topic 8 - nutrition, digestion & excretion

Autotroph

Synthesise their food by transforming energy either from chemicals - chemoautotrophs - or the sun - photo autotrophs

Heterotroph

Obtain energy from other organisms in the levels below

Herbivores

Adapted to eat plant material and often require symbiotic bacteria for digestion of cellulose

Omnivores

Are more generalist consumers and have intermediate adaptations for consuming varied food sources

Carnivores

Are adapted to a diet of animal tissue and fine require adaptations for prey capture

Detritivores

Also called decomposers, usually bacteria or fungi that consume dead organisms, can exist on any heterotrophic level and play a critical role in the recycling of nutrients and matter in the ecosystem

Autotrophs main adaptation to generate own energy

Chloroplast - Calvin cycle primarily responsible for conversion of carbon dioxide to glucose.

Energy for transforming carbon into food can come from the oxidation of inorganic nutrients, for example, by bacteria and archaea through the process of chemosynthesis.

Chemosynthesis typically occurs in ecosystems that lack sunlight but have high concentrations of particular inorganic compounds such as hydrogen sulfide gas

Heterotrophs main adaptations to gain nutrients

Collect/capture food

Mechanical digestion - break down into soluble and transportable compounds

Chemical digestion

Absorption - digestion

Two nutrients essentials or plant life

Carbon and water

Carbon is a fundamental component of all organic molecules in a plant, including sugars, proteins and DNA

Water is crucial for photosynthesis, the process which plants create energy from sun’s light energy

Describe the three groups of essential macromolecules used by animals in digestion.

What form of each of these nutrients can be used in glycolysis?

Proteins, carbohydrates and lipids

Carbohydrates glucose, broken down into pyruvate

Carbohydrate digestion

Human body possess several enzymes that break down carbohydrates into simple sugars. While glucose can enter glycolysis directly, some simple sugars, such as fructose and galactose are first converted into sugars that are intermediates of the glycolysis pathway

Protein digestion

Proteins are broken down by enzymes into their constituent amino acids, which are usually recycled to create new proteins.

If the body is starving or has a surplus of amino acids, some amino acids can lose their amino groups and subsequently enter cellular respiration.

The lost amino groups are converted into ammonia and incorporated into waste products.

Different amino acids enter cellular respiration at various stages, including glycolysis, pyruvate oxidation, and the citric acid cycle. Amin acids can also be produced form intermediates in cellular respiration processes.

Fat digestion

Lipids, such as cholesterol and triglycerides, commonly known as fats, can also be produced and broken down in cellular respiration pathways. Triglycerides, for example, are composed of glycerol and three fatty acids. Phosphorylated glycerol enters glycolysis. Fatty acids enter the citric acid cycle after being converted into acetylene CoA through a series of reactions called beta-oxidation

Symbiotic relationship between microbes such as fungi and plants aid in nutrient acquisition

Some plants rely on soil-dwelling organisms to acquire resources form the soil

Nitrogen critical component of proteins and nucleic acids.

Plants have a lower need for waste excretion of byproducts of cellular respiration

Plants are capable of recycling the majority of these wastes because the products of photosynthesis form the reactants of cellular respiration and the products of cellular respiration form the reactants of photosynthesis.

* Plants remove the majority of their metabolic waste via the leaf stomata through the process of transpiration. Evaporation of water vapour from open stomata, generates pressure in the leaves which draws water up the plant’s stem via the xylem and facilitates absorption of water via the roots

* Protein metabolism creates nitrogenous waste products. Reused for protein synthesis. Convert nitrogenous waste into reusable forms to synthesise the proteins they need for further growth and development

Fungal digestion

Assist in nutrient recycling. Can obtain their carbon compounds either from non-living organic substrates or living organic material by absorption of nutrients across their cell walls.

Gastrovascular cavities

Foregut, midgut, hindgut

Foregut

Intake and storage of food as well as initial stages of chemical and mechanical digestion

Midgut + Hindgut

Important for chemical digestion and absorption of nutrients prior to defamation or evacuation of waste products

Three main forms that nitrogenous waste is excreted

Ammonia must be removed directly or converted into urea or uric acid (toxic to body)

Urea less toxic requires less water for removal, however requires energy

Uric acid requires very little water because it is solid

Ammonia

Must be removed directly or converted into urea or uric acid

Urea

Less toxic so requires less water for removal, however requires energy

Uric acid

Requires very little water because solid

Mammalian kidneys adaption (for arid environment)

Loop of Henley

Mammals have developed a particularly effective adaptation to increase urine concentration and conserve water

Elongation of the proximal tubule which functions as a counter-current multiplier, changing the concentration gradient of the surrounding tissue

Loop of Henley extends into the medulla region of the kidney and the area of this tissue correlates directly with the concentration of urine produced by mammals