Component 3 - Nutriton Flashcards
How do unicellular organisms consume food e.g amoeba
- Amoeba pseudopodia move around prey and enclose it in a food vacuole
- Enzymes are released from lysosomes that fuse with the food vacuole and the prey is digested
- Products of digestion are absorbed into the cytoplasm and the undissolved waste is egested by exocytosis
Describe the gut of a hydra - single food source
Undifferentiated, sac-like gut with a single opening
Describe the gut of an earthworm - varied foods
A tube gut with different openings for ingestion and egestion and specialised regions for the digestion of different food
Describe the gut of a Human - Omnivorous diet
Specialised regions of gut. The wall of the gut contains the
following layers
List the different layers of the gut from the outside to the inside
- Serosa
- Longtitudinal Muscle
- Circular Muscle
- Sub Mucosa
- Mucosa
- Epithelium
What is the Serosa layer
Tough outer coat of connective tissue
What do the circular and longtitudinal mucles do
Longitudinal muscle contracts to shorten the gut
circular muscle contracts to reduce diameter.
These waves of contraction called peristalsis force food along the gut.
What does the submuosa layer do
Contains blood and lymph vessels to remove digested food products
What does the mucosa layer do
Inner layer that secretes mucus for lubrication. In some areas it secretes digestive juices; in others it absorbs products.
What does the epithelium layer do
Layer of cells in contact with food
What is autotrophic nutrition and what are the two types
makes complex organic molecules from simple inorganic ones
* Photoautotrophic
* Chemoautotrophic
What is Photoautotrophic nutrition
Use light as a source of energy for synthesis of
food
What is Chemoautotrophic nutrition
Oxidise inorganic molecules to provide energy for the synthesis of food
What is Heterotrophic nutrition and what are the two types
consume complex organic food molecules
* Saprophytic
* Holozoic
What is Saprophytic Nutrition
External digestion of food using secretion of enzymes followed by absorption of the products of digestion into the organism, e.g. fungi.
What is Holozoic nutrition
internal digestion of food. Involves ingestion, absorption, assimilation and egestion
What are the two types of proteases
Endopeptidase
Exopeptidase
What do endopeptidases do
endopeptidases hydrolyse peptide bods between specific amino acids in the middle of the polypeptide chain to form shorter polypeptide chains
What do exopeptidases do
Exopeptidases hydrolyse peptide bonds on the end of peptides, from the free amino end or the free carboxyl end
What happens at the buccal cavity
Mechanical digestion
* The tongue moves food to the cutting
and grinding surfaces of the teeth
* The tongue rolls the food into a bolus which is swallowed
Chemical digestion
* Starch and glycogen into maltose by the enzyme amylase. Saliva moistens food and also maintains the pH for the enzyme
What does the Oesophagus do
Peristaltic waves of muscle contraction push the bolus of food down to the stomach
Mucus lubricates the way
What does the Stomach do
- 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 or peptic cells produce pepsinogen, the inactive precursor of the endopeptidase enzyme, pepsin
- This is activated by the HCl
- Goblet cells produce mucus to protect the stomach lining
What does the Stomach do
- 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 or peptic cells produce pepsinogen, the inactive precursor of the endopeptidase enzyme, pepsin
- This is activated by the HCl
- Goblet cells produce mucus to protect the stomach lining
- Churns Food
What does the Liver do
- Produces bile.
- Bile emulsifies lipids to increase the surface area available for lipase enzymes to digest them.
- It neutralises stomach acid to create a slightly alkaline pH in the duodenum for the pancreatic enzymes
What does the Gall Bladder do
stores the bile before delivering it to the duodenum via the bile duct.
What does the pancreas do
Produces enzymes that are transported to the duodenum via the pancreatic duct
* Carbohydrase - pancreatic amylase
* Protease – trypsinogen activated into the endopeptidase Trypsin by enterokinase in the duodenum
* Pancreatic lipase enzymes digest triglycerides into monoglycerides and eventually glycerol and fatty acids
What does the duodenum do
further digestion occurs on the epithelial cells of the villi.
* Sucrose digested by sucrase into glucose and fructose.
* Maltose digested by maltase into alpha glucose.
* Lactose digested by lactase into glucose and galactose.
* Further digestion of polypeptides by endopeptidases and exopeptidases.
What is the structure of a villus
On the outside, there are columnar epithelial cells. On the inside, there are capilliaries and lacteals .
What type of diet are carnivores adapted to
High Protein Lipid Energy diet
What are the features of the dentition of Carnivores
- Incisors on upper and lower jaw grip and tear flesh
- Canines – long and pointed to pierce flesh and seize and kill prey
- Carnassial teeth - act like shears, sliding past each other to rip muscle from bone
- Premolars and molars - have sharp cusps that cut and crush. The jaw has strong muscles and moves in a vertical plane to hold prey
How is a carnivore’s gut adapted to it’s diet
- Relatively short gut
- Usually a large stomach for digestion of mostly protein diet
- Small caecum
What diet is a herbivore adapted to
A high Cellulose diet
What are the 2 types of Herbivores
- Ruminants
- Non Ruminants
How is a herbivore’s dentition adapted to it’s diet
- Incisors – on lower jaw and cut vegetation against a horny pad on the upper jaw. Canines absent or indistinguishable
- Diastema – space where tongue can push food to the grinding cheek teeth
- Premolars and molars – cheek teeth. Fit together. Jaw moves in a horizontal plane so teeth grind food. Teeth have open, unrestricted roots and so grow throughout life
How is a non-ruminant gut adapted to it’s diet
- Very long gut for the difficult process of cellulose digestion
- Large caecum containing bacteria that produce cellulase for cellulose digestion
What is the main example of a Ruminant Gut
A cow
How is a cow’s gut (ruminant) adapted to it’s diet
- Mouth - Grass is mixed with saliva and then chewed (forming cud) before being swallowed
- Rumen - Cud enters the rumen. Bacteria produce cellulase, breaking down cellulose into glucose. This ferments into organic acids which are absorbed. Produces greenhouse gasses
- Reticulum - Fermented cud enters the reticulum. The cud is regurgitated from here and the rumen back into the mouth to be rechewed
- Omasum - Rechewed cud is swallowed and enters the Omasum Water absorption occurs here
- Abomasum - Protein Digestion
- Small Intestine - Digested products absorbed into the blood
What is a Parasite
Live on or in a host organism, obtaining their nutrition from the host and harming the host
What is an ectoparasite
Lives on the surface of another organism
What is an Endoparasite
lives inside another organism
What is an example of an ectoparasite and how is it adapted
The head louse feeds by sucking blood from the scalp of the host.
* It has claws to hold onto the hairs.
* Lays eggs which are glued to the base of hairs.
* Transfer between hosts is by direct contact as it cannot jump, only crawl
Give an example of an endoparasite and how it’s adapted
The adult pork tapeworm (Taenia solium) lives in the gut of humans.
1. Primary host – a larval form develops in
pigs.
2. Secondary host – infection of humans
occurs when a person eats pork containing
live larval forms (tapeworm cysts in muscle
tissue).
The gut is a hostile environment due to the
presence of various secretions and peristalsis.
The tapeworm has adapted to living in the
gut as follows:
* Thick cuticle produces anti-enzymes.
* Scolex to attach to the gut wall.
* Taenia solium has a reduced gut and feeds by absorbing pre-digested nutrients through its cuticle.
* To increase the chances of infecting a secondary host, it produces large numbers of eggs that pass out in shit
