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A level Biology > Unit 2.4 - Adaptations for nutrition > Flashcards

Unit 2.4 - Adaptations for nutrition Flashcards

1
Q

What can living organisms be divided into 2 main groups depending on?

A

The method by which they obtain nutrients to provide energy and raw-materials for carrying out living processes

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2
Q

What are the 2 main groups that living organisms can be divided into?

A

Autotrophs
Heterotrophs

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3
Q

Why do living organisms need to obtain nutrients?

A

To provide energy and raw-materials for carrying out living processes

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4
Q

Which type of organisms use autotrophic nutrition?

A

Organisms which are able to manufacture complex organic compounds from simple inorganic molecules (e.g - CO2, H2O)

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5
Q

Name 2 simple inorganic molecules

A

CO2, H2O

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6
Q

What are organisms that use autotrophic nutrition referred to as and why?

A

Producers - they synthesise their own complex organic compounds so there’s no need for them to eat or consume them

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7
Q

Example of organisms that use autotrophic nutrition

A

Plants

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8
Q

What type of nutrition do plants rely on?

A

Autotrophic

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9
Q

Where does photosynthesis take place in plants?

A

Chloroplasts

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10
Q

In which plants does photosynthesis take place in the chloroplasts?

A

Green plants
Algae

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11
Q

How do plants use autotrophic nutrition?

A

Chlorophyll traps light and the energy is used to combine simple inorganic compounds (H2O and CO2) to form complex organic compounds (sugars and starches)

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12
Q

What are the two types of autotrophic bacteria?

A

Photosynthetic
Chemosynthetic

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13
Q

What do photosynthetic autotrophic bacteria use to drive the reactions of photosynthesis?

A

A photosynthetic pigment called bacteriochlorophyll

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14
Q

Photosynthetic pigment in photosynthetic autotrophic bacteria

A

Bacteriochlorophyll

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15
Q

Compare bacteriochlorophyll to regular chlorophyll?

A

Bacteriochlorophyll is simpler and comes in 2 forms - green and purple

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16
Q

2 forms of bacteriochlorophyll

A

Green and purple

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17
Q

What are green and purple 2 forms of?

A

Bacteriochlorophyll

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18
Q

What is the source of enegrgy driving photosynthesis in photosynthetic autotrophic Bactria?

A

Light

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19
Q

Complex organic compounds formed by plants

A

Sugars
Starches

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20
Q

How is the hydrogen source different in photosynthetic autotrophic bacteria compared to plants?

A

Bacteria - comes from hydrogen sulphide
Plants - comes from water

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21
Q

Why do photosynthetic bacteria and plants need hydrogen?

A

To reduce CO2

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22
Q

What can chemosynthetic autotrophic bacteria do that photosynthetic autotrophic bacteria can’t?

A

Synthesise organic compounds from inorganic materials in the absence of light

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23
Q

What the source of energy to synthesise organic foods in chemosynthetic autotrophic bacteria?

A

Special methods of respiration

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24
Q

Why do bacteria need energy?

A

To synthesise organic foods

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25
Q

Give 4 examples of chemosynthetic autotrophic bacteria and what they do

A

Iron bacteria oxidise divalent iron salts
Colourless sulphur bacteria live in decaying organic matter and oxidise hydrogen sulphide to sulphur
Hydrogen bacteria can oxidise hydrogen to form water
Nitrifying bacteria - essential in the nitrogen cycle

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26
Q

Where do chemosynthetic sulphur bacteria live and what do they do?

A

In decaying organic matter
Oxidise hydrogen sulphide to sulphur

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27
Q

What do chemosynthetic iron bacteria do?

A

Oxidise divalent iron salts

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28
Q

What do chemosynthetic hydrogen bacteria do?

A

Oxidise hydrogen to form water

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29
Q

Which chemosynthetic bacteria are essential in the nitrogen cycle?

A

Nitrifying bacteria

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30
Q

What are chemosynthetic nitrifying bacteria essential in?

A

The nitrogen cycle

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31
Q

Describe organisms that use heterotrophic nutrition

A

Cannot synthesise their own organic food
Have to consume complex organic food material produced by autotrophs

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32
Q

Where do organisms that rely on heterotrophic nutrition get their food?

A

Form autotrophs

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33
Q

What are organisms that rely on heterotrophic nutrition known as and why?

A

Consumers
Eat and consume ready-made organic compounds

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34
Q

Give some examples of organisms that use heterotrophic nutrition

A

Animals
Fungi
Some types of protoctists and bacteria

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35
Q

What are the 4 types of heterotrophic nutrition?

A

Holozoic feeders
Saprophytes or saprobionts
Parasites
Mutualism or symbiosis

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36
Q

Holozoic feeders

A

Take food into their bodies and break it down by the process of digestion, internally

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37
Q

What type of heterotrophic nutrition sub-unit are most animals?

A

Holozoic feeders

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38
Q

What do Holozoic feeders have?

A

A specialised digestive system

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39
Q

What happens in the specialised digestive system of Holozoic feeders?

A

Digested material is absorbed into the body tissues and used by the body cells

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40
Q

What are the 4 different types of Holozoic feeders?

A

Herbivores
Carnivores
Omnivores
Detritivores

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41
Q

Herbivores

A

Holozoic feeders that feed solely on plant material

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42
Q

Carnivores

A

Holozoic feeders that feed on other animals

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43
Q

Omnivores

A

Holozoic feeders that feed on both plant and animal material

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44
Q

Detritivores

A

Holozoic feeders that feed on dead and decaying material

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45
Q

Example of Detritivores

A

Worms

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46
Q

Holozoic feeders that feed on dead and decaying material

A

Detritivores

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47
Q

Holozoic feeders that feed on both plant and animal material

A

Omnivores

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48
Q

Holozoic feeders that feed on other animals

A

Carnivores

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49
Q

Holozoic feeders that feed solely on plant materials

A

Herbivores

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50
Q

Saprophytes or saprobionts

A

Feed on dead and decaying matter and do not have a specialised digestive system

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51
Q

Organisms that feed on dead and decaying matter and do not have a specialised digestive system

A

Saprophytes and saprobionts

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52
Q

What do saprophytes and saprobionts include?

A

All fungi and some bacteria

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53
Q

How do saprophytes or saprobionts feed?

A

By secreting enzymes such as proteases, amylases, lipases and cellulases onto the food material outside the body and then absorb the soluble products across the cell membrane by diffusion

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54
Q

What do proteases enzymes do?

A

Digest proteins

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55
Q

What do amylases enzymes do?

A

Digest starch

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56
Q

What do lipases enzymes do?

A

Digest lipids

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57
Q

What do cellulases enzymes do?

A

Digest cellulose

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58
Q

Which enzyme has evolved specifically in fungi that isn’t in animals and why?

A

Cellulase to digest cellulose
There’s an abundance of it in dead organic material, and it forms a large part of the nutrition of fungi

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59
Q

What’s the name for the digestion used by saprophytes or saprobionts?

A

Extracellular digestion

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60
Q

What type of organisms use extracellular digestion?

A

Saprophytes or saprobionts

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61
Q

Decomposers

A

Microscopic saprophytes

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62
Q

Microscopic saprophytes

A

Decomposers

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63
Q

Why are decomposers important?

