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✅Biology AS Unit 2 > 🔺🔥2.5 Adaptations For Nutrition > Flashcards

🔺🔥2.5 Adaptations For Nutrition Flashcards

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1
Q

Define Autotroph

A

An organism that synthesis it’s own complex organic molecules using either light or chemical energy

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2
Q

Define Heterotroph

A

An organism that obtains complex organic molecules from other organisms

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3
Q

Define Saprotroph

A

An organism that derives energy and raw material for growth from the extra cellular digestion of dead or decaying material

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4
Q 
Define photoautorophic 
(An autotrophic organism)
A

Organisms use light as the energy source and perform photosynthesis, they are green plants some protoctista and some bacteria. This type of nutrition is described as holophytic

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5
Q

Define Chemoautotrophic organisms

A

Use the energy from chemical reactions. (All prokaryotes)

Less efficient than photosynthesis

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6
Q

What can’t heterotrophic organisms do?

A

Make their own food, they are consumers

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7
Q

Name some examples of heterotrophs

A

Animals, fungi, some protoctista and some bacteria

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8
Q

Who uses saprotrophic nutrition?

A

All fungi and some bacteria

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9
Q

How do saprotrophic organisms gain energy (extracellular digestion)

A
  • Secrets enzymes including proteases, Amalyses, lipases and cullulases on to food material outside the body
  • This is extracellular digestion
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10
Q

What don’t saprotrophic organisms have?

A

Don’t have a specialised digestive system

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11
Q

How do saprotrophs obtain the digested nutrients?

A

Absorb soluble products of digestion across cell membrane by diffusion and active transport

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12
Q

Define parasite

A

An organism that obtains nutrients form another living organism or host, to which is causes harm

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13
Q

What is parasitic nutrition?

A

Obtaining nutrients from another living organism (host)

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14
Q

What is an endoparasite?

A

A parasite which lives in the body of the host?

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15
Q

What is an ecto parasite

A

Parasite that lives of the surface of a host

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16
Q

Name examples of parasite

A 
Tapeworm (taenia solium) 
Head lice (pediculus capitis)
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17
Q

What is holozoic nutrition?

A
  • nutrition used by most animals
  • ingest food, digest it in a specialised digestive system
  • digested material is absorbed into the body tissues and used by cells
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18
Q

What are herbivores?

A

Animals that eat plant material only

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19
Q

What are carnivores

A

Animals that eat other animals only

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20
Q

What are omnivores

A

Animals that eat both plant and animal material

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21
Q

What are detrivores

A

Animals that feed on dead and decaying matter

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22
Q

What nutrition do animal like protoctista use? (E.g Amoeba)

A

Holozoic nutrition
Large SA:V ratio
:: Obtain nutrients through diffusion, facilitated diffusion or active transport across the cell membrane

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23
Q

How do amoeba take in large molecules for nutrition?

A

Larger molecules and microbe by endocytosis, into food vacuoles

  • these fuse with lysosomes
  • contents digested by lysosomal enzymes have
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24
Q

What happens to the products of digestion Inside an amoeba

A

Products of digestion are absorbed into the cytoplasm

Indigestible remains are egested by exocytosis

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25
Q

What happens to the pH of the contents of the food vacuole during digestion?

A

Changes from 7 to 2 to 7

-resembling the oH changes of food on its passage through the mammalian gut

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26
Q

What is a hydra?

A

A multicellular organism with a single body opening(mouth) (more complex than an amoeba)
E.g sea anemones

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27
Q

What does a hydra comprise of

A

It is diploblastic :: comprises two layers of cells, an organism ectoderm and endoderm separates by a jelly layer

  • cylindrical
  • has tentacles at the top surrounding mouth
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28
Q

Where do hydra live?

A

Lives in fresh water, attached to leaves or twigs

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29
Q

How do hydra gain nutrients? (Capture)

A

When hungry it extends its tentacles and when small organisms brush against them, their stinging cells discharge and paralyse prey
-tentacle move prey through the mouth into hollow body cavity

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30
Q

What happens once the hydra has its prey in the hollow body cavity?

