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Bio Component 3 > Adaptations for Nutrition > Flashcards

Adaptations for Nutrition Flashcards

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1
Q

What type of nutrition do amoeba use?

A

Holozoic

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2
Q

How do amoeba obtain nutrients such as oxygen and glucose?

A

Through their cell membrane via:
- diffusion
- facilitated diffusion
- active transport

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3
Q

How do amoeba take in large food molecules such as bacteria and microscopic algae?

A

Endocytosis

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4
Q

The food vacuoles in amoeba fuse with ________ containing _________ ____________ which _______ the contents of the food molecules. The products of digestion are then absorbed into the ____ _____________

A

Lysosomes, hydrolytic enzymes, digest, cell cytoplasm

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5
Q

In amoeba, indigestible remains are egested by ______________

A

Exocytosis

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6
Q

Describe digestion and nutrition in hydra

A
  • Their tentacles move paralysed prey in through the mouth into the hollow sac like body cavity where the prey is digested
  • The products of digestion are absorbed into body cells
  • The indigestible remains are egested through the mouth
  • They only have a single opening in their digestive system
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7
Q

Describe a tube gut

A

Food is ingested at the mouth and indigestible waste is egested at the anus

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8
Q

Name the 4 functions of the human gut

A
  1. Ingestion
  2. Digestion (mechanical and chemical)
  3. Absorption
  4. Egestion
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9
Q

Define ingestion

A

Taking food into the body through the mouth

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10
Q

Define digestion

A

The breakdown of large insoluble molecules into soluble molecules that are then small enough to be absorbed into the blood

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11
Q

Define mechanical digestion

A

Cutting and crushing by teeth and muscle contractions of the gut wall, increasing the surface area over which enzymes can act

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12
Q

Define chemical digestion

A

Breakdown using digestive enzymes. Bile and stomach acid also contribute to this

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13
Q

Define absorption

A

The passage of small soluble molecules and ions through the gut wall into the blood

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14
Q

Define egestion

A

The elimination of indigestible waste

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15
Q

Define peristalsis

A

The wave of muscular contractions and relaxations of the gut wall which propel the contents along the whole length of the gut

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16
Q

What is the function of the mouth?

A

Ingestion. Mechanical digestion of food due to crushing action of teeth. Chemical digestion of starch by salivary amylase

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17
Q

What is the function of the oesophagus?

A

Carriage of food to the stomach by peristalsis

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18
Q

What is the function of the stomach?

A

Contraction of stomach muscles to churn up food (mechanical digestion). Secretion of hydrochloric acid. Chemical digestion of proteins by enzymes.

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19
Q

What is the function of the duodenum?

A

Receives pancreatic juice from the pancreas and bile from the gall bladder. Chemical digestion of carbohydrates, fats and proteins by enzymes

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20
Q

What is the function of the ileum?

A

Chemical digestion of carbohydrates, fats and proteins by enzymes. absorption of digested food.

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21
Q

What is the function of the colon?

A

Absorption of water

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22
Q

What is the function of the rectum?

A

Storage of faeces

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23
Q

What is the function of the anus?

A

Site of egestion

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24
Q

What is the function of the serosa?

A

Contains tough connective tissue which protects the gut wall. It helps to reduce friction with other abdominal organs during peristalsis

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25
Q

What is the function of the muscularis (inner circular muscles and outer longitudinal muscles)?

A

They make co-ordinated waves of contraction (peristalsis), pushing the ball of food along the alimentary canal

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26
Q

What is the function of the sub-mucosa?

A

Consists of connective tissue containing blood and lymph vessels which remove the absorbed products of digestion. This layer also contains nerves which coordinate peristalsis

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27
Q

What is the function of the mucosa?

A

The epithelium secretes mucus which lubricates and protects the mucosa. In some regions of the gut it secretes digestive juices and in others it absorbs digested food

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28
Q

What do endopeptidases do?

A

Hydrolyse peptide bonds within the protein molecule eg pepsin and trypsin

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29
Q

What do exopeptidases do?

A

Hydrolyse peptide bods at the end of shorter polypeptide chains to make amino acids/dipeptides

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30
Q

What reaction does amylase catalyse?

A

Starch –> maltose

31
Q

What is secreted in the mouth to create the optimum pH for amylase?

A

Bicarbonate ions (slightly alkaline)

32
Q

What does gastric juice contain?

A
  • Mucus
  • Hydrochloric acid
  • Pepsin (secreted as inactive pepsinogen)
33
Q

What is the function of mucus in the stomach?

A
  • Secreted by goblet cells
  • It forms a protective lining which protects the stomach wall from digestive enzymes and HCl
  • Also helps to lubricate food
34
Q

How is pepsinogen activated?

A

Hydrochloric acid

35
Q

Why are enzymes in the stomach secreted in an inactive form?

A

Active form would digest the cells of the stomach wall

36
Q

What are the functions of bile salts?

A
  • They emulsify lipids, breaking up large globules into smaller droplets, increasing the surface area for lipase action
  • Bile is alkaline and neutralises the acid in the food coming from the stomach creating an optimum pH for enzymes in the small intestine
37
Q

What are the 4 pancreatic secretions and their functions?

A

Endopeptidases hydrolyse proteins into shorter polypeptides
Trypsinogen inactive enzyme converted into the endopeptidase trypsin by enterokinase
Pancreatic amylase chemically digests any remaining starch to maltose
Lipase hydrolyses lipids into fatty acids and glycerol

38
Q

What are the 2 duodenal secretions and their functions?

A

Sodium hydrogen carbonate raises the pH to make pancreatic juice more alkaline
Enterokinase an enzyme that converts trypsinogen to trypsin

39
Q

What adaptations of the ileum make it appropriate for absorption?

A
  • It is very long
  • Its lining is folded
  • On the surface of the folds are villi
  • The epithelial cells lining the villi have microscopic projections called microvilli
40
Q

What are the 2 types of specialised cells in the mucosa of the ileum

A
  1. Columnar epithelial cells have microvilli (large SA) and many mitochondria to produce ATP for active transport
  2. Goblet cells secrete mucus which lubricates and protects the lining of the intestine
41
Q

What is the function of the lacteal?

A

Absorbs glycerol and fatty acids

42
Q

In Crohn’s disease, villi in the small intestine are destroyed. Suggest how this could lead to diarrhoea

A
  • Shorter villi
  • Reduced surface area
  • So less enzymes on the membrane
  • Less absorption of products of digestion
  • More solute in the lumen lowers the water potential
  • More water moves from the epithelial cells into the lumen
43
Q

How are fatty acids and glycerol absorbed in the ileum?

A

Diffusion from the lumen into the epithelial cell then reassembled into triglycerides. Diffusion into lacteal then carried via lymphatic system to the blood

44
Q

How are glucose and galactose absorbed in the ileum?

A

Co-transport with Na+ ions from lumen to epithelial cell. Facilitated diffusion into capillary.

45
Q

How is Na+ absorbed in the ileum?

A

Co-transport with glucose from lumen into the epithelial cell. Facilitated diffusion into capillary.

46
Q

How are amino acids absorbed in the ileum?

A

Active transport from lumen into epithelial cell. Facilitated diffusion into capillary.

47
Q

How is water absorbed in the ileum?

A

Osmosis from lumen into epithelial cell. Osmosis into capillary

48
Q

How will substances absorbed into blood be transported to the liver?

A

Via the hepatic portal vein

49
Q

Explain how active transport of Na+ from the epithelial cells into the blood helps with the passage of glucose from the lumen into the blood

A
  • lower concentration of Na+ in epithelial cells, which creates a concentration gradient for Na+
  • Na+ and glucose enter epithelial cell from lumen by co-transport
  • increases the glucose concentration in cell, which creates a concentration gradient for glucose
  • glucose moves into blood by facilitated diffusion
50
Q

What 3 substances are absorbed in the large intestine?

A
  1. water
  2. mineral ions
  3. vitamins produced by symbiotic bacteria in gut eg vitamin K and folic acid
51
Q

Define autotrophic nutrition

A

Organisms synthesis their own complex organic molecules from simpler molecules using either light or chemical energy. Can be photoautotrophic or chemoautotrophic

52
Q

Define photoautotrophic organisms

A

Use energy from sunlight to carry out photosynthesis to maker organic molecules (glucose) from inorganic molecules (carbon dioxide and water) eg green plants, algae

53
Q

Define chemoautotrophic organisms

A

Use energy from chemical reactions to synthesise organic molecules eg bacteria respiring in deep sea hydrothermal vents

54
Q

Define heterotrophic nutrition

A

Organisms cannot produce their own organic molecules so obtain complex organic molecules from other organisms. They then break this material down into smaller, soluble molecules which they then absorb and assimilate

