Exchange and Transport Systems Flashcards
Why is exchange key?
Cells need to take in oxygen and nutrients, need to excrete waste like carbon dioxide and urea, need to maintain same temporary restraining so heat exchanged.
Do smaller or bigger animals have a higher surface area : volume ration?
Smaller animals.
Describe exchange in single celled organisms.
Substances diffuse directly across cell surface membrane with a fast rate due to small distance of travel.
Describe exchange in multi cellular animals.
Diffusion across outer member wine is too slow as there it is a large distance as some cells are deep in the body or there is a low SA : V ratio.
Mass transport in plants and animals.
In mammals often refers to circulatory system which carries glucose and oxygen in blood, as well as hormones, antibodies and waste such as CO2.
Plants it involves transport of water and solitudes in xylem and phloem.
Behavioural and physiological adaptations to aid exchange.
- Small mammals have high metabolic so ones living in cold regions eat lots of high energy foods - seeds and nuts.
- Smaller mammals have thick layers of fur or hibernate in cold.
- Large organisms in hit regions find it hard keeping cool as they have slow heat loss (small SA : V) so elephants have large easy and hippos spend time in water.
Main adaptations of gas exchange surfaces.
- large SA
- thin one cell thick epithelial (often squamous)
- maintained steep concentration gradient
How do fish conduct gas exchange?
- O2 containing water enters through mouth and passes gills
- Each Gill ha smash gill filaments increasing SA for exchange
- Lamellae increase SA further and have lots of capillaries and think surface layer of cells
- Counter current created with blood in lamellae flowing one way and water the other maintaining large concentration gradient as concentration in water always higher than blood
How do insects conduct gas exchange?
- Air moves into trachea through pores on surface called spiracles
- O2 travels down concentration gradient towards cells
- Tracheae branch into tracheoles with thin, permeable walls that lead to cells so O2 diffuses directly into respiring cells
- CO2 from cells moves down concentration gradient towards spiracles to be released
- Rhythmic abdominal movements move air in and out of spiracles
How do plants conduct gas exchange?
- Need CO2 for photosynthesis and O2 for respiration
- Surface of mesophyll cells have large SA for exchange
- Mesophyll inside lead, gases move in and out through stomata
- Open to allow gas exchange, close to prevent water loss - controlled by guard cells
How do insects control water loss?
Close their spiracles using muscles and have waterproof waxy cuticle with tiny hairs around spiracles that reduce evaporation.
How do plants reduce water loss?
Water enter guard cells making them turgid and opens stomatal pore, when dehydrated guard cells lose water becoming flaccid which closes the stomata.
Describe adaptations of xerophytic plants.
- hairs on epidermis to trap moist air
- curled leaves with stomata inside protecting them from wind which could increase rate of diffusion and evaporation
- waxy waterproof cuticle to reduce evaporation
- fewer stomata so less places for water to escape
How do humans conduct gas exchange?
- Air enters trachea as you inspire
- Trachea splits into two bronchi leading to each lung
- Each bronchus branches into bronchioles which end in alveoli where gases are exchanged
What is ventilation?
The process of inspiration and expiration controlled by the contraction and relaxation of diaphragm, and internal and external intercostal muscles.