A

Essential in the decomposition of dead plant and animal material
And
The recycling of nutrients such as nitrogen

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64
Q

Parasites

A

Live in or on another living organism (the host) and causes harm to the host

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65
Q

What’s the name for the living organism that a parasite lives in or on?

A

The host

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66
Q

What has to be true for a parasite to be classed as this?

A

Has to cause harm to the host

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67
Q

What do parasites feed on?

A

Their host

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68
Q

What’s the name for parasites that live inside the host?

A

Endoparasites

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69
Q

Whats the name for parasites that live on the surface?

A

Ectoparasites

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70
Q

Describe parasites

A

Highly specialised organisms
Show considerable adaptation

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71
Q

Give 3 examples of parasites

A

Tapeworm
Potato blight
Plasmodium

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72
Q

What type of parasite is the tapeworm and where is it found?

A

Endoparasite
In the gut of mammals

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73
Q

What is the parasite potato blight caused by?

A

A fungus

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74
Q

What is plasmodium?

A

A protoctist - the malarial parasite in the blood

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75
Q

Mutualism or symbiosis?

A

Involves a close relationship between members of 2 different species, but in this case, both benefit from the relationship

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76
Q

Give an example of mutualism/symbiosis occurring

A

Cows and sheep feed mainly on grass, a high proportion of which is made up of cellulose cell walls
Herbivores do not secrete cellulase and cannot digest cellulose
Mutualistic bacteria which live in a specialised region of the gut (the rumen)
Benefits the herbivore
Bacteria absorb digested products such as amino acids which allow them to grow and thrive

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77
Q

How is the relationship between the bacteria in the rumen of a cow and the cow itself an example of mutualism or symbiosis?

A

Benefits the herbivore - allows it to digest cellulose in the grass eaten by producing the enzyme cellulase
Benefits the bacteria - absorb interested products such as amino acids which allow them to grow and thrive

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78
Q

Which specialised region of the gut does the mutualistic bacteria that produces cellulase live in a cow?

A

The rumen

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79
Q

Where does one species live on the other during symbiosis?

A

Inside or on the surface

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80
Q

Why is an organism that lives inside or on the surface of another in symbiosis not a parasite?

A

It doesn’t cause harm

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81
Q

What must be broken down by digestion and then be absorbed in the body tissues?

A

Large insoluble organic molecules

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82
Q

What happens to large insoluble organic molecules to be used in body cells?

A

Broken down by digestion
Absorbed into the body tissues from the digestive system

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83
Q

Where does digestion and absorption take place?

A

In the gut

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84
Q

What takes place in the gut?

A

Digestion and absorption

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85
Q

What IS the gut?

A

A long, hollow muscular tube

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86
Q

How is the gut organised?

A

To allow the movement of its contents in one direction only

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87
Q

What type of gut do Simple organisms have and why?

A

Undifferentiated
Only feed on 1 type of food

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88
Q

What type of gut do advanced organisms have and why?

A

Gut is divided into different parts along its length
Varied diet

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89
Q

What is the purpose of the different parts that the gut is divided into in advanced organisms?

A

Each part is specialised to carry out particular steps in the processes of mechanism and chemical digestion + absorption

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90
Q

Give an example of a simple, single celled organisms

A

Amoeba

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91
Q

Describe the gut of an amoeba

A

Doesn’t have one

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92
Q

Describe the process of digesting materials in an amoeba

A

Engulfs food particles or other unicellular organisms using pseudopodia
A food vacuole forms as the pseudopodia fuse together
Lysosomes fuse with the food vacuole, releasing their digestive enzymes
Digestion is carried out intracellularly (inside the cell)

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93
Q

What type of feeders are amoeba and why?

A

Holozoic - the take organic materials into cells and digest them internally

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94
Q

Draw and label an amoeba during digestion

A

(GWELER NODIADAU)

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95
Q

How does a food vacuole form in amoeba?

A

Pseudopodia fuse together

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96
Q

What do amoeba engulf?

A

Food particles
Other unicellular organisms

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97
Q

Name another single-celled Holozoic feeder as opposed to amoeba?

A

Hydra

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98
Q

Describe the gut of hydra

A

Simple
Undifferentiated
Sac-like

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99
Q

What is the only opening of hydra and where?

A

The mouth
In the middle of the tentacles

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100
Q

Inner layer of cells in hydra

A

Gastrodermis

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101
Q

Gastrodermis

A

Inner layer of cells in hydra

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102
Q

What do the Gastrodermis in hydra do?

A

Secrete digestive enzymes into the lumen of the gut

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103
Q

What is digested food absorbed by in hydra?

A

The gut wall

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104
Q

What happens to undigested food in hydra?

A

Egested

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105
Q

Draw and label hydra

A

(See notes)

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106
Q

What type of gut do more complex organisms have?

A

The tube gut

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107
Q

Name 2 different organisms with the tube gut

A

Earthworm
Humans
(Lol)

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108
Q

Describe the process that occurs in the tube gut

A

Food is taken in through the mouth
Passes through specialised regions where the food is processed
Small, soluble molecules are absorbed into the body tissues to provide nutrition
Waste is egested from the body through the anus (hahaha stop)

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109
Q

What type of organisms have tube guts?

A

More complex organisms

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110
Q

What are absorbed into body tissues to provide nutrition?

A

Small, soluble molecules

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111
Q

Why are small, soluble molecules absorbed into body tissues?

A

To provide nutrition

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112
Q

What are the 4 stages in the tube gut?

A

Ingestion
Digestion
Absorption
Egestion

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113
Q

Draw and label the process occurring in the tube gut

A

(See notes)

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114
Q

What type of digestion occurs in the ingestion stage of the tube gut and when is this?

A

Mechanical digestion
Before swallowing

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115
Q

What type of digestion occurs during the digestion stage in the tube gut and where is this?

A

Chemical digestion
In the stomach

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116
Q

What happens in the stomach during chemical digestion?

A

Enzymes break molecules into simple, small, soluble molecules

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117
Q

What’s good about the process taking place in the tube gut?

A

Enables the animal to continuously ingest food
Makes the process of digestion more efficient

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118
Q

Why is the tube gut more efficient for digestion than the simple, undifferentiated gut of the hydra?

A

The hydra has to wait until its digested and got rid of waste before it can carry on eating
The tube gut allows the animal to continuously ingest food

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119
Q

Describe the human gut

A

Highly specialised with distinct regions

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120
Q

Why does the human gut have different regions?

A

Each region has a specific function
Different regions allow for the digestion of different food substances

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121
Q

What are the main regions of human gut?

A

Mouth
Oesophagus
Stomach
Small intestine (duodenum and ileum)
Large intestine
Anus

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122
Q

Label the human gut

A

(See notes)

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123
Q

What happens to food as it passes along various regions of the gut?

A

It’s processed

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124
Q

When is food processed?

A

As it passes along various regions of the gut

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125
Q

How is food propelled along the gut?

A

By the process of peristalsis

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126
Q

What does persistalsis do?

A

Propel food along the gut

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127
Q

Draw and label a diagram to represent perstalsis

A

(See notes)

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128
Q

What are the main stages in the processing of food in the human gut?