55
Q

Name the 2 types of heterotrophic nutrition

A
  1. Holozoic nutrition
  2. Saprotrophic nutrition
56
Q

Define holozoic nutrition

A

These organisms ingest food, digest it and egest any indigestible remains.
1. Ingestion
2. Digestion
3. Absorption into the bloodstream
4. Assimilation
5. Egestion

57
Q

Define saprotrophic nutrition

A

Saprotrophs feed on dead or decaying organic material. They carry out extracellular digestion:
- enzymes are secreted onto the food material outside of their body
- they then absorb the soluble products of digestion into their cells by diffusion or active transport

58
Q

Define parasitic nutrition

A

Parasites are organisms that live on or in another organism, called the host, and obtain nourishment at the expense of the host. They cause harm and often death

59
Q

What is the difference between endoparasites and ectoparasites?

A

Endoparasites live in the host, whereas ectoparasites live on the host

60
Q

How does a human become infected with tapeworm?

A

The larval form is found in pigs. The pig becomes infected if it feeds on drainage channels contaminated by human faeces containing eggs. Humans become infected by eating contaminated undercooked pork.

61
Q

How has the tapeworm adapted to fix the problem of the gut being in constant motion?

A

Suckers and hooks for attachment to gut wall

62
Q

How has the tapeworm adapted to fix the problem of extreme pH along the gut, exposure to digestive enzymes and the host’s immune response?

A

A thick cuticle and the production of inhibitory substances on its surface to prevent digestion by the host’s enzymes

63
Q

How has the tapeworm adapted to fix the problem of reproduction (unlikely to find a mate in host, high offspring mortality, difficult for eggs to reach new host)

A
  • Tapeworm has both male and female reproductive organs so can self fertilise
  • Large numbers of eggs are produced
  • Eggs have resistant shells and can survive until eaten by another host
64
Q

How has the tapeworm adapted to fix the problem of host death?

A

If the host dies, so does the tapeworm - adult tapeworms cause little discomfort to the host

65
Q

How has the tapeworm adapted to fix the problem of having no digestive system?

A

The tapeworm is long and thin so has a large SA:V. it lives in the small intestine and is surrounded by the host’s digested food which can be absorbed over the entire body surface of the tapeworm by diffusion

66
Q

What is the function of incisors?

A

Biting and cutting

67
Q

What is the function of canines?

A

Tearing and ripping meat

68
Q

What is the function of molars and premolars?

A

Grinding and chewing

69
Q

What are 6 structural features of herbivore dentition?

A
  • incisors and horny pad
  • canines
  • diastema
  • interlocking molars
  • loose articulation of lower jaw
  • open roots
70
Q

Name and describe 6 structural features of carnivore dentition

A
  • small sharp incisors to grip and tear flesh from bone
  • large curved canines to seize and hold onto prey
  • premolars/molars for cutting and crushing food
  • carnassials slide past each other like blades and crush bone
  • vertical jaw movements so jaw can open widely and cannot be dislocated when prey is struggling in its grip
  • powerful jaw muscles to grip prey
71
Q

Describe cellulose digestion in cows

A
  1. Grass is chewed, mixed with saliva and swallowed
  2. This grass passes into the rumen and it is churned and mixed with bacteria that secrete cellulase to digest cellulose to beta glucose. The beta glucose is absorbed into the blood, providing energy for the animal.
  3. Any undigested grass passes to the reticulum chamber and is formed into cud. The cud is regurgitated into the mouth for further chewing which increases the surface area of the grass to allow for more cellulose digestion to take place.
  4. The cud then passes to the omasum where water is absorbed into the blood.
  5. In the abomasum, bacteria are killed and digested. They provide an important source of protein.
72
Q

What are non-ruminant herbivore adaptations for nutrition eg rabbit

A

In the rabbit the caecum is enlarged to accommodate cellulose digesting bacteria
As the bacteria are towards the end of the gut, regurgitation is not possible. Instead, refection occurs, where rabbits ingest faecal pellets so that the material passes through the gut twice to increase the efficiency of digestion

73
Q

Compare carnivore and herbivore guts

A

The carnivore gut is relatively short compared to the length of its body because they have a diet high in protein and protein is easily digested. The gut of a herbivore is longer compared to the length of its body as they eat a diet high in cellulose which is much harder to digest

Bio Component 3 (8 decks)

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