Unit 3.2.7 - Mass Transport Flashcards
Do smaller organisms have a larger or smaller surface are to volume ratio?
Larger
Why do waste substances have to be removed from cells?
So that they don’t damage the cell
How do smaller single celled organisms exchange substances to their cells?
The substances can diffuse directly across the plasma membrane into the cell
Why can’t multicellular cells diffuse substances straight into their cells?
They are too large and so diffusion to some of the cells is too slow and so it is difficult to exchange substances straight into all of the cells
How do multicellular organisms exchange substances to all of their cells?
By mass transport - with specialised exchange organs and systems
How does surface area to volume ratio affect heat loss in animals?
The smaller the surface area to volume ratio the less the heat loss as it is hard to lose heat from a greater volume over a relatively small surface area
Do more or less compact animals have a large surface area to volume ratio?
Animals with a less compact shape
Gas exchange occurs over?
A gas exchange surface
Name three features of gas exchange systems which means they are adapted for efficient diffusion?
- ) Large surface area
- ) Are thin - short diffusion pathway
- ) Maintained concentration gradient
How are single celled organisms suited for efficient diffusion?
They have a thin exchange surface - plasma membrane
Large surface are to volume ratio
What is the gas exchange system in insects called?
Tracheal system
What do gases enter through in insects?
Spiracles
How do gases travel through insects so that they can be exchanged?
Gas enters through spiracles
Spiracles open onto tubes called tracheal tubes
The tracheal tubes branch into smaller tracheoles
The gases then diffusion from the tracheoles into the respiring cells
Do the tracheoles have thin or thick walls and why?
Thin walls to increase the diffusion of gases between the air and the respiring cells
How do insects move the air in and out of the spiracles?
By rhythmic abdominal movements which keep the air moving
Give three ways insects prevent water loss?
- ) They can close their spiracles
- ) They have a water proof, waxy cuticle around their body to reduce evaporation
- ) They have tiny hairs around their spiracles to reduce evaporation
Why do fish have to have special adaptations in their gas exchange system?
As their is a lower concentration of oxygen in water than in air, so it means they can get enough oxygen
How does water move through a fish so it can exchange substances with it?
Water containing oxygen enters through the fishes mouth and then leaves out of the gills
Describe how the structure of the gill is adapted in increases the rate of diffusion?
Each gill is made up of lots of thin plates called gill filaments, the gill filaments are then covered in tiny structures called lamellae. These both increase the surface area for diffusion to happen across.
Give two reasons how the lamellae are adapted to increase the rate of diffusion of oxygen into the blood and why these adaptations help?
1.) Lot of blood capillaries
2.)Thin surface layer of cells
Short diffusion pathway
Other than the structure of the gills name another adaptation that fish have to increase the rate of diffusion of oxygen into the blood?
The counter current system
What is the counter current system?
Blood flows through the lamellae in one direction and then water flows over in the opposite direction
How does the counter current system increase the rate of diffusion of oxygen into the blood?
Water with a high concentration of oxygen always flows next to the blood with a lower concentration of oxygen, this maintains a steep concentration gradient and so increasing the rate of diffusion
What is the main surface for gas exchange in dicotyledonous plants?
The mesophyll cells
What are the two types of mesophyll cells?
Palisade and spongey mesophyll
What is main the function of the palisade mesophyll cells?
Using carbon dioxide in the process of photosynthesis to produce energy
What is the main function of the spongey mesophyll cells?
Allows the carbon dioxide to get to the palisade cells
What are the stomata?
Special pores in the epidermis of a leaf that control gase exchange
What controls the opening and closing of the stomata?
The guard cells
Label the diagram of a leaf?
See flash card
How are the guard cell adapted to prevent water loss at night and why?
At night there isn’t any sunlight so no photosynthesis happens, so they don’t need the gases so the stomata remains closed to prevent water loss
How do the guard cells close when the plant is dehydrated to prevent further water loss?
When the plant is dehydrated the guard cells lose water and become flaccid closing the stomata preventing any water from evaporating
Name a plant that is especially adapted to live in a warm, dry and wind habitats?
Xerophytes
Name five adaptations of xerophytes?