A

Ingestion
Mechanism digestion
Chemical digestion
Absorption
Egestion

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129
Q

What happens during the ingestion stage of the digestive process?

A

Taking food into the body through the mouth

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130
Q

What happens during the mechanism digestion stage of the digestive process?

A

Cutting or crushing action of the teeth, followed by rhythmical contractions of the gut
The gut wall, particularly the stomach, has layers of muscle which contract and relax
These muscles are responsible for mixing food with enzymes and pushing it along the gut (peristalsis)

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131
Q

What does the gut wall contain and what do they do?

A

Layers of muscle that contract and relax

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132
Q

What are the muscles in the walls of the gut responsible for?

A

Mixing food with enzymes
Pushing food along the gut (peristalsis)

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133
Q

What happens during the chemical digestion stage of the digestive process?

A

The breakdown of large insoluble molecules into small soluble molecules using enzymes (chemical bonds are broken)

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134
Q

What are broken down into what during chemical digestion?

A

Large insoluble molecules into small soluble molecules

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135
Q

What is used to break down molecules during the chemical digestion stage of the digestive process and why?

A

Enzymes
Chemical bonds are broken

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136
Q

What happens during the absorption stage of the digestive process?

A

The passage of digested food through the gut wall into the blood

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137
Q

What happens during the Egestion stage of the digestive process?

A

The elimination of undigested food from the body
(E.g - cellulose cell walls of plants, containing fibre)

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138
Q

How many tissue layers does the mammalian gut contain throughout its length?

A

5 tissue layers surrounding the gut cavity or lumen

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139
Q

What are the 5 layers throughout the length of the mammalian gut?

A

Serosa
Longitudinal muscle
Circular muscle
Sub-mucosa
Mucosa

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140
Q

Where do the 5 tissue layers in mammalian gut surround?

A

The gut cavity or lumen

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141
Q

Draw and label the tissue layers in the gut wall

A

(See notes)

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142
Q

What type of cells does the epithelium of the gut wall contain?

A

Columnar epithelium cells

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143
Q

What does the mucosa of the gut do?

A

Secretes mucus and digestive enzymes
absorbs nutrients

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144
Q

What does the submucosa of the gut contain?

A

Blood and lymph vessels
Nerve fibres and glands

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145
Q

What does the serosa of the gut wall do?

A

Forms a protective layer of fibrous protein and connective tissue (e.g - collagen)

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146
Q

What forms the muscular layers in the gut wall?

A

Longitudinal muscle
Circular muscle

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147
Q

Which muscles are responsible for peristalsis in the gut wall

A

Longitudinal muscle
Circular muscle

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148
Q

What does the muscularis mucosa do?

A

Forms a thin layer of muscle involved in moving the inner wall of the gut

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149
Q

Draw and label the transection of the stomach

A

(See notes)

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150
Q

Draw and label the transection of the small intestine

A

(See notes)

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151
Q

Draw and label the transection of the large intestine

A

(See notes)

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152
Q

Duodenum

A

The first part of the small intestine

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153
Q

The first part of the mall intestine

A

Duodenum

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154
Q

Ileum

A

The last part of the small intestine

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155
Q

The last part of the small intestine

A

Ileum

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156
Q

Where are glands in the duodenum?

A

Extend below muscularis mucosa

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157
Q

Where are glands in ileum?

A

Mainly in mucosa

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158
Q

What do both the duodenum and ileum contain?

A

Intestinal gland

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159
Q

Colon

A

The longest part of the large intestine

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160
Q

The longest part of the large intestine

A

Colon

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161
Q

What are villi present in?

A

Duodenum and ileum of the small intestine

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162
Q

What are villi absent from?

A

The stomach
Colon

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163
Q

Where are villi longer, in the ileum or duodenum?

A

Longer in the ileum

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164
Q

What’s the purpose of digestion?

A

To break down large,insoluble molecules into soluble ones that can be absorbed through the epithelial lining of the small intestines into the blood

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165
Q

Where are digested molecules absorbed through and to?

A

Through - epithelial lining of small intestines
To - the blood

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166
Q

What absorb nutrients during digestion?

A

The gut epithelial cells

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167
Q

How are larger molecules broken down into smaller ones during digestion?

A

Using enzymes

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168
Q

What types of large molecules are broken down during digestion?

A

Carbohydrates, fats, proteins

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169
Q

What are there different enzymes for?

A

Different food substrates

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170
Q

What is usually required for the complete digestion of a particular foodL

A

More than one type of enzyme

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171
Q

What are the stages in the digestion of carbohydrates?

A

Polysaccharides —> disaccharides —> monosaccharides

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172
Q

What are the stages starch goes through during its digestion?

A

Starch —> maltose —> glucose

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173
Q

Which enzyme catalyses polysaccharides into disaccharides?

A

Amylase

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174
Q

Which enzyme catalyses disaccharides into monosaccharides?

A

Maltase enzyme

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175
Q

What does the amylase enzyme do?

A

Catalyse polysaccharides into disaccharides

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176
Q

What does the Maltase enzyme do?

A

Catalyse disaccharide’s into monosaccharides

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177
Q

What are the stages in protein digestion?

A

Proteins —> polypeptides —> dipeptides —> amino acids

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178
Q

General name for protein digesting enzymes

A

Peptidase

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179
Q

Peptidase

A

General name for protein digesting enzymes

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180
Q

What do we need to digest proteins and why?

A

Different types of enzymes as they’re very large molecules

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181
Q

Endopeptidases

A

Hydrolyse peptide bonds within the protein molecule to form shorter polypeptides

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182
Q

Exopeptidases

A

Hydrolyse peptide bonds at the ends of shorter polypeptides, releasing amino acids

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183
Q

Enzymes that Hydrolyse peptide bonds at the ends of shorter polypeptides, releasing amino acids

A

Exopeptidases

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184
Q

Enzymes that Hydrolyse peptide bonds within the protein molecule to form shorter polypeptides

A

Endopeptidases

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185
Q

Which protein enzymes hydrolyse peptide bonds…
Within the molecule?
At the ends of the molecule?

A

Endopeptidases
Exopeptidase

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186
Q

What types of bonds are hydrolysed with Peptidase enzymes?

A

Peptide bonds

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187
Q

What happens to the peptide bonds in proteins with Peptidase?

A

Hydrolysed

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188
Q

Which Peptidase enzyme forms smaller polypeptides?

A

Endopeptidases

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189
Q

Which Peptidase enzyme releases amino acids?

A

Exopeptidases

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190
Q

What does using both Endopeptidases and Exopeptidases in the digestion if proteins do?

A

Speed up the process of digestion

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191
Q

Draw an Endopeptidase reaction

A

(See notes)

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192
Q

Draw an Exopeptidase reaction

A

(See notes)

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193
Q

2 types of exopeptidases

A

Amino Peptidase
Carboxopeptidase

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194
Q

What are both amino Peptidase and carboxo Peptidase types of?

A

Exopeptidases

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195
Q

Describe the steps in the digestion of lipids

A

Triglycerides —> glycerol + fatty acids

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196
Q

How many enzymes is used in the digestion of lipids?

A

1

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197
Q

The digestion of what required only one enzyme?