A
  • endodermal cells secrete protease and lipase (not amalyse) and prey is digested extracellularly
  • products of digested are absorbed into the cells
  • indigestible remains are egested through mouth
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31
Q

What do the tentacles of hydra contain?

A

Photosynthesising protoctista

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32
Q

Basically describe the tube gut

A

Digestive system that is a tube with 2 openings at anterior and posterior e.g food ingested at mouth and indigestible waste is egested at the anus

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33
Q

HUMAN DIGESTIVE SYSTEM:

Why must food be digested?

A

Because molecules are:

  • insoluble and too big to cross membranes :: absorbed into the blood
  • polymers must be converted to monomers so they can be rebuilt into molecules needed by body cells
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34
Q

Where do digestion and absorption occur(brief)

-movement??

A

In the gut, a long, hollow, muscular tube.

-allows movement of contents in one direction during peristalsis

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35
Q

Describe the process of peristalsis

A
  1. Longitudinal muscles contract to push food forewords and then relax
  2. Circular muscles contract behind the boules and then relax
  3. Wave of contraction pushes boules down the gut
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36
Q

What are the 4 main functions of the gut

A
  • ingestion
  • digestion
  • absorption
  • egestion
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37
Q

What is ingestion?

A

Taking food into the body through the mouth

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38
Q

What is digestion

A

The breakdown of large insoluble molecules that are small enough to be absorbed in the blood

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39
Q

What is mechanical digestion?

What is its benefit?

A

Cutting and crushing by teeth and muscle contractions of the gut wall.
-it increases the surface area over which enzymes can act

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40
Q

What is chemical digestion?

What aids it?

A

Digestion by the secretion of enzymes

-bile and stomach acid contribute to chemical digestion

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41
Q

What is absorption?

A

The passage of molecules and ions through the gut walk into the blood

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42
Q

What is egestion?

A

The elimination of waste not made by the body, including food hat can’t be digested e.g cellulose

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43
Q

What is the function of the mouth?

A

Ingestion

Digestion of starch

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44
Q

What is the function of the oesophagus

A

Carriage of food to the stomach

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45
Q

What is the function of the stomach

A

Digestion of protein

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46
Q

What is the function of the duodenum

A

Digestion of carbohydrates, fats and proteins

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47
Q

What is the function of the ileum

A

Digestion of carbohydrates, fats and proteins

Absorption of digested food

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48
Q

What is the function of the colon

A

Absorption of water

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49
Q

What is the function of the rectum

A

Storage of faeces

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50
Q

What is the function of the anus

A

Egestion

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51
Q

What is the general structure of the gut wall?

A

4 tissue layers surrounding a cavity, the lumen.

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52
Q

What are the 4 tissue layers called?

A
  • serosa (outer)
  • muscle
  • submucosa
  • mucosa(inner)
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53
Q

Describe the structure of the serosa in the gut

A

-Tough connective tissue, protecting the gut wall.

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54
Q

What is the purpose of the serosa in the gut

A

The gut moves while processing food and the serosa reduces the friction with other abdominal organs

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55
Q

What is the structure of the muscle layer in the gut

A

Comprises of two layers:
-inner circular muscles
-outer longitudinal muscles
(Responsible for making the co-ordinated waves for peristalsis)

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56
Q

Describe the purpose of the layers of muscles in the gut

A

Behind the boules circular muscles contract and longitudinal muscles relax, pushing the food along

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57
Q

Describe the structure of submucosa in the gut

A

Connective tissue containing blood and lymph vessels

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58
Q

What is the purpose of the submucosa in the gut?

