Gas Exchange: Insects, Fish and Plants Flashcards
as the organism gets larger the ——— gets ——-
surface area to volume ratio
smaller
what is ficks law
diffusion rate = surface area x concentration gradient / diffusion distance
what is the weakness to having a large surface area to volume ratio
they lose more heat
how do single celled organisms exchange oxygen and carbon dioxide
simple diffusion across their cell surface membranes
name 3 things that make a good exchange surface
- large surface area
- large concentration gradient
- thin exchange surface - short diffusion pathway
explain the movement of oxygen in insects
- oxygen enters through spiracles and into the trachae
- spriacles close
- oxygen diffuses through the trachae into the tracheoles where gas exchange occurs
- oxygen is delivered directly to respiring tissues
where does gas exchange in insects occur
tracheoles
give 4 adaptations of the tracheoles which make it an efficient gas echange
- highly branched which provides a large surface area
- thin walls so there is a short diffusion pathway
- supply tissues so diffusion is directly into cells
- walls are permeable to oxygen
what is abdominal pumping
movement of the insects body by its muscles
explain how abdominal pumping helps maintain the concentration gradient of gases in insects
- during movement, muscles around the trachea contract and pump air in the sacs deeper into the tracheoles
- this pumps out carbon dioxide and pushes oxygen through their tracheal system
- this maintains the concentration gradient for oxygen and carbon dioxide
explain 3 ways insects balance water loss with efficient gas exchange
- exoskeleton - impermable which reduces water loss
- spiracles close to prevent water loss
- small hairs around the spiracles trap water which reduces the water potential gradient
explain the movement of oxygen in Fish
- water carrying oxygen moves in through the mouth and out through the gills
- the gills have many finger like projections called gill filaments
- each filament has many lamellae
- the lamellae contain capillaries and are the site of gas exchange
- as water carrying oxygen passes through the lamellae, most of the oxygen is removed and enters the capillaries
- water containing little oxygen leaves through the gill opening
what is the site of gas exhange in fish
lamellae
explain 3 adaptations of the lamellae that make it an efficient gas exhange surface
- many gill filaments that contain many lamellae which provide a large surface area
- the lamellae have a thin epithelium which means there is a short diffusion distance between water and blood
- the lamellae are positioned at right angles which allows water to pass through the gills
describe the term countercurrent flow
water and blood move in opposite directions
explain how countercurrent flow increases the fishes ability to absorb oxygen from water
- water and blood move in opposite directions
- thie means the concentrationgradient is maintained along the entire length of the gill lamellae
explain the movement of carbon dioxide into plants
- carbon dioxide enters by the stomata which are opened by guard cells
- it diffuses into the air sacs of the spongy mesophyll down a concentration gradient
explain 3 adaptations of the leaf that allow efficient gas exchange
- flat so they have a larger surface area to volume ratio
- contain many stomata which allow ait to move in and out of the leaf
- air spaces in the spongy mesophyll which means there is a short diffusion pathway
give 4 adaptations of a plant that reduces their water loss
- at night the guard cells close the stomata
- upper and lower surfaces have a waxy cuticle
- most stomata are found in the lower epidermis
- air spaces are saturated with water vapour from the xylem which reduces the water potential gradient
what are xerophytes and give an example
plants that live in dry environments, such as a cactus
explain 4 adaptations of xerophytes that help them to reduce water loss
- thick waxy cuticles which means there is an increased diffusion distance which decreases transpiration
- hairs, stomata in pits and rolled leaves all trap water vapor and decrease the water potential gradient
- leaves are reducd to spines which reduces the surface area to volume ratio
- small leaves with reduced number of stomata