A

Lipids

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198
Q

What is the enzyme required in the digestion of lipids?

A

Lipase

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199
Q

What is lipase required in?

A

The digestion of lipids

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200
Q

What does lipase do during the hydration of lipids?

A

Hydrolyses fats

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201
Q

What does the gut have for digestion?

A

Highly specialised regions which perform different functions in digestion

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202
Q

How is each region of the gut specialised to perform different functions in digestion?

A

Different glands and secretions

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203
Q

What do the different glands and secretions of the different areas of the gut do?

A

Maintain optimal conditions for the action of digestive enzymes + protect the lining of the gut

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204
Q

Why does the lining of the gut need protection?

A

Cells in contact with enzymes have no protections and could get digested by them

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205
Q

What are the different stages in the journey of food through the gut?

A

Mouth
Stomach
Small intestine
(Duodenum and Ileum)
Large intestine

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206
Q

Mechanical digestion

A

When food is chewed using the teeth

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207
Q

Where does mechanical digestion occur?

A

When food is chewed in the mouth using the teeth

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208
Q

What’s the name for the digestion when food is chewed in the mouth?

A

Mechanical digestion

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209
Q

Why is food chewed during mechanical digestion?

A

Easier to swallow
Creates a larger surface area for enzymes to digest it faster

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210
Q

What happens to food in the mouth?

A

Chewed using the teeth
Moistened by saliva

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211
Q

What does saliva do to food?

A

Moistens it

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212
Q

Where is saliva secreted?

A

In the salivary glands

213
Q

Why do we have saliva?

A

To bind food together and lubricate it to make it easier to swallow

214
Q

Describe the salivary glands in a human

A

3 major salivary glands
(Back of law, lower jaw, front of jaw)
Numerous minor ones

215
Q

What do minor salivary glands do?

A

Secrete saliva continuously

216
Q

What do major salivary glands do?

A

Are stimulated by sight, smell, taste or even the thought of food

217
Q

Which salivary glands secrete saliva continuously?

A

Minor salivary glands

218
Q

Which salivary glands secrete saliva at the thought of smell or sight etc of food?

A

Major salivary glands

219
Q

Saliva

A

Watery mixture of mucus, the enzyme salivary amylase and mineral ions

220
Q

Enzyme in saliva

A

Salivary amylase

221
Q

Salivary amylase enzyme purpose

A

Used in starch digestion

222
Q

What’s the purpose of mineral ions in saliva?

A

Maintain a slightly alkaline pH in the mouth which is optimum for amylase

223
Q

What does saliva do as food is chewed?

A

Moistens it

224
Q

What is food bound together and lubricated by in the saliva (so gross what)?

A

Mucus

225
Q

What’s the name of the ball of food formed by the saliva?

A

Bolus

226
Q

What happens upon swallowing of food?

A

The bolus is forced down the oesophagus

227
Q

Name for the oesophagus

A

Gullet

228
Q

Gullet

A

Oesophagus

229
Q

Epiglottis

A

A valve which prevents food from entering the trachea

230
Q

How is a bolus of food produced pushed down the oesophagus?

A

By localised contraction of circular muscles - peristalsis

231
Q

Where is a bolus of food forced down during peristalsis?

A

Down the oesophagus

232
Q

Describe the stomach

A

Wide, sack-like structure

233
Q

What’s the widest part of the gut?

A

The stomach

234
Q

Sphincter

A

A ring of muscle that controls the entry of food into the stomach

235
Q

A ring of muscle that controls the entry of food into the stomach

A

Sphincter

236
Q

What are the names of the 2 sphincters in the stomach?

A

Lower oesophageal sphincter (cardiac sphincter)
Pyloric sphincter

237
Q

Which sphincter in the stomach is the weakest and why?

A

Cardiac sphincter is weaker
It’s at the top and gravity keeps food in the stomach

238
Q

Acid reflux - what is it and why does it happen?

A

When stomach contents go up the oesophagus
Weaker sphincter at the top of the stomach

239
Q

What can acid reflux cause damage to?

A

The oesophagus

240
Q

Draw and label a stomach

A

(See notes)

241
Q

What do mucosa and epithelium do in the gut?

A

Secrete gastric juices into the lumen of the gut
Gastric juices are produced in pits - gastric glands

242
Q

What are responsible for secreting gastric juices into the lumen of the gut?

A

Mucosa and epithelium

243
Q

Where are gastric juices produced?

A

In pits known as gastric glands

244
Q

What does gastric juice contain?

A

HCl
Peptidase enzymes

245
Q

What’s the pH of the stomach contents and why?

A

2
Optimal pH for pepsin
Kills most bacteria in food

246
Q

What are the enzymes in the stomach?

A

Peptidase enzymes

247
Q

What do Peptidase enzymes do?

A

Hydrolyse proteins to polypeptides in the stomach

248
Q

What is the pepsin enzyme an example of?

A

Protease enzyme

249
Q

What happens to amylase when it reaches the stomach? Why?

A

Instantly denatures
Very low pH

250
Q

How long does food remain in the stomach?

A

Up to 4 hours

251
Q

Why do we have meals and wait time in between eating again?

A

Food remains in the stomach for up to 4 hours

252
Q

What happens in the 4 hours in which food is in the stomach?

A

Muscle in the stomach wall contract rhythmically to mix up the food with gastric juice

253
Q

What lines stomach walls?

A

Mucus

254
Q

Why does mucus line stomach walls?

A

Forms a protected barrier between the acid and enzymes
Lubricates and assists the movement of food within the stomach

255
Q

Name the specialised cells in the gastric gland

A

Goblet (mucous) cells
Oxyntic cells
Chief/peptic cells

256
Q

Where are goblet, oxyntic and chief cells found?

A

In the gastric gland

257
Q

Function of goblet (mucous) cells in the gastric gland

A

Produce mucus

258
Q

Which cells product mucus in the gastric gland?

A

Goblet (mucous) cells

259
Q

What do oxyntic cells do in the gastric gland?

A

Produce HCl

260
Q

Which cells produce HCl in the gastric gland?

A

Oxyntic cells

261
Q

What do chief/peptic cells do in the gastric gland?

A

Produce pepsinogen, an inactive precursor of the Peptidase enzyme pepsin
Pepsinogen is activated by HCl in the stomach lumen

262
Q

What produce pepsinogen in the gastric gland?

A

Chief/peptic cells

263
Q

When is pepsinogen produced by chief/peptic cells activated?

A

By HCl in the stomach lumen

264
Q

Draw and label the gastric glands

A

(See notes)

265
Q

What are the 2 regions of the small intestine?

A

Duodenum (top)
Ileum (base)

266
Q

Which part of a mammals gut contains both the duodenum and the ileum?

A

The small intestine

267
Q

How does food enter the duodenum of the small intestine in small amounts at a time?

A

Relaxation of the muscle (sphincter) at the base of the stomach

268
Q

How much of the small intestine does the duodenum make up?

A

The first 20cm

269
Q

Where does the duodenum receive secretions from?

A

The liver
The pancreas

270
Q

Where is bile produced?

A

In the liver

271
Q

Where is bile stored?

A

In the gall bladder

272
Q

How does bile pass into the duodenum,?

