2.4 - adaptations for nutrition

Question 1

What is nutrition?

Answer 1

the process by which organisms obtain energy to maintain life functions and matter to create and maintain structure
obtained from nutrients

Question 2

Autotrophic organisms?

Answer 2

such as green plants use the simple materials carbon dioxide and water to synthesise their organic requrirements

Question 3

Autotrophs?

Answer 3

living organisms that can make their own food
they provide food for all other life forms and so they are known as producers

Question 4

2 types of autotrophic nutrition?

Answer 4

photosynthesis

chemosynthesis

Question 5

Photosynthesis?

Answer 5

process by which green plants build up complex organic molecules such as sugars, from carbon dioxide and water
source of energy comes from sunlight which is absorbed by chlorophyll and accessory pigments
algae and certain types of bacteria can also photosynthesise using energy from sunlight

Question 6

Chemosynthesis?

Answer 6

a process carried out by autotrophic bacteria
they use the energy derived from special methods of respiration to synthesise organic food

Question 7

heterotrophic nutrition?

Answer 7

cannot make their own organic food
they have to consume complex organic food material produced by autotrophs
known as consumers - since they consume ready made food
all animals = consumers and are dependent on producers for food

Question 8

Types of heterotrophic nutrition?

Answer 8

holozoic feeders

Question 9

holozoic feeders?

Answer 9

this includes nearly all animals
they take their food into their bodies and break it down by digestion
most carry out process within a specialised digestive system
digested material is absorbed into the body tissues and used by the body cells

Question 10

Animals that feed on?

Answer 10

plant - herbivores
other animals - carnivores
decaying / dead material - detritivores

Question 11

Saphtrophtes?

Answer 11

group = saprobionts
include all fungi and some bacteria
they feed on dead or decaying matter and do not have a specialised digestive system
feed by secreting enzymes such as proteases, amylases,lipases and cellulases to food material outside the body and then absorb soluble products across the cell membrane by diffusion
known as extracellular digestion

Question 12

What are called decomposers?

Answer 12

microscopic saprophytes
and their activities are important in the decomposition of leaf litter and the recycling of valuable nutrients such as N or C

Question 13

Mutualism?

Answer 13

known as symbiosis - involves a close association between members of 2 different species, where both species derive from the relationship
for example cows and sheep feed mainly on grass, made of cellulose cell walls
cows and sheep do not secrete cellulase and so cannot digest cellulose
insead have mutualistic bacteria which live in the ru,em
bacteria produces enzymes for them and in return the bacteria gain other digestive products and suitable conditions for growth

Question 14

Parasotedef?

Answer 14

organism that lives in or on another organism, gaining nourishment at the expense of the host
some live in the body endoparasites
some live on surface
ectoparasites

Question 15

Parasitism?

Answer 15

host always suffers harm to some degree and often death
they are considered to be very highly specialised organisms and show considerable adaptations to their particular way of life
e.g tapeworm , head lice, potato blight cased by fungus
plasmodium - malarial parasite

Question 16

Commensalism?

Answer 16

association between 2 species - 1 benefits
other one - either harmed or benefits

Question 17

Holozoic nutrition?

Answer 17

feeding on solid organic matter
involves 5 main processes
Ingestion
Digestion
Mechanical
Chemical
Absorption
Assimilation
Egestion

Question 18

Ingestion?

Answer 18

act of eating, taking food into gut where can be processsed

Question 19

Digestion?

Answer 19

breakdown of large biological molecules in food into smaller constituent moleucules

Question 20

Mechanical digestion?

Answer 20

by chewing action of jaws and teeth
and also the churning action of the stomach wall

Question 21

Chemical digestion?

Answer 21

as a series of hydrolytic reactions in different regions of the gut
each regions has its own specific types of enzymes

Question 22

Absorption?

Answer 22

any useful digested products and other soluble substances are transported across the gut lining into the bloodstream and lymph

Question 23

Assimilation?

Answer 23

absorbed digested food are transported by the bloodstream to the body cells
these molecules = used in respiration to build new cells or cell structures or simply stored for future use

Question 24

Egestion?

Answer 24

the removal of indigestible material in the form of faeces from the gut to the anus

Question 25

Excretion?

Answer 25

removal of metabolic waste
urea

Question 26

Human alimentary canal?

Answer 26

tubular passage divided into different regions where different processes take place
main parts =
mouth
tongue
pharynx
oesophagus
stomach
small intestine
large intestine
rectum
anus
other organs ourside alimentary canal also contribute to the process of digestion by secreting digestive juices into thealimentary canal through the ducts
includes salivary glands, pancreas and liver

Question 27

Bile?

Answer 27

digestive secretion of the liver = stored in the
gallbladder before passes to the small intestine

Question 28

Structure of alimentary canal?

Answer 28

epithelial tissue lines the lumen of the gut
tissue = glandular secreting the chemicals into the gut lumen to ease the passage of food or to help with the process of digestion
type of secretion with the gut region
in some regions, only mucus is secreted, whereas in other regions mucus and enzymes are secreted

Question 29

4 layers of alimentary canal?

Answer 29

Mucosa
Submucosa
Muscularis externa
Serosa

Question 30

Mucosa?

Answer 30

nearest layer to the lumen
inner surface = thin epithelium
Epithelium contains goblet cells , which secrete mucus to lubricate and protect the cells from abrasion by food and from hydrolysis by digestive enzymes
However, epithelium still parts of the mucosa, is a layer of connective tissue and beneath that is a thin layer of smooth muscle, = muscularis mucosa
sooth muscle = attached to the skeleton - is not under voluntary control
able to contract slowly and rhythmically for long periods of time without tiring

Question 31

Submucosa?

Answer 31

made of connective tissue within which blood vessels and nerves
connective tissues contains high proportion of collagen and elastin

Question 32

Muscularis externa?

Answer 32

made up of smooth muscle
muscle = arranged in 2 band
one of which fibres lie lengthwise along wall
( longitudinal muscle )
one of which they lie around the wall
( circular muscle )
contraction and relaxation of these muscles move the food through the alimentary canal by peristalsis and also help to mix the food within the canal and with various secretions
by means of churning movements

Question 33

serosa?

Answer 33

thin layer of connective tissue that makes up the outer layer of the wall

Question 34

Vili?

Answer 34

highly folded structures
which increase the surface area for digestion and absorption
all parts of the gut contain longitudinal and circular muscles which propel food along alimentary canal by peristalsis
takes approx 12 hours for food to travel entire length of gut, although time can vary depending on persons diet
e.g fatty diet, extends time considerably

Question 35

peristalsis def?

Answer 35

wave of rhythmic contraction

Question 36

Digestion?

Answer 36

process starts in the mouth
food = bitten and chewed using teeth
while chewing, food = mixed with saliva from salivary glands
saliva consists mainly of water and mucoproteins which lubricate food
also contains buffers to moderate effects of acids in foods, antibacterial agents to kill some bacteria before they enter the stomach
amylase hydrolyses starch to maltose
food = lubricated and moulded into a rounded ball, a bolus by the muscular tongue before being swallowed
food = delivered rapidly to the stomach by contractions of longitudinal and circular muscles in oesophagus
entry of food into stomach = controlled by cardiac sphincter ,a ring of smooth muscle which relaxes when food = swallowed

Question 37

Somach?

Answer 37

highly muscular wall and elastic organ which expands easily to hold a large meal
stomach = highly folded and dotted with pits leading to gastric glands which secretes gastric juices
presence of food in mouth stimulates secretion of gastric juices from gastric glands in stomach lining

Question 38

What do gastric juices consist mainly of?

Answer 38

Mucus - from goblet cells
HCl - from oxyntic cells
Pepsinogen - from chief cells

Question 39

Pepsinogen?

Answer 39

inactive precursor of protease enzymme pepsin
converted to active form by HCl acid in the stomach
Pepsin = endopeptidase, breaks down large polypeptide chains into smaller polypeptide chains by hydrolysing peptide bonds within polypeptide chain
by secreting enzyme in an inactive form, this prevents damage to protein containing cells lining stomach
( self digestion or autolysis)

Question 40

Prorennin?

Answer 40

important in young mammals
Precursor of enzyme rennin which catalyses the conversion of the soluble milk protein caseinogen to casein which = insoluble
this causes milk to coagulate and helps to keep the milk in the stomach for longer and allows more complete digestion

Question 41

Mechanical breakdown?

Answer 41

also occurs within the stomach by continual churning movements of muscular stomach wall
this also helps to mix food with the gastric juices
combination of mechanical and chemical digestion in the stomach reduces the food into a uniform creamy paste called acid chyme

Question 42

How long does food remain in the stomach?

