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AP® Biology flashcards Biology 101 flashcards
1
Q

What is the equation for photosynthesis?

A

6CO2 + 6H2O —-> C6H12O6 + 6O2

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2
Q

What is the equation for respiration?

A

C6H12O6 + 6O2 —-> 6CO2 + 6H2O

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3
Q

How are leaves adapted?

A

Large SA
Thin
Selectively permeable
Diffusion gradient

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4
Q

Why is it good that leaves have a large SA?

A

Greater surface for diffusion

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5
Q

Why is it good that leaves are thin?

A

Short diffusion pathway

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6
Q

Why is it good that leaves are selectively permeable?

A

Controls what comes in and out

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7
Q

Why is it good that leaves have a diffusion gradient?

A

Large diffusion gradient increases the rate of diffusion

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8
Q

How are fish adapted?

A

Small SA:Vol
Waterproof, gas tight coating
Surrounded by water (salt water has lower water potential)
Specialised internal gas exchange system (gills)

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9
Q

What are the features of gills?

A

Large SA provided by gill lamellae
Rich blood supply
Countercurrent flow

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10
Q

What is countercurrent flow?

A

Blood + water flows in opposite directions
Most O2 rich blood + water comes into contact
Most O2 poor blood + water comes into contact

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11
Q

What is good about countercurrent flow?

A

Maintains favourable concentration gradient across exchange surface

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12
Q

Where are the gills positioned?

A

Behind their head

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13
Q

How do gills work?

A

Water enters the mouth + forced over gills then out through the opening

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14
Q

What are gills made of?

A

Gill filaments staked on top of each other covered in lamellae

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15
Q

What do highly active fish do?

A

Swim with their mouths open

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16
Q

Why do some fish swim with their mouths open?

A

Since it maintains high rate of water flow across the gills to provide sufficient O2 for rate for respiration

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17
Q

What is an example of a fish that swims with their moths open?

A

Sharks

Mackerel

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18
Q

What does the rate of respiration and photosynthesis effect?

A

Vol of gas

Type of gas

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19
Q

Why can’t insects use their body surface to exchange respiratory gases?

A

Bodies aren’t permeable
Molecules can’t diffuse in or out
Don’t have a large SA

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20
Q

Why do insects have mechanisms that allow them to conserve water?

A

Since they are terrestrial

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21
Q

What do terrestrial insects have to balance?

A

Their need to conserve water with gas exchange

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22
Q

If you were to increase the SA of an insect what would it conflict with?

A

Water conservation

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23
Q

How do insects reduce water loss?

A

Rigid exoskeleton
Waterproof
Small SA
Spiracles - open + close to prevent water loss

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24
Q

What is the internal network of tubes called in an insect?

A

Tracheae

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25
Q

What is the trachea supported by in insects to prevent water loss?

A

Rings

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26
Q

What does the trachea in insects divide into?

A

Tracheoles

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27
Q

What do tracheoles in insects allow to happen?

A

Air to be brought directly to respiring tissues

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28
Q

Why are insects small?

A

Not enough O2 for them to grow bigger
Trachea system cannot sustain enough O2
Rely on diffusion rather than transport system
Must have a short diffusion pathway

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29
Q

What are the three ways gases move in and out of the tracheal system in insects?

A

Diffusion gradient
Muscle contractions
Water filled tracheoles

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30
Q

How does the diffusion gradient allow gases to diffuse in and out of insects?

A

During respiration O2 is used
O2 conc at tracheole ends fall
Creates diffusion gradient
O2 diffuses from atmosphere into tracheoles then cells
CO2 is produced by respiring cells
Diffusion gradient in opposite direction
CO2 diffuses out of the tracheoles + into atmosphere

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31
Q

How does muscle contractions allow gases to diffuse in and out of insects?

A

Abdominal pumping - contraction of insect muscles
Trachea squeezed and reduced in volume
Some air expelled from trachea
Uses energy

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32
Q

What is abdominal pumping common in?