A

Via the bile duct

273
Q

What are the enzymes in bile?

A

No enzymes

274
Q

What does bile contain?

A

Bile salts

275
Q

Why are bile salts important?

A

Important in emulsifying lipids present in food

276
Q

How do bile salts emulsify lupus?

A

Lower the surface tension of the lipids
Large globules break into tiny droplets

277
Q

Why are lipids globules before bile salts emulsify them?

A

They don’t dissolve in water

278
Q

Why is it important that bile salts emulsify lipids?

A

Action of the enzyme lipase is more efficient
(Lipid droplets have a larger surface area)

279
Q

Which enzyme breaks down lipids?

A

Lipase

280
Q

What else is bile important in apart from containing bile salts?

A

Helps to neutralise the acidity of food as it comes from the stomach
= optimum pH for the enzymes in the duodenum

281
Q

How does bile neutralise the acidity of food as it comes form the stomach?

A

Has a high alkaline pH

282
Q

Draw and label the liver and duodenum

A

(See notes)

283
Q

What combine before entering the duodenum?

A

Pancreatic and bile ducts

284
Q

Where is pancreatic juice secreted?

A

From the exocrine glands in the pancreas

285
Q

How does pancreatic juice enter the duodenum?

A

Through the pancreatic duct

286
Q

Why is pancreatic juice important?

A

Contains a number of enzymes

287
Q

Name some of the enzymes that pancreatic juice contains

A

Endopeptidase
Amylase
Lipase

288
Q

Why is Endopeptidase in pancreatic juice important?

A

Hydrolysed proteins to peptide

289
Q

Why is amylase important in pancreatic juice?

A

Breaks down the remaining starch to maltose

290
Q

Why is lipase important in pancreatic juice?

A

Hydrolyses lipids into fatty acids and glycerol

291
Q

What do the walls of the duodenum contain?

A

Gland that secrete juice and mucus

292
Q

What’s the name for the glands in the walls o the duodenum that secrete alkaline juice and mucus?

A

Brunner’s glands

293
Q

What do Brunner’s glands do and where?

A

Secret alkaline juice and mucus in the walls of the duodenum

294
Q

What do alkaline juices do?

A

Help keep the contents of the small intestine at the correct pH for enzyme function

295
Q

What is mucus for?

A

For lubrication and protection

296
Q

Where are enzymes secreted by cells?

A

At the tips of the villi

297
Q

Villi

A

Finger- like projections on the inner surface of the duodenum

298
Q

What does the enzyme Maltase do to complete digestion?

A

Hydrolyses maltose into 2 glucose molecules

299
Q

What do Endopeptidase and Exopeptidase do to complete digestion?

A

Complete the digestion of polypeptides to amino acids

300
Q

At which point in the gut is the process of digestion complete?

A

At the end of the duodenum

301
Q

What are our final products at the end of digestion?

A

Monosaccharides
Amino acids
Fatty acids
Glycerol

302
Q

What happens to the final products of digestion in the duodenum?

A

Absorbed into the ileum

303
Q

What are the end products of carbohydrate digestion?

A

All monosaccharides

304
Q

Describe the final stage of carbohydrate digestion

A

Intracellular

305
Q

Describe the intracellular final stage of carbohydrate digestion

A

Disaccharides are absorbed by the plasma membrane of the epithelial cells before being broken down into monosaccharides

306
Q

What is the ileum adapted for?

A

The absorption of the products of digestion into the bloodstream

307
Q

What adaptations does the ileum have for absorption?

A

Very long
Lining is folded
Villi
Epithelial cells with microvilli on the villi
Crypts of Lieberkuhn on the base of the villi

308
Q

Why is the lining of the ileum folded in the ileum?

A

To give a large surface area compared to a smooth tube

309
Q

What’s the name of the finger like projections on the folds of the ileum?

A

Villi

310
Q

Where are microvilli found?

A

On the surface of the villi in the ileum

311
Q

What do microvilli form in the ileum?

A

A brush border

312
Q

What’s the purpose of the microvilli in the ileum?

A

Increase the surface area of the cell membrane of the epithelial cells for absorption

313
Q

Where are the crypts of Lieberkuhn found?

A

At the base of the villi in the ileum

314
Q

What’s the name for the glands at the base of the villi in the ileum?

A

Crypts of Lieberkuhn

315
Q

What do the crypts of the Lieberkuhn (glands at the base of villi in the ileum) do?

A

The epithelial cells of the crypts produce digestive enzymes which complete digestion, often intracellularly

316
Q

Which process follows digestion?

A

Absorption

317
Q

Where does absorption mainly take place?

A

In the small intestine

318
Q

What do epithelial cells in the small intestine contain lots of and why?

A

Mitochondria
ATP is needed for the active absorption of some of the products of digestion, by active transport

319
Q

Draw and label the walls of the small intestine

A

(See notes)

320
Q

What are villi lined with?

A

Epithelial cells

321
Q

Describe the villi of the small intestine

A

Lined with epithelial cells, which are in direct contact with the contents of the ileum

322
Q

Describe the epithelial cells of the ileum

A

Columnar
Sit on a basement membrane

323
Q

What does each epithelial cell of the ileum have?

A

A brush border of microvilli, which greatly increases the surface area available for absorption

324
Q

Lacteal in the ileum

A

Branch of the lymph system

325
Q

What does the lacteal in the ileum do?

A

Ambroses fatty acids in digested food

326
Q

What happens to the fatty acids absorbed by the lacteal in the ileum?

A

Returns to the bloodstream after being returned to the thoracic duct in the lymphatic system

327
Q

What are absorbed in the ileum?

A

Glucose
Amino acids
Lipids

328
Q

Where are both glucose and amino acids absorbed in the ileum?

A

Across the epithelium

329
Q

How are glucose and amino acids absorbed in the ileum?

A

Combination of diffusion and active transport

330
Q

Where does glucose and amino acids pass to upon absorption in the ileum?

A

The capillary network that supplies each villus

331
Q

Describe the process of the absorption of glucose and amino acids in the ileum

A

Abrobed across the epithelium of the villi
Combination of diffusion and active transport
Pass into the capillary network that supplies each villus
Blood from the venues (tiny veins) which contains the dissolved food eventually reaches the hepatic portal vein and is carried to the liver

332
Q

What vein caries blood that contains dissolved food in the ileum to the liver?

A

Hepatic portal vein

333
Q

Draw and label a villi of the ileum

A

(See notes)

334
Q

Describe the process of lipid absorption in the ileum

A

Fatty acids and glycerol are passed into the lacteal
Fatty acids and glycerol are transported into the lymphatic system, which ultimately opens into the blood stream at the thoracic duct
Fluid transported into the lymphatic system is lymph

335
Q

Lymph appearance

A

(Ew) creamy colour yum

336
Q

Lacteal

A

Blind ending lymph capillary found at the centre of each villus

337
Q

When do the fatty acids and glycerol transported in the lymphatic system open up into the blood stream?

A

At the thoracic duct

338
Q

What is the last part of the digestive system in the gut?

A

The large intestine

339
Q

How long is the large intestine?

A

Roughly 1.5m

340
Q

What is the large intestine divided into?

A

Caecum
Appendix
Colon
Rectum

341
Q

What’s the first stage that takes place in the large intestine?