A

Remove absorbed products of digestion, and nerves that co-ordinate peristalsis

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59
Q

Describe the structure of the mucosa in the gut

A

Innermost layer of gut wall

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60
Q

What is the structure of the mucosa in the gut

A

Epithelium secrets mucus lubricating and protecting the mucosa
Secrets digestive juices and in others, absorbs digested food

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61
Q

What are some examples of macromolecules

A

Carbohydrates, fats and proteins etc

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62
Q

How are carbohydrates digested (short)

A

-polysaccharides digested into disaccharides (by amalyse to produce maltose + maltose) and then monosaccharides (by maltase to produce glucose)

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63
Q

Name the different enzymes digesting different carbohydrates

A

Amalyse hydrolyses starch
Sucrase digests sucrose
Lactase digests lactose

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64
Q

What is the general name for a carbohydrate digesting enzyme?

A

Carbohydrase

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65
Q

How are proteins digested (short)

A

Digested into polypeptides (by protease and peptidase) then dipeptides and then amino acids.

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66
Q

What do endopeptidases hydrolyse?

A

Peptide bonds within the protein molecule (middle)

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67
Q

What do exopeptidases hydrolyse?

A

Peptide bonds at the ends of polypeptides

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68
Q

How are fats digested?

A

Digested to fatty acids and monoglycerides by lipase

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69
Q

What factors can reduce the ph in in the gut below 7

A

Acid secretion in the stomach and the production of amino acids and fatty acids in the ileum

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70
Q

What increases the pH above 7 in the gut?

A

Alkaline secretions in the duodenum increase the pH above 7

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71
Q

What is the buccal cavity?

What occurs here?

A

Buccal cavity = mouth

-where mechanical digestion begins as food is mixed with saliva by the tongue and chewed with teeth

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72
Q

Why is it vital to chew food?

A

Food surface area increase giving enzymes more access

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73
Q

What does saliva contain? Why is each constituent vital for digestion?

A

Watery solution containing:

  • amalyse (starch—> maltose)
  • HCO3 and CO3 ions (pH in mouth alkaline optimum for amalyse)
  • mucus (lubricating the foods passage down oesophagus)
74
Q

What is the purpose of the oesophagus

A

-no role but it does carry food to stomach

75
Q

What tissue layers are present in the oesophagus?

A 
Mucosa 
Submucosa 
Circular muscle 
Longitudinal muscle
Serosa
76
Q

Where is the cardiac sphincter (Ring of muscle) located?

A

At the junction with the oesophagus and stomach

77
Q

Where is the pyloric sphincter locates?

A

Junction between stomach and duodenum

78
Q

How is food kept in stomach?
How long for?
What is the volume of the stomach?

A
  • kept in stomach by contraction of two sphincters (rings of muscle; cardiac and pyloric)
  • May stay for several hours
  • 2dm cubed
79
Q

What happens to food in the stomach?

A

Stomach walls contract rhythmically and mix the food with gastric juice

80
Q

Where is gastric juice secreted from?

A

-secreted from glands in the mucosa, called gastric pits

81
Q

What is gastric juice formed from?

A
  • peptidases (secreted by chief cells at the base of gastric put)
  • pepsinogen (inactive enzyme)
  • HCL (secreted by oxyntic cells)
  • mucus (secreted by goblet cells, at the top of gastric pit)
82
Q

What is the role of pepsinogen in gastic juice?

A

Inactive enzyme, activated by H+ ions to pepsin, an endopeptidase which hydrolyses protein to polypeptides

83
Q

What is the role of HCL in gastric juice?

A

Lowers the pH of the stomach contents to pH2, the optimum for the enzymes and kills most bacteria in food

84
Q

What is the role of the mucus in gastric acid?

A

Mucus forms a lining which protects the stomach wall from the enzymes and lubricates food

85
Q

What enhances mechanical digestion in the stomach

A

Stomach wall has folds in its surface called rugae, and an oblique muscle at an angle to circular and longitudinal muscle, which provides extra contractions

86
Q

What causes ‘heartburn’

A

When stomach contents move up into oesophagus, causing pain due to the acid on the oesophagus wall

87
Q

Name the parts of a gastric pit

A 
Goblet cells (secreting mucus) 
Chief cell (secrets enzymes) 
Oxyntic cell (secreted HCL)
Mature and immature mucus producing cells 
Submucosa
88
Q

What are the two regions of the small intestine?

