physiology Flashcards
list two advantages of aerobic respiration
- releases more ATP molecules (32-38)
- allowed for the evolution of multicellularity and larger organism size
explain how the advantages of aerobic respiration may have led to the evolution of multicellularity
increased energy production, which also supports the growth of larger organisms
describe the features of gas exchange surfaces that maximise diffusion in relation to Fick’s Law
- membrane thickness/area
- large SA:V ratio speeding up the rate of exchange
- keep the diffusion pathways short
- partially permeable allowing only selected material
- movement of external/internal medium to maintain a diffusion gradient
define respiration
process by which an organism exchanges gases between themselves and their environment, all organisms do this to release energy from their food and to fuel cellular processes
what are the mechanisms of respiration?
Organisms can extract energy from food via:
→ Aerobic respiration: ATP synthesis in the PRESENCE of oxygen
- Releases more ATP molecules than anaerobic respiration
- May have allowed for the evolution of multicellularity and larger organism size
→ Anaerobic respiration: ATP synthesis in the ABSENCE of oxygen
- Quick releases energy
- Can occur in low oxygen environments
reason for large SA:V ratios
speed up the rate of exchange
reason for membrane to be very thin
keep the diffusion pathway short
reason for movement of external/internal medium e.g. air/blood
to maintain a diffusion gradient
reason for membrane to be partially permeable
to allow for selected materials to diffuse easily
describes stomata’s physical and physiological mechanisms for plant’s gas exchange
physical
small pores located on the underside of leaves, allows plants to regulate gas exchange
physiological
plants regulate the opening/closing of stomata through guard cells, which responds to the environmental conditions
the surface of plants in terms of efficient gas exchange
Each living cell is also located close to the surface - reducing the distances gasses have to travel once inside the plant
The only living stem cells in the stem are organised in thin layers just beneath the bark - while the cells in the interior are dead and serve only to provide mechanical support in woody stems and shoots that do not photosynthesise as much as leaves there is no stomata, but instead, small pores lenticels which allow gases directly in/out and interact directly with the living tissue
why do the upper parts of the leaves have more stomata than the rest of the plant
Plants do not have a specific gas exchange system, thus have stomata located on most places of the plant as it is responsible for its own area
However, the upper parts of the leaves in plants usually have the most stomata as they are the most metabolically and photosyntheically active
Generally very thin (large surface area) + low volume to maximise efficient gas exchange
the membrane of plants in terms of efficient gas exchange
Part of the membrane is exposed to air as the cells are loosely packed which provides an interconnecting system of airspaces, gases diffuse through air way faster than through water
In many plant stems, these airfield spaces form aerenchyma which assist in the transport of gases between stems and roots - formed when cells separate from one another/collapse
The aerenchyl spaces rely on pressure gradients to drive the gases from areas of high pressure to areas of low pressure
plants in wetland environments, and their mechanism for efficient gas exchange
Environment where gas exchange in very moist soils and underwater is considerably lower than in air plants, have developed another way to move gasses through the body - air enters into common reeds from broken stems/dead plants that are all connected via underwater structures called rhizomes
Many plants have rhizomes which grow horizontally just below the surface of the soil, with many stems growing up and many roots growing down
Air taken in through one broken stem or dead plant is able to reach other healthy sections through this network and CO2 can diffuse out through these other broken stems
The O2 carrying air moves through the aerenchyma driven by changes in air pressure due to the different sizes of the broken stems of the plants
fungi and their efficient mechanism for gas exchange
Rely on diffusion across their cell or body walls and lack specialised gas exchange structures
As many fungi can be slow growing or remain dormant for long periods of time, simple diffusion can be quite effective as their requirements are low
E.g. yeast - regularly switch between aerobic and anaerobic respiration based on oxygen availability
The majority of gas exchange in multicellular fungi takes place via large branching network of mycelium whic possess microscopic hypae that extend into small crevices in the soil/other substrates to interact with small air pockets
The mycelium has a large SA:V and can form colonies which produce fruiting bodies that extend above the substrate into the air - fruiting bodies exchange gas via their thin body walls (porous and rely on diffusion between cells for supplying oxygen throughout the body)
explain the key difference between gas exchange in water and air
as in the air, oxygen is more readily available for exchange than water, organisms living in water must be highly efficient in extracting oxygen
identify structural differences in the lungs of different vertebrates that are related to oxygen requirements
animals with higher oxygen demands have more complex lung structures to ensure efficient oxygen exchange
why are trachea so efficient at gas transport
as they allow for direct oxygen delivery to tissues and cells
animals gas exchange in aquatic environments
Animals with thin tissues can avoid the need for specialised gas exchange structures by simply reling on oxygen diffusion across their body wall
gas exchange for larger/more active organisms
- Ventilation
Gasses are moved across the gas exchange surface, either via body movements/movements of the respiratory structure itself
- Ensures the pressure gradient for diffusion is optimised and increases the rate of diffusion across the gas exchange surface - Circulation
Gas is moved to and from the gas exchange surface and the body tissues
- Occurs via dissolution into a circulatory fluid e.g. blood/directly via a network of branching tubes
gas exchange in terrestrial environments - oxygen levels high, but water loss is an issue
To ensure respiratory surfaces stay moist, terrestrial animals have internal gas exchange structures
E.g. insects uses a network of tubes called trachea - allows for direct oxygen delivery to tissues and cells
Air enters the body through small openings called spiracles located along the sides of the thorax and abdomen
From the spiracles, air travels through the trachea which branch into finer tubes called tracheoles that extends to individual cells
The large tracheoles provide a large surface area for gas exchange, allowing oxygen to diffuse directly into cells while CO2 diffuses out
gas exchange in larger terrestrial animals
The specialised internal gas exchage system is comprised of highly vascularised lungs
Air enters through the nose/mouth, travelling down the trachea and branching into the bronchi - depending of O2 requirements, the lungs may also be further divided into bronchioles which end in alveoli
The walls of the lungs are thin and surrounded by many small capillaries to transport O2 to and CO2 from the body tissues
The branching network of the lunch provides a vast surface area for gas exchange and is kept moist by surfactants (special molecules with a hydrophilic and hydrophobic end, secreted by pneumocyte cells withing the lung)
Surfactants reduce surface tension of the lung to aid in the diffusion of gasses
define the differences between autotrophs and heterotrophs
autotrophs generate their own food from inorganic sources
heterotrophs depend on consuming other organisms for their food
Heterotrophic adaptations
Collect/capture food - obtain organic matter from external sources, rely on capture of prey organisms or collection of food
Break down mechanisms of food into soluble and transportable compounds through:
Mechanical digestion
Chemical digestion
Absorption - tissues and transport systems associated with the absorption and its simulation of nutrients into the body
gas exchange in aquatic species
Whether internal and external, the gills are made up of many individual filaments covered in lamellae to increase the surface area for gas exchange
As water flows over the gill surface, oxygen diffuses from the water into the blood within the gill capillaries, while CO2 diffuses from the body into the water to be expelled
Internal gills of fish employ a countercurrent exchange mechanism where water and blood flow in opposite directions, maintaining a concentration gradient that maximises oxygen uptake and carbon dioxide removal
explain why nutrients are important for life
nutrients provide the necessary material and energy needed for organisms to grow, develop and maintain biological function
gas exchange in birds
Gas exchange involves a unidirection flow of air
The lungs do not move but are ventilated by air sacs which pump air to and from the lunches in different specific orders - fresh air passes over the gas exchange surfaces during both inhalation and exhalation resulting in a constant supply of fresh air, enabling the bird to experience a near-continuous state of gas exchange within the lungs
The parabronchi within the lungs increase the surface area and interact directly with a large capillary network to effectively exchange gasses and transport them around the body
Autotrophic adaptations
Capture radiant energy from the sun and within specialised organelles (chloroplasts), fix it into organic compounds using carbon dioxide and water
Within the chloroplasts is where the calvin cycle converts CO2 to glucose
In some organisms, the nutrients can also come from the oxidation of inorganic nutrients e.g. bacteria and archaea through the process of chemosynthesis - transforming energy from chemicals
define Cchemoautotrophs
transforming energy from chemicals
define detritvores
secrete digestive enzymes that break down organic material, converting it into inorganic compounds that can be utilised again by primary producers
define herbivores
adapted to eat plant material and often require symbiotic bacteria for digestion of cellulose
define carnivores
adapted to a diet of animal tissues and often require adaptations for prey capture
define photoautotrophs
transforming energy from the sun
define omnivores
intermediate adaptations for consuming varied food sources
Groups of essential nutrients
Macronutrients (C, H, O and N) - required in relatively large amounts
Micronutrients - required in smaller quantities for proper plant functioning e.g. cofactors Fe
Carbohydrate digestion
Enzymes breaking down carbohydrates into simple sugars
Protein digestion
