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AS BIOLOGY > 11 - Adaptations for Nutrition (C3) > Flashcards

11 - Adaptations for Nutrition (C3) Flashcards

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1
Q

How do autotrophic organisms obtain their food?

A

Make their own food from simple inorganic raw materials, CO2 and H2O

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2
Q

What are 2 types of autotrophs?

A
  • Phototrophic organisms

- Chemoautotrophic organisms

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3
Q

What is the definition of an autotroph?

A

An organism that synthesises its own complex organic molecules from simpler molecules, using either light or chemical energy

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4
Q

What are photoautotrophic organisms and how do they make their food?

A
  • They are green plants, some Protoctista and some bacteria
  • They use light as energy source and perform photosynthesis
  • This type of nutrition is described as holophytic
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5
Q

What are chemoautotrophic organisms and how do they make their food?

A
  • All prokaryotes
  • Use energy from chemical reactions and perform chemosynthesis
  • This is less efficient than photosynthesis and organisms that do this are no longer dominant life forms
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6
Q

How do heterotrophic organisms obtain their food?

A
  • Can’t make their own food, so are consumers

- Eat autotrophs or organisms that have eaten autotrophs

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7
Q

What is the definition of a heterotroph?

A

An organism that obtains complex organic molecules from other organisms, such as animals, fungi and bacteria

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8
Q

What is the definition of a saprotroph?

A

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

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9
Q

What is the definition of a parasite?

A

An organism that obtains nutrients from another living organism or host, to which it causes harm, e.g. tapeworms and head-lice

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10
Q

What do herbivores eat?

A

Plants only

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11
Q

What do carnivores eat?

A

Animals only

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12
Q

What do omnivores eat?

A

Both plants and animals

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13
Q

What do detritivores feed on?

A

Dead and decaying material

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14
Q

What is holozoic nutrition?

A

When food is ingested, digested and indigestible remains are egested

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15
Q

How do single-celled organisms such as Amoeba use holozoic nutrition?

A
  • Large SA to volume
  • Obtain nutrients by diffusion, FD or AT across cell membrane
  • Take in larger molecules by endocytosis
  • Egest indigestible remains by exocytosis
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16
Q

How does Hydra consume food?

A
  • It extends its tentacles
  • When small organisms brush past them they sting and paralyse the prey
  • Tentacles move prey through mouth into hollow body cavity
  • Endodermal cells secrete protease and lipase and prey is digested extracellularly
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17
Q

Why must food in humans be digested?

A

Because the molecules are:

  • Insoluble, and too big to cross membranes and be absorbed into blood
  • Polymers, and must be converted to monomers, so they can be rebuilt into molecules needed by body cells
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18
Q

How is food propelled along the gut?

A

By peristalsis

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19
Q

What is the definition of ingestion?

A

Large food particles are taken into the mouth and broken down by the action of teeth, saliva and the tongue (mastication) so it may then move into the gut

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20
Q

What is the definition of digestion?

A

Chemical breakdown of large insoluble molecules into small soluble molecules that can be absorbed into the blood

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21
Q

What are the 2 types of digestion?

A
  • Mechanical digestion

- Chemical digestion

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22
Q

What is mechanical digestion?

A
  • Cutting and crushing by teeth and muscle contractions of gut wall
  • Increases SA over which enzymes act
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23
Q

What is chemical digestion?

A

Secretion of digestive enzymes, such as bile and stomach acid

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24
Q

What is the definition of absorption?

A

Passage of small, soluble food molecules from the small intestine through the gut wall into the blood, which transports them to cells

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25
Q

What is the definition of egestion?

A

Elimination of undigested food e.g. cellulose, out of the body as faeces via the colon, rectum and anus

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26
Q

What is the order of the structures in the digestive system?

A

Mouth - Oesophagus - Stomach - Duodenum - Ileum - Colon - Rectum - Anus

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27
Q

What is the function of the mouth?

