Adaptations for nutrients Flashcards
What is an autotroph?
An organism that synthesises its own complex organic molecules from simpler molecules using either light or chemical energy.
What is an heterotroph?
An organism that obtains complex organic molecules from consuming other organisms.
Describe what parasitic nutrition is:
Means obtaining nutrition from another living organism (host). Endoparasites lives inside the host, ectoparasites live on the surface.
What is a saprotroph?
An organism that derives energy and raw materials for growth from the extracellular digestion of dead or decaying material.
What is Holozoic nutrition?
Feeding method of many animals which involves the processes of ingestion, digestion, absorption, assimilation and egestion.
Describe nutrition is unicellular organisms:
They obtain all nutrition through diffusion, facilitated diffusion or active transport across the membrane. However larger molecules are taken in by endocytosis (into food vacuoles, which fuse with lysosomes, and its digested by lysosomal enzymes). The products are either absorbed into the cytoplasm or the indigestible material is egested by exocytosis.
Describe nutrition in multicellular organisms using the example of the Hydra:
Hydra lives in fresh water. When hungry it will extend its tentacles and when a small organism brush against the tentacles, their stinging cells will discharge and paralyse the prey. The tentacles move the prey through its mouth and into the hollow body cavity. Enzymes like protease and lipase are released to digest the organism extracellularly, the products of digestion is absorbed into cells. Some of the endodermal cells are phagocytic and engulf the food particles. indigestible remains are egested through the mouth.
Give two reasons why food must be digested:
- Insoluble and too big to cross through the cell membranes
- They are polymers and must be converted into monomers so it can be rebuilt into molecules needed by body cells
What are the four functions of the Gut (describe)?
- Ingestion: Taking food into the body through the mouth
- Digestion: Breaking down large insoluble molecules into soluble molecules so that it can be absorbed into the blood (Via Mechanical or Chemical digestion)
- Absorption: Passage of molecules and ions through the gut wall into the blood
- Egestion: Elimination of waste not produced by the body, including food that cannot be digested
What are the functions of the following?
1. Stomach
2. Duodenum
3. Ileum
4. Colon
5. Rectum
6. Anus
- digestion of protein
- digestion of carbohydrates, fats and proteins
- Digestion of carbs, fats, proteins and absorption of digested food and water
- Absorption of water
- Storage of faeces
- Egestion
Describe where the serosa is in the gut wall and what its function is:
Outermost layer, tough connective tissue. The gut wall moves whilst processing food and the serosa reduces friction with other organs.
Describe where the two muscle layers are in the gut wall and what their function is:
Outer longitudinal muscle= Behind the ball of food, it relaxes
inner Circular muscle= Contracts
These work together to make coordinated waves of contraction (peristalsis)
Describe where the submucosa is in the gut wall and what its function is:
Connective tissue after the circular muscle, containing blood and lymph vessels, which remove absorbed products of digestion and nerves that co-ordinate peristalsis.
Describe where the mucosa is in the gut wall and what its function is:
After submucosa. Innermost layer. its epithelium secretes mucus, lubricating and protecting the mucosa.
What does gastric juice contain, and where are these substances secreted from?
Peptidases= secreted by zymogen cells, at the base of the gastric pit. pepsinogen is an inactive enzyme that is activated by H+ ions to pepsin (an endopeptidase)
Hydrochloric acid= secreted from oxyntic cells, lowers the ph of the stomach contents providing optimum ph for enzymes and kills bacteria in food.
Mucus= secreted by goblet cells, at the top of the gastric pit. the mucus protects the stomach wall from the enzymes and lubricates the food.
What allows partially digested food from the stomach into the duodenum?
Relaxation of the pyloric sphincter
Where is bile made, stored and passed though and into?
Made in liver, stored in gallbladder, passes through bile duct into the duodenum.
Explain why bile is useful:
-Contains bile salts which are amphipathic, helping to emulsify lipids by lowering surface tension and breaking up large globules, increasing the surface area which allows for more efficient use of lipase.
-Bile is alkali and neutralises the food from the stomach, providing suitable ph for enzymes in small intestine.
Where is pancreatic juice secreted from, enter to and through what?
Secreted from islet cells, enters the duodenum through the pancreatic duct.
The pancreas secrets enzymes. What enzymes are they, and what are their functions?
Trypsinogen= Inactive enzyme converted into Trypsin by the enzyme in duodenum, enterokinase.
Endopeptidases= Hydrolyse proteins and polypeptides to peptides
Amylase= Digests any remaining starch into maltose
Lipase= Hydrolyses lipids into fatty acids and monoglycerides
The pancreas secrets sodium hydrogen carbonate. What is the function of this?
- Neutralising acid from the stomach
- Providing appropriate ph for the enzymes to work efficiently
What features of the ileum ensure that it is well adapted for absorption?
It is several metres long and its lining is folded. On the surface of the folds are villi and their epithelial cells have microscopic projections called microvilli, all together this provides a very high surface area for absorption.
Explain how amino acids are absorbed into the blood:
Absorbed into epithelial cells by active transport, and as individual amino acids they pass into the capillaries by facilitated diffusion. They are water soluble and therefore dissolve into plasma.
Explain how glucose passes into the blood:
Into epithelial cells with sodium ions by co-transport. They move into the capillaries sodium by active transport and glucose by facilitated diffusion. As these transport methods are slow, not all glucose is absorbed, and to prevent it leaving the body, some is absorbed via active transport.
Where do fatty acids and monoglycerides absorb into?
Diffuse into epithelial cells and into the lacteals.
How are minerals taken into the blood?
Via diffusion, facilitated diffusion and active transport, then it dissolve into the plasma.
Describe the fates of nutrients (Lipids, glucose, amino acids):
Lipids= used in membranes and to make some hormones but excess is stored
-Other molecules like glucose and protein are taken through the hepatic portal vein where they are processed in the liver
Glucose= taken to body cells and respired for energy or stored as glycogen in liver or muscle cells.
Amino acids= taken to body cells for protein synthesis, excess cannot be stored so its converted into -NH2 groups to urea and then excreted via kidneys.
What ends up passing into the colon?
Undigested food, mucus, bacteria, dead cells.
Describe the adaptations to different diets in carnivores, herbivores and omnivores:
Carnivores= Its small intestine is short in relation to body size, reflecting the ease with which protein is digested. Large intestine is straight with a smooth lining
Herbivores= Small intestine is long in relation to body, plant material is not readily digested and a long gut allows for more time for absorption. Large intestine is pouched, it can stretch to accommodate the larger volume of faeces produced whilst digesting plants.
Omnivores= Intermediate in length. Large intestine is pouched, it can stretch to accommodate the larger volume of faeces produced whilst digesting plants.
Describe the dentition of herbivores:
Has incisors on the lower jaw only along with canine teeth which are undistinguishable to the incisors.
Diastema separates the front teeth from premolars. Tongue and cheeks operate in this area moving the cut plants to the large grinding surface (Premolars/molars)
The molars interlock, the lower jaw moves from side to side to produce a circular grinding motion. With time the teeth become sharper further increasing the efficiency of grinding (teeth continue to grow throughout the animals life)
Herbivores dont need strong muscles attached to their jaw, skull is relatively smooth
Describe the dentition of carnivores:
- Sharp incisors to grip and tear muscle from bone
- The canine teeth are large, curved and pointed for piercing and seizing the prey
- Premolars and molars have cusps, which are sharp points that help to cut and crush
- Carnassials on each side which slide past each other, these shear the muscle off the bone
- Lower jaw moves vertically
- Strong and well-developed jaw muscles allowing a good grip and crush bone.
Why do ruminants have difficulty digesting their food?
As their diet consists of mainly plants, they do not make cellulase to digest cellulose and therefore cannot digest the beta-glycosidic bonds. Therefore they rely on mutualistic microbes.
Describe what happens at the rumen:
After the cud passes into the rumen, the food mixes with the microbes, these secrete the necessary enzymes which digest cellulose into glucose. This is then fermented into organic acids which is absorbed into the blood, proving an energy source for the cow.
Describe what happens at the reticulum:
The fermented food passes into it and is re-formed into cud, it is regurgitated into the mouth for further chewing.
Describe what happens at the omasum:
Cud passes in, where water and organic acids made from the fermented glucose is absorbed into the blood.
Describe what happens at the abomasum:
True stomach, protein is digested by pepsin at Ph2
What is the definition of a parasite?
An organism that lives off another organism, it obtains nutrients from it to which causes harm.
Describe and explain the structural modifications of the pork tapeworm:
-Scolex with hooks and suckers allowing it to attach to duodenum wall
-Thick body covering, protecting it from the hosts enzymes and immune system
-Makes enzyme inhibitors which prevents hosts enzymes from digesting it
-Large number of eggs produced, increasing chances of infecting secondary host
-Eggs have resistant shells and survive until eaten by pig.
What does a long-term infection of a tapeworm produce?
Taeniasis
