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AS Biology > 2.11 - Adaptations For Nutrition > Flashcards

2.11 - Adaptations For Nutrition Flashcards

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1
Q

What are autotrophic organisms?

A

They make their own food from simple inorganic raw materials like carbon dioxide and water
Photoautotrophic and chemoautotrophic

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2
Q

What is meant by photoautotrophic?

A

Using light as energy source and perform photosynthesis.
Green plants, some protoctista and some bacteria (holophytic nutrition)

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3
Q

What is meant by chemoautotrophic?

A

Energy from chemical reactions, all prokaryotes and they perform chemosynthesis
No longer dominant life forms

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4
Q

What is meant by a heterotrophic organism?

A

They cannot make their own food so have to consume complex organic molecules produced by autotrophs, so they are consumers
Includes animals, fungi, some protoctista and some bacteria

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5
Q

What are the 3 types of heterotrophic nutrition?

A

Saprotrophic
Parasitic
Holozoic

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6
Q

What is meant by saprotrophic nutrition?

A

Used by all fungi and some bacteria
They derive energy and raw materials for growth from the extracellular digestion of dead or decaying material

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7
Q

What is meant by parasitic nutrition?

A

Obtaining energy from other living organisms, hosts. Parasites host always suffers harm or death.
2 types - endoparasites, ectoparasites

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8
Q

What is meant by holozoic nutrition?

A

Used by most animals. They ingest, digest and egest (inc. carnivores, omnivores, herbivores + detrivores)

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9
Q

Why must food be digested in humans?

A
  • foods are insoluable and too big cross membranes and be absorbed into the blood
  • polymers must be converted into monomers so that they can be rebuilt into molecules needed by cells
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10
Q

Describe the process of peristalsis

A

In the oesophagus
Longitudinal muscles contract to push food fowards and then relax
Circular muscles contract behind the bolus and then relax
The wave of contraction pushes the bolus down

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11
Q

What are the 4 main functions of the gut?

A

Ingestion, digestion, absorption, egestion

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12
Q

What is meant by ingestion?

A

Taking food into the body through the mouth

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13
Q

What is meant by digestion?

A

The breakdown of large insoluable molecules into soluable molecules that are small enough to be absorbed into the blood.

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14
Q

What are the 2 types of digestion?

A

Mechanical and chemical

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15
Q

What is mechanical digestion?

A

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

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16
Q

What is chemical digestion?

A

Secretion of digestive enzymes
Bile and stomach acid contribute here

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17
Q

What is meant by absorption?

A

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

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18
Q

What is meant by egestion?

A

The elimination of waste not made by the body, including food like cellulose that cannot be digested

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19
Q

Name the 8 parts of the digestive system and their function
MOSDCRA
most otters save dams creating river alternations

A

mouth - ingestion and digestion of starch
oesophagus - carries food down to the stomach
stomach - digestion of protein
duodenum - digestion of carbohydrates, fat and proteins, absorption of digested food
colon - absorption of water
rectum - storage of faeces
anus - egestion

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20
Q

Name the 4 features of the gut wall.

A

Serosa
Inner circular muscle
Sub-mucosa
Muscosa

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21
Q

What does the serosa in the gut wall do?

A

Tough connective tissue protecting the gut wall, reduces friction from movement between other abdominal muscles

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22
Q

What do the inner circular muscles and outer longitudinal muscles muscles do in the gut?

A

Waves of contractions behind the food circular muscle contracts, longitudinal muscle relax to push food along

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23
Q

What does the submucosa do in the gut?

A

Connective tissue containing blood and lymph muscles, which remove absorbed products of digestion and nerves that co-ordinate peristalsis.

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24
Q

What does the mucosa do in the gut?

A

Lines the inner gut wall, epithelium secretes mucus, which acts as a lubricant and protector, it secretes digestive juices and absorbs digested food.

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25
Q

How are carbohydrates digested?

A
  • polysaccharides are digested into disaccharides and then monosaccharides
  • amylase hydrolyses starch to the disaccharide maltose and maltase digests maltose to the monosaccharide glucose
  • sucrase digests sucrose and lactase digests lactose
  • the enzymes are generalised as carbohydrases
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26
Q

How are proteins digested?

A
  • extremely large molecules
  • digested into polypeptides, then dipeptides and then amino acids
  • the protein digesting enzymes are protease and peptidase
  • endopeptidases hydolyse peptide bonds within the protein molecules, then exopeptidases hydrolyse peptide bonds at the ends of these shorter polypeptides
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27
Q

How are fats digested?

A

Digested to fatty acids and monoglycerides by the enzyme lipase

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28
Q

What begins in the buccal cavity?

A

Mechanical digestion begins in the mouth, foods surface area increases giving enzymes more access

29
Q

What does saliva contain?

A
  • amylase, beggining the digestion of starch into maltose
  • HCO3- and CO32- ions so that the pH in the mouth is slightly alkaline, the optimum for amylase
  • mucus, lubricating the foods passage down the oesophagus
30
Q

Name the 6 layers of the stomach lining.

A

-mucosa has large folds called ruggae
- submucosa
- circular muscle
- oblique muscles allow extra contractions
- longitudinal muscle
- serosa

31
Q

Where does gastric juice come from?

A

Secreted from glands in depressions of the mucosa, called gastric pits.

32
Q

What 4 things does gastric juice contain?

A
  • peptidases, secreted by zymogen, or chief cells, at the base of the gastric pit
  • pepsinogen, an inactive enzyme, is secreted and activated by H+ ions to pepsin, an endopeptidase which hydrolyses protein to polypeptides
  • hydrochloric acid, secreted by oxyntic cells, lowers pH of the stomach contents to about pH 2, the optimum pH for the enzymes, and kills most bacteria in food
  • mucus secreted by goblet cells, at the top of the gastric pit, mucus forms a lining which protects the stomach wall from the enzymes and lubricates the food
33
Q

What are the regions of the small intestine?

A

The duodenum and the ileum

34
Q

What is bile and what does it contain?

A

Made in the liver, stored in the gall bladder then passes through the bile duct into the duodenum
- it contains no enzymes
- contains bile salts, which are amphipathic, they emulsify lipids in the food, by lowering their surface tension and breaking up large globules into smaller globules which increases the surface area
- bile is alkaline and neutralises the acid in food coming from the stomach , it provides a suitable pH for the enzymes in the small intestine

35
Q

Where does pancreatic juice come from?

A

Secreted by Islet cells, which are exocrine glands in the pancreas, it enters the duodenum through the pancreatic duct.

36
Q

What enzymes are found in pancreatic juice and what do they do?

A

Endopeptidases - hydrolyse protein to peptides
Trypsinogen - inactive enzyme converted into the protease typsin by the duodenal enzyme enterokinase
Amylase - digests any remaining starch to maltose
Lipase - hydrolyses lipids into fatty acids and monoglycerides

37
Q

What substance other than enzymes are found in gastric juice?

A

Sodium hydrogen carbonate - raises the pH to make pancreatic juice slightly alkaline and contributes to -
- neutralising the acid from the stomach
- providing the appropriate pH for all the pancreatic enzymes to work efficiently

38
Q

What are secreted at the villus tips?

A

Endopeptidases and exopeptidases
they continue the digestion of polypeptides, dipeptides are digested to amino acids by enzymes on the cell membranes of the epithelial cells

39
Q

What happens to disaccharides at the villi?

A

They are absorbed into the epithelial cells, carbohydrases in their cell membranes digest them into monosaccharides so their final stage of carbohydrate digestion is intracellular.

40
Q

Name the 3 processes of intracellular carbohydrate digestion.

A

Maltase hydrolyses maltose into 2 glucose
Sucrase hydrolyses sucrose into glucose+fructose
Lactase hydrolyses lactose into galactose+glucose

41
Q

Where and how does absorption work?

A

Mainly in the small intestine
Diffusion, facilitated diffusion, active transport
Active transport needs ATP so epithelial cells have many mitochondria

42
Q

Name the 10 features of the small intestine

A

Epithelium
Villi
Capillary
Lacteal
Crypt of lieberkuhn
Artiole
Venule
Lymph vessel
Circular muscle
Longitudinal muscle

43
Q

What happens to amino acids in the small intestine?

A

Absorbed into epithelial cells by active transport and as amino acids they pass into the capillaries by facilitated diffusion. They are water soluable and dissolve in the plasm.

44
Q

What happens to glucose in the small intestine?

A

Glucose passes into the epithelial cells with sodium ions by co-transport. They move into the capillaries, sodium by active transport and glucose by facilitated diffusion, and dissolve in the plasma.
Both processes are slow and not all the glucose is absorbed. To prevent it leaving the bod, some is absorbed by active transport.

45
Q

What happens to fatty acids and monogycerides in the small intestine?

A

Diffuse into epithelial cells and into the lacteals. The lacteals are part of the lymphatic system, which transports fat soluable molecules to the left subclavian vein near the heart.

46
Q

What happens to minerals in the small intestine?

A

Minerals are taken into the blood by diffusion, facilitated diffusion and active transport and dissolve in the plasma

47
Q

What happens to vitamins in the small intestine?

A

Vitamins B and C are water soluable and are absorbed into the blood. VItamin A, D and E are fat soluable and are absorbed into the lacteals.

48
Q

What happens to water in the small intestine?

A

Water is absorbed into the epithelial cells in the ileum and into the capillaries by osmosis.
Most water absorption comes from the large intestine.

49
Q

What happens to lipids after they are absorbed?

A

They are used in membranes and to make some hormones but excess is stored.

50
Q

Where do most molecules go after being absorbed?

A

Most are taken into the hepatic portal vein to the liver, after which the fates vary.

51
Q

What happens to glucose after it get absorbed?

A

It is taken to body cells and respired for energy or stored as glycogen, in liver and muscle cells, excess is stored as fat.

52
Q

What happens to amino acids after absorption?

A

Amino acids are used for protein synthesis, liver deaminates the amino acids and converts the NH2 groups to urea. Remainder is converted into carbs or storage as fat.

53
Q

What 4 parts make up the large intestine?

A

Caecum, appendix, colon and rectum.

54
Q

What happens in the colon?

A

Undigested food, mucus, bacteria and dead cells pass into the colon. The colon wall has fewer villi than the ileum and they have a major role in water absorption.

55
Q

What happens as food passes through the colon?

A

Vitamin K and folic acid are secreted by mutualistic micro-organisms living there and minerals are absorbed from the colon. As materials passes along the colon, water is absorbed, and by the time it reaches the rectum, the material is semi-solid. Defaction then occurs.

56
Q

What is different in the mucosa in the large intestine?

A

Mucosa has larger villi than the small intestine.

57
Q

How are carnivores adapted to their diet?

A

Carnivores only eat animals and so its diet is mainly protein. Its small intestine is short in relation to its body length, reflecting the ease in which protein is digested.

58
Q

How are herbivores adapted to their diet?

A

Herbivores only eat plant material. Its small intestine is long in relation to its body length, because plant material is not readily digested and a long gut allows enough time for digestion and absorption of nutrients.

59
Q

Describe the dentition of herbivores.

A
  • incisors on the lower jaw only, canine teeth are indistinguishable
  • diastema for tongue to reach plants
  • molars interlock to break down plant fibres
  • jaw is absent of muscles as they do not need to hunt and kill
60
Q

Describe the dentition of carnivores.

A
  • Sharp incisors grip and tear muscle from bone
  • Canine teeth are sharp, curved and long
  • Premolars have sharp cusps
  • carnissials behind canines for extra support
  • lower jaw moves vertically to avoid dislocation from prey
  • jaw muscles are well developed and powerful
61
Q

What is a ruminant?

A

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

62
Q

What is meant by mutualism in ruminants?

A

A close association of organisms from more than one species providing benefit to both.

63
Q

Describe the process of cellulose digestion in cows.

A
  • grass is mixed with saliva to form cud, which moves down the oesphagus to the rumen
  • in the rumen food mixes with microbes, enzymes turn cellulose into glucose(energy)
  • the fermented grass goes to the reticulum to reform cud, then is regurgitated to the mouth for further chewing
    -cud goes to the omasum where water and organic acids made from fermented glucose are absorbed into the blood
  • the abomasum protein is digested by pepsin at pH 2
  • passes to small intestine, absorption into blood
  • large intestine the same as human
64
Q

What is an example of
an endoparasite?

A

Pork tapeworm
- scolex of suckers and hooks, attaches to deodenum wall
- body linear sections of proglettids
- primary host, human - secondary host, pig

65
Q

Why is the tapeworms environment hostile?

A
  • it lives surrounded by digestive juices and mucus
  • perastalsis produces constant motion
  • it experiences pH changes in its passage in the duodenum
  • exposed to the hosts immune system
  • if host dies, so does the parasite
66
Q

What must a tapeworm do to survive a hostile environment?

A
  • penetrate the host
  • attach to the host
  • protect itself against the hosts immune responses
  • develop organs only essential for survival
  • produce many eggs, high choice of transmission to secondary host
  • have an intermediate host
  • have resistant stages away from the host
67
Q

What are the structural modifications of the tapeworm?

A
  • suckers and double row of curved hooks
  • a thick body, cuticle, protecting it from hosts immune repsonses
  • large surface area to volume ratio it from digestion
  • simple organ system as it has a stable environment
  • they are self- reproducing hermaphrodites
  • eggs have resitant shells that survive until eaten by secondary host.
68
Q

What are the harmful effects of tapeworms?

A
  • little discomfort, but can lead to taeniasis
  • improved sanitation, education, requent inspection of meat
  • dirct egg ingestion can cause cysts in eyes
69
Q

What is the example for an ectoparasite?

A

Pediculus (lice)

AS Biology (11 decks)

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