A

Duodenum and ileum

89
Q

What affect does the relaxation of the pyloric sphincter muscle (between stomach and duodenum) have on food passage?

A

Allows partially digested food into the duodenum

90
Q

What is the duodenum?

A

First 25 cm of small intestine

Receives secretions from the liver and pancreas

91
Q

Where is bike made, stored and travel?

A

Made in the liver
Stored in the gall bladder
Passes through the bile duct into duodenum

92
Q

What does bile contain?

A
  • no enzymes

- bile salts which are amphipathic (hydrophilic and phobic parts)

93
Q

What is the role of the bile salts?

A
  • They emulsify lipids in the food by lowering their surface tensions
  • break up large globules increasing surface area, making lipase digestion more efficient.
94
Q

What is the benefit of the bile being alkaline?

A

Neutralises the acid in food coming from the stomach, providing a suitable pH for enzymes in small intestine (7/8)

95
Q

What secrets pancreatic juice?

Where does pancreatic juice enter the duodenum?

A
  • Secreted by islet cells, exocrine glands in the pancreas.

- Enters duodenum through pancreatic duct

96
Q

Why are exocrine glands?

A

Glands that secrete enzymes

97
Q

What are endocrine glands?

A

Glands that secrete hormones

98
Q

What is the function of the pancreatic secretion of sodium hydrogen carbonate in the small intestine?

A

Raises pH to make pancreatic juice slightly alkaline ::

  • neutralises acid from the stomach
  • provides the optimum pH for the pancreatic enzymes
99
Q

What is the role of enzymes secreting (endopeptidases, trypsinogen, amylase and lipase) in the pancreatic secretion in the small intestine?

A

Endopeptidases= hydrolyse protein to peptides

Trypsinogen= inactive enzyme converted into the protease trypsin by the duodenal enzyme enterokinoase

Amylase= digests remaining starch to maltose

Lipase= hydrolyses lipids into fatty acids and monoglycerides

100
Q

What are Pepsin and Trypsin secreted by?

Why is this important?

A

Secreted by inactive precursors pepsinogen and trypsinogen

Important as this is why they don’t digest cells in which they are synthesised

101
Q

What are the brunners glands?

A

Cells at the base of the crypts of Lieberkühn which secrete alkaline secretions

102
Q

In the small intestine (ileum), what are on the villi?

A

Enzymes associates with the epithelial cells (secreted by cells at the villus tips such as endo/exopeptidases) which continue the digestion of polypeptides in the gut lumen

103
Q

Why are the enzymes on the cell membranes of epithelial cells of the villi important?

A

dipeptides are digested to amino acids by enzymes on the cell membranes of epithelial cells

104
Q

Where are disaccharides absorbed into in the small intestine?
Explain this xx

A

Into the epithelial cells of the villi

  • carbohydrases in the cell membranes of epithelial cells digest disaccharides into monosaccharides
  • :: final stage of digestion is intracellular
105
Q

What 3 enzymes are in the cell membrane of epithelial cells in villi?

A

Maltase (maltose—> glucose + glucose)

Sucrase (sucrose—> glucose + fructose)

Lactase (lactose—> glucose and galactose)

106
Q

How is the ileum well adapted for absorption?

A
  • very long (approx 6m in humans with folded lining)
  • on surface of folds are villi whose epithelial cells have microscopic projections called microvilli (large SA for absorption)
107
Q

Name the 3 ways monosaccharides are absorbed in small intestine

A
  1. Diffusion
  2. Facilitated diffusion
  3. Active transport
108
Q

Why do epithelial cells have mitochondria?

A

Because active transport requires energy in the form of ATP

109
Q

What are the main 2 components of epithelial cells on villi?

A
  • microvilli

- goblet cells

110
Q

Name the tissue layers in the small intestine

A

Serosa
Longitudinal muscle
Circular muscle
Mucosa with villi (and villi have microvilli)

111
Q

How are amino acids absorbed into the epithelial cells?

Where do they go now?

A
  • By active transport
  • Travel as individual amino acids into the capillaries by facilitated diffusion
  • water soluble so next dissolve into plasma
112
Q

How does glucose pass into epithelial cells?

A
  • by co-transport with sodium ions
  • move into capillaries (sodium by active transport and Glucose by facilitated diffusion)
  • dissolve into plasma
113
Q

Why is some glucose actively transported into epithelium cells on the villi?

A

-diffusion and facilitated diffusion are slow and :: not all of it can be absorbed :: active transport prevents glucose leaving body in faeces

114
Q

Where are fatty acids and monoglycerides absorbed into?

How?

A

Absorbed into epithelial cells and lacteals

By diffusion

115
Q

What are lacteals

A

Parts of the lymphatic system which transport day soluble molecules to the left subclavian vein near the heart

116
Q

How are minerals absorbed into the blood

A

Diffusion, facilitated diffusion and active transport, then dissolve in the plasma

117
Q

Why are Vitamins B & C absorbed into the blood?

A

Because they are water soluble

118
Q

Why are Vitamins A, D and E absorbed into lacteals?

A

Because they are fat soluble

119
Q

What are lipids used for after being absorbed into the blood?

A

Used in membrane and to make some hormones, excess is stored

120
Q

What is glucose used for after being absorbed into the blood?

A

Taken to body cells and respires for energy or stored as glycogen in the liver and muscle cells

-excess stored as fat

121
Q

What are amino acids used for after being absorbed into the blood?

A

Takes to body cells for protein synthesis

  • excess can’t be stored so liver deaminates the amino acids and converts NH2 groups to urea
  • remaining AA are converted to carbohydrates for storage or fat conversion
122
Q

How long is the large intestine?

What parts make up the large intestine?

A
  1. 5m long

- the caecum, appendix, colon and rectum

123
Q

What passes into the colon?

A

Undigested food, mucus, bacteria and dead cells

124
Q

Why does the colon have a major role in water absorption?

A

It has villi (smaller value of larger villi compared to villi in the ileum)

125
Q

What happens as material passes along the colon?

A

As it passes along water is absorbed and by the time it reaches the rectum the material is semi solid

126
Q

What happens in the rectum

A

Food passes along rectum and is egested as faeces (defecation)

127
Q

Describe the tissues in the colon wall

A 
Serosa 
Longitudinal muscle 
Circular muscle
Submucosa 
Mucosa with larger villi than small intestine
128
Q

How do reptiles and amphibians ingest food?

A

Ingest food and swallow it whole

129
Q

How do mammals ingest food (brief)

A

Retain food in the buccal cavity, while it is cut and chewed and then swallowed

130
Q

Why is the palate separating nasal and mouth cavities vital in mammals (only found in mammals)

A

So food can be held in the mouth and chewed whilst breathing

131
Q

What mostly comprises a carnivores diet?

What adaptation reinforces this fact?

A

Eats only animals :/ high protein diet

  • gut= 5x length of body
  • small intestine is short compared to body showing ease at which proteins digested
132
Q

Why is the small intestine of a herbivore relatively long in relation to its body?

A

Plant material is not readily digested :: a long gut allows enough time for digestion and absorption of nutrients
-gut= 10x length of body

133
Q

How long is the gut in an omnivore?

A

Intermediate length

134
Q

What are the 4 types of teeth in humans?

A

Incisors
Canines
Premolars
Molars

135
Q

Why are humans teeth less specialised than carnivores or herbivores?

A

Humans are omnivores :: intermediate

136
Q

Why do herbivores teeth have to be modified?

A

Because plant cell walls contain cellulose, lignin and sometimes silica which are tough to eat

137
Q

Name the dentition parts of herbivores that i should know

A 
Dental pad 
Incisors 
Canine 
Diastema 
Premolars 
Molars
138
Q

Where does a herbivore has incisors and canines?

A

On the lower jaw only, canine distinguishable from incisors in shape and size

139
Q

How does the herbivore use the dental pad to aid grass digestion?

A
  1. Wraps tongue around grass
  2. Pulls it right across ‘dental pad’ on its upper jaw
  3. Lower incisors and canines slice through it
140
Q

What is the diastema featured in herbivores?

A

A gap separating the front teeth from the side teeth (premolars)

141
Q

Why is the diastema needed

A

Allows room for the tongue and cheeks to move the grass to the large grinding surface of the cheek teeth or molars

142
Q

How do the molars fit in the mouth?

A

Interlock like a W fitting into an M

143
Q

How does the lower jaw move in a herbivore?

A

From side to side producing a circular grinding action in a horizontal plane

144
Q

What happens to the teeth or herbivore over time?

Why is this beneficial?

A

-grinding surfaces on the teeth become worn exposing shape edged enamel ridges (increasing efficiency of grinding)

145
Q

Why are herbivores having open unrestricted roots a benefit

A
  • Allow the teeth to continue to grow throughout the animals life
  • replacing material worn down by chewing
146
Q

Why does a herbivore not need strong muscles attached to its jaws?

A

Because it’s food is not likely to escape

147
Q

Describe the skull of a herbivore

A

Relatively smooth

148
Q

What adaptations are the teeth of a carnivore suited to?

A

Catching and killing prey, cutting or crushing bones and tearing meat

149
Q

What is the purpose of incisors in a carnivore?

A

Sharp incisors grip and tear muscle from bone

150
Q

Describe canine teeth in carnivore

A

Large, curved and pointed for piercing and seizing prey, tearing muscle and killing

151
Q

What do the molars and premolars of carnivores have? Benefit?

A

Have cusps which are sharp point that cut and crush

152
Q

What are carnassials?

A

Pair of large specialised cheek teeth in carnivores which slide past each other like scissor blades
(Sheer muscle off the bone)

153
Q

Which direction does the lower jaw of a carnivore move? Benefit?

A

Moves vertically

Open their jaws more widely than herbivores

154
Q

Describe the jaw muscles in a carnivore

A

Well developed and powerful allowing carnivore to grip prey firmly and crush bone

155
Q

Why are there protrusions on the skull of a carnivore?

A

Caused by the jaw muscles inserting into the bone

156
Q

Define ruminant

A

A cud chewing herbivore possessing a ‘stomach’ divided into 4 chambers, the largest of which is called the rumen which contains mutualistic microbes

157
Q

Name examples of ruminants

A

Cows and sheep

158
Q

How do ruminants digest cellulose (cell wall material from their plant diet)

A

Rely on mutualistic microns living in their gut to secret enzymes e.g fungi, bacteria and protoctista which live in the rumen

159
Q

Why do ruminants have to rely on mutualistic microbes to digest cellulose?

A

-animals don’t make cellulase and can’t digest B-glycosidic bonds in cellulose

160
Q

Describe how grass becomes a source of energy for a ruminant

A

-grass cut by teeth and mixed with saliva to form w cud which is swallowed down oesophagus
-in rumen food mixes with microbes which secrete cellulase which digest cellulose to glucose
-mixture is fermented to organic acids that are absorbed into the blood and are now a source of energy for the cow
Glucose—> 2CH3COOH + CO2 + CH4
(Carbon dioxide and methane are waste products)

161
Q

Describe the digestion of the fermented grass in the cow

A
  • rumen—> reticulum and is reformed into cud
  • regurgitated into mouth for further chewing (can be swallowed and regurgitated several times
  • reticulum—> omasum where water and organic acids made from fermented glucose are absorbed into blood
  • omasum—> abomasum where protein is digested by pepsin at pH2
  • digested food passes into small intestine were products of digestion pass into blood
162
Q

What are plants and animals parasitised by?

