to respiring tissue
  • there is a short diffusion pathway from the tracheole to any body cell
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7
Q

What three ways do respiratory gases move in and out of the tracheal system?

A
  • along a diffusion gradient
  • oxygen concentration at the end of tracheoles falls when being used for respiration, CO2 is produced by respiration, creates diffusion gradient in the opposite direction
  • mass transport
  • contraction if muscles squeezes trachea for aid to move in and out
  • ends of tracheoles are filled with water
  • lactate is produced in the cells, water moves in and out, draws more air in, diffusion is rapid
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8
Q

How are fish adapted for efficient gas exchange?

A
  • contain many gill filaments which contain many gill lamellae
  • increases surface area
  • gill lamellae are at right angles which creates a short diffusion pathway
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9
Q

Describe the structure of the gills

A
  • located within the body of the fish
  • girls are developed to extract dissolved oxygen from the water
  • made of gill filaments stacked together
  • gills are extremely thin, cannot support themselves and stick together without water
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10
Q

What is the countercurrent flow?

A

Where the flow of water and blood are in opposite directions

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11
Q

What does this mean?

A
  • maximises O2 uptake and increases gas exchange by ensuring good diffusion gradient along the width of the lamellae
  • makes sure blood meets water with lots of oxygen so oxygen can diffuse from high conc in the water to a lower conc in the blood
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12
Q

What is the movement of water inside a fish?

A
  • operculum closed
  • mouth open
  • floor of mouth lowers causing buccal cavity to be larger increasing the sa: v
  • pressure is lower in the mouth compared to outside, water therefore enters down a concentration gradient
  • opercular cavity bulges causes a slight pressure drop, water enters the opercular cavity from the mouth
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13
Q

What is the movement of water out?

A
  • operculum opened
  • mouth closes
  • floor of the mouth raised which increases pressure
  • water is forced out
  • maintains a flow of water over the gills
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14
Q

How are plants adapted for efficient gas exchange?

A
  • air spaces in the leaf have a large surface area
  • many stomata, no cell is far away from stoma, the diffusion pathway is short
  • interconnecting air spaces occur through mesophyll, gases can come into contact with them
  • large sa of mesopgyll means there is rapid diffusion
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15
Q

How does the stomata open and close?

A
  • each stoma is surrounded by guard cells
  • these open and close the stomatal pores
  • controls the rate of gaseous exchange
  • tries to prevent water loss
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16
Q

What are adaptations do xerophytic plants have to try and limit water loss?

A
  • they cannot have a small sa: v ratio as they need to conduct photosynthesis meaning it has to be large to attract light
  • water proof coverage and stomata to limit water loss
  • thick cuticle, the thicker the less is lost
  • hairy leaves, traps moist air, less water is lost through evaporation
  • rolling of leaves, protects stomata, traps moist air and becomes saturated with water vapour, no water potential gradient meaning none is lost
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17
Q

What are the lungs protected by?

A

The ribs

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18
Q

What is the trachea?

A

A flexible airway
Supported by rings of cartilage

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19
Q

What is the bronchi?

A

Produce mucus
Contain cilia

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20
Q

What are bronchioles?

A

Increase sa
They control the flow of air in and out of the alveoli

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21
Q

What is the alveoli?

A

They fill with air
They contain elastic fibres to stretch

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22
Q

What is inspiration?

A

Inhalation

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23
Q

What is expiration?

A

Exhalation

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24
Q

What is the process of inspiration?

A

External intercostal muscles contract
Ribs are pulled upwards and outwards
Diaphragm contacts and flattens
Increase in volume in the lungs
Decrease in pressure in the lungs
Atmospheric pressure is now greater outside the lungs than in, so air is forced in

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25
Q

What is the process of expiration?

A

Internal intercostal muscles contract
Ribs move inwards and downwards
Diaphragm relaxes and is pushed upwards
Decreased volume in the lungs
Increased pressure in the lungs
Atmospheric air is greater inside the lungs than outside, air is pushed out

26
Q

What are the sites of gas exchange?

A

Alveoli

27
Q

How do you get a constant supply of oxygen to the body?

A

Diffusion gradient maintained
Thin, large membrane
Movement of environmental medium and internal medium

28
Q

How is diffusion of gases between the alveoli and the blood rapid?

A

The distance between the two is reduced as the red blood cell flattens
the walls of both are very thin
large surface area
blood flow through the pulmonary capillaries maintains a concentration gradient

29
Q

What is the human digestive system made up of?

