2.4 - adaptations for nutrition Flashcards
1
Q
what are the two main types of nutrition?
A
- autotrophic
- heterotrophic
2
Q
what is autotrophic nutrition?
A
organisms which can synthesise complex organic compounds from simple inorganic molecules
3
Q
what is an autotroph?
A
a producer ( do not need to eat/consume as creates their own organic compounds
4
Q
what is an example of an autotrophic reaction?
A
photosynthesis - creating complex organic compunds (sugars) from simple inorganic compounds like co2
5
Q
what are the two types of autotrophic bacteria?
A
- photosynthetic bacteria
- chemosynthetic bacteria
6
Q
what is cheomsynthetic bacteria?
A
- synthesise organic compounds from inorganic materials in the absence of light
- uses energy from special methods of respiration to synthesise organic foods
- important example is nitrifying bacteria in the nitrogen cycle
7
Q
what is photosynthetic bacteria?
A
- uses a pigment called bacteriochlorophyll
- uses light as driving force for photosynthesis
- gets its hydrogen not from water but from hydrogen sulphide
8
Q
what is a heterotroph?
A
- cannot synthesise their own food
- have to consume complex organic food material produced by autotrophs
9
Q
what are some exmaples of heterotrophs?
A
animals, fungi, bacteria
10
Q
what are the four types of heterotrophic nutrition?
A
- holozoic feeders
- saprophytes
- parasites
- mutualism
10
Q
what is a holozic feeder?
A
- almost all animals
- takes food into body and digests it via digestion
- specialised digestive system
- the digested materials are absorbed into the body tissues and then used by them
11
Q
what are some exampels of holzic feeders?
A
herbivore
carnivore
omnivores
12
Q
what is a saprophyte?
A
- all fungi/bacteria
- feed on dead/decaying matter
- feed via secreting digestive enzymes and then absorb the soluble products aby diffusion across the cell membrane (extracellular digestion)
- these can be decomposers
13
Q
what is a parasite?
A
- lives in/on another living organism and causes harm to the host by feeding on it
- some parasites can live inside the host and others on the surface
- e.g. tapeworm
14
Q
what is mutualism?
A
- clsoe relation between members of two different species, both derive benefit from the relationship
- (e.g. cows and gut bacteria - cows cannot digest cellulose and therefore have a mutualistic relationship with bacteria in the gut, so it digests it for them, which allows the bacteria to grow)
14
Q
A
15
Q
what is the gut?
A
long, hollow, muscular tube
16
Q
how is the gut specialised?
A
- large insoluble, organic molecules must be broken down by digestion and absorbed into the body tissues here
-movement of content in one direction only - can be specialised to have different components where digestion occurs
17
Q
how is nutrition in unicellular organisms?
A
- unicellular organsims have no gut and engulf the food particles using a pseudopodia (food vacuole)
- lysosomes fuse with food vacuole an secrete digestive enzymes this is INTRACELLULARLY
17
Q
what is the gut like in an earthworm?
A
- tube-like gut –> opening at both ends
mouth for ingestion
anus for egestion - each region is specialised for its specific function
18
Q
what is hydra?
A
- multi-cellular
- sac-like gut
- mouth is the only opening and secretes digestive enzymes into the lumen of the gut
- digested food is absorbed through the gut wall
19
Q
what is the human guts regions?
A
- buccal cavity
- teeth
- salivary glands on the tongue
- oesophagus
- stomach
- liver
- duodenum
- pancreas
- ileum
- colon
- rectum
- anus
20
Q
what is peristalsis?
A
- where food gets propelled along the gut in waves of muscular contractions, pushing the food along the oesphagus and the tube gut
- behind the bolus the circular muscles contract, longitudinal relax
21
Q
what is ingestion?
A
- taking food into the body through the mouth
22
what is mechanical digestion?
cutting/crushing action of the teeth followed by rhythmical contractions of the gut
the gut wall has layers of muscles which contract and relax which are responsible for mixing of food with enzymes and peristalisis
23
what is chemcial digestion?
- the breakdown of large insoluble molecuels into small soluble molecules using enzymes
24
what is absorption?
- the passage of digsted food through the gut wall into the blood
25
what is egestion?
the elimination of undigested food from the body (fibre)
26
what are the five tissue layers surrounding the gut?