A

Large insects

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33
Q

How does water filled tracheoles allow gases to diffuse in and out of insects?

A

Anaerobic respiration produces lactate
Lactate is water soluble so lowers W.P of muscle cells
Water moves into muscle cells from tracheoles
Volume in tracheole ends decrease
Drawing in air

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34
Q

What happens to the level of oxygen in the trachea when spiracles are closed?

A

They are low

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35
Q

What causes spiracles to open?

A

When level of O2 is too low and when level of CO2 is too high

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36
Q

The tracheal system relies on diffusion and a short diffusion pathway, what factor will this limit in all insects?

A

Size - must be small to ensure a short diffusion pathway

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37
Q

What are the organelles of a palisade cells?

A 
Cell wall
Cell membrane
Chloroplast
Mitochondria
Amyloplast
SER
RER
Golgi apparatus 
Ribosomes
Vacuole
Nucleus
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38
Q

What do stomatas create?

A

Short diffusion pathway

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39
Q

What do air spaces all?

A

An increased SA + allows gases to diffuse around

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40
Q

What do spongy mesophyll layer allow?

A

Maximum diffusion

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41
Q

What do the stomata, air spaces and spongy mesophyll layer all provide?

A

Short + fast diffusion pathway

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42
Q

What does the stomata control?

A

Diffusion of gases and water vapour

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43
Q

What is the stomata surrounded by?

A

Guard cells

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44
Q

What do card cells control?

A

Opening + closing of the stomata

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45
Q

Why is the stomata open in the daytime?

A

Photosynthesis

Needs lots of CO2

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46
Q

Why is the stomata closed in the dark/night?

A

No photosynthesis

No need for CO2

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47
Q

What does the transpiration stream do?

A

Transports water from roots to leaves

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48
Q

How is the transpiration stream created?

A

As water evaporates from the surface of the leaf

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49
Q

What is the transpiration stream supported by?

A

Cohesion Tension Theory

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50
Q

What are xerophytes?

A

Plants living in an area with short water supply

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51
Q

Where are xerophytes’ roots?

A

Near the surface since that is where the water is

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52
Q

How is the leaf adapted to reduce water loss?

A 
Thick cuticle
Rolling up leaves
Hairy leaves
Sunken stomata
Reduced SA:Vol
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53
Q

How does a thick cuticle reduce water loss?

A

Less water can evaporate off its surface

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54
Q

How does rolling up of leaves reduce water loss?

A

Traps still, moist air so WP gradient between inside and outside so they’re the same so no water loss

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55
Q

How does hairy leaves and sunken stomatas reduce water loss?

A

Trap still, moist air so WP gradient is reduced between inside and outside so less water evaporated

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56
Q

How does a reduced SA:Vol reduce water loss?

A

Smaller SA:Vol = slower rate of diffusion

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57
Q

What is an example of a plant with a thick cuticle?

A

Holly

58
Q

What is an example of a plant that rolls up its leaves?

A

Marram grass

59
Q

What is an example of a plant with hairy leaves?

A

Heather

60
Q

What is an example of a plant with sunken stomatas?

A

Pine tress

61
Q

What is an example of a plant with a reduced SA:Vol?

A

Pine tree leaves

62
Q

Why is the volume of O2 that needs to be absorbed + the volume of CO2 that needs to be reduced large in mammals?

A

They’re large organisms with a large volume of cells

Maintain a high body temp as they have a high metabolic + respiratory rate

63
Q

What is the structure of the lungs?

A

Lobed structure

64
Q

Describe the trachea

A

Flexible airway supported by cartilage rings

65
Q

What are the muscular walls of the trachea lined with?

A

Ciliated epithelium and goblet cells

66
Q

Why is the trachea supported by cartilage rings?

A

To prevent the trachea from collapsing since the pressure falls when breathing in

67
Q

Describe the bronchi

A

Two divisions of the trachea, each leading to one lung

68
Q

Why do the bronchi produce mucus?

