Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A-level Biology > Chapter 6 - Exchange > Flashcards

Chapter 6 - Exchange Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

name three things that organisms need to exchange with their environment

A

oxygen, waste products and heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is passive exchange

A

no metabolic energy is required

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

give two examples of passive exchange

A

diffusion and osmosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is active exchange

A

metabolic energy is required

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

give an example of active exchange

A

active transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

why can substances diffuse directly out of the cell across the cell surface membrane in single celled organisms

A

they have a large SA:V which ensures efficient exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

why is diffusion across the cell membrane too slow in multicellular animals

A

there is a large distance between cell deep inside the body and the outside environment
large animals have a small SA:V so the exchange is inefficient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is mass transport

A

the use of an efficient system to carry substances to and from individual cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the exchange system in plants

A

xylem and phloem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

how are multicellular organisms adapted for efficient exchange

A

they have a flat shape for a short diffusion pathway or they have specialised exchange surfaces to increase the SA:V

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

why dp specialised exchanged surface normally have a large SA:V

A

it increases the rate of exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

why are specialised exchange surfaces normally very thin

A

the diffusion pathway is short so materials can cross the surface very rapidly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is Fick’s law

A

surface area x concentration gradient / length of diffusion pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

why do smaller organisms generally need a higher metabolic rate

A

smaller organisms normally have a larger surface area which means that much more heat is lost. they must have a higher metabolic rate in order to generate heat and stay warm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

why might an animal living in the Arctic have round shape

A

it has a small surface area which reduces heat loss and helps the animal stay warm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

why might an animal living in the desert have a pointed nose and long ears

A

both of these increase its surface area so it is easier to lose heat and stay cool

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

why might animals with a high SA:V have kidney structure adaptations

A

they tend to lose more water because of their large surface area so they produce less urine to compensate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

why might mammals living in cold regions need to eat lots of high energy food like nuts

A

because of their large surface area they need fast metabolic rates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

why do elephants have large ears

A

this increases their surface area so it is easier to cool down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what do most gas exchange systems have in common

A

they have a large surface area and are often just one cell thick

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what are tracheae

A

an internal network of tubes supported by strengthened ring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what are tracheoloes

A

dead end tubes found on the end of tracheae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

how does the insect respiratory system achieve a large surface area

A

there are lots of tracheoles which span the whole body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

how does the insect respiratory system achieve a small diffusion pathway

A

the walls of the tracheoles are 1 cell thick

there is no chitin in the walls of the tracheoles for support they connect to the majority of cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

how does the insect respiratory

system achieve the maximum diffusion gradient

A

when the cells at the end of tracheoles are respiring the oxygen is used up and this creates a steep concentration gradient between the outside air and tracheoles
respiration also produces carbon dioxide in the cells which creates a steep concentration in the opposite direction. because of this oxygen diffuses into cells and carbon dioxide diffuses out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what are spiracles

A

tiny pores which cover the insects body and can be opened and closed on demand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

how does the respiratory system of insects hinder their size

A

because the system relies mostly on the diffusion of gases into and out of the body the diffusion pathway must be short so insects must be a small size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

why do insects keep their spiracles closed for most of the time

A

to avoid water loss by evaporation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

how do insects move air into and out of the spiracles

A

their abdominal muscles can expand to lower the pressure and pull oxygen into the tracheoles then contract to increase the pressure and force carbon dioxide out of the tracheoloes then contract to increase the pressure and force carbon dioxide out of the tracheoles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what happens when anaerobic respiration occurs

A

lactate is produced in the muscles around traheoles which lowers their water potential. water therefore moves into these cells from the tracheoles by osmosis lowering the volume of water in the tracheoles. air gets drawn into the tracheoles because of the lower pressure. this increases the rate at which air is moved into tracheoles because diffusion is faster in a gas phase rather than in a liquid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what is the specialised gas exchange system in fish

