3.3 - adaptations for nutrition Flashcards
define autotrophic
- organisms that produces its own food
- manufactures complex organic compounds from simpler inorganic molecules such as water + CO2
name the 2 types of autotrophic organisms
- photoautotrphic
- heteroautotrphic
what’s a photoautotrophic organism
organisms that obtains nutrition through photosynthesis
what’s a chemoautotrophic organism
organism that obtains nutrition through inorganic molecules, such as sulfur, in absence of light
define heterotrophic
organism that can’t produce its own food
obtains energy by feeding on organic compounds produced by other organims
what’s a saprotroph
organism that feeds by extracellular digestion
e.g: fungi
describe extracellular digestion by saprotrophs
- release enzymes that catalyse breakdown of dead plant + animal material into simper organic matter
- absorbs products of digestion
what’s meant by the term holozoic
describes a heterotrophic organism that internally digests food substances
what processes does holozoic nutrition involve
- ingestion
- digestion
- absorption
- assimilation
- egestion
define ingestion
process by which organisms take food into their bodies
define digestion
process by which large, insoluble molecules broken down into smaller, soluble molecules that can be absorbed across cell membranes
name the 2 types of digestion
- mechanical digestion
- chemical digestion
what’s mechanical digestion
- type of digestion that involves physically breaking down food into smaller features
- increases total SA for chemical digestion
what’s chemical digestion
type of digestion that involves breaking down large, insoluble molecules into smaller, soluble molecules using enzymes
what’s assimilation
synthesis of biological compounds from absorbed simpler molecules
define absorption
movement of useful substances into bloodstream
define egestion
removal of undigested waste material from body
describe how unicellular organisms obtain nutrients
- ingestion via phagocytosis
- intracellular digestion (using hydrolytic enzymes) breaks down large, insoluble molecules into smaller, soluble molecules
- products of digestion pass into cytoplasm by diffusion + active transport
- undigested material removed by exocytosis
what’s a hydra
small, multicellular, freshwater organism of phylum Cnidaria
describe the structure of hydra
- basic, undifferentiated sac-like gut
- single opening, surrounded by tentacles, that serves as mouth + anus
- single gut cavity (enteron)
outline process of digestion in hydra
- hydrolytic enzymes secreted into enteron by endodermis
- extracellular digestion partially digests food molecules
- partially digested food transported, via phagocytosis, into endodermal cells where intracellular digestion takes place
- undigested material egested from enteron via single opening
describe shape of gut in more complex organisms
tube like w/ 2 openings
mouth for ingestion
anus for egestion
what type of diet is human hut adapted to
omnivorous diet consisting of plant + animal material
state the names of the different layers of the gut wall
- epithelium
- mucosa
- submucosa
- muscle layer
- serosa
what’s the epithelium
single layer of cells that line gut wall
describe the structure of the mucosa layer of the gut wall
- mucous membrane lining gut wall
- contains glands that secret digestive enzymes, mucus, + acid/alkaline liquid that provides optimum pH
describe the structure of the sub-mucosa layer of the gut wall
- layer of connective tissue below mucous membrane
- contains blood vessels + lymph for transport of digestion product + glands that secret an alkaline fluid
describe the muscle layer of the gut
layer of circular + longitudinal muscles beneath the submucosa
explain the action of circular + longitudinal muscles in peristalsis
contraction of circular muscle behind bolus of food + relaxation of longitudinal muscle in front forces food down gut
what’s the serosa
tough, protective layer that surrounds gut
what’s the buccal cavity
oral cavity through which food enter the body
which types of digestion take place in the buccal cavity
mechanical digestion + chemical digestion of starch
what’s the normal pH range of the buccal cavity
pH 6.5 to 7.5
what’s the function of teeth
crush + grind food into smaller pieces, increasing SA
what’s the tongue
muscular organ in buccal cavity that’s vital in chewing + swallowing of food
describe the function of salivary glands
secret amylase, mineral ions + mucus into buccal cavity
what’s the function of the oesophagus
carries food from buccal cavity to stomach by peristalsis
describe the processes that take place in the stomach
mechanical digestion (mixing + grinding) + chemical digestion of protein
what type of glands are found in the stomach
gastric glands
describe the function of gastric glands
secrete endopeptidases, hydrochloric acid + and alkaline mucus into stomach
what’s the normal pH of the stomach
pH 2
what’s the role of the liver
secretes bile into small intestine via gallbladder + bile duct
describe the composition + function of bile
- consists of bile salts + and alkaline fluid
- neutralise stomach acid, providing ideal pH for lipase
state the 2 main divisions of the small intestine
- duodenum
- ileum
what’s the duodenum
first section of small intestine where proteins + lipids are hydrolysed
what’s the ileum
second section of small intestine that serves as main site of absorption of products of digestion
what’s the normal pH range of the small intestine
pH 7 to 8
what’s the pancreas + where is it located
large gland situated behind stomach
describe the role of the pancreas
secretes enzymes + an alkaline fluid into duodenum via pancreatic duct
what’s the large intestine also called
colon
describe the function of the colon
reabsorbs water + minerals from waste materaial
what’s the rectum
segment o large intestine that stores faeces prior to egestion
which enzymes are involved in carbohydrate digestion
where are they found
- amylase in saliva + pancreatic juice
- maltase, sucrase, lactase on membrane of epithelial cells of small intestine
what are the substrates + products of carbohydrates
- amylase hydrolyses starch to maltose
- maltase hydrolyses maltose to alpha-glucose
- sucrase hydrolyses sucrose to glucose + fructose
- lactase hydrolyses lactose to glucose + galactose
what’s the optimum pH of amylase
pH 8
which enzymes are involved in protein digestion
what are their roles
endopeptidases - hydrolyse non-terminal peptide bonds within protein to form smaller peptides
exopeptidases - hydrolyse terminal peptide bonds of protein to form dipeptides + amino acids
give examples of endopeptidases
- trypsin
- pepsin
describe how trypsin is produced
- secreted by pancreas as inactive trypsinogen
- enter kinase converts inactive trypsinogen into active trypsin in duodenum
name the inactive form of pepsin
pepsinogen
where is pepsinogen secreted from
gastric glands
describe how inactive pepsinogen is converted into its active form, pepsin
hydrochloric acid converts inactive pepsinogen into active pepsin
where are lipids digested
small intestine
what must happen before lipids can be digested
must be emulsified by bile salts produced by liver
- breaks down large fat molecules into smaller, soluble molecules called micelles, increasing SA
how are lipids digested
lipases hydrolyse lipids into monoglycerides, fatty acids + glycerol
where are lipases found
in pancreatic juice
state the processes by which absorption takes place in ileum
- simple diffusion
- facilitated diffusion
- active transport
- osmosis
which molecules are absorbed by simple diffusion in ileum
monoglycerides, fatty acids + glycerol
why can monoglycerides, fatty acids + glycerol be absorbed via simple diffusion
are non-polar molecules so can easily diffuse across membrane of epithelial cells
what happens to monoglycerides, fatty acids + glycerol once absorbed into cells
are reformed into triglycerides, absorbed into lacteals + transported via lymphatic system into blood
how are amino acids absorbed from lumen of gut
va active transport into epithelial cells + then into bloodstream by facilitated diffusion
which molecules rely on co-transport from lumen of gut into cytoplasm of epithelial cells
glucose + other monosacchrides
explain how sodium ions are involved in co-transport
actively transported out of cell into lumen, creating diffusion gradient
nutrients then taken up into cells along with Na+ ions
how do monosaccharides pass from epithelial cells into bloodstream
via facilitated diffusion
what are herbivores
animals that only eat plants
describe the adaptations of herbivores to a high cellulose diet
- long gut
- loose articulation of lower jaw
- horny pad on upper jaw
- specialised dentition for grinding tough plant material
describe how dentition of herbivores is adapted to its diet
- small, flat incisors on lower jaw for cutting grass against upper horny pad
- diastema between incisors + premolars - separates fresh grass from cud + enable manipulation of food by tongue
- premolars + molars have large SA + sharply rigged biting surfaces for grinding plant material
what are ruminants
mammals that digest plant material slowly in specialised four-chambered stomach + regurgitate it to chew is again, enabling efficient breakdown of fibre
name the 4 chambers of the ruminant stomach
- rumen
- reticulum
- omasum
- abomasum
describe the rumen
first stomach of ruminant
contains mutualistic bacteria that are able to hydrolyse cellulose into glucose
what’s a carnivore
animal that preys on + eats other animals
describe the adaptations of carnivores to high protein diet
- short gut
- powerful jaw muscles
- specialised dentition for cutting + tearing meat
describe how dentition of carnivore is adapted to its diet
- sharp incisors to remove flesh from bone
- large, pointed canines required to grow + kill prey
- sharp carnissals (modified premolars + molars) to slice + shear meat
- molars w/ sharp, flattened edges to crush bone
what’s a parasite
organism that live on/in host + takes nourishment at expense of other organism
name the 2 types of parasites
- ectoparasites
- endoparasites
what are ectoparasites
give examples
parasites living on host
e.g: head louse
what are endoparasites
give examples
parasites living in host
e.g: pork tapeworm
how does head louse feed + transfer from one host to another
- feeds by sucking blood from hosts scalp
- transfer between hosts by direct contact
where does pork tapeworm live
primary host - adult tapeworm lives in human gut
secondary host - larval form can develop in pigs
how can humans + pigs become infected by pork tapeworm
- humans become infected by consuming undercooked pork (containing larval forms of tapeworm)
- pigs may become infected by ingesting contaminated faeces
how does pork tapeworm feed
absorbs pre-digested nutrients in gut through cuticle
how is pork tapeworm adapted to living in gut
- thick cuticle
- secretes anti-enzymes that prevent its digestion by host enzymes
- scolex has strong suckers + hooks for attachment to gut wall
- long, thin body proves large SA:V for absorption
