Topic 8: Exchange and Transport in Animals Flashcards
Why do large multicellular organisms require specialised exchange surface?
Small SA/V ratio, diffusion insufficient to provide all cells with the required oxygen and nutrients, and to remove all waste products and exchange surfaces increase rate of diffusion and shorten diffusion distance
Why do some multicellular organisms not require specialised exchange surfaces?
Terese have a large number of leaves which provide a large SA/V ration for diffusion
How does the size of an organism affect its surface area to volume ratio?
The larger the organism, the smaller the SA/V
What are some of the substances transported into and out of the human body?
Oxygen, carbon dioxide, water, dissolved food molecules and urea
How does oxygen enter and carbon dioxide leave cells?
They diffuse into and out of cells
How does water enter cells?
It diffuses into cells by osmosis
How do food molecules and mineral ions enter cells?
They are dissolved in water which diffuses into cells
Why must urea be excreted from the body?
It’s a waste product so must be excreted
How is urea excreted from the body?
Urea diffuses out of cells into the blood plasma, the kidney filters urea out of the blood and urea is excreted in urine
Why must the human body exchange oxygen and carbon dioxide with the environment?
Oxygen is required for respiration so diffuses into the body and carbon dioxide is toxic waste product of respiration so diffuses out the body
How does oxygen enter and carbon dioxide leave the bloodstream?
Oxygen diffuses from air in the alveoli into blood in the capillaries and carbon dioxide diffuses from blood in the capillaries into the air in the alveoli
How are alveoli adapted for gaseous exchange?
Large surface area, network of capillaries provide a good blood supply, rapid blood flow maintains a steep concentration gradient, thin walls give a short diffusion distance, cell walls have partially permeable membrane enabling diffusion and moist lining which enables gases to dissolve
What factors affect the rate of diffusion?
Diffusion distance, concentration gradient and surface area
How does diffusion distance affect the rate of diffusion?
The greater the distance distance, the further the molecules must travel and the slower the rate of diffusion
How does concentration gradient affect the rate of diffusion?
The steeper the concentration gradient, the faster the rate of diffusion
How does surface area affect the rate of diffusion?
The larger the surface area, the greater the number of molecules that can diffuse across in a given time, so the faster the rate of diffusion
How can the rate of diffusion be calculated?
Surface area x concentration gradient / thickness of membrane
What is respiration?
A process that releases energy in the form of ATP from the breakdown of organic compounds
What is ATP?
Short term energy store in all cells and is universal energy carrier
Why must respiration occur continuously in living cells?
ATP is required for many essential processes in living cells
Why type of reaction is respiration?
It’s an exothermic reaction that releases energy in the form of heat
Where do plants get the glucose required for respiration?
They produce their own glucose during photosynthesis
Where do animals get the glucose required for respiration?
From the breakdown of carbohydrates that they have ingested
What are the two types of respiration?
Aerobic and Anaerobic respiration
What is aerobic respiration?
Respiration in the presence of oxygen that forms ATP from the breakdown of glucose
What is the word equation for aerobic respiration?
Glucose + oxygen -> carbon dioxide + water