B5 Exhange Of Materials Flashcards
Complete the sentence
Humans and other animals must ……… the substances they need from the environment and ……… of any waste products.
Take in
Get rid
What do cells need oxygen for?
Aerobic respiration
What is the waste product of aerobic respiration?
Carbon dioxide
How do oxygen and carbon dioxide move between the cells and the environment?
By diffusion
Water is needed for many chemical reactions. How is it taken up by the cells?
By osmosis
What is taken up by cells during osmosis?
Water and dissolved food molecules
Where are the dissolved food particles from that get taken up along with water through osmosis?
Products of digestion
Eg amino acids and glucose
What are the water and dissolved food particles taken up during osmosis used for?
Synthesis reactions
See p51
What is urea?
A waste product from the breakdown of proteins in the liver.
Complete this sentence
Urea diffuses from …… into the …….
Cells
Blood plasma
How is urea filtered out of the blood?
By the kidneys and excreted as urine.
Complete the sentence
How easy it is for an organism to exchange substances with its environment depends on the organisms ………….. to …….. ratio.
Surface area
Volume
What does SA:V show?
How big one value is compared to another.
Complete the sentence
The larger the organism is, the ……… its surface area is compared to its ……..
Smaller
Volume
See page 67 for calculating surface area to volume ratio
.
Why do urea and CO2 need to be removed from the body?
Because they are toxic, if the reach a certain level.
Complete the sentence
Multicellular organisms have relatively ….. surface area to volume ratios, which makes ………. to and from cells deep within their bodies slow.
Small
Diffusion
Complete the sentence
Multicellular organisms have a relatively small surface area to volume ratio, this makes it difficult to exchange ………… to supply their ………. across their outside surface alone.
Enough substances
Entire volume
How do multicellular organisms get enough substances to supply their entire volume?
They usually have specialised exchange surfaces to increase their SA:V.
What do specialised exchange surfaces do?
They increase their SA:V and therefore the rate at which substances are able to diffuse.
What is a mass transport system?
A circulatory system
What does a mass circulatory system do?
Moves substances around the body, this shortens the distance these substances have to diffuse to and from cells.
Give an example of a small multicellular organisms that has a big enough SA:V that they don’t need specialised exchange surfaces.
Worms
Name the 4 systems that need to work together for all movement into, out of and around the human body.
Gaseous exchange systems
Circulatory systems
Digestive systems
Excretory systems
See p 67 for question
See page 116 for answer