A

Water and mineral salts are absorbed from the colon along with vitamins secreted by micro-organisms living in the colon

342
Q

What are absorbed from the colon?

A

Water
Mineral salts
Vitamins secreted by microorganisms

343
Q

What are the micro-organisms living in the colon responsible for?

A

Making vitamin K and folic acid

344
Q

Why are the micro-organisms in our gut essential for health?

A

They’re responsible for making vitamin K and folic acid

345
Q

In what condition is indigestible food by the time it reaches the rectum?

A

Semi-solid

346
Q

Name some indigestible foods

A

Fibres
Cellulose

347
Q

What does the semi-solid, indigestible food in the large intestine consist of?

A

Residues of indigested cellulose
Bacteria
Sloughed cells (dead cells that fall away from the intestine lining every few weeks)

348
Q

Sloughed cells

A

Dead cells that fall away form the intestine lining every few weeks

349
Q

Defecation

A

The contents of the colon passes along the colon and is egested as faeces

350
Q

When the contents of the colon passes along the colon and is egested as faeces

A

Defecation

351
Q

What does dentition have to do with an organisms diet?

A

An organisms teeth reflects its diet

352
Q

What are teeth important in?

A

The mechanical digestion of food

353
Q

Why is chewing important?

A

Makes it easier to swallow food
Increases the surface area for enzyme action

354
Q

What are humans (in terms of our diets)?

A

Omnivores

355
Q

Omnivores

A

Eat plant and animal material

356
Q

Are the teeth of humans specialised? Why?

A

Not particularly, as we’re omnivores

357
Q

How many different types of teeth do humans have?

A

4

358
Q

How many teeth do adults have in total?

A

32

359
Q

Name 3 types of teeth in humans

A

Incisors
Canines
Premolars and molars

360
Q

Adaptation and function of incisors (teeth)

A

Chisel shaped for biting and cutting

361
Q

Adaptations and function of canine teeth

A

Pointed for tearing

362
Q

Adaptation and function or premolar and molar teeth

A

Flat for chewing and grinding

363
Q

Herbivore diet

A

Plant food

364
Q

What’s the problem with a herbivores diet?

A

Plant food is hard to digest

365
Q

What are herbivores teeth modified to ensure?

A

That food is thoroughly ground up before it is swallowed

366
Q

Examples of grazing herbivores

A

Cows and sheep

367
Q

Where are the incisors in a herbivores mouth?

A

On the lower jaw only

368
Q

What’s on the upper jaw of herbivores?

A

Horny pad

369
Q

How are canine teeth different to incisors in a herbivore?

A

They’re indistinguishable

370
Q

What’s the name of the gap in the mouth of a herbivore and what does it do?

A

Diastema
Separates the front teeth from the side teeth/premolars

371
Q

Draw and label the dentition of a herbivore

A

(See notes)

372
Q

Where does the tongue operate in the mouth of a herbivore and what does this do?

A

In the diastema, moving freshly cut grass to the large grinding surfaces of the cheek teeth
(Premolars and molars)

373
Q

Cheek teeth

A

Premolars and molars

374
Q

How does the jaw in a herbivore operate?

A

In a circular grinding action in a horizontal plant

375
Q

What happens to the teeth of a herbivore?

A

Interlock like a letter W and a letter M

376
Q

What happen to the grinding surfaces of herbivores over time and what does this do?

A

Become worn down
Exposes sharp-edged enamel ridges, which further increase the efficiency of the grinding process

377
Q

Describe the roots of herbivores teeth - why is this beneficial?

A

Open, unrestricted roots
Can continue to grow throughout the life of the animal

378
Q

Example of a carnivore

A

Tiger

379
Q

What are the teeth of carnivores adapted for?

A

Catching and killing prey
Cutting or crushing bones
Tearing meat

380
Q

What dentition adaptations do carnivores have?

A

Sharp incisors
Large, curved, pointed canine teeth
Premolars and molars
Carnassials

381
Q

What do the sharp incisors of carnivores do?

A

Grip and tear flesh from bone

382
Q

Describe the canine teeth of carnivores - why is this important?

A

Large, curved pointed
Seizing prey, killing, tearing flesh

383
Q

What are premolars and molars for in carnivores?

A

Cutting and crushing

384
Q

What’s the name of the pair of specialised cheek teeth in a carnivore?

A

Carnassials

385
Q

Carnassials
What are they and what do they do?

A

Pair of specialised cheek teeth in carnivores
Slide past each other like the blades of gardening shears to cut through tendons and ligaments

386
Q

Describe the jaw of carnivores

A

Lower jaw is firmly attached to the skull for a strong bite
Well developed and powerful
No side to side movement
Greater vertical jaw movement than herbivores

387
Q

Why is having the lower jaw firmly attaches to the skill beneficial for carnivores?

A

Strong bite

388
Q

Why is having well developed and powerful jaw muscles beneficial to carnivores?

A

Grip prey firmly and crush bone

389
Q

Do carnivores have a side to side jaw movement? Why?

A

No
Would lead to the jaw being dislocated when dealing with prey

390
Q

Why is the vertical jaw movement of carnivores greater than herbivores?

A

Allows the jaw to open widely for capturing and killing prey

391
Q

Draw and label the skull of a carnivore

A

(See notes)

392
Q

Why can’t mammals digest the cellulose in plant cell walls?

A

Don’t produce the enzyme cellulase

393
Q

What break down a high proportion of cellulose in herbivores diets?

A

Bacteria

394
Q

What break down a high proportion of the cellulose in herbivores diets and why?

A

Bacteria
Can produce cellulase

395
Q

Where is the bacteria that can produce cellulase to digest cellulose in mammals found?

A

An enlarged region of the gut
Caecum

396
Q

Caecum

A

An enlarged region of the gut where bacteria that produce the enzyme cellulase are found

397
Q

Describe a herbivores gut and explain why it’s like this

A

Long
Reflects the difficulty of cellulose digestion

398
Q

Why is the gut of a herbivore so log?

A

Food takes longer to travel down the gut to allow time for cellulose digestion

399
Q

What’s the name of the hydrolysis of cellulose by cellulase produced by bacteria?

A

Bacterial fermentation

400
Q

Bacterial fermentation

A

The hydrolysis of cellulose by cellulase produced by bacteria

401
Q

Describe the gut of the carnivore and explain this

A

Short gut (protein is easy to digest)
Small caecum (not as much cellulose to digest)

402
Q

Why is the gut of carnivores short?

A

Protein is easy to digest

403
Q

Describe the gut of omnivores and explain why this is the case

A

Intermediate gut length
Mixture of meat and plant food

404
Q

What’s the problem with the location of the caecum in herbivores? How is this overcome?

A

After the small intestine, where nutrients are absorbed into the blood
Rabbits eat their own faecal pellets

405
Q

What did ruminant animals eat mainly?

A

Grass and forage

406
Q

What does the diet of ruminant animals consist largely of due to so much grass and forage being eaten?

A

Cellulose cell walls

407
Q

Example of a ruminant animal

A

Cow

408
Q

What’s the problem with cellulose cell walls for ruminant animals?

A

Difficult to digest

409
Q

Where is mutualistic bacteria in ruminant animals?