A

gills

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

how do fish gills achieve achieve a high surface area

A

they consist of filaments and lamellae which are at right angles to the filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

how do fish gills achieve a small diffusion pathway

A

there is a network of blood capillaries next to the lamellae which have one cell thick walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what is countercurrent flow

A

the flow of water over the lamellae and the flow of blood inside them air in opposite directions. therefore the blood and water never reach equilibrium and oxygen continually diffuses into the blood the two never reach equilibrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

if fish didnt have a countercurrent flow mechanism what would be the maximum percentage of oxygen removed from the water

A

50% an equilibrium will be reached and no more oxygen will be extracted from the water because there is no concentration gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

what percentage of oxygen is removed from the water

A

80%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

what are the two processes that plants conducted

A

photosynthesis and aerobic respiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

equation for photosynthesis

A

6CO2 + 6H20 -> C6H12O6 + 6H20

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

the equation for aerobic respiration

A

C6H1206 + 6O2 -> 6CO2 + 6H20

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

when photosynthesis isn’t occuring, why is carbon dioxide still produced

A

it is produced by aerobic respiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

state two ways in which gas exchange in plants is similar to that in insects

A

no living cell is far from the external air

diffusion takes place in the gas phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

how do plants balance the conflicting needs of gas exchange vs water loss

A

they have guard cells which can open and close stomata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

why are the stomata mainly at the bottom of the leaf

A

reduces transpiration and evaporation as not in direct sunlight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

what is the function of guard cells

A

to retain water when it is needed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

what is the function of the waxy cuticle

A

to stop evaporation from the leaf surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

why must the cell surface be wet

A

to allow the gases to dissolve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

how are mesophyll cells adapted in the leaf

A

they create big air spaces which increases the surface area available for diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

why can a leaf be a maximum of 10 cells thick

A

must have a short diffusion pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

state three ways in which insect minimise water loss

A

they have a small surface area to volume ration they are surrounded by a waterproof coating spiracles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

how can spiracles help to conserve water

A

they are surrounded by a ring of muscle which can contract to close the spiracles when gas exchange isn’t occurring

51
Q

why can’t plants have a small surface area to volume ratio

A

photosynthesis requires a large surface area to capture light and exchange gases

52
Q

what are xerophytes

A

plants that are well adapted to reducing water loss through transpiration

53
Q

state five ways in which plants reduce water loss

A 
a thick waxy cuticle 
the rolling of leaves
hairy leaves
stomata sunk in pits
small surface area to volume ration of leaves
54
Q

how does a thick waxy cuticle reduce water loss

A

it reduces the amount of evaporation occurring

55
Q

how can rolling leaves reduce water loss

A

when leaves roll the lower epidermis where the stomata are found on the inside of the leaf. a layer of moist air is trapped which becomes saturated with water and has a very high water potential. because of this, there is no water potential gradient between the leaf and the air so no water is lost

56
Q

how do hair leaves reduce water loss

A

still moist air is trapped near to the surface. this means that the water potential gradient between the lead and the air is reduced so less water is lost by evaporation

57
Q

how does having stomata in pits or grooves help to reduce water loss

A

a layer of still, moist air is trapped next to the stomata. this means that the water potential gradient between the leaf and the air is reduced so less water is lost by evaporation

58
Q

why do plants found of beaches have to be well adapted

A

the water is quickly absorbed by the sand so they must have long roots. it is windy and dry which means increased evaporation
the water is often salty which means it is harder to pull water into cells by osmosis

59
Q

how does having leaves with a smaller surface area to volume ratio help reduce water loss

A

having leaves with a smaller surface area means that the rate of water loss can be reduced because of the slower rate of diffusion but this must be balanced with the need for a large surface area for photosynthesis

60
Q

why do mammals have to absorb large amounts of oxygen and release large amounts of CO2

A

they are relatively large organisms they maintain a high body temperature which is controlled by metabolic and respiratory rate

61
Q

why are lungs located inside the body

A

the body would otherwise lose a great deal of water

air isn’t dense enough to support and protect them

62
Q

what are the lungs

A

lobed structures made of series of bronchioles

63
Q

what is the trachea

A

a flexible airway supported by rings of cartilage.