Proteins are broken down by enzymes into their constituent amino acids - usually recycled to create new proteins
Fat digestion
Lipids can also be produced and break down in cellular respiration pathways
define nitrogen fixations and its requirements
Nitrogen fixation: soil-dwelling bacteria convert atmospheric nitrogen to ammonia
This requires large amounts of ATP that bacteria derive from plant-provided carbohydrates
Other groups of bacteria convert ammonia to nitrate during a two-step process called nitrificaiton
These processes provide plants with forms of nitrogen that they can use to synthesise proteins and nucleic acids
describe the symbiotic relationship between fungi and plants that aids in nutrient acquisition
Fungal mycorrhizae are important to plant nutrition and function in water acquisition, growth factor signalling, and plant protection
Ectomycorrhizae cover roots and help absorb water and minerals
Arbuscular mycorrhiaze are embedded within the root tissue, increasing contact between the plant cells and the branching filaments of the fungus - hyphae
The transport of water and nutrients within plants occurs via the vascular tissue - xylem (water and minerals) and phloem (carbohydrates)
the three main forms that nitrogenous waste is excreted and their costs benefits
ammonia, urea and uric acid
cost - toxic in high concentrations but in low concentrations can be used as a fertiliser
describe two mechanisms by which plants excrete unwanted by-products
- guttation
exudation of xylem sap in the form of water droplets through structures called hydathodes found in the margins of leaves - transpiration
facilitates the diffusion of excess oxygen out of plants via the stomata
Mineral salts and other compounds can be stored in the vacuole of cells in plant structures like the leaves, bark and fruits which are eventually shed as they age and die
excretory systems in animals for terrestrial environments
Malpighian tubules - open into the mid/hind gut
The cells of the tubules actively transport uric acid from the extracellular fluid into the tubules
The high concentration of solutes in the tubules causes water to flow osmotically which flushes the tubule contents towards the gut
The epithelial cells of the hund guy and rectum actively transport ions from the gut contents back into the extracellular fluid
This local transport of salts create an osmotic gradient that pulls water out of the rectal contents
As the uric acid concentration increases, it forms a colloidal suspension, freeing even more water to be reabsorbed
The kidney is the main organ involved in waste excretion in terrestrial vertebrates, however the nephrons change depending on the class of vertebrates, the nitrogenous waste they excrete and the habitat in which they live
digestion and nutrient transport in animals
occurs via the digestive system and the circulatory system.
The complexity of food resources an animal consumes correlates with the complexity of their digestive system.
The digestive tract is hughly vascularised to ensure that broken down macromolecules can be transported throughout the body, and the circulatory system is similarly complex based on the needs of the animal
excretory systems in animals for aquatic environments
- Excrete nitogenous waste as ammonia due to its high solubility and the abundant supply of water
- As ammonia is so easily diffused many organisms do not possess a specialised excretory system and simply rely on passage across the body wall
- Some organisms e.g. flatforms excrete wastes through an elaborate network of tubules
- Others can excrete nitrogenous ions through the gills or the kidney
- The kidney’s functional unit is the nephron, which made up of a blood vessel and tubule component
Urine formation in aquatic vertebrates includes:
Filtration
- where blood interacts with the tubules via the glomerulus (dense knot of capillaries that are highly permeable), water and other ions are filtered into the tubule capsule - Bowman’s capsule
Reabsorption and secretion
- blood continues from the filtration step to flow to another network of capillaries that interact with the renal tubules to reabsorb and secrete solutes
- this process alters the composition of fluid in the tubules, generally causing an increase in ionic concentration
Urination
- as it flows towards the collecting ducts of the kidney before being excreted as urine
loop of henle
An elongation of the proximal tubule which functions as a counter-current multiplier, changing the concentration gradient of the surrounding tissue
Extending into the medulla region of the kidney and the area of this tissue correlates directly with the concentration of urine produced by mammals
In arid environments, where water conservation is extremely important the kidney is particularly efficient
define cue
is often an incidental source of information, it has not evolved as a vehicle for information transfer and it inadvertently provides useful information to the receiver.
Selection may favour greater detection abilities in the receiver, but will not act on the cue unless it disadvantages the source of the cue
Difference sensory modalities must be used for an organism to detect the cue - depending on where it lives and its lifestyle e.g. chemical, electrical, mechanical, photic, magnetic auditory modalities
define signal
derived from a biotic source - an act or behaviour that triggers a specific response in a receiver organism. This act has evolved in order to trigger this response
