exchange and transport systems Flashcards
How is the size of an organism related to its
surface area: volume ratio?
The smaller the organism, the larger the surface area: volume ratio.
Which equations should you use to calculate
the surface area and volume of a cube?
Surface Area: length x width x no. of sides
Volume: length x width x depth
What is mass transport?
A mechanism within an organism to transport substances from the exchange surfaces to the organs that require them
Explain why smaller organisms have a
relatively high metabolic rate.
Their large surface area: volume ratio means that they lose heat
quickly
Explain how the size of an organism
influences heat exchange with the
environment.
The smaller the organisms, the larger the surface area: volume ratio,
therefore the more heat is lost to the environment.
The larger an organisms is, the smaller the surface area: volume ratio,
and so they are better at retaining heat.
Give two physiological adaptations an
animal may have to survive in extreme
temperatures.
Cold: Smaller extremities (like ears), rounder, shorter or wider
body/features.
Hot: Larger extremities, taller, slimmer, longer body/features.
Other than body size or shape, give two
behavioural adaptations an animal may
display to survive in extreme temperatures.
Cold: Higher metabolic rate, hibernate, thick layer of fur/fat.
Hot: Stay in water, flap ears, seek shade by burying itself.
What is Fick’s Law?
Rate of diffusion α Surface area x Concentration gradient / Diffusion distance
Describe the structure of fish gills.
A central gill arch runs from the top to the bottom of the space. The
arch has two rows of filaments sticking out from one side, all of which
are covered with tiny lamellae that stick out perpendicular to the
filaments.
Explain how the counter- current system
maximises the efficiency of gas exchange.
The counter-current system maintains the concentration gradient
over the whole length of the gill.
How does the structure of the gas exchange system in insects maximise gas exchange?
They have spiracles on their surface to allow air into trachea
Trachea branch off into smaller tracheoles which have permeable walls
Oxygen can diffuse directly from tracheoles into surrounding cells
How are insects adapted to reduce water
loss?
They close their spiracles. They have a waterproof, waxy cuticle over their body
How are leaves adapted to reduce water
loss?
They have a waxy cuticle on the upper surface of leaves. If plants start to become dehydrated guard cells lose water and become flaccid causing stomata to close.
What adaptations do xerophytic plants have to prevent water loss?
Sunken stomata – trap water vapour reducing the water potential gradient between the leaf and the air
Hairs – trap water vapour around stomata
Curled leaves protecting the lower side of the leaf from environmental factors such as wind
Reduced number of stomata
Thicker waxy, waterproof cuticles.
Describe the structure of the gas exchange system in humans.
The main windpipe is called the trachea, which splits into two bronchi, one leading to each lung. Each bronchus branched into many bronchioles which each end in an alveolus.