Answer 42

for about 4 hours, after which the pyloric sphincter relaxes and regulates the flow of acid chyme into the duodenum of the small intestine

Question 43

Duodenum?

Answer 43

receives acid chyme from the stomach and secretions from the
gallbladder and the pancreas
duodenum = a site of intense chemical activity where all 4 types of macromolecules
( carbohydrates, fats, proteins + nucleic acids = digested by specific hydrolytic enzymes with the help of the other substances)

Question 44

What does the protease enzymes in the duodenum include?

Answer 44

endopeptidases and exopeptidases

Question 45

endopeptidases?

Answer 45

hydrolyse peptide bonds within the polypeptide chain
resulting in the formation of smaller polypeptide fragments

Question 46

exopeptidases?

Answer 46

hydrolyses peptide bonds at the terminal ends of the polypeptide chain, releasing individual amino acids

Question 47

Hydrogen carbonate ions?

Answer 47

are secreted by the pancreas and by the Brunner’s Glands in the duodenum
they neutralise the acidic pH of the acid chyme as it enters the duodenum and provides the optimum pH for he activity of the enzymes in the small intestine

Question 48

Bile?

Answer 48

produced by the liver cells, emulsifies large globules of fat into tiny droplets
increasing the surface area of the fats for the activity of lipase enzymes

Question 49

Ileum?

Answer 49

second part of the small intestine and is the most important site of absorption in the gut
has a structure that is highly suited to its function
intestinal wall = highly folded, giving it a large surface are
finger like projections called villi
villi + microvilli form the brush border and further add to the surface area available for absorption
epithelial cells - large number of mitochondria which provides energy required for active transport of nutrients that need to be absorbed against a conc gradient

Question 50

Each villi?

Answer 50

has good blood supply to carry sugars, amino acids, minerals and other water soluble substances to the liver
laceals (branches of the lymphatic system )
transport fat soluble substances

Question 51

triglycerides?

Answer 51

hydrolysed to fatty acids and glycerol and pass into lacteal where they recombine to form neutral fat
lymphatic system returns the products of fat digestion to the main circulation ( along with any excess tissue fluid_
at the thoracic duct, where it drains into the subclavian vein

Question 52

How are glucose and amino acids absorbed across the epithelium of the villi?

Answer 52

by a combination of diffusion and active transport and pass into the capillary network that supplies each villus

Question 53

What are excess glucose and other monosaccharides converted to?

Answer 53

fat and stored as adipose tissue

Question 54

excess amino acids?

Answer 54

deaminated in the liver as body is unable to store excess nitrogen
remaining keto acid can either be converted to respiratory intermediate and respired ot converted to fat and stored

excess lipids are also converted to fat and stored

Question 55

Large intestine?

Answer 55

after most nutrients have been absorbed in small intestine
intestinal contents ( faeces)
pass slowly along large intestine

Question 56

Function of large intestine?

Answer 56

reabsorb water into bloodstream, making faeces less bulky

failure to do so would result in individual becoming badly dehydrated with potentially fatal consequences

large intestine is also where vitamins such as vitamin k and folic acid = secreted by microorganisms are also reabsorbed

Question 57

Dentition?

Answer 57

teeth are important in the mechanical digestion of food,
Chewing food is important as it makes it easier to swallow and increases the surface area for enzyme action
Humans = omnivores, as they eat both plant and animal material
teeth = not specialized but having 4 different types of teeth to carry out different function reflects a mixed diet

Question 58

What are the teeth for Humans?

Answer 58

32 teeth
8 chisel-shaped incisors at the front of the mouth for biting and cutting
4 pointed canines that function as incisors
10 large flat teeth on each side used for chewing
these are premolars and molars

Question 59

Dentition in herbivores?

Answer 59

plant food is a tough material and the teeth of herbivores are modified to ensure that it is thoroughly ground up before it is swallowed
Grazing herbivores e.g cows or sheep have incisors on the lower jaw only and cut against a horny pad on the upper jaw
canine teeth = indistinguishable from the incisors
gap called diastema separates front teeth from side teeth or premolars
tongue operates in this gap moving the freshly cut grass to the large grinding surfaces of the cheek teeth
jaw move in circular grinding action in a horizontal plane
cheek teeth interlock like the letter W fitting into the letter N
with time, grinding surfaces become women down, exposing the sharp-edge enamel ridges which further increases the efficiency of the grinding process
teeth have open, unrestricted roots so they can continue to grow throughout the life of the animal

Question 60

Dentition in carnivores?

Answer 60

have teeth adapted for catching and killing prey,cutting or crushing bones and for tearing meat
sharp incisors grip and tear flesh from bone
Canine teeth - large,curved and pointed for seizing prey, for killing and also tearing fresh
premolars and molars are for cutting and crushing
carnivores have a pair of specialized cheek teeth called carnassials which slide past each other like the blades of gardening shears
Jaw muscles = well developed and powerful and enable the carnivore to group the prey firmly and help in crushing bone
there is no side to side movement of the jaw
as this would lead to the jaw being dislocated when dealing with prey
Vertical jaw movement = greater than inherbivores, allowing jaw to open widely for capturing and killing prey

Question 61

Cellulose digestion?

Answer 61

Herbivores all share the commonproblem that the nutrient content of their food is low and a high proportion of it is difficult to digest
this is due to the large amount of cellulose in their diet
If maximum value = to be derived from plant food, cellulose must be digested
requires the enzyme cellulase, a powerful carbohydrate which breaks beta glycosidic links and so splits cellulose into its consituent monosaccharides

Variety of microorganisms are able to secrete cellulase so can fungi which use it to dissolve cell walls so a to penetrate the cells
but apart from this cellulase is really rare so is practically unheard of in the animal kingdom

Mammals cannot produce cellulase themselves and yet so many of the meat and milk producers, such as cattle, sheep, goats and camels have herbivores and cellulose is certainly digested in their guts
cellulose is also digested in other herbivores such as horses and rabbits

Question 62

Ruminants?

Answer 62

they have a specialised stomach or rumen in which mutualistic bacteria live
mutualism involves a close association between members of 2 different species and where both organisms derive some benefit from the relationship
Herbivorous mammals such as cows and sheep lack the ability to produce cellulase enzymes and so cannot digest cellulose
In this association, the mammal acquires the products of cellulose digestion and the bacteria receive a constant supply of food and can grow in a suitable sheltered environment

Question 63

What does the cow provide?

Answer 63

a region of the gut for the bacteria to inhibit and in return the bacteria digest the cellulose for the cow

Question 64

Why does he region of the gut must be kept separate from the main digestive system?

Answer 64

food can be kept there long enough for the bacteria to carry out the digestion of the cellulose
the bacteria are isolated from the mammal’s own digestive juices so they are in optimum pH for their activities and they are not killed by extremes of pH

Question 65

How many chambers does Ruminants have?

Answer 65

4
rumen reticulum and omasum - derived from lower partof esophagus and 1 chamber - the abomasum = true stomach

Question 66

Process of celllulose digestion?

Answer 66

grass = chopped by the teeth, mixed with copious amounts of saliva and the crud formed = swallowed
In the rumen, the cud is mixed with cellulose digesting bacteria to produce glucose, this is fermented to form organic acids that are absorbed into the blood and provides energy for the cow. the waste products = carbon dioxide + methane that are passed out from both ends of the digestive tract
The cud passes to the next region before being regurgitated into the mouth and chewed again
the cud passes directly into the third chamber where water is reabsorbed. the fourth and final chamber functions like a normal stomach and protein is digested
digested food passes to the next region, the small intestine, where the products of digestion are absorbed

Question 67

how are the ruminants more efficient?

Answer 67

in terms of nutrients extracted from cellulose than other herbivores
the rumen contains a greater variety of mutualistic organisms than the caecum and they are able to achieve a more complete breakdown of cellulose
Another advantage in ruminants is that the rumen is the first chamber located before the main region of enzyme production so that when the bacteria die they pass through this region with the food and form an important source of protein to the organism

Question 68

Non Ruminants?
Horses + Rabbits

Answer 68

non ruminant herbiverous mamals also posess fermentation chambers where microorganisms digest cellulose
In horses and rabbits, they are caecum and appendix - a blind ending diverticulum of the gut situated at the junction of the small and large intestines

Question 69

What is the disdvantages of having a fermentation chamber near the end of the gut?

Answer 69

food cannot be regurgitated and the producs of digestion cannot be efficiently shunted forwards into the small intestine for absorption to take place

Question 70

How do rabbits and hares make up for this deficiency?

Answer 70

The first are soft and are eaten directly from the anus, a phemenin known as coprophagy.
Soft faeces contain significant amounts of digested food which is absorbed as it passes through the gut a second time
If rabbits are prevented from eating their soft feaces as they show signs of nutritional deficiency
the second type of faeces is the familiar form of hard pellets which are dropped and contain relatively little food material

Question 71

What are parasites?

Answer 71

organisms that live on ectoparasite or in endoparasite another organism called the host and obtain the nourishment at the expense of the host

Question 72

What are plants paratised by?

Answer 72

bacteria, fungi,viruses, nematodes,insects+ mites

Question 73

What are bacteria parasitized by?

Answer 73

bacteriophages

Question 74

Multicellular parasites?

Answer 74

made up of more than a single cell and are relatively complex organisms

Question 75

Examples of endoparasites?

Answer 75

tapeworms, flukes and roundworms cause disease directly and are highly specalised to live inside their hosts

Question 76

Examples of ectoparasites?

Answer 76

insects and arachnids

Question 77

Morehighly developed parasites?

Answer 77

have more than one host speciies as this greatly increases its chance of survival
If host dies, then so does the parasite
However, transferring to another host is a chance process and many parasites cannot survive outside the body of its host
therefore there is a need to produce a vast number of eggs

Question 78

Head louse

Answer 78

known as pediculus
it is an ectoparasite feeding on blood but can live for short periods away from the body
Affects only humans and cannot be passed on to or caught from animals
They are tiny wingless insects which feed by sucking blood from the scalp
Has a short life cycle and reproduces rapidly with numbers increasing alarmingly if not treated
eggs = nits and are laid glued to the base of hairs
Insects have adapted to grasping and attaching to the fine hairs of the head by having clawws on the end of their legs
they are able to walk from 1 hair to another and are transferred by close hair to hair contact
Symptoms = itching of the scalp
Intesticidies for treating head lice are available as lotions, liquids or cream rinses and are very effective

Question 79

Pork tapeworm?

Answer 79

human gut parasite also known as taenia solium
all animals have a struggle to survive to avoid competition with others and to avoid being preyed upon by other animals
Tapeworm is ribbon like and can be up to 10 m long
head made up of muscle on which there are suckers and hookers
Body consists of a linear series of thin segments
Pork tapeworm has 2 hosts
primary host = human and pig = the secondary host
pig becomes infected if it feeds in drainage channels contaminated by human faeces
Humans are infected by eating undercooked infected pork
Althoough tapeworm lives in an immediate source of food if it needs to survive the hostile environmental conditions found in the gut

Question 80

Whar are the problems that the gut parasite has to overcome in order to survive?

Answer 80

It lives surrounded by digestive juices and mucus
Food, mixed with digestive juices, is in constant motion as it is churned about us being propelled along the length of the gut by peristalic contractions of the muscular wall
Lives in extreme conditions of pH along the length of the gut
Immune system of the host
If the host dies then so does the parasite

Question 81

Adaptations for survival?

Answer 81

have a means of penetrating the host
have a means of attachment to the host
protect itself against the immune response of the host
Develop only those organs that are essential for survival
produce many eggs
have an intermediate host
have resistant stages to overcome the period away from the host

Question 82

Adaptations of parasitic way of life?

Answer 82

Sucker sand a double row of curved hooks for attachment to the wall of the gut
A body covering which protects it from the host’s immune response
A thick cuticle and production of inhibitory substances on the surfaces of the segments to prevent digestion by the host’s enzymes
because it lives in a stable environment it does not need to move around and does not require a sensory system
this has led to the degeneration unnecessary organs
it does have a simple excretory and nervous system but most of the body is concerned with reproduction
tapeworm = thin and has large surface area to volume ratio
has a very simple digestive system as pre digested food can be absorbed over the entire body surface

Question 83

The gut cannot accommodate 2 tapeworms?

Answer 83

each segment conrain borh male and female reproductive organs
vast numbers of eggs are produced with each mature segment containing up to 40,000 eggs
mature segment containing up to 40,000 eggs
mature segments pass out of the hosts body with the faeces
eggs have resistant costs and coats and can survive until eaten by the secondary host
further development can then take place and the embryos which hatch from the eggs move into the muscles of the pigs and remain dormant until the meat of the pig = eaten by a human

Question 84

Harmful effects of the tapeworm?

Answer 84

The adult worm causes little discomfort but if the eggs are eaten by humans, dormant embryos form cysts in various organs and damage the surrounding tissues
Adults can be treated with appropriate drugs
Public health measures and frequent inspection of meat are essential measures