A 
Bacteria 
Fungi 
Virus 
Nematodes
Insects 
(Humans also parasitised by tapeworm and mites)
163
Q

What is a parasite that affects bacteria

A

Bacteriophages

164
Q

What problems to parasites cause

A

Disease in humans, crops and domesticated animals

165
Q

Why does the gut parasite pork tapeworm (taenia solium) survive?

A
  1. It has no competition

2. It is an endoparasite and :: can’t be preyed upon

166
Q

Describe the structure of the pork tapeworm (taenia solium)

A
  • ribbon like (thin so allows hosts food to pass)
  • up to 10m long
  • anterior end=scolex
  • body= linear series of sections called proglottids
167
Q

Why is the scolex vital to the tapeworms survival?

A

The muscle carries suckers and hooks which attach to the duodenum wall

168
Q

Name the pork tapeworms (taenia solium) hosts

A

Primary host= human

Secondary host= pig

169
Q

How are pigs/humans infected by pork tapeworm (taenia solium)

A

Pig= infected when it’s food is contaminated with human faeces

Human= eating undercooked, infected pork.

170
Q

What challenges in humans does the tapeworm have to overcome? (5)

A
  • lives surrounded by digestive juices and mucus
  • peristalsis produces constant motion
  • experience pH changes in passage to duodenum
  • exposed to hosts immune system
  • if host dies so does the parasite
171
Q

Describe the pork tapeworm cycle (from pig to human and back)

A
  1. Human eats meat infected with pork tapeworm
  2. Adult tapeworm attach to duodenum via hooks on their scolex
  3. Mature proglottids contain uterus with embryos
  4. Terminal (dead) proglottids fall off tapeworm and are discharged with human faeces
  5. Eggs and embryos from within proglottids remain alive in the ground
  6. cycle only continuous of consumed by pig
172
Q

Wha must the tapeworm do to survive the hostile environment?

A
  • penetrate the host
  • attach to the host
  • protect itself against hosts immune system
  • develop only organs essential for survival
  • produce many eggs, giving high chance of transmission to secondary host
  • have resistant stages whilst away from host
173
Q

Name the structural modifications enabling tapeworm to live as a parasite

A
  • suckers and double row of curved hooks attaching it to duodenum wall
  • thick body covering (cuticle) protecting against hosts immune response
  • produce enzyme inhibitors (prevent host digesting it)
  • large SA:V ration so food absorbed over whole surface
  • only have simple excretory and nervous system + complex reproductive system
  • eggs have resistant shells + survive until eaten by secondary host (pig)
174
Q

What effects can the pork tapeworm cause in humans?

A

Long term infection causes taeniasis
Symptoms include abdominal pains and weakness
Can be treated with drugs

175
Q

Name an example of an ectoprasite

Describe this

A

Pediculus (lice)

  • wingless insects
  • can’t fly and legs poorly adapted for jumping and waking
  • if removed from human they die
176
Q

Describe the life cycle of a headlouse

A
  1. nuts are empty eggs (easily seen in hair)
  2. After 1-2 weeks egg hatches into a nymph (like adult but smaller)
  3. Nymphs become adults after 10 days and both feed of blood which they suck
177
Q

Why is mating of the pork tapeworm impossible?

How do they reproduce?

A

The gut only accommodated one tapeworm :: mating is impossible

Tape work is a hermaphrodite (male and female organs in each proglottids :: they fertilise their own eggs

178
Q

Suggest why the pH in the Rumen May alter from its normal of 6.2?

A

Because a solution of carbon dioxide is produce when microbes respire

179
Q

How do cows control its rumens pH

A

HCO3- and CO3- in saliva swallowed into the rumen raising pH

180
Q

What is the point of the smooth muscle cells in the small intestine?

A
  • moves villus to change material in contact with it

- movement forces material from lacteals

181
Q

Explain how the gut of a hervivore is adapted for nutrition

A

Herbivore gut has 4 chambers (including rumen)
Rumen contains mutualistic microbes that produce cellulase
Long gut allows longer time for digestion
Cud is regurgitated for extra chewing

✅Biology AS Unit 2 (5 decks)

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