this stops the trachea collapsing when you breathe in

64
Q

what are the bronchi

A

two mucus containing tubes which connect the trachea to each lung

65
Q

what are bronchioles

A

subdivisions of the bronchi. they are surrounded by rings of muscles to control air flow to the alveoli

66
Q

what are alveoli

A

minute air sacs cross which gas exchange. elastic fibres allow them to stretch and contract

67
Q

how is surface area maximised in the lungs 5

A
  • the bronchioles are branching subdivisions of bronchi
  • millions of alveoli which have the ability to stretch
  • alveoli are highly folded
  • large capillary network surrounding alveoli
  • biconcave red blood cells
68
Q

how is the length of the diffusion pathway minimised 3

A

the walls of the alveoli are one cell thick
the lining of the capillaries are also one cell thick
squamous epithelial cells

69
Q

how is the concentration gradient maximised 3

A
  • lungs ventilated by a tidal stream of air which ensures the air within them is constantly replenished
  • ventilation keeps oxygen high in the alveoli
  • circulation keeps oxygen low in the capillaries
70
Q

what is ventilation

A

the movement of air into and out of the lungs

71
Q

what is inspiration

A

when the pressure inside your chest is lower than the outside pressure so air is forced into the lungs

72
Q

what is expiration

A

when the pressure inside your cheat is higher than the outside pressure so air is forced out of your lungs

73
Q

what are the three sets of muscles that control ventilation

A

internal intercostal muscles
external intercostal muscles
diaphragm

74
Q

when the internal intercostal muscles contract what happens

A

expiration

75
Q

when the external intercostal muscles contract what happens

A

inspiration

76
Q

what happens when you breathe in

A

the external intercostal muscles and diaphragm contract
the ribs are pulled upwards and outwards and the diaphragm flattens which increases the volume of the thorax . the increased volume results in reduced pressure in the lungs. atmospheric pressure is now greater so air is forced into the lungs

77
Q

what happens when you breathe out

A

the internal intercostal muscles contract and the diaphragm relaxes. the ribs move down and in increasing the pressure of the thorax. the decreased volume results in increased pressure in the lungs. atmospheric pressure is now less so air is forced out of the lungs

78
Q

equation of pulmonary ventilation rate dm3min-1

A

tidal volume x ventilation rate

79
Q

what is pulmonary ventilation rate

A

total volume of air taken in one minute

80
Q

what is tidal volume

A

volume taken in with each breath

81
Q

what is ventilation rate

A

number of breaths per minute

82
Q

where does gas exchange take place in mammals

A

the epithelium of the alveoli

83
Q

how does oxygen diffuse from the alveoli into blood

A

the oxygen diffuses out of the alveoli across the alveolar epithelium and the capillary endothelium and the capillary endothelium and into the haemoglobin in the blood

84
Q

why are red blood cells slowed as they pass through

A

capillaries are so small that the red blood cells must flatten themselves against the walls of the capillaries to pass trough

85
Q

why is it good that red blood cells are slowed down as they pass through capillaries

A

there is more time for diffusion

86
Q

why is it beneficial that red blood cells are pushed against the capillary walls

A

there is a shorter diffusion pathway

87
Q

why is it beneficial that the walls of both the alveoli and capillaries are thing

A

there is a short diffusion pathway

88
Q

how is a steep concentration gradient maintained in the lungs

A

ventilation keeps oxygen concentration high in alveoli and circulation keeps in low in the blood

89
Q

when does a correlation occur

A

when a change in one of two variables is reflected by a change in the other variable

90
Q

name 5 risk factors for lung cancer

A 
smoking
genetics 
air pollution
infections 
occupation
91
Q

what happens during digestion

A

large insoluble food molecules are broken down into smaller soluble food molecules by hydrolysis by enzymes

