Ch8: Nutrition & Excretion Flashcards
Define what a detrivore is?
Organisms that consume dead/decaying organic material to acquire their nutrients - often aid primary producers
Define what an autotroph is (what are the 2 different kinds)?
Autotrophs: organisms that are able to harness/produce their own necessary energy and nutrients
Chemoautotrophs: oxidise inorganic molecules to organic energy compounds to produce essential nutrients
Photoautotrophs: get their nutrients by utilising energy from sunlight
Define heterotrophs:
Must get their energy from other organisms (autotrophs or other heterotrophs)
Hydrothermal vents: hosts?
Hosts use inorganic compounds to fix CO2
What are the adaptations of heterotrophs that allow them to gain nutrients: (hint there are 3)
1) Capture/collection of prey
2) Mechanical + chemical digestion
3) Absorption (and assimilation of key nutrients into the body)
Name some morphological traits of animals: (hint there are 4)
1) Different teeth/positioning
2) Different jaws
3) Mouthparts (in insects for sucking liquid)
4) Limb modification
What are organic nutrients vs inorganic nutrients? Why are nutrients important?
Organic: carbon based molecules
Inorganic: minerals
Important: needed for growth and homeostasis
Define essential nutrients
Nutrients required for the life cycle of an organism (plant) that they cannot produce themselves
What are macronutrients? Give some examples and their roles;
Nutrients required for large proportions;
Carbon: necessary for nucleic acids, proteins + carbohydrates
Nitrogen: necessary for nucleic acids, proteins + chlorophyll
Potassium: regulating gas exchange (+ photosynthesis)
What are micronutrients? What is their other role?
Required in smaller proportions;
They can function as cofactors for enzymes
What are polysaccharide and disaccharides?
Poly: chain of glucose (hydrolysed to glucose) and used in pyruvate, NADH and ATP
Di: sugar that is broken down in 2 simpler sugars (glucose + fructose)
What are the roles of rhizobacteria or fungi (mycorrihizae)?
They fix atmospheric nitrogen into something biologically useful for plants.
What kind of relationship is the one between nitrogen fixing agents and plants? What does the fixing agent gain from this relationship and what does it do?
Symbiotic relationship
GAIN:
- produces antibiotics to protect the plant (acts as a physical barrier)
- absorbs unwanted chemicals from the soil
- facilitates the acquisition of essential nutrients (fixes N2 –> NH4 (ammonium) or NO3 (nitrate)
Where does nitrogen fixation occur in legumes?
Nodules on their roots
Why does a plant need to get rid of its waste products?
To maintain homeostasis (these wastes are generally recycled)
How does plant waste removal occur? What does this cause? (hint: has to do with pressure in leaves)
Occurs via transpiration of the stomata
This transpiration generates pressure in leaves and causes water to be brought up the XYLEM. Hence the roots begin to take up more water
Causes stomatal openings need to be regulated; some plants keep their pores permanently open pores (LENTICELS) to remove wastes
What is stomatal opening regulated by?
CO2, humidity, light, stress hormone (abscisic acid)
What happens to nitrogen waste, and how is nitrogen absorbed by the plant?
It is absorbed through the plants xylem sap.
nitrogen waste occurs due protein metabolism, BUT a lot of it can be RE-USED in protein synthesis for growth and development
What are the 2 types of nitrogen removal? describe them
1) Shedding; method of waste removal
- plants can store unwanted waste products in VACUOLES of the cell (amino acids, water, mineral salts)
- the wastes are shed as fruits, bark or leaves
2) Guttation: at night stomata close (prevent H2O)
- This leads to an accumulation of H2O as ROOT PRESSURE causes roots to continue to absorb H2O
- To excrete this excess water some plants can excrete water and minerals in small droplets of XYLEM SAP from leaf margins; goes through secretory cells (HYDATHODES - modified stomata cells)
How do fungi absorb their food (hint: there are 2 ways)
1) small soluble molecules can simply diffuse into the hyphae
2) large insoluble molecules need to undergo PRELIMINARY digestion: exudation of enzymes that break them down
Define the circulatory system:
transportation of essential vitamins, minerals, and macromolecules around the body
Define the digestive tract
A highly vascularised system - depends on what food is consumed by that organism for what level of vascularisation
Define what a simple gut is
Simple organisms:
- They have gastrovascular cavities allow for food to enter, and the walls are lined with cells that produce digestive enzymes
Ex~ sponges with open channel to absorb food particles
Define the 3 sections of the gut
1) Foregut: initial stages of chemical and mechanical digestion + storage and intake of food
2) Midgut + Hindgut:
- Mainly chemical digestion + absorption of nutrients prior to evacuation of water
Describe the diet of herbivores
Food: low energy, hard to digest
How does the foregut of a herbivore digest?
