Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A-Level EDUQUAS Biology > Component 3: Digestion & Nutrition > Flashcards

Component 3: Digestion & Nutrition Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is an Autotrophic organism?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a Heterotrophic organism?

A

An organism that obtains complex organic molecules from other organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the difference between autotrophs and heterotrophs?

A

Autotrophs use simple organic materials to manufacture complex organic compounds whereas heterotrophs consume complex organic food material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 2 types of autotrophs?

A
  1. Photoautotroph - organisms that use energy to convert simple organic molecules into complex organic ones (i.e. perform photosynthesis to produce glucose)
  2. Chemoautotroph - organisms use the energy derived from oxidation to convert simple organic molecules into complex organic ones (these all are all prokaryotes that perform chemosynthesis, not dominant life forms)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is an saprotroph organism?

A

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

  • all bacteria and some fungi
  • heterotroph organism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is holozoic nutrition?

A
  • include nearly all animals (heterotrophs)
  • They take food into their bodies and break it down by digestion.
  • Many have a specialised digestive system.
    (have a digestive tract)
  • They can be further divided into herbivores, carnivores and detritivores (feed on dead and decaying material)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is parasitic nutrition?

A
  • Organism that feeds on another organism (host) (heterotroph)
  • Live in/on the host & the host always suffers harm and often death
  • Parasites are highly specialised and show adaptations to their lifestyle. Eg. Tapeworms, potato blight, and Plasmodium (malaria)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is 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. This is an example of mechanical digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is digestion?

A

The chemical breakdown (enzymes) of large food molecules to small, soluble molecules.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is absorption?

A

Small, soluble food molecules move from the small intestine, through the gut wall into the blood stream, which transports them to the cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is egestion?

A

Undigested food exits the body as faeces, via the colon, rectum and anus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do unicellular organisms such as Amoeba gain nutrition?

A
  • use holozoic nutrition
  • they are unicellular organisms which obtain their nutrients by diffusion, facilitated diffusion or active transport across cell membrane
  • they take in larger molecules by endocytosis which in turn fuse with lysosomes so that the contents can be digested
  • products of digestion are absorbed into the cytoplasm and indigestible material is egested by exocytosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the gut like for simple organisms?

A

feeding on one type of food, so gut is undifferentiated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the processes of holozoic nutrition?

A

ingestion, digestion, absorption, assimilation and egestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Explain how simple multicellular organisms Hydra gain nutrition

A
  • cylindrical body shape with tentacles at the top surrounding mouth (only opening)
  • feeds by extending tentacles when small organisms brush against them (e.g. Daphnia)
  • stinging cells discharge a barb to paralyse prey, excreting venom
  • tentacles move prey into mouth and into hollow body cavity
  • endodermal cells secrete lipase and protease so prey is digested extracellularly
  • products of digestion absorbed by cells and indigestible material exits via mouth
  • undifferentiated gut
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why do larger more complex organisms such as humans require a more complex digestive system?

A

Have a more complex and varied diet

  • molecules are insoluble and too large to cross membrane
  • polymers must be converted into monomers as they can be rebuilt into molecules for body cells
  • therefore there are different sections with different roles to digest food
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Fully explain saprotrophic nutrition in fungi

A
  • Digestion takes place extracellularly (extracellular digestion), feeding on dead/decaying matter
  • Extend branching hyphae into the food material and secrete enzymes which digest food into soluble products by entering the cells
  • soluble products are then absorbed into hyphae by facilitated diffusion or active transport
  • soluble products then are transported within fungi and excess stored
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is a decomposer?

A

Microscopic saprotrophs involved in decaying leaf litter and recycling nutrients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the parts of the human digestive system (1-19)?

A
  1. tongue
  2. teeth
  3. salivary glands
  4. pharynx
  5. epiglottis
  6. oesophagus
  7. liver
  8. bile duct
  9. stomach
  10. gall bladder
  11. duodenum
  12. pancreatic duct
  13. pyloric sphincter
  14. pancreas
  15. ileum
  16. appendix
  17. colon
  18. rectum
  19. anus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the function of the mouth?

A

ingestion; digestion of starch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the function of the oesophagus?

A

carriage of food to the stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the function of the stomach?

A

digestion of protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the function of the duodenum?

A

digestion of carbohydrates, fats and proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the function of the ileum?

A

digestion of carbohydrates, fats and proteins; absorption of digested food

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the function of the colon?

A

absorption of water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the function of the rectum?

A

storage of faeces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the function of the anus?

A

egestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What happens in digestion?