A

In the rumen of the stomach

410
Q

What is found in the rumen of the stomach of ruminant animals? Why?

A

Mutualistic bacteria
To digest cellulose by producing cellulase

411
Q

What kind of relationship do a cow and ruminant bacteria have?

A

Symbiotic

412
Q

How do ruminant bacteria benefit the cow in the symbiotic relationship?

A

Bacteria provide cellulase enzymes to digest cellulose
When they die, they become part of the cows diet (vitamins and proteins)

413
Q

How does the cow benefit ruminant bacteria in the symbiotic relationship?

A

Ruminant provides a region of the gut for the bacteria to inhabit
Plentiful supply of food

414
Q

Why must the rumen be kept separate from the main digestive region?

A

So that food can be kept there long enough for the bacteria to carry out the digestion of cellulose
The bacteria are isolated from the mammal’ an digestive juices - optimum pH for activities (not denatured)

415
Q

Draw and label the parts of the digestive system in a cow (ruminant)

A

(See notes)

416
Q

Which part of a ruminant’s digestive system is it’s “true” stomach? Why?

A

Abomasum
Protein digestion happens here

417
Q

What’s the order of the chambers travelled through during digestion in ruminant animals?

A

Rumen
Reticulum
Mouth
Omasum
Abomasum
Small intestine

418
Q

What are the stages of digestion in ruminant animals?

A

Grass is cut by teeth and mixed with saliva and the cud is formed and swallowed
In the rumen (first chamber), the cud is mixed with cellulose digesting bacteria to produce glucose
This is fermented to form organic acids (which are supplied into the blood to supply energy to the cow)
CO2 and NH3 are waste and are passed out
The fermented cud passes to the next region, reticulum, before being regurgitated into the mouth and chewed again (reverse peristalsis)
The cud passes directly to the third chamber, the omasum, where water is re absorbed
The fourth and last chamber, the abomasum, functions like a normal stomach and protein is digested
The digested food passes into the small intestine, where the products of digestion are absorbed into the blood

419
Q

Parasites

A

Organisms that live in or on another organism, called the host

420
Q

How do parasites obtain nourishment?

A

At the expense of the host

421
Q

What do parasites do to a host?

A

Cause harm and often death?

422
Q

How do parasites usually cause death in a host?

A

By overpopulating

423
Q

Does a parasite kill a host on purpose? Why?

A

No
It needs the host to survive

424
Q

Which organisms are parasitised during their lives?

A

Most organisms for at least part of their lives

425
Q

What are plants parasited by?

A

Bacteria
Fungi
Viruses
Nematodes
Insects (e.g - aphids)

426
Q

What are animals parasited by?

A

Bacteria
Fungi
Viruses
Protoctista
Tapeworms
Nematodes
Insects
Mites

427
Q

What are bacteria parasitised by?

A

Viruses called bacteriophages

428
Q

The study of parasites

A

Parasitology

429
Q

Why is parasitoloy (the study of parasites) of economic importance?

A

Parasites cause disease in humans, crops and domesticated animals

430
Q

How do parasites survive in their hosts?

A

Have become specialised
Have undergone considerable evolutionary changes

431
Q

What are the 2 parasite examples we need to know about?

A

Pork tapeworm
Pediculus

432
Q

Latin name of the tapeworm

A

Taenia solium

433
Q

Where do tapeworms live?

A

In the gut of other animals

434
Q

Which part of the gut do tapeworms live?

A

In the gut of other animals

435
Q

What type of parasite is the tapeworm and why?

A

Endoparasite
Lives in the gut of other animals

436
Q

Describe the tapeworm

A

Ribbonlike, can be up to 10 metres long

437
Q

Linear series of thin sections on the tapeworm

A

Proglottids

438
Q

Linear series of thin sections on the tapeworm

A

Proglottids

439
Q

Where is digested food taken from in a tapeworm?

A

The hosts gut

440
Q

Hosts of the tapeworm

A

Humans
Pigs

441
Q

Primary host of tapeworms

A

Humans

442
Q

Secondary hosts of tapeworms

A

Pigs

443
Q

Why does eating pork that is cooked properly not give you tapeworm?

A

Larvae are killed

444
Q

Explain the lifecycle of the tapeworm

A

Humans infected by eating undercooked, infected pork
Proglottids at end of the tapeworms body break off and pass out in faeces of host
Each Proglottids contains many fertilised eggs
Eggs ingested by a pig feeding in drainage channels contaminated with human faeces
Larvae burrow into the muscle of the pig, forming cysts

445
Q

How do humans get infected by the tapeworm?

A

By eating undercooked, infected pork

446
Q

What do larvae of the tapeworm do in pigs?

A

Burrow into the muscle of the pig, forming cysts

447
Q

What can happen if the eggs of the tapeworm are eaten directly by humans?

A

Dormant embryos burrow into the muscles and form cysts in various organs and damage to surrounding tissue

448
Q

Which organ, for example, can have cysts forming in it from humans consuming tape worm eggs?

A

The brain

449
Q

Do adult tapeworms cause discomfort to people?

A

No

450
Q

How can we get rid of tapeworms?

A

Adults can be treated with appropriate drugs

451
Q

What are essential in controlling the number of people affected by tapeworm?

A

Public health meeasures
Frequency inspection of meat

452
Q

What are the adaptations of pork tapeworm for a parasitic mode of nutrition?

A

Suckers and a double row of curved hooks
Mucus body covering
Thick cuticle and production of inhibitory substances on the surface of the segments
Degeneration of unnecessary organs
Very thin and large
Hermaphrodites
Eggs have resistant shells

453
Q

What’s the function of the suckers and the double row of curved hooks on the pork tapeworm?

A

Attachment to the wall of the gut and prevent removal by peristalsis

454
Q

What’s the purpose of the mucus body covering of the tapeworm?

A

Protects them from the host’s immune system

455
Q

What’s the purpose of the thick cuticle and production of inhibitory substances on the surface of the segues on a tapeworm?

A

Prevents their digestion fm the host’s enzymes

456
Q

Which systems do tapeworms have?

A

Simple excretory and nervous system

457
Q

What is most of the body of a tapeworm concerned with?

A

Reproduction

458
Q

What’s the function of the adaptation that tape worms are very thin and large?

A

Large surface area to volume ratio so that digested food can be absorbed over the entire body surface

459
Q

Why is the tapeworm a Hermaphoridite?

A

Both male and female reproductive organs in each segment

460
Q

What’s the word for the fact that a tapeworm has both male and female reproductive organs in each segment?

A

Hermaphrodites

461
Q

What’s the function of the fact that tapeworms are hermaphrodites?

A

Self-fertilisation
Vast numbers of eggs are produced, with each mature segment consisting of 40,000 eggs

462
Q

How do Proglottids pass out of the host’s body?

A

With the faeces

463
Q

Why is it important that the eggs of the tape worm have resistant cells?

A

Can survive until eaten by the secondary host

464
Q

What do the eggs of tapeworm hatch into and where?

A

Embryos which move into the pig’s muscle tissue

465
Q

Where do the embryos of the eggs of tapeworm remain and for how long?