Chemical: has acids and digestive enzymes
Mechanical: contract/churn to expose to chemicals
Define/describe foregut fermenters:
Have 4 sections to the foregut;
- Rumen, reticulum,
omasum, abomasum
See Doc, 8a:
They first ‘take’ food to rumen to begin chemical + mechanical digestion
- They regurgitate their food to continue mechanical digestion and then bring it back through the foregut to be fermented by microbes
Define/describe hindgut fermenters:
See Doc, 8b:
Have a simple stomach;
- Have long hindguts to lengthen digestion
- These lead to a caecum (winding that is lined) with microbes to ferment the plant food
Adaptations of carnivores have to eat their food. Why do they have these adaptations?
they have sharper/serrated curved teeth to help shred tissue (mechanical digestion)
Tissue is easier to break down: so they rely on chemical digestion
Trends of carnivorous guts compared to herbivores?
Normally have shorter less complex guts
- The stomaches = acidic and are effective for protein digestion (foregut)
- Midgut = where lipid digestion occurs (where special bile is secreted)
How do organisms maximise their SA in the gut? (Hint: there are 3 things)
1) Have foldings in the gut = increased SA
2) Have extra tissue structures = increased SA
3) Villi (adsorptive tissues) have microvilli (small extending tubes) = increased SA
What is nitrogenous waste converted to? What about this waste makes it significant?
Nitrogen is converted to ammonia, which is highly toxic
How do marine animals, land mammals, and birds, insects + reptiles excrete nitrogenous waste?
1) Marine animals: directly excrete the ammonia as they have ample access to water to dilute ammonia
2) Do not have enough access to water to directly release ammonia so they convert it to UREA (requires ENERGY), but conserves water as urea (is LESS toxic)
3) Convert it to uric acid (solid form) which requires MORE energy, but less water
What does:
1) Water-solubility of urea allow for:
2) Solid-nature of uric acid:
1) Water-solubility of urea: allows mammalian embryos to remove waste in their mother’s blood
2) Allows waste from bird embryos to form harmless lamps in eggs, which have had shells that urea could NOT pass through
How do marine organisms excrete nitrogen through their body walls:
Unspecialised;
- Some do have specialised systems
- The flatworms have excretory pores connected to tubules that end in flame cells (cilia going into tubule) (PROTONEPHRIDIA)
Define metanephridia
See Doc, 8c:
Tubules that connect to the sac around (pericardium) the heart that contains nitrogenous waste
- The tubules take this waste into the mantle cavity to be released as urine
Describe how aquatic vertebrates mostly excrete via the kidney and its functional unit (NEPHRON):
See Doc, 8d:
1) Filtration: the blood vessels interact in a knot, GLOMERULUS, with the capsule/tubule (BOWMAN’s capsule) and due to the vessels permeability secrete into the capsule
2) Secretion/Absorption: as the renal tube (connected to the capsule) the capillaries secrete + absorb ions, increasing the renal rubes ionic concentrations
3) Excretion: the fluid travels towards ducts of kidney before being excreted as urine
What adaptation of renal tubes assist with diffusion?
It’s elongated and folded to increase SA
How do freshwater organisms urine compare to saltwater organisms urine?
Freshwater organisms have a HIGHER OSMOTIC concentration so they have LARGER filtration systems (glomerulus + Bowman’s capsule) to produce dilute urine
dilute urine gets rid of excess water that enters their bodies through osmosis
Define Malpighian Tubules: Hint: has to do with the process of urine production
See Doc, 8e:
Blind-ended (one end = solid) tubules
- they connect between the midgut + hindgut
The cells of the tubules actively transport URIC acid, potassium ions and soidum ions from the extracellular fluid in the tubules
A HIGH concentration of solutes in tubules causes water to enter tubules to flush the contents towards the gut
The epithelial cells of the hind gut + rectum actively transport the solutes (NOT uric acid) back into the extracellular fluid
Creating an OSMOTIC gradient which pulls water OUT of rectal contents =creating colloidal suspension (more H2O absorbed)
Uric acid remains in rectum and is excreted as urine
What is the structure of nephrons based on? (Hint: 3 things)
1) Class of invertebrates
2) nitrogenous waste they excrete
3) the habitat in which they live
Define the Loop of Henle: found in mammals
See Doc, 8f:
- an elongation of the PROXIMAL TUBULE
- functions as a counter-current multiplier that changes concentration gradient of surrounding tissue
main function is to reabsorb water and sodium chloride from urine, which allows the body to produce urine that is more concentrated than blood. This concentration of urine reduces the amount of water needed to survive.
This extends into the medulla region (middle of nephron) of the kidney
Area f this tissue correlates with concentration of urine produced by mamals
What kinds of environment is the kidney most efficient in?
Arid environments