A
  • large organic molecules are broken down into small soluble organic molecules
  • these are absorbed into cells
  • the raw materials are used to synthesise molecules which can be used in the body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Name the 5 layers of the gut wall from the most outer to the most inner layer

A
  1. serosa
  2. longitudinal muscle (muscularis externa)
  3. circular muscle (muscularis externa)
  4. submucosa
  5. muscosa
    (6. lumen)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the structure and function of the serosa?

A

Structure: outer layer of tough connective tissue

Function: protects gut wall from friction from other organs in the abdomen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the structure and function of the muscularis externa?

A

Structure: the inner circular muscle has fibres in rings and the outer longitudinal muscle has fibres running lengthways

Function: responsible for waves of muscular contraction that makes food move along gut (peristalsis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the structure and function of the submucosa?

A

Structure: contains blood and lymph vessels and has a rich network of nerve fibres

Function: takes away absorbed food products and co-ordinates muscular contractions of peristalis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the structure and function of the mucosa?

A

Structure: lines the gut wall, stratified cells and contains goblet cells/other cells specialised for absorption

Function: secretes mucus to lubricate passage of food and protects gut from damage (protection)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the function of the liver?

A

secretes bile via the gall bladder and bile duct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is happening in the buccal cavity during digestion?

A
  • food is broken up into smaller pieces here by mastication
  • mechanical breakdown of food, food now called bolus
  • it is moistened by saliva which consists of…
    (aid in digestion)
    · water
    · mineral salts, maintain slightly alkali conditions fro amylase
    · mucus which acts as a lubricant for passage down oesophagus
    · lysozyme an enzyme which kills bacteria
    (chemical digestion)
    · salivary amylase
36
Q

What is another name for the digestive tract?

A

alimentary canal

37
Q

What is happening in the oesophagus during digestion?

A
  • the bolus moves to the stomach by a series of rhythmic contractions called peristalsis
  • peristalsis propels food along the gut, behind the bolus the circular muscles contract and the longitudinal muscles relax, helping move food along
38
Q

What is happening in the stomach to help digestion?

A
  • ridges called rugae to help with mechanical breakdown of food
  • has 3 thick layers of muscles to help contract and relax, grinding the food
  • muscles are found at the upper and lower ends of the stomach:
    · the cardiac sphincter relaxes at the upper end, allowing food to enter
    · the pyloric sphincter relaxes to allow food into the duodenum
  • 3 types of cell in the mucosa:
    1. Goblet cells - secrete mucus to protect stomach mucosa from enzymes and acid
    2. Oxyntic Cells
    3. Chief Cells
39
Q

What can the stomach absorb?

A

Simple chemicals: alcohol, aspirin, water and salts

40
Q

What is the role of oxyntic cells in the stomach?

A 
Aid in Digestion
Secretes HCl which...
- kills most bacteria in food
- provides optimum pH for enzymes 
- activates pepsinogen into pepsin
- gives stomach a pH value of 1-2
41
Q

What is the role of the chief cells in the stomach?

A

They secrete the endopeptidase enzyme pepsinogen (pepsin) which hydrolyses protein to polypeptides

42
Q

What is the role of the liver in helping digestion?

A
  • the liver produces bile which is then stored in the gall bladder where it can enter the duodenum via the bile duct
43
Q

How does bile aid in digestion?

A
  • emulsifies lipids into smaller droplets, increasing surface area of lipid droplets, increasing rate of digestion
  • aids in neutralising the stomach acid as it enters the duodenum with food
44
Q

What is the role of the duodenum during digestion?

A

Aids in digestion, Brunner’s glands in the submucosa of the duodenum secrete:

  • mucus (lubrication & protection)
  • alkaline juice which helps maintain the optimum pH for the functioning of the enzymes in this area
45
Q

What is the role of the duodenum/ileum during digestion?

A

Chemical digestion:
carbohydrate and protein digestion is completes by enzymes fixed in the membrane of the epithelial cells of mucosa/secreted by cells at the base of the villus
- maltose (hydrolyses maltose into 2 glucose molecules)
- dipeptidase (hydrolyses dipeptidases to amino acids)

46
Q

What is the role of the pancreas during digestion?

A

Exocrine glands in the pancreas secrete pancreatic juice, juice enters the duodenum via the pancreatic duct which contain the following enzymes (acting in the duodenum)

  • endopeptidases hydrolyse proteins into peptides e.g. trypsin, secreted as inactive trypsinogen which is activated by enterokinase
  • exopeptidases hydrolyse terminal ends of polypeptides into dipeptides
  • amylase hydrolyse starch into maltose
  • lipase hydrolyses lipids into fatty acids and glycerol
  • contains sodium hydrogen carbonate which raises pH of juice to neutralise stomach acid and providing appropriate pH for pancreatic enzymes to work in
47
Q

What do the lipid enzymes break down and where are the located in the alimentary canal?