92
Q

what is the function of the oesophagus

A

it carries food from the mount to the stomach

93
Q

what is the function of the stomach

A

a muscular sack that produces enzymes to digest food

94
Q

function of the rectum

A

the faeces are stored here before egestion

95
Q

what is the function of the large intestine

A

it absorbs water

96
Q

what do carbohydrates form when they are broken down

A

disaccharides

97
Q

what do fats form when they are broken down

A

monoglycerides and fatty acids

98
Q

what do proteins form when they are broken down

A

amino acids

99
Q

what is the function of the small intestine

A

it secretes enzymes to further digest the food

100
Q

what is the function of the salivary glands

A

secrete amylase which hydrolyses starch into maltose

101
Q

what is the function of the pancreas

A

secretes enzymes to hydrolyse proteins lipids and starch

102
Q

what is the physical breakdown of food

A

structures such as teeth break down the food and increase the surface area for digestion

103
Q

what is the chemical reaction of food

A

enzymes use hydrolysis to add water to chemical bonds holding the molecule together and break it apart

104
Q

how are lipids broken down

A

enzymes called lipase hydrolyse the ester bond found in triglycerides to produce fatty acids and monoglycerides

105
Q

how are lipids emulsified

A

bile salts made by the liver turn larger lipids into smaller droplets with a larger surface area

106
Q

what does lactose form when hydrolysed

A

alpha glucose + galactose

107
Q

what does sucrose form when hydrolysed

A

alpha glucose + fructose

108
Q

what are three different peptidases

A

endopeptidases
exopeptidases
dipeptidases

109
Q

what do endopeptidases do

A

hydrolyse the peptide bonds in the centre of polypeptide chains

110
Q

where are endopeptidases found

A

the stomach

111
Q

where are exopeptidases found

A

small intestine

112
Q

what do exopeptidases do

A

hydrolyse the peptide bonds at the ends of polpypetide chains

113
Q

what do dipeptidases do

A

hydrolyse the peptide bond between just two amino acids

114
Q

where are dipeptidases found

A

attached to the membrane of the small intestine

115
Q

how are carbohydrates broken down

A

saliva enters the mount and is mixed with the food via chewing.
saliva contains amylase which begins to hydrolyse the glycosidic bonds in the starch into maltose
the food is swallowed and enters the stomach where the amylase denatures
the food enters the small intestine where it is mixed with pancreatic juice
pancreatic amylase hydrolyses any remaining starch into maltose
salts are produced by the small intestine and pancreas to keep the solution alkaline which is where amylase works best
muscles push the food along the ileum maltase a membrane bound disaccharidase is produced by the ileum
maltase hydrolyses the maltose to form alpha glucose

116
Q

how is glucose absorbed into the bloodstream

A

cotranport with sodium ions

117
Q

how is galactose absorbed into the blood stream

A

cotransport with sodium ions

118
Q

how is fructose absorbed into the bloodstream

A

facilitated diffusion

119
Q

how are amino acids absorbed into the blood stream

A

co-transport with sodium ions through sodium dependent transportation

120
Q

what properties do villi possess which increases the efficiency of absorption 5

A
  • they massively increase the surface area
  • 1 cell thick walls = short diffusion pathway
  • well supplied with blood vessels to maintain the concentration gradient
  • microvilli increase surface area even more
  • they are able to move which mixes the contents of the ileum and maintains the concentration gradient
121
Q

how are monosaccharides absorbed into the blood

A

facilitated diffusion and co transport

122
Q

how are triglycerides absorbed into the blood

A

micelles come into contact with the villi and microvilli of lumen
micelles break down releasing fatty acids and glycerol
they are small and uncharged so pass through the bilayer through simple diffusion
monoglycerides and fatty acids recombined to form triglycerides
triglycerides combined with cholesterol and lipoproteins to form chylomicrons
chlymicorns move out of the cell by exocytosis
they enter lacteals at the centre of each villus
chylomicrons hydrolysed by cells of capillary walls
monoglycerides and fatty acids diffuse into cells

123
Q

how do chylomicrons exit cells

A

exocytosis they are too large to leave otherwise

A-level Biology (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions