Adaptations For Nutrition🍽 Flashcards
What does autotrophic mean?
Uses light energy/energy from chemical reactions to make their own food.
E.g. green plants, algae and some bacteria
What does photoautotrophic mean? (Autotrophic)
Gets energy for food synthesis from light and uses CO2 as its primary source of carbon.
E.g. autotrophic plants, algae, some bacteria
What does chemoautotrophic mean? (Autotrophic)
Uses energy from chemical reactions to make food.
Allows them to survive in areas with no light.
E.g. nitrogen-fixing bacteria and iron oxidising bacteria
What does heterotrophic mean?
Feed on other organisms.
Animals, fungi, some protoctists and bacteria
What does saprotrophic mean? (Heterotrophic)
Feed on dead or decaying material using extracelluar digestion.
E.g. fungi and bacteria
What is extracellular digestion?
Secrete digestive enzymes into food externally.
Food is digested and soluble products are absorbed.
What does holozoic mean? (Heterotrophic)
Take food into body and digest it - many use a specialised digestive system.
E.g. herbivores, carnivores and detritivors
What does symbiotic mean? (Heterotrophic)
Interaction between two different organisms living in close physical association
What does mutualistic mean? (Symbiotic)
A close association between two species where both partners benefit.
E.g. lichens made up of algae and fungi
What does parasitic mean? (Symbiotic)
Feed on host organisms by digesting their cells and absorbing the products.
E.g. tapeworms, fleas
What does endoparasitic mean? (Parasitic)
Feed inside the host.
E.g. tapeworm
What does ectoparasitic mean? (Parasitic)
Feed on outside of the host.
E.g. fleas
Info on headlouse/pediculus humanus capitis (ectoparasite)
- Eggs are laid in different areas, depending on temperature
- Female secretes glue which hardens into nit sheath
- Travel directly from head to head and feed using mouthparts
Information on pork tapeworm/Taenia solium (endoparasite)
- Flat, ribbon-like body - increases SA:V
- 2-3m long
- No body cavity, no circulation, no digestive system
- Scolex with 4 suckers and chitinous hooks as organs of attachment to intestinal wall of host
- Thick cuticle protects from immune responses and digestion by host
- Hermaphrodite - self-fertilisation
- Each proglottid is a complete reproductive unit
- Body growth starts from neck
- Accidental infection by humans at larval stage causes cysticercosis
- Primary host is humans - cysticercus from pork
- Secondary host is pigs - ingest eggs from human faeces which hatch inside intestine and use digestive enzymes to enter blood and lymphatic vessels. Embryos migrate to tissues to from cysticerci
- Prevent by not eating undercooked pork and ensuring prevention of faecal contamination of pig feeds
How do holozoic feeders such as an amoeba obtain nutrition?
- Intracellular digestion
- Diffusion, facilitated diffusion or active transport across the cell membrane
- Take in larger molecules by endocytosis
Hydra features (extracellular digestion and intracellular digestion)
- Tentacles - stinging cells paralyse prey and move into mouth, into hollow cavity
- Endodermal cells - secrete protease and lipase
- Ectoderm
- Jelly layer
- Hollow body cavity - digestion
- Mouth - egests indigestible remains
What are the functions of the digestive system?
- Ingestion
- Peristalsis
- Digestion
- Absorption
- Egestion
What is the inner mucosa? (structure of gut wall)
- Lines gut wall and secretes mucus - lubricate passage of food and protects gut
- Cells are layered for protection
- Some regions secrete digestive enzymes, some absorb food
- Acid/alkaline fluid to provide optimum pH for enzymes
What is the sub mucosa? (Structure of gut wall)
- Contains blood and lymph vessels which take away the absorbed products
- Contains a network of nerve fibres that coordinate the muscular contractions involved in peristalsis
- Contains glands that produce alkaline fluid
What is the muscle layer? (Structure of gut wall)
- Two layers of muscle running in different directions
- Circular muscle (inner) - fibres arranged in rings
- Longitudinal muscle (outer) - fibres rubbing lengthways
- Antagonistic muscle pair - both layers are made up of smooth involuntary muscle and are responsible for peristalsis
What is the serosa? (Structure of gut wall)
Layer of tough connective tissue which protects the gut wall from friction from other organs in the abdomen
What happens behind the food? (peristalsis)
- Circular muscle contracts
* Longitudinal muscle relaxes
What happens in front of food? (Peristalsis)
•Longitudinal muscle contracts
•Circular muscle relaxes
Widens and shortens the gut
Different body parts and different roles
- Mouth - ingestion
- Stomach - digestion
- Duodenum - digestion
- Ileum - absorption
- Colon - absorption of water
- Rectum - egestion
What is mastication?
- The chewing of ingested food
- Makes food easier to swallow
- Increases surface area for enzyme action
Incisor function
Chisel-shaped for biting and cutting
Canine function
Pointed for piercing and tearing in carnivores
Premolar function
Uneven cusps for grinding and chewing
Molar function
Used for chewing
Digestion of lipids
- Bile salts - emulsifies lipids (mechanical)
* Lipase - fatty acids + glycerol (chemical)
Digestion of starch
- Amylase (pH 8) - disaccharide
* Disaccharidase - monosaccharides (inside cells of gut mucosa)
Protein digestion
- Endopeptidase - polypeptides
- Exopeptidase - dipeptides
- Dipeptidase - amino acids (inside cells of gut mucosa)