C3: Adaptations for nutrition Flashcards
Define autotroph
An organism that synthesises its own complex orgnic molecules using either light or chemical energy
Define Heterotroph
An organism that obtains complext organic molecules from other organisms
Describe the two different autotrophic organisms
Photoautotroph - use light as the energy source and perform photosynthesis. this is called holophytic nutrition
Chemoautotroph - use energy from chemical reactions all orokaryotic and this is not sufficient so not dominant.
Desscribe three different types of heterotrophic nutrition
Saprophytic- Organisms that derive their energy from the extracellular digestion of dead or decaying material by secreting enzymes. They absorb the soluble products of digestion across their cell membrane by diffusion and active transport.
Holozoic – internal digestion of food. Involves ingestion, absorption,
assimilation and egestion.
Parasitic - endoparasites live in the organism ectoparasites live on it. They obtain nutrients from the living host which harms the host.
Describe the process of digestion in an unicellular organism like amoeba
They have a large SA and obtain all nutrients by diffusion, facilitative diffusion and/or active transport
They take in larger molecules by endocytosis.
The food are in vesicles which combine with lysosomes which break down the food molecules.
The waste products of this digestion are egested by exocytosis
Describe each layer of the human gut
Serosa - Tough outer coat of connective tissue.
Muscle - Longitudinal muscle contracts to shorten the gut and circular muscle contracts to reduce diameter. These waves of contraction called peristalsis force food along the gut.
Submucosa - Contains blood and lymph vessels to remove digested food products.
Mucosa - Inner layer that secretes mucus for lubrication. In some areas it secretes digestive juices; in others it absorbs products.
Epithelium - Layer of cells in contact with food.
Name 11 parts of the human digestion system and associated glands and organs
Buccal cavity (mouth)
Oesophagus
Stomach
liver
duodenum
Pancreas
ileum
Colon
Rectum
Anus
Describe the role of the buccal cavity in digestion
3 points
Ingestion (cutting and grinding of food by the teeth)
Chemical digestion of startch into maltose by amylase in saliva which is excreted by the salivary glands.
saliva (slightly alkaline) maintains pH for enzyme activity
The tounge rolls food into a bolus so it can be swollowed
Describe the role of the oesophagus in digestion
peristaltic waves of muscle contraction (longditudinal and cicular muscle) push the bolus of food down
to the stomach. Mucus lubricates the way
Describe the role of the stomach in digestion
3 points
gastric glands in the mucosa
produce gastric juice:
The Oxyntic cells produce hydrochloric acid (HCl) that kills bacteria and lowers the pH to 2.
The chief cells produce pepsinogen, the inactive form of endopeptidase/ pepsin. This is activated by the
HCl.
The goblet cells produce mucus to protect the stomach lining.
Describe the role of the Liver in digestion
Produces bile ( stored in the Gall bladder). Bile emulsifies lipids
to increase the surface area available
for lipase enzymes to digest them.
It also neutralises stomach acid to
create a slightly alkaline pH in the
duodenum for the pancreatic
enzymes.
Describe the role of the pancreas in digestion
Secretes an alkaline fluid called pancreatic juice.
Pancreatic juice consists of enzymes such as Tripepsinogen(activated by enterokinase, carbohydrases and lipase
Describe the role of the duodenum in digestion
Further digestion occurs on the epithelial cells of the villi:
Sucrose digested into glucose and fructose by sucrase
Maltose digested into alpha
glucose by maltase.
Lactose digested into glucose
and galactose by lactase.
Further digestion of polypeptides by
endopeptidases and exopeptidase.
State the difference between endopeptidase and exopeptidase
endopeptidases hydrolyse peptide bods between specific amino acids in the middle of the polypeptide chain to form shorter polypeptide chains.
Exopeptidases hydrolyse peptide bonds on the end of peptides, from the free amino end or the free carboxyl end.
Describe the role of the illeum in absorption
They have villi and microvilli for a large SA they also have a good blood supply and epithelial cells have a large amount of mitochondria to provide ATP for active transport.
Absorption mainly occurs here by diffusion, facilitative diffusion and active transport Eg:
Amino acids are actively transported into the epithelial cells of the villi; facilitated diffusion then occurs into the capillaries in the villi.
Glucose and other monosaccharides move into epithelial cells by co-transport with sodium ions;
facilitated diffusion then occurs into the capillaries in the villi.
Fatty acids and glycerol diffuse into epithelial cells and are reassembled into triglycerides and carried
by the lacteal to the lymphatic system.