- serosa (outer)
- longitudinal muscle
- circular muscle
- sub-mucosa
- mucosa
- epithelium (inner)
27
what is the serosa made of?
- consists of a tough outer connective tissue that protects the wall of the gut and reduces friction from other organs in the abdomen as the gut moves during digestion
28
what is the role of the sub-mucosa?
- connective tissues, containing blood vessels to take away the absorbed food
- contains nerves to coordinate the muscular contractions
28
what are the longitudinal/circular muscles?
these together cause the waves of muscular contractions, peristalsis which propels food along the gut
29
what is the role of the mucosa?
- innermost layer and lines the wall of the gut, it secretes mucus to lubricate and protect the mucosa
30
what is the role of the epithelium in the gut?
- outermost layer of cells of the mucosa
- makes direct contact with the food of the lumen and secretes substances into the lumen
31
what is the role of the glands?
produce many secretions which often contains digestive enzymes
32
what are the three glands found in the gut?
- large glands with secretions that lead to the gut
- glands in the sub-mucosa
- glands in the mucosa
33
what is an examaple of the glands in the sub-mucosa?
- glands secretes mucus into the eduodenum
34
what is an example of a gland that leads to the gut?
- salivary glands with secrete saliva in the mouth
- liver secretes bile into the duodenum
- pancreas secretes pancreatic juice into the duodenum
35
what is an examaple of the glands in the mucosa?
- gastric glands in the stomach secrete gastric juice into the stomach
36
what is the duodenum?
the uppermost part of the small intestine
37
what is the ileum?
- the lower part of the small intestine
38
how are carbohydrates broken down?
carbohydrates broken down into disaccharides then into monosaccharides
39
how does starch get absorbed by the gut?
- starch gets hydrolysed by amylase to form maltose
- maltose is hydrolysed by maltase to form glucose
- glucose can be absorbed by the gut
40
what is the protein-digesting enzyme during digestion?
**peptidase** breaks polypeptides into dipeptides, --> amino acids
40
what are the two varients of peptidase?
endopeptidase - hydrolyse a polypeptide chian into a smaller polypeptide chain
exopeptidase - hydrolyses peptide bonds at shorter polypeptide chains releasing amino acids FROM THE TERMINAL END
41
what enzyme breaks down lipids?
lipase breaks down fats to form glycerol and fatty acids
42
what occurs in the mouth?
mechanical digestion - chewing of food via the teeth moistened by salivary glands and saliva
- the saliva contains amylase enzyme which breaks down starch into maltose
- this forms a bolus as the saliva binds the food together
- bolus is pushed down the oesophagus by peristalsis
(prevented from entering the trache by epiglottis)
43
what occurs in the stomach?
- wide sack like structue
- ring of muscular sphincter controls the entry of food into the stomach
- gastric glands produce gastric juices which contains hydrochloric acid giving the stomach a pH of 2
- the pH of 2 is optimum for stomach enzymes and kills bacteria in food
- the **gastric juice** contains pepsin enzyme which hydrolyse proteins into polypeptides
- muscles of stomach contract rhymically and mix food with gastric juices
- mucus lines the stomach wall which forms a protective barrier against the acid and enzymes as well as lubriacting/assisiting the movement of food in the stomach`
44
what are the three specialised cells in the gastric gland?
- goblet cell (produces mucus)
- oxyntic cells (produces hydrochloric acid)
- peptic cells (produces inactive pepsinogen to be activated by the hydrochloric acid to form pepsin which is an endopeptidase)
45
what secretions are in the duodenum?
- **bile from the liver:**
- bile *salts* emulsifies large globules of lipids to break into small lipid droplets
- this allows the enzyme lipase to work more effectively as the lipid droplets have a larger surface area
- actual bile neutralises acidity of food from the stomach
- **pancreatic juice from pancreas:**
- contains endopeptidase (trypsinogen) - hydrolyses proteins into peptides
- contains amylase - breaks down starch into maltose
- contains lipase - hydrolyses lipids into fatty acids and glycerol
- brunner glands aswell - optimises pH
46
where is bile stored and transferre?
bile is stored in the gall bladder
bile is transferred to the duodenum via the bile duct
47
how does pancreatic juices enter the duodenum?
the pancreatic duct
47
what happens in the duodenum?
- recieves the secretions from the bile duct and pancreatic duct
- secretes mucus and alkaline juice: this is to keep the pH the optimum for the enzymes and for lubrication/protection
- enzymes are secreted from the duodenums villi ( maltase and end/exopeptidase )
therefore end products are monosaccharides
48
how is the ileum adapted for absorption?
- very long so has a large surface area
- has villi
- on surface of villi are microvilli which increase the surface area
- the microvilli prodcue digestive enzymes at its base to complete digestion
48
what are the crypts of lieberkuhn?
at the base of villi, contains the epithelial cells
49
what membrane do epithelial cells sit on?
basement membrane
50
what cells line the microvilli?
epithelial cells which requires lots of ATP to actively transport absorption of products
51
what is the structure of the villus?
- epthelial cells
- lacteal ( lymph vessel)
- capillary
52
how do the villi absorb products?
- diffusion and active transport passes the products into the capillary network, the blood eventually reaches the hepatic portal vein and carried to the liver
53
what gets absorped by the villi into the lacteal?
fatty acids and glycerol
54
what is the structure of the walls of the ileum?
- villus
- goblet cells ( mucus secreting )
- blood capilaries
- epithelial cells
- muscular layer
55
how are dipeptides absorped?
- actively transported into and requires ATP
- often digested intracellularly
- diffuses into the blood in the capillaries
56
how are glucose and amino acids absorped?
- actively transported into and requires ATP
- diffuses into the blood in the capillaries
57
how are vitamins and fatty acids/glycerol absorped?
diffusion
58
what gets absorped in the large intestine?
water and mineral salts
59
whats the purpose of the large intestine?
- semi-solid state by the time the indigestible food reaches the rectum and is defected
60
how are lipids used in the body?
used for cell membranes
excess stored as fat and as an insulator
61
how is glucose used in the body?
used for energy release in respiration
excess stored as fat
62
how are amino acids used in the body?
- used for protein synthesis
- excess converted into urea in the liver
63
what do mammals have in their mouth which helps with food chewing?
palate which separates the air pathway from the mouth, allows food to be retained (chewed) in mouth rather than swallowed whole
64
what are the four types of teeth?
incisors
canines
premolars
molars
65
whats the function of the incisors?
chisel shaped for gripping and cutting
66
whats the function of the canines?
- pointed for tearing flesh
67
whats the function of the premolars/molars?
flats for chewing and grinding
68
what is the structure of a herbivores mouth?
- incisors for cutting on the lower jaw only
- diastema ( gap between incisors and molars)
- molars/premolars at the back
69
what is the purpose of the diastema in herbivores? and the chewing motion?
-tongue operates in the gap to move freshly cut grass to the large grining surfaces of the molars/premolars
- jaw moves in a circular grining action in a horizontal plane
70
what is the purpose of a herbivores open, unrestricted roots in their teeth?
- continue to grow throughout the life of an animal
71
what are a carnivores teeth characterised by?
- sharp incisors for tearing grip flesh/tear flesh
- canines are curved, large for seizing prey
- premolars/molars are for cutting and crushing
- carnassials slide past eachother like blades
72
what are the differences between a herbivores dentiton and a carnivores dentition?
herbivore - incisors for cutting in the lower jaw only
carnivore - incisors for tearing flesh on the upper and lower jaw
herbivore - canines and incisors are the same
carnivore - large curved canines for seizing and piercing the prey
herbivore - lower jaw moves from side to side
carnivore - jaw moves vertically to open wide
herbivore - diastema present
carnivore - no diastema
herbivore - (pre)molars have a large grinding surface and sharp ridges
carnivores - molars have cusps
herbivore - weak jaw as food will no escape
carnivore - strong jaw muscles to grip moving prey
herbivore - molars have an open rot system and get worn down to grow
carnivore - molars do not get worn down
72
what is the jaw movement in carnivores?
- vertical jaw movement as otherwise the jaw would be dislocated when dealing with prey
- easier to capture prey
73
what is a herbivores gut characterised by?
- long, as cellulose (in plant cell walls) is difficult to digest it gives it more tim eot be digested
- cellulose gets hydrolysed by cellulase and it is called bacterial fermentation ( the cellulase gets produced by bacteria for cellulose to be broken down) - CARBOHYDRATE
bacterial fermentation occurs in the **caecum**
73
what is a carnivores gut characterised by?
- short, as proteins are easy to digest
74
what is an omnivores gut characterised by?
gut of intermediate length, due to mixture of meat and plant food
75
what is a ruminant?
- mainly eat grass and forage
- specialised stomach/rumen in which the mutualistic bacteria live (to help digest cellulose)
76
what is another term for the pork tapeworm?
taenia solium
76
what are the steps of digestion in a ruminant?
- grass is cut by teeth, mixed with saliva - CUD is formed and swallowed
- in the rumen, the cud is mixed with cellulase to produce glucose, then fermented to form acids that get absorbed in the blood
- it is then chewed in the mouth again after passing the reticulum
- water is then absorbed in the third stomach (omasum)
- proteins are digsted in the last stomach (abomasum)
- then to the small intestine
76
what is a parasite?
organisms that live in/on another organism, called the host
- parasites obtain nourishment at the hosts expense
76
why must the caecum be kept seperate in ruminants from the main digestive tract?
- food containing cellulose must be kept there longer for the mutualistic bacteria to work
- kept at an optimal pH for their activities
76
what must the tapeworm do the survive?
- have a means of penetrating the host
- have a means of attaching to the host
-protect itself against the hosts immune system
- produce eggs
- have an intermediate host
- peristalsis
76
where does the tapeworm live?
- lives in the gut of other animals mianly pigs and humans
76
what must the tapeworm overcome to survive in the gut?
- digestive juices and enzymes
- constant churning of food in the gut to mix with enzymes
- extremes of pH
- hosts immune system
- the host to keep living
77
how has the pork tapeworm adapted to its environment?
- suckers and a double row of curved hooks to attach to the guts wall
- thick waxy cuticle and produces anti-enzymes to prevent being digested
- removal of unnecessary organs - only reproductive organs
- very thin and large surface area
- has male and female reproductive organs - lots of eggs are produced to ensure reproduction
- eggs have resistant shells which can survive until eaten by the host
78
what are the steps to infection in a pork tapeworm?
- tapeworm eggs in the feces are passed into the environment
-eggs are ingested by pigs/humans
- the egg embryos hatch and penetrate the intestinal wall and enter the muscles
- embryos develop in the muscles of pigs/humans
- humans then eat the infected pig meat
- the tapeworm theen attaches intself to the intestine via its double row of curved hooks
- then adult tapeworms are in the small intestine
78
what are the effects on humans of a tapeworm?
- adult worms can cause little discomfort
- can form cysts in organs and damage tissues
78
how are tapeworms treated?
often by appropriate drugs and inspection of meat
79
what is a pediculus? what are the varients?
louse which affects humans
pedicures humanus humanus - infects the body
pediculus humanus capitis - infects the scalp
80
what are ectoparasites and endoparasites?
ectoparasites - parasites live on organism
endoparasites - parasites live in organism
80
how do headlice spread?
head-to-head contact
81
how do headlice feed?
biting the scalp and feeding on the blood
82
what are stages of life of a headlice?
- 1-2 weeks the egg hatches into a nymph
- empty eggs are seen on scalp as nits
- nymphs become adults after 10 days
- these suck blood form the hosts scalp
83
how do headlice lay eggs?
it has claws to hold onto the hairs
and lays eggs which are glued to the base of hairs
84
describe protein digestion in a herbivore?
stomach - makes pepsin - hydrolyses the peptide bonds in polypeptides to form shorter amino acid chains
pancreas - endopeptidase is made - breaks the polypeptide chain down into shorter ones
small intestine - peptidase completes the protein digestion into amino acids, which gets absorbed by the blood
85
where is trypsin secreted
pancreas
86
in what form is trypsin secreted
trypsinogen
87
why is trypsin secreted as inactive trypsinogen
the surrounding organs are made of protein and trypsin is a protease so it must be inactive so as not to digest them
88
what activates trypsin
enterokinase
89
where is enterokinase secreted
Brunner's glands