A

Lipase
- secreted by the pancreas and enters the duodenum via the pancreatic duct
triglycerides -> glycerol + 3 fatty acids

48
Q

What do the carbohydrate enzymes break down and where are they located in the alimentary canal?

A
  • Amylase (salivary amylase works in buccal cavity and pancreatic amylase works in duodenum via pancreatic duct) hydrolyses starch -> maltose
  • Lactase (epithelial cells of duodenum) hydrolyses lactose -> glucose + galactose
  • Sucrase (epithelial cells of duodenum) hydrolyses sucrose -> glucose + fructose
  • Maltase (epithelial cells of duodenum & cells at base of villi) hydrolyses maltase -> glucose + glucose
49
Q

What do the protein enzymes break down and where are they located in the alimentary canal?

A
  • Pepsinogen is secreted by chief cells in the stomach. Activated by low pH (HCl) to become pepsin (endopeptidase) hydrolysing proteins -> peptides
  • Trypsinogen is secreted by the pancreas. It enters the duodenum via the pancreatic duct. It’s activated by enterokinase (pancreatic) to become trypsin (endopeptidase) hydrolysing proteins -> peptides
  • Exopeptidases (pancreatic) hydrolyse the terminal ends of polypeptides into dipeptides
  • Dipeptidases (ileum/duodenum) hydrolyse dipeptides into amino acids
50
Q

What are endopeptidases?

A

Endopeptidases work by hydrolysing the middle of a polypeptide

51
Q

Why proteases secreted as inactive enzymes?

A

The enzymes may digest proteins in the cell that has produced the enzyme itself

52
Q

What is meant by hydrolysis?

A

Addition of a water molecule to break a bond

53
Q

What are the adaptations of the ileum?

A
  • very long (around 5m)
  • folded lining
  • villi
  • microvilli (brush border) on each epithelial cell on villi
  • large surface area (from villi and microvilli)
  • epithelial cells contain many mitochondria as absorption is an active process
54
Q

What is the muscularis mucosa?

A
  • a thin layer of muscle, under the mucosa
  • smooth muscle which contracts for a long time without tiring
  • contractions move the villi for a greater contact with food so there is more efficient absorption
55
Q

Describe absorption generally in the ileum

A
  • monosaccharides, amino acid, fatty acids, glycerol minerals and vitamins are absorbed through plasma membrane of epithelial cells on villi
  • the fat soluble molecules are absorbed into the lacteals of the lymphatic system
  • water soluble molecules are absorbed into blood capillaries
  • all absorbed by passive, facilitated diffusion or active transport
56
Q

What happens to any undigested carbohydrates in ileum?

A
  • carbohydrate digestion produces monosaccharides
  • remaining disaccharides are absorbed by the plasma membrane of the epithelial cells and broken down into monosaccharides intracellularly
57
Q

Describe how glucose and amino acids cross the epithelial cells into capillaries in the villi (co-transport)

A
  • Na+ ions are actively transported out of the epithelial cells
  • This creates a low concentration of Na+ inside the cell
  • Na+ ions move into the epithelial cells from the ileum lumen by co-transport with either glucose or amino acid molecules
  • Then the glucose/amino acid moves by facilitated diffusion from a high concentration in the epithelial cell to a low concentration in the capillaries
  • blood carrying dissolved foods travels to the liver via the hepatic portal vein
58
Q

What is the fate of the absorbed food?

A

Glucose:
- absorbed from the blood by cells and used in respiration
- any excess glucose is converted to glycogen or fat for storage
Lipids:
- used to produce phospholipids in cell membranes, hormones and excess is stored as fat
Amino Acids:
- absorbed by cells for protein synthesis
- any excess can’t be stored and therefore is deaminated, amino group (NH2) removed and converted into urea fro excretion
- the remaining C H O is converted to carbohydrate and either respired or stored

59
Q

What the 4 main sections of the large intestine?

A

Caecum, Appendix, Colon and Rectum

60
Q

What is the function of the colon?

A
  • water and mineral salts are absorbed from the colon along with vitamins secreted by microbes living in the colon (these bacteria are responsible for making vitamin K and folic acid)
61
Q

What is the function of the rectum?

A
  • here the food is in a semi-solid state
  • consists of residues of undigested cellulose, bacteria and sloughed cells (dead)
  • it passes along the colon and is egested as faeces (this is called defecation)
62
Q

What are the types of teeth in a carnivore’s buccal cavity and what are their function?

A

Incisors -> grip and tear muscle from the bone
Canine -> pointed for piercing and seizing prey and large to tear muscle and kill
Molars and Premolars -> cut and crush food
Carnassials -> shear muscles off the bone

63
Q

What are the types of teeth in a herbivore’s buccal cavity and what are their function?

A

Incisors and horny pad -> cropping of the grass against horny pad and allows to slice through food
Diastema -> gap which allows tongue and cheeks to operate in this gap acting as a grinding surface
Premolars and molars -> grind down food

64
Q

Describe and explain the difference between the articulation of the lower jaw in dogs and sheep

A
  • carnivore jaws move vertically in order to dislocate prey so it won’t escape (a tight hinge)
  • herbivore jaws move from side to side as the food must be grinded down well before entering the stomach
65
Q

Suggest why the length of the gut in the carnivore is shorter than in a herbivore

A

Their diet is high in protein which is easy to digest whereas plant material is very difficult to digest

66
Q

What is meant by the term ‘ruminant’?

A

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

67
Q

What is meant by mutualism?

A

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

68
Q

What is the function of the oesophagus in ruminants (cow)?

A
  • The grass is chopped by teeth mixed with saliva and the cud is formed
  • The saliva contains urea to provide a nitrate source for bacteria
  • Food will pass back and forth between reticulum, rumen and mouth
69
Q

What is the function of the rumen in ruminants (cow)?

A
  • Chamber where food mixes with microbes that secrete enzymes converting cellulose to glucose
  • Then fermented to organic acids that are absorbed into the blood (energy source)
  • Waste products of CO2 and CH4 are released
70
Q

What is the function of the reticulum in ruminants (cows)?

A

Fermented grass passes to the reticulum and is reformed into cud which is regurgitated to the mouth several times

71
Q

What is the function of the omasum in ruminants (cows)?

A

Cud passes into the omasum, H2O and organic acids are made from fermented glucose, absorbed into the blood

72
Q

What is the function of abomasum in ruminants (cows)?

A
  • Considered the true stomach

- The protein is digested by pepsin at 2 pH (coverts proteins of symbolic cells into amino acids)

73
Q

Describe absorption of fat soluble molecules in the villi

A
  • The fatty acids and glycerol (as a monoglyceride) diffuse across the membrane of the epithelial cells.
  • Inside the cells they enter the SER and are recombined to form triglycerides.
  • They are packaged into vesicles along with phospholipids and cholesterol.
  • The lipids are transferred from the cells into the lacteals by exocytosis
  • The lacteal is a lymph capillary found in the centre of each villus, which leads into the lymphatic system, which opens into the bloodstream at the thoracic duct.
74
Q

The caecum is packed with bacteria, explain why this is necessary to ruminants

A

Mammals are unable to digest cellulose

Bacteria can secrete enzymes that hydrolyse cellulose into glucose which is in high concentration in their diet

75
Q

Why does refection sometimes occur

A

Doubles the exposure to cellulose digestion

76
Q

Why do cows not show refection?

A
  • cows have 4 stomachs
  • food is regurgitated for further grinding of the cud
  • additional stomachs are for bacterial fermentation (converting cellulose to glucose)
77
Q

What are some characteristics of tapeworms which are adaptations to their parasitic life?

A
  • possession of hooks
  • suckers
  • thick cuticle
78
Q

What is the one organ system that is absent by the tapeworm and explain how it survives without it?

A

Digestive system

- absorption of host nutrients over parasite’s body surface

79
Q

Name 2 features of tapeworm’s reproductive system and explain their importance

A
  1. Large numbers of embryos
    - high offspring mortality (difficult to reach a new host)
  2. Hermaphrodite, male and female organs present
    - fertilises its own eggs
80
Q

Why is the human digestion system divided into several regions?

A

Different parts carry out different functions

- different food groups digested in different areas

81
Q

What is meant by the term parasite?

A
  • an organism that lives in or on another organism
  • obtains products of digestion from host
  • host always suffers harm
82
Q

What is the benefit of the tapeworm living in the intestine?

A

It has the highest concentration of the products of digestion

83
Q

How do tapeworms overcome the problem of digestive enzymes?

A

Thick cuticle which secretes enzyme inhibitors

84
Q

Why do tapeworms produce a large number of eggs?

A

Increases chance of species survival

85
Q

How do hooks and suckers help survival of tapeworm?

A
  • Attaches the worm to the wall of the gut

- prevents it being egested (resists peralistis)

86
Q

State how the shape of the tapeworms body enables it to feed without a mouth or gut?

A

It is very long - gives a large surface area to absorb digested food

It is thin and flat - short diffusion for diffusion

87
Q

How does the tapeworm’s reproductive strategy help ensures its survival?

A
  • hermaphrodite so it can fertilise itself
  • it lays a large number of eggs
  • eggs can overcome adverse conditions

A-Level EDUQUAS Biology (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions