Adaptations In Large Organisms to Facilitate Exchange Flashcards
Single-celled organisms have a …………….. SA:V ratio which allows for the exchange of substances to occur via ……………
high
simple diffusion
The large surface area allows for
The large surface area allows for maximum absorption of nutrients and gases and secretion of waste products
The small volume means
The small volume means the diffusion distance to all organelles is short
As organisms increase in size their SA:V ratio …………..
decreases
As organisms increase in size their SA:V ratio decreases
There is less surface area for ……………………….
the absorption of nutrients and gases and secretion of waste products
As organisms increase in size their SA:V ratio decreases
The greater volume results in a …………………………………
longer diffusion distance to the cells and tissues of the organism
Large multicellular animals and plants have evolved adaptations to facilitate the exchange of substances between their environment
They have a large variety of specialised
cells, tissues, organs and systems
Eg. gas exchange system, circulatory system, lymphatic system, urinary system, xylem and phloem
The Need for a Specialised System for Gas Exchange
Supply of Oxygen as
Removal of Carbon Dioxide as
Organisms require ATP in order to carry out the biochemical processes required for survival. The majority of ATP is produced through aerobic respiration which requires oxygen
Carbon dioxide is a toxic waste product of aerobic respiration
If it accumulates in cells/tissues it alters the pH
Chlamydomonas is a single-celled organism that is found in fresh-water ponds. It is spherical in shape and has a diameter of …..μm. Oxygen can diffuse across the cell wall and membrane of the Chlamydomonas
The maximum distance that oxygen molecules would have to diffuse to reach the centre of a Chlamydomonas is …μm, which would only take …….milliseconds
If the cell was larger and the diffusion distance increased to…………μm the diffusion time would increase substantially to …..milliseconds
20
10
100
20
4000
This demonstrates how diffusion is a viable transport mechanism for single-celled organisms but not for larger multicellular organisms
The time taken for oxygen to diffuse from the cell-surface membrane to the tissues would be
to long
Students often only focus on the transport of nutrients and gases when writing about the adaptations for facilitating exchange. Make sure you don’t forget about the importance of removing toxic waste products from tissues and cells. If toxic waste products build-up (e.g. ……………………………..) within cells or tissues they can cause damage/death.
urea and carbon dioxide
