Circulatory System Flashcards
Why do unicellular organisms not need a circulatory system?
Because their surface area is high compared to their low volume, so diffusion distance is short and it happens very quickly
Why do multicellular organisms need a circulatory system?
Because their surface area is low compared to their high volume, so diffusion couldn’t happen fast enough for the body to survive
What is the role of the xylem in a plant?
The xylem transports nitrates, phosphates, water and other mineral salts from the roots to other parts of the plant like the leaves or the flower
Substances that are transported are dissolved in water
How is water absorbed by root hair cells?
The water is absorbed by osmosis, this is aided by the large surface area that is created by the root hair cells
What is transpiration?
The evaporation of water from the surface of the plant
How does humidity affect transpiration?
High water content outside the leaf will mean there is little difference in concentration, so the water will not be able to move
How does wind speed affect transpiration?
Increased wind speed moves humid air away from the leaf, increasing water concentration difference and more water can evaporate
How does temperature affect transpiration?
Increased heat makes evaporating easier, faster transpiration
How does light intensity affect transpiration?
More heat from the light is absorbed by the leaf meaning more water will be evaporated, also there is more photosynthesis meaning more water is being transported through the leaf (so more will need to leave the leaf)
Describe an experiment to investigate the effects of environmental factors on the rate of transpiration
4 Potometers, 4 leafy shoots, cut and placed in the top of the potometer
Place each in a different environment (Control, Bag over the plant with humid air inside, Wind from a fan, heat and bright light)
Measure how much the bubble in the potometer has moved in each every 3 minutes for 30
minutes
That’s it
What is the composition of human blood?
55% Plasma - carries CO2 and other substances
Many red blood cells
Not as many white blood cells (phagocytes and lymphocytes)
Platelets for clotting
What is the role of the plasma in blood?
It transports CO2, digested food, urea, hormones and thermal energy
How are red blood cells adapted for oxygen transport?
Biconcave shape increases surface area
Haemoglobin binds with oxygen to form oxyhaemoglobin
No nucleus, less space taken up
No mitochondria as they respire anaerobically
How do phagocytes kill pathogens?
They detect pathogens because of the chemicals they release
The phagocytes then engulf the pathogen and destroy it using digestive enzymes
How do lymphocytes kill pathogens?
They release antibodies that are specific for the pathogen
When the lymphocyte meets the pathogen it creates memory cells and anti-bodies to destroy the pathogen
One type of anti-body attracts phagocytes, another will disable the cell, and the last will group pathogens so they can be all engulfed by a phagocyte.