A
  • Ingestion

- Digestion of starch

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28
Q

What is the function of the oesophagus?

A

Carriage of food to stomach

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29
Q

What is the function of the stomach?

A

Digestion of protein

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30
Q

What is the function of the duodenum?

A

Digestion of carbohydrates, fats and proteins

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31
Q

What is the function of the ileum?

A
  • Digestion of carbohydrates, fats and proteins

- Absorption of digested food

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32
Q

What is the function of the colon?

A

Absorption of water

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33
Q

What is the function of the rectum?

A

Storage of faeces

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34
Q

What is the outermost layer of the gut wall?

A

Serosa

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35
Q

What does the serosa in the gut wall do?

A
  • Tough connective tissue

- Reduces friction with other abdominal organs as the gut processes food

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36
Q

What are the 2 layers of muscle in the gut wall?

A
  • Inner circular muscles

- Outer longitudinal muscles

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37
Q

What does the muscle in the gut wall do?

A
  • Peristalsis

- Behind the ball of food, circular muscles contract and longitudinal muscles relax, pushing it along

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38
Q

What does the submucosa in the gut wall have and do?

A
  • Connective tissue containing blood and lymph vessels, which remove absorbed products of digestion
  • Has nerves that co-ordinate peristalsis
  • Is the inner layer from the muscles in the gut
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39
Q

What does the mucosa in the gut wall do?

A
  • Lines gut wall, innermost layer
  • Its epithelium secretes mucus, lubricating and protecting the mucosa
  • In some regions of gut, secretes digestive juices and in others absorbs digested food
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40
Q

Why aren’t polysaccharides instantly absorbed in digestion?

A
  • Too large

- They must be digested into disaccharides and then monosaccharides

41
Q

How is starch digested?

A
  • Amylase hydrolyses to maltose

- Maltase hydrolyses maltose to glucose

42
Q

What do endopeptidases do?

A

Hydrolyse peptide bonds within the protein molecule

43
Q

What do exopeptidases do?

A

Hydrolyse peptide bonds at the terminal ends of a polypeptide into dipeptides

44
Q

What does saliva contain?

A
  • Water
  • Amylase
  • Mineral salts, making it alkaline, optimum for amylase functioning
  • Lysozyme, which kills bacteria
  • Mucus, lubricating food’s passage down oesophagus
45
Q

What does the stomach do?

A

Stomach walls contract rhythmically, mixing food with gastric juice secreted by glands in stomach wall

46
Q

What does gastric juice, secreted by glands in mucosa, contain?

A
  • Peptidases. Pepsinogen, an inactive enzyme, is secreted and activated by H+ ions to pepsin, an endopeptidase which hydrolyses protein to polypeptides
  • Hydrochloric acid
  • Mucus, which forms a lining that protects stomach wall from enzymes and lubricates food
47
Q

Why does the stomach contain hydrochloric acid?

A
  • To lower the pH so it is the optimum for enzymes

- To kill most bacteria in food

48
Q

What do oxyntic cells secrete?

A

Hydrochloric acid

49
Q

What do goblet cells secrete?

A

Mucus, to protect the stomach mucosa

50
Q

What are the 2 regions of the small intestine?

A

Duodenum and ileum

51
Q

How does food enter the duodenum?

A

By relaxation of the pyloric sphincter muscle at the base of the stomach

52
Q

Where does the duodenum receive secretions from?

A
  • Bile from liver

- Pancreatic juice from pancreas

53
Q

Where is bile made and stored and how does it pass into the duodenum?

A
  • Made : liver
  • Stored : gall bladder
  • Transported : through bile duct
54
Q

What does bile contain?

A

Bile salts which emulsify lipids in the food, providing a larger SA for lipase digestion

55
Q

What does bile do?

A
  • Neutralises stomach acid
  • Provides suitable pH for enzymes in small intestine
  • Emulsifies lipids into smaller droplets, increasing SA and rate of digestion
56
Q

What do exocrine glands secrete?

A

Enzymes

57
Q

What do endocrine glands secrete?

A

Hormones

58
Q

Why are the proteases pepsin and trypsin secretes as inactive enzymes, pepsinogen and trypsinogen?

A

So they don’t digest the cells in which they are synthesised

59
Q

What do Brunner’s glands in the submucosa of duodenum secrete?

A
  • Alkaline juice to maintain optimum pH for enzymes in duodenum
  • Mucus for lubrication
60
Q

Why is the final stage of carbohydrate digestion intracellular?

A

Because carbohydrases in cell membranes of villi epithelial cells digest the carbohydrates into monosaccharides

61
Q

Why do villi and microvilli have folds?

A

To increase the SA for absorption

62
Q

Why do epithelial cells have many mitochondria?

A

If absorption of molecules, mainly in small intestine, is done by active transport then ATP is required

63
Q

How are glucose / amino acids absorbed into blood from the ileum?

A
  • Na+ ions actively transported out of epithelial cells, creating a low conc of Na+ in cell
  • Na+ move into epithelial cells from lumen of ileum by co-transport with glucose / amino acids
  • Glucose/AAs moves by FD from high conc inside epithelial cell to low conc in capillaries
64
Q

What happens to fatty acids and monoglycerides in the ileum?

A
  • Diffuse across membrane of epithelial cells
  • Inside the cells they enter SER and are recombined to form triglycerides
  • Packaged into vesicles along with phospholipids and cholesterol
  • Lipids transferred from cells into lacteals (part of lymphatic system) by exocytosis
  • Travels in lymph system to sub clavian vein from thoracic duct
65
Q

Where are vitamins A-E absorbed to?

A
  • B, C absorbed into blood as water soluble

- A, D, E absorbed into lacteals as they’re fat-soluble

66
Q

Where is glycogen stored?

A

In liver and muscle cells

67
Q

What happens to excess amino acids?

A
  • Can’t be stored
  • Liver deaminates amino acids and converts NH2 groups to urea
  • Remains of amino acid molecules converted into carbohydrate for storage or conversion to fat
68
Q

What parts make up the large intestine?

A
  • Caecum
  • Appendix
  • Colon
  • Rectum
69
Q

What is the role of the colon?

A

Absorption of water

70
Q

Why do carnivores have shorter small intestines in proportion to their size?

A

Their diet is mostly protein which is easily digested

71
Q

Why do herbivores have longer small intestines in proportion to their size?

A
  • Plant material not readily digested

- Long gut allows time for digestion and absorption of nutrients

72
Q

Why do herbivores have larger large intestines?

A

So it can stretch to accommodate larger volumes of faeces produced in digesting plants, much of which is cellulose

73
Q

What are the 4 types of teeth that humans have?

A

Incisors, canines, premolars, molars

74
Q

How do herbivores chew their food?

A
  • Wraps its tongue around grass and pulls it across dental pad, then slices it with incisors and canines
  • Food is moved to molars
  • Jaw moves from side to side and produces circular grinding action
75
Q

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

A

As its food is not likely to escape

76
Q

Why do carnivores jaws moves vertically not side-to-side?

A

As side-to-side could cause dislocation when dealing with prey

77
Q

What teeth do carnivores have which herbivores don’t?

A

Carnassials

78
Q

What are the main differences between the dentition of herbivores and carnivores?

A
  • Carnivores have incisors on upper and lower jaw ; herbivores have incisors on lower jaw only
  • Carnivores have carnassials ; herbivores don’t
  • Carnivores have strong jaw muscles ; herbivores don’t
  • Carnivores have large canines ; herbivores have small canines
  • Carnivores jaw moves vertically ; herbivores lower jaw moves side to side
79
Q

What is the definition of a ruminant?

A

A cud-chewing herbivore possessing a stomach divided into 4 chambers

80
Q

What is the largest of the 4 parts of the stomach of a ruminant?

A

The rumen

81
Q

Why can’t herbivorous mammals digest cellulose?

A

They lack the ability to produce cellulase enzymes

82
Q

Why do rabbits have to reswallow their faeces in order to absorb the products of cellulose digestion?

A
  • They have their symbiotic cellulose producing bacteria in their apendix and caecum
  • This is after the ileum where absorption occurs
83
Q

What are the names of the 4 parts of a ruminent’s stomach?

A

Rumen, Reticulum, Omasum, Abomasum

84
Q

Why do cow’s saliva contain urea?

A

To provide a nitrate source for the symbiotic cellulose digesting bacteria

85
Q

How is cellulose digested by a cow?

A
  • Grass chopped by teeth and mixed with saliva forming the cud
  • Cud is digested in rumen containing bacteria, turned first to sugars then to fatty acids, which pass through walls of rumen
  • Rumen contents passed to reticulum where it forms boluses before being regurgitated back to mouth
  • Cud re-chewed and swallowed back to omasum
  • In omasum water is absorbed before cud passes to abomasum (true stomach)
  • In abomasum peptidase enzymes convert proteins of bacterial symbiotic cells to amino acids. Long ileum for absorption
86
Q

What is the cycle of the tapeworm between pigs and humans?

A
  • Humans get infection by eating undercooked or raw meat of infected animal
  • Cysticerci migrate to small intestine of human and develop into adult tapeworm within 2 months
  • Infected humans excrete eggs or gravid proglottids in faeces, passing parasite onto nearby vegetation
  • Pigs acquire infection by eating eggs or gravid proglottids along with parasitized vegetation
  • They migrate to pig’s intestine, and as oncospheres, break through intestinal wall
  • Via circulatory system, they embed themselves in muscles of pig and develop into cysticerci
87
Q

Why do tapeworms have hooks and suckers on scolex (head)?

A

To attach it to duodenum wall

88
Q

Why do tapeworms have a lack of many organs and systems?

A

It has a simple structure as its geared for reproduction only

89
Q

Why do tapeworms have a long flattened body?

A

Large SA to volume ratio for absorption of pre-digested food from host

90
Q

Why do tapeworms have a body covered in cuticle and secrete anti-enzyme?

A

Protects it from host’s immune response

91
Q

Why do tapeworms have reproductive structures called proglottids?

A

Proglottids contain male and female reproductive organs

92
Q

What are some features of tapeworms?

A
  • Hooks and suckers on scolex
  • Lack of circulatory, digestive and gas exchange organs / systems
  • Long flattened body
93
Q

What are the 2 intracellular enzymes produced by the duodenum and ileum?

A
  • Maltase, maltose -> glucose

- Dipeptidases, -> dipeptidases to amino acids

94
Q

What 4 enzymes are in pancreatic juice?

A
  • Amylase, starch -> maltose
  • Endopeptidases (trypsinogen to trypsin), protein -> polypeptides
  • Exopeptidases, polypeptides -> dipeptides
  • Lipase, lipids -> fatty acids and glycerol
95
Q

Where is the cardiac sphincter found and what does it do?

A
  • Upper end of stomach

- Relaxes to allow food to enter

96
Q

What are 5 features of the ileum?

A
  • Thin - 1 microvilli epithelial cell thick - short diffusion pathway
  • Large SA - large no of villi made up of microvilli cells
  • Permeable, to AAs, monosaccharides, fatty acids and glycerol
  • Conc gradient - large network of capillaries and lacteals
  • Moist
97
Q

What is the definition of a parasite?

A

Parasites live on or in an organism of another species, the host, and obtain nourishment at the host’s expense, causing some degree of harm and often death

98
Q

What challenges will the tapeworm face in the gut?

A
  • It lives surrounded by digestive juices and mucus
  • Peristalsis produces constant motion
  • It experiences pH changes in its passage to the duodenum
  • It’s exposed to the host’s immune system
  • If the host dies, so does the parasite

AS BIOLOGY (13 decks)

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