A

To trap dirt particles

69
Q

What are the bronchi lined with to trap dirt particles?

A

Ciliated epithelium + goblet cells

70
Q

Describe the bronchioles

A

Series of branching subdivisions of the bronchi

71
Q

What are the walls of the bronchioles made up of?

A

Muscle lined with epithelium cells

72
Q

What does mucus allow the bronchioles to do?

A

Constrict so they can control air flow in and out of the alveoli

73
Q

Describe alveoli?

A

Air sacs at the end of bronchioles

74
Q

What is between the alveoli?

A

Collagen and elastic fibres

75
Q

What is the alveoli lined with?

A

Epithelium cells

76
Q

What do the elastic fibres allow alveoli to do?

A

Stretch as they fill with air and spring back during breathing out in order to expel CO2

77
Q

What is the alveolar membrane?

A

Gas-exchange surface

78
Q

What is breathing?

A

Ventilation

79
Q

What is inspiration/inhalation?

A

When air pressure of the atmosphere is greater than air pressure inside of the lungs, so air is forced into the lungs

80
Q

What is expiration/exhalation?

A

When air pressure is of the atmosphere is lower than air pressure inside of the lungs, so air is forced out of the lungs

81
Q

The pressure changes due to what muscles?

A

Diaphragm
Internal intercostal muscles
External intercostal muscles

82
Q

What is the diaphragm?

A

A sheet of muscle that separates the thorax from the abdomen

83
Q

Where do the intercostal muscles lie?

A

Between the ribs

84
Q

Label a diagram of the lungs

A

Look up A-level diagram

85
Q

Describe inspiration

A 
External contract + internal relax
Ribs pull upwards + outwards
So vol of thorax increases
Diaphragm contracts = flattens
So vol of thorax increased
Atmospheric pressure greater
So air forced IN
86
Q

Describe expiration

A 
External relaxes + internal contract
Ribs move downwards + inwards
So vol of thorax decreases
Diaphragm relaxes = pushed up
So vol of thorax decreases
Pulmonary pressure greater
So air forced OUT
87
Q

What type of process is inspiration (breathing in)?

A

Active

88
Q

What type of process is expiration (breathing out)?

A

Passive

89
Q

What is each alveolus surrounded by?

A

Network of pulmonary capillaries

90
Q

How thick are the pulmonary capillaries?

A

Width of one red blood cell

91
Q

How thick are the alveolus walls?

A

One layer of cells thick

92
Q

Why are the diffusion of gases rapid between alveoli and blood?

A

RBCs slowed as they pass through capillary
Very thin walls = short diffusion pathway
Large SA
Constant breathing movements + constant circulatory blood = steep concentration

93
Q

What does the blood flow through the pulmonary capillaries maintain?

A

Concentration gradient

94
Q

Why is good that RBCs are faltened against pulmonary capillary walls?

A

Short distance between RBCs and alveolar air

95
Q

Describe the path which O2 goes from an alveolus to the blood

A

Enters through the alveolar epithelium then enters the blood through the endothelial cell of the capillary

96
Q

Describe the structure of the ileum

A 
Walls folded
Villi
Thin walls, lined with epithelium cells
Rich network of capillaries
Large SA
97
Q

Why does the ileum have a large SA?

A

For an increased rate of absorption

98
Q

How do villi increase efficiency of absorption?

A

Large SA for diffusion
Thin walls = short diffusion pathway
Well supplied with blood vessels
Epithelium cells posses microvilli = further increased SA

99
Q

Why do villi have muscles?

A

To help them to move so they can mix the contents of the ileum and maintain a conc gradient

100
Q

How are amino acids absorbed?

A

Co-transport

101
Q

Describe the structure of bile salts

A

One end lipophilic (fat soluble) + hydrophobic

Other end lipophobic + hydrophilic

102
Q

Because of their structure, how do bile salts arrange themselves?

A

Lipophilic ends in fat droplets, leaving lipophobic end sticking out

103
Q

How are monosaccharides absorbed?