A

Dormant in the pig’s muscle tissue until the pig is eaten by a human

466
Q

Segments of a tapeworm

A

Proglottids

467
Q

Proglottids

A

Segments of a tapeworm

468
Q

What do the Proglottids of a tapeworm contain?

A

The organ systems of the tapeworm

469
Q

What’s different about each Proglottid in a tapeworm?

A

Nothing - they’re all identical

470
Q

Why are tapeworms hermaphrodites?

A

Each segment has a reproductive system containing both male and female organs

471
Q

Which systems do the tapeworms contain and where?

A

Simple nervous system
Simple excretory system
In each proglottid (segment)

472
Q

Which organ system don’t tapeworms have and why?

A

Digestive system
Pre-digested food is absorbed across the outer surface of the tapeworm

473
Q

How does the tapeworm take in food?

A

Pre-digested food is absorbed across the outer surface of the tapeworm

474
Q

Pediculus Human us

A

A louse which infects humans

475
Q

Name the louse which infects humans that we need to remember

A

Pediculus humanus

476
Q

How many hosts does the Pediculus have? What is this?

A

1 (humans)

477
Q

What type of parasite is the Pediculus and why?

A

Ectoparasite
Lives on the host rather than in it

478
Q

Why is the Pediculus an ectoparasite?

A

Lives on the host rather than in it

479
Q

What are the 2 sub-species of the Pediculus?

A

Pediculus humanus humanus
Pediculus humanus capitis

480
Q

Pediculus humanus humanus

A

Infects the human body

481
Q

Pediculus humanus capitis

A

Infects the human scalp

482
Q

Which sub-species of the Pediculus is the head louse?

A

Pediculus humanus capitis

483
Q

Which sub-species of Pediculus infects the human body?

A

Pediculus humanus humanus

484
Q

Which sub-species of Pediculus infects the human scalp?

A

Head louse

485
Q

Which sub-species of Pediculus is rarest?

A

Pediculus humanus humanus (infects the human body)

486
Q

What does the Pediculus feed exclusively on?

A

Human blood

487
Q

How does the Pediculus feed on human blood?

A

Bite the scalp

488
Q

Describe the body of a Pediculus

A

Wingless louse

489
Q

Where does the Pediculus spend its entire life cycle?

A

On the skin of the host

490
Q

How are Pediculus spread from one individual to another and why?

A

By head-to-head contact
Legs are poorly adapted for jumping

491
Q

Where does the Pediculus lay eggs?

A

On the hair shaft, close to the scalp

492
Q

What’s the name for the eggs of Pediculus humanus?

A

Nits

493
Q

When do lice hatch from the eggs of the Pediculus?

A

After 7-10 days

494
Q

How long after hatching can the lice from the eggs of the Pediculus lay their own eggs?

A

9 days

495
Q

What happens to the Pediculus if it’s removed from the human from which it lives?

A

It dies

496
Q

Draw and label the proglottid of a tape worm

A

(See notes)

497
Q

Under what circumstance can many parasites not live?

A

Without their host

498
Q

What are the stages in the lifecycle of the Pediculus?

A

Egg —> nymph —> adult

499
Q

Where are the eggs of Pediculus glued?

A

The base of the hair follicle

500
Q

What do nymph and adult Pediculus do?

A

Suck blood from the host scalp

501
Q

Explain the stages in the lifecycle of the Pediculus

A

Eggs glued to the base of hair follicle
After 1-2 weeks, an egg hatches into a nymph, which looks like an adult but it smaller (incomplete metamorphosis)
The nits seen on the hair shaft are empty eggs
Nymphs grow and mature to become adults after about 10 days
Adults can survive for 3 months
After mating has occurred, a female louse lays up to 10 eggs per day

502
Q

How long does it take a nymph to grow into an adult Pediculus?

A

10 days

503
Q

How long can adult Pediculus survive for?

A

3 months

504
Q

How many eggs does a female Pediculus louse lay per day after mating has occurred?

A

10 eggs per day

505
Q

What are the adaptations of Pediculus for a parasitic mode of nutrition?

A

Adults —> claws
Nits —> “glue”
Holozoic
Piercing mouthparts
Separate sexes

506
Q

What’s the function of the adaptations of adult Pediculus having claws and the nits having a “glue”?

A

To attach to hairs and prevent removal by scratching

507
Q

What does it mean that the Pediculus is Holozoic?

A

Has a gut for digestion/absorption

508
Q

Why does the Pediculus have piercing mouthparts?

A

To suck blood

509
Q

Why does the Pediculus have different sexes?

A

A mate is easy to find

510
Q

What are the general adaptations shown by both the tapeworm and Pediculus for a parasitic mode of life?

A

Heterotrophic
Obtain nutrition from host
Produce large numbers of eggs/offspring
Resistant stages/eggs

511
Q

How are proteins made available to the muscles of the herbivore?

A

Pancreas produces peptididases that break polypeptide chains into smaller chains
Cells in small intestine secrete peptidases that complete the breakdown of polypeptides into amino acids
Bacteria that make protein are killed by the acid in the true stomach, and are digested and absorbed

512
Q

How does having both endopeptidase and exopeptidase speed up the process of digestion?

A

Endopeptidase creates more ends for exopeptidase

513
Q

Definition of saprotophic

A

Feed by secreting enzymes onto the food material outside the body and then absorb the soluble products across the cell membrane by diffusion

514
Q

Additional adaptations of the body wall of a tapeworm

A

Lime cell’s alkaline secretions neutralise acid
Muscles allow tapeworm to increase contact with digested food
Microvilli increase surface area for absorption of digested food

515
Q

What does having the stomata in pits do in xerophytic plants and why?

A

Reduces the rate of transpiration as it…
Creates a humid microenvironment
Allows water vapour to accumulate above the stomatal pore

516
Q

On which surface are there more stomata on a xerophyte?

A

Lower

517
Q

What is starch digested to in the mouth?

A

Maltose

518
Q

Compare mechanical and chemical digestion

A

Mechanical -
Breaks down food into smaller pieces to increase its total surface area
Chemical -
Involves the use of enzymes to break larger molecules into smaller molecules

519
Q

How do chemosynthetic autotrophic bacteria obtain energy?

A

Use chemical reactions

520
Q

Alimentary canal

A

The whole passage along which food passes through the body from mouth to anus during digestion

521
Q

The whole passage along which food passes through the body from mouth to anus during digestion

A

Alimentary canal

522
Q

Main purpose of canine teeth

A

For killing prey

523
Q

Which region in the human alimentary canal does the digestion of lipids begin?

A

Duodenum

524
Q

Which region in the human alimentary canal does the digestion of starch begin?

A

Mouth

525
Q

Which region in the human alimentary canal does the digestion of proteins begin?

A

Stomach

526
Q

What’s the purpose of villi in the ileum?

A

Absorption of nutrients

527
Q

Where are the walls thickest - in the duodenum or the oesophagus? Why?

A

In the oesophagus
More peristalsis
More solid food

528
Q

What does the submucosa do?

A

Blood and lymph vessels that remove absorbed products of digestion

529
Q

Excretion vs egestion

A

Excretion - eliminating waste made within the body (e.g - CO2)
Egestion - getting rid of undirected food via faeces

A level Biology (26 decks)

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