Term
| What is the mode of nutrition for Amoeba? |
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Definition
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Term
| How do Amoeba take nutrients such as O2 and glucose? |
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Definition
Diffusion
Active Transport
Facilitated Diffusion |
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Term
How do Amoebas take in large food molecules?
(4 marks) |
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Definition
Via endocytosis
The food is surrounded by membranes, forming a vacuole.
The vacuoles fuse with lysosomes
Digest the contents
Products are absorbed into the cytoplasm |
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Term
| How are indigestible remains egested by amoebas? |
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Definition
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Term
| What does the tentacles of the hydra do? |
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Definition
Move the paralysed prey in through the mouth
In a sac-like hollow body cavity where it is digested |
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Term
| How are productes egested in hydra? |
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Definition
| They are absorbed into body cells and the indigestible remains are egested through the mouth |
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Term
| Hydra only have a single opening in their digestive system and a cavity called...? |
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Definition
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Term
| Why must food be digested? |
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Definition
-Insoluble and large to cross membrane and be absorbed into the bloodstream
-Polymers must be converted to their monomers, so they can be rebuilt into molecules needed by body cells. |
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Term
| What are the four main functions of the human gut? |
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Definition
1. Ingestion-taking food into the body by mouth
2. Digestion-breakdown of large insoluble molecules into soluble small enough to be absorbed into the bloodstream;
Two types;
Mechanical: cutting and crushing by teeth, peristalsis
Chemical: breakdown using digestive enzymes. Bile and HCl
3. Absorption- passage of small soluble molecules and ions through the gut wall into the blood
4. Egestion-the elimination of indigestible waste |
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Term
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Definition
Wave of muscular contractions and relxations of the gut wall which propel the contents along the whole lenght of the gut
Circular muscles contract and relax
Dietary fibre aids peristalsis in the intestines |
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Term
| What is the function of the mouth? |
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Definition
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Term
| What is the function of the oesophagus? |
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Definition
| Carriage of food to the stomach by peristalsis |
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Term
| What is the function of the stomach? |
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Definition
| Contraction of stomach muscles to churn up the food- mechanical digestion. Secretion of HCl, chemical digestion of proteins by enzymes. |
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Term
| What is the function of the duodenum? |
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Definition
| Receives pancreatic juice from the pancreas and bile from the gall bladder. Chemical digestion of carbohydrates, fats and proteins by enzymes |
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Term
| What is the function of the ileum? |
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Definition
Chemical digestion of carbohydrates, fats and proteins by enzymes.
Absorption of digested food |
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Term
| What is the function of the large intestine? |
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Definition
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Term
| What is the function of the rectum? |
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Definition
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Term
| What is the function of the anus? |
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Definition
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Term
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Definition
| Contains tough connective tissue which protects the gut wall, helps reduce friction with other abdominal organs during peristalsis |
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Term
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Definition
Two layers;
Inner circular and outer longitudinal muscles
Make coordinated waves of contraction (peristalsis), pushing bolus along the alimentary canal |
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Term
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Definition
| Connective tissue containing blood and lymph which remove the absorbed products of digestion. Also contains nerves which coordinate peristalsis |
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Term
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Definition
| Inner most layer, epithelium secrets mucus which lubricates and protects the mucosa. In some regions of the gut, it secrets digestive juices and in others it absorbs digested food |
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Term
| Starch is broken down into maltose by...? |
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Definition
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Term
| Maltose is broken down into glucose by..? |
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Definition
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Term
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Definition
| Proteins that hydrolyse peptide bonds within the protein molecule e.g. pepsin and trypsin |
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Term
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Definition
| Proteins that hydrolyse peptide bonds at the end of shorter polypeptide chains to make amino acids/dipeptides |
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Term
| Fats are broken down into fatty acids and glycerol by...? |
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Definition
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Term
| What happens in the mouth? |
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Definition
Mechanical digestion- food mixed with saliva and chewed.
This increases S.A. of food for enzymes to work on |
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Term
| What does saliva contain? (3 marks) |
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Definition
-Amylase
-Bicarbonate ions create an optimum pH for amylase
-Mucus which lubricates the food
- |
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Term
| What is the role of the oesophagus? |
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Definition
| Connects buccal cavity to the stomach |
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Term
| What does the gastric juice contain? (3 marks) |
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Definition
*Mucus-secreted by goblet cells it forms a protective lining on the stomach walls against the digestive enzymes and HCl and helps lubricate food
*HCl-lowers pH to pH2 for enzymes and kills bacteria
*Pepsin-secreted as inactive pepsinogen-works optimally in acidic environments- activation by HCl forms active pepsin |
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Term
| Why are enzymes secreted in an inactive form? |
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Definition
| As active form would digest the protein in the stomach wall |
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Term
| What are the two regions that the stomach consists of? |
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Definition
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Term
| Where does the duodenum receive secretions from? |
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Definition
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Term
| What happens to the food in the duodenum? |
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Definition
| Lubricated by mucus and HCl neutralised by NaHCO3 from cells in sub mucosa |
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Term
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Definition
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Term
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Definition
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Term
| How is it passed into the duodenum? |
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Definition
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Term
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Definition
| Bile salts which are hydrophilic and hydrophobic |
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Term
| What do the bile salts do to lipids? |
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Definition
| They emulsify them and break up large globules into smaller droplets increasing S.A. for lipase action |
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Term
| What is bile and what does it do? |
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Definition
| Is alkaline and neutralises acid in food coming from stomach creating an optimum pH environment for enzymes in the small intestine |
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Term
| What does pancreatic secretion release? (4 marks) |
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Definition
Endopeptidase
Trypsinogen
Amylase
Lipase |
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Term
| What is function of endopeptidase? |
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Definition
| Hydrolyses protein into shorter polypeptides |
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Term
| What is the function of trypsinogen? |
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Definition
| Inactive enzyme converted into the endopeptidase trypsin by enterokinase |
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Term
| What is function of amylase? |
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Definition
| Chemically digests any remaining starch into maltose |
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Term
| What is the function of lipase? |
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Definition
| Hydrolyses lipids into fatty acids and glycerol |
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Term
| What are the two duodenal secretions? |
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Definition
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Term
| What is the function of NahCO3? |
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Definition
| Raises the pH to make pancreatic juice more alkaline |
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Term
| What is the function of enterokinase? |
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Definition
| An enzyme that converts trypsinogen in trypsin |
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Term
| How is the ileum adapted for absoption? |
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Definition
-Very long
-Its lining is folded
-On the surface of the folds are villi
-Epithelial cells lining the villi have microvilli |
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Term
| What are the two specialised cells in the mucosa of the ileum? |
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Definition
1. Columnar epithelial cells
2. Goblet cells |
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Term
| Whta is the function of columnar epithelial cells? (2 points) |
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Definition
Microvilli providing a large S.A. for absorption of the products of digestion
Large number of mitochondria to rpoduce ATP energy for active transport |
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Term
| What is the function of goblet cells? |
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Definition
| Secrete mucus which lubricates the food and protects the lining of the intestine |
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Term
| What does the lymph capillary does? |
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Definition
| Absorb fatty acids and glycerol |
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Term
| Where are endo/exopeptidases secreted from? |
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Definition
| By cells at the tips of the villi |
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Term
| What happens to protein once secreted into the gut lumen? |
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Definition
Continue digestion of polypeptides
Dipeptides are hydrolysed to amino acids by enzymes on cell membranes of the epithelial cells |
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Term
| What are lipids used for? (3 points) |
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Definition
| Energy storage, protection of vital organs, thermal insulation under the skin |
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Term
| What are amino acids used for? (2 points) |
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Definition
| Used in protein synthesis, excess deaminated in the liver |
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Term
| What is glucose used for? (2 points) |
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Definition
Respiration to produce ATP energy
Excess stored as glycogen |
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Term
| What is the large intestine divided into? 4 points |
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Definition
| Caecum, appendix, colon and rectum |
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Term
| What substances are absorbed in the L.I.? 3 pts |
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Definition
H2O
Mineral ions
Vitamins produced by symbiotic bacteria in the gut like vitamin K and folic acid |
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Term
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Definition
| The process by which organisms obtain energy to maintain life functions and matter to create and maintain structure |
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Term
| What is autotrophic nutrition? |
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Definition
| Organisms that synthesise their own organic molecules using light or chemical energy |
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Term
| What are photoautotrophic organisms? |
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Definition
| Use energy from sunlight to carry photosynthesis to make their own organic molecules from inorganic molecules |
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Term
| What are chemoautotrophic organisms? |
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Definition
| Use energy from chemical reactions to synthesise organic molecules |
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Term
| What are heterotrophic organisms? |
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Definition
| Cannot produce their own organic molecules so obtain complex organic molecules from other organisms. |
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Term
| What is holozoic nutrition? |
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Definition
| They ingest food, digest it and egest indigestible remains |
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Term
| What do detritivores feed on? |
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Definition
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Term
| What is saprotrophic nutrition? |
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Definition
| All fungi and some bacteria, feed on dead or decaying organic material |
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Term
| What is extracellular digestion? |
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Definition
Enzymes are secreted
Absorb soluble products of digestion |
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Term
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Definition
| Saprotrophes that decay leaf litter and recycling nutrients such as nitrogen |
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Term
| What is the definition of parasite? |
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Definition
| Live in or on another organism and obtain nourishment at the expense of the host. Cause harm or death |
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Term
| What are the two types of parasites? |
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Definition
Endo/Ectoparasites
Endo-lives in the host
Ecto-lives on the host |
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Term
| What are the 4 different types of tooth and their functions? |
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Definition
Incisors-biting and cutting food
Canines-Tearing and ripping meat
Molars and pre molars- grinding and chewing food |
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Term
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Definition
Animals that mainly eat grass and forage so they are unable to digest cellulose as they don't produce cellulase.
They have 4 chamber stomach
Bacteria live in the rumen |
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Term
| Why is the caecum enlarged in rabbits? |
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Definition
| To accomodate cellulose digesting bacteria |
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Term
| Whta happens in on-reminant herbivores? |
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Definition
| Refection occurs, rabbit ingests faecal pallets so that the material passses through the gut twice to increase efficiency of digestion |
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