A

A long muscular tube
Associated glands

30
Q

What do the glands produce?
And what do they do?

A

Produce enzymes
Hydrolyse large molecules

31
Q

What is the digestive system known as?

A

An exchange surface through which food substances are absorbed

32
Q

What is the stomachs role?

A

Store and digest food
Release enzymes that digest proteins

33
Q

What is the ileum’s purpose?

A

Absorb products of digestion into the bloodstream

34
Q

What is an adaptation of the ileum?

A

The inner walls are folded into villi
Creates large surface area
Further increased by micro villi

35
Q

What is the large intestines role?

A

Absorbs water

36
Q

What is the rectums role?

A

Faeces stored

37
Q

What is the salivary glands role?

A

Secrete amylase
Hydrolysis of starch into maltose

38
Q

What is the pancreas role?

A

Protease to hydrolyse protein
Lipase to hydrolyse lipids
Amylase to hydrolyse starch

39
Q

What are the two stages of digestion?

A

Physical breakdown
Chemical breakdown

40
Q

What is physical breakdown?

A

Large molecules broken down by the teeth
Gives large surface area for chemical digestion
Food is churned by muscles in the stomach and is physically broken up

41
Q

What is chemical digestion?

A

Hydrolysis of large molecules into small molecules
Carried out by digestive enzymes

42
Q

What are the types of digestive enzyme?

A

Carbohydrase
Lipase
Protease

43
Q

What doe carbohydrase do?

A

Hydrolyse carbohydrates into monosaccharides

44
Q

What does lipase do?

A

Hydrolyse lipids into glycerol and fatty acids

45
Q

What does protease do?

A

Hydrolyse proteins into amino acids

46
Q

What is carbohydrate digestion?

A

Amylase hydrolyses starch into maltose
Maltose is hydrolysed into alpha glucose by maltase found in the ileum

47
Q

What is the process of the breakdown of carbohydrates

A

1) saliva enters, contains amylase, amylase hydrolyses starch into maltose
2) food enters stomach, denatures amylase, no further hydrolysis of starch
3) into small intestine
4) pancreas release amylase, starch -> maltose, alkaline salts in pancreas wall makes it remain neutral ti allow amylase to function
5) muscles push food along, maltase is produced in epithelial lining
6) maltase hydrolyses maltose to alpha glucose

48
Q

What are other to disaccharides that are hydrolysed?

A

Sucrose
Lactose

49
Q

What is sucrose hydrolysed into?

A

Glucose and fructose

50
Q

What is lactose hydrolysed into?

A

Glucose and galactose

51
Q

What is lipid digestion?

A

Hydrolysed by lipase
In the pancreas

52
Q

What is lipid digestion?

A

1) Lipids split into tiny droplets (micelles) by bile salts which are produced in the liver
2) called emulsification
3) increases the surface areas of lipids so the action of lipase enzymes would speed up

53
Q

How is protein digestion conducted?

A

Hydrolysed by a group of enzymes peptidase

54
Q

What are the types of different peptidase?

A

Endopeptidase
Exopeptidase
Dipeptidase

55
Q

What is endopeptidase?

A

Hydrolyse peptide bonds between amino acid in central region of protein

56
Q

What is exopeptidase?

A

Hydrolyse on the terminal amino acid of peptide molecules

57
Q

What is dipeptidase?

A

Hydrolyse the bond between two amino acids in a dipeptide

58
Q

What are the adaptations of the small intestine?

A
  • walls are folded, contain villi and microvilli which increases the sa
  • thin walls with epithelial cells= short diffusion pathway
  • rich network of blood capillaries
  • contains muscle to move, maintains diffusion gradient
59
Q

What produces amino acids?

A

The digestion of proteins

60
Q

What is the absorption of triglycerides?

A

1) micelles move to epithelial cells, break down into monoglyceride and two fatty acids
2) non polar so move through phospholipid bilayer
3) move to smooth endoplasmic reticulum, reform as triglyceride
4) move to Golgi complex, join with cholesterol to form chylomicrons (for lipid transport)
5) moves out cell via exocytosis and enters lymphatic capillaries (lacteals)
6) triglycerides hydrolysed by enzyme
7) diffuse into cell

61
Q

What are chylomicrons used for?

A

Lipid transport

biology paper 1 (10 decks)

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