A

Glucose = active transport with NA+ via co-transporter protein

104
Q

How are amino acids absorbed?

A

Co-transport

105
Q

How are monoglycerides and fatty acids absorbed?

A

Micelles help move them towards epithelium as constantly break up and reform to release them
Fatty acids + monoglycerides lipid-soluble so diffuse easily across epithelium

106
Q

Describe the oesophagus

A

Carries food from the mouth to stomach

107
Q

Describe the stomach

A

Muscular sac with an inner layer that produced enzymes

108
Q

What is the role of the stomach?

A

To store and digest food

109
Q

Describe the ileum

A

Long muscular tube where food is further digested by enzymes produced by its walls + glands

110
Q

Describe the large intestine

A

Absorbs water from the secretions of many digestive glands

111
Q

Describe the rectum

A

Final section of the intestines, where the faeces is stored before being removed by the anus

112
Q

What is the process of the faeces being removed?

A

Egestion

113
Q

Describe the salivary gland

A

Secretes amylase via a duct, situated in the mouth

114
Q

Describe the pancreas

A

Large gland situated below the stomach

115
Q

What does the pancreas secrete?

A

Pancreatic juice

116
Q

What does pancreatic juice contain?

A

Protease, lipase and amylase

117
Q

What two stages does digestion take place in?

A

Physical breakdown

Chemical breakdown

118
Q

Describe physical breakdown

A

Large food is broken down into smaller pieces by means of structures

119
Q

Describe chemical breakdown

A

Large insoluble molecules hydrolysed by enzymes into smaller soluble molecules

120
Q

What is needed to hydrolyse a larger molecule?

A

More than one enzyme

121
Q

What do all digestive enzymes functions by?

A

Hydrolysis

122
Q

What is hydrolysis?

A

Splitting up larger molecules by adding H2O to the bonds that hold them together

123
Q

What are carbohydrates hydrolysed by?

A

Carbohydrase/amylase

124
Q

What are lipids hydrolysed by?

A

Lipase

125
Q

What are proteins hydrolysed by?

A

Protease

126
Q

What are the hydrolysis products of carbohydrates?

A

Monosaccharides

127
Q

What are the hydrolysis products of lipids?

A

Fatty acids + glycerol

128
Q

What are the hydrolysis products of proteins?

A

Amino acids

129
Q

How are carbohydrates digested?

A 
Amylase produced by salivary gland
Hydrolyses alternative glycosidic bond of starch
Maltose formed
Hydrolysed by disaccharidase maltase 
Form monosaccharide alpha glucose
130
Q

How are lipids digested?

A

Lipase produced in pancreas
Hydrolyses ester bond in triglyceride
Forms fatty acids + monoglycerides
Lipids split into micelles by bile salts

131
Q

How are micelles formed?

A

Large lipid molecule emulsified by bile salts
Forms small lipid molecules
Lipase digestion
Form micelles

132
Q

Where are the bile salts produced?

A

Liver

133
Q

What is a monoglyceride?

A

Glycerol molecule with one fatty acid attached

134
Q

What are proteins digested by?

A

Peptidases (proteases)

135
Q

What do endopeptidase do?

A

Hydrolyses peptide bonds within protein molecules

136
Q

What do exopeptidase do?

A

Hydrolyses peptide bonds at the ends of protein molecules

By removing single amino acids from proteins

137
Q

What do dipeptidase do?

A

Hydrolyses peptide bond between 2 amino acids of a dipeptide

138
Q

Where is a dipeptidase located?

A

Cell-surface membrane of epithelial cells in the small intestine (ileum)

139
Q

What two examples of endopeptidases that are synthesised in the pancreas and secreted into the small intestine?

A

Trypsin

Chymotrypsin

140
Q

What is an example of an endopeptidase that is released into the stomach by cells in its lining?

A

Pepsin

141
Q

What conditions does pepsin only work in?

A

Acidic

A-Level Biology (21 decks)

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