- ) the stomata are sunk in pits
- ) curled leaves with the stomata inside
- ) a reduced number of stomata
- ) waxy, waterproof cuticle on the leaves and stem
- ) hairs on the epidermis
Why does the stomata being sunk in pits on xerophytes reduce water loss?
It traps water vapour lowering the concentration gradient and so reducing diffusion
Why does the curled leaves with the stomata inside on xerophytes reduce water loss?
It protects them from the wind lowering the concentration gradient and so reducing diffusion
Why does a reduced number of stomata on xerophytes reduce water loss?
There are fewer places for water to evaporate from
Why does the waxy, waterproof cuticle on xerophytes reduce water loss?
It reduces evaporation
Why do the hairs on the epidermis of the xerophytes reduce water loss?
The hairs trap water vapour round the stomata lowering the concentration gradient and so reducing diffusion
Why do mammals need a specialised circulatory system?
They have a low surface area to volume ratio and so without it the cells wouldn’t be able to exchange the substances that they need to
Name the four categories of blood vessels?
Arteries, arterioles, veins and capillaries
Name nine of the important blood vessels in the body?
- ) Pulmonary artery
- ) Pulmonary vein
- ) Aorta
- ) Vena cava
- ) Hepatic artery
- ) Hepatic vein
- ) Hepatic portal vein
- ) Renal artery
- ) Renal vein
The pulmonary artery carries blood from? to?
From the heart to the lungs
The pulmonary vein carries blood from? to?
From the lungs to the heart
The aorta carries blood from? to?
From the heart to the body
The vena cava carries blood from? to?
From the body to the heart
The hepatic artery carries blood from? to?
From the body to the liver
The hepatic vein carries blood from? to?
From the liver to the vena cava
The hepatic portal vein carries blood from? to?
From the gut to the liver
The renal artery carries blood from? to?
From the body to the kidneys
The renal vein carries blood from? to?
From the kidneys to the vena cava
Does blood pressure increase or decrease along the circulatory system?
Decrease
What is meant by mammals have a double circulatory system?
The heart flows through the heart twice during one circuit around the body
How does the heart gets its blood supply?
From the left and right coronaries arteries
Name four things the blood transports around the body?
Respiratory gases, products of digestion, metabolic waste and hormones
What is the function of arteries?
To carry blood from the heart to the rest of the body
How are the walls of arteries adapted so they can carry blood at high pressures?
They have thick, muscular walls with elastic tissue, the endothelium is also folded which slows the artery to stretch and cope with the high pressures
Which is the only artery that doesn’t carry oxygenated blood?
The pulmonary artery
What do arteries divide into?
Arterioles
What is the function of the arterioles?
Branch of from arteries to take the blood to different areas of the body depending on the demand
How do the arterioles only take blood to the areas of demand?
They constrict to restrict blood flow or relax to allow blood flow
What do arterioles divide into?
Capillaries
What is the function of the capillaries?
Branch of from the arterioles to take blood right to the cells where the substances can be exchange
Name two adaptations of the capillaries and how this increases the diffusion of substances into and out of the blood?
- ) Endothelium only one cell thick to create a short diffusion pathway
- ) Many of them to increase the surface area for diffusion to happen over
What is the function of veins?
To take the blood back to the heart under low pressure
Name two differences between arteries and veins?
Veins have valves to stop blood flowing backwards arteries don’t
Veins have very little elastic tissue
How is blood flow helped in the veins?
By contraction of the body muscles surrounding them
What is the only vein that doesn’t carry deoxygenated blood?
Pulmonary vein
Why does the pressure decrease along blood vessels?
Because there is less friction
What is tissue fluid?
The tissue that surrounded cells in tissues
Name four things that tissue fluid does contain?
Oxygen, water, amino acids and glucose
How is tissue fluid formed at the arterial end?
There is a high hydrostatic pressure which forces the fluid and small molecules from the blood out into the tissue fluid, where substances can be exchanged between the cells
How does tissue fluid re-enter the capillary at the venous end?
As the fluid leaves the pressure reduces in the capillaries, lowering the hydrostatic pressure at the venous and so fluid moves back into the capillaries
Also because of fluid loss the water potential at the venous end is lower than the tissue fluid and so water will re enter by osmosis
Name two things tissue fluid doesn’t contain and why?
Red blood cells and big proteins because they are too large to be pushed through the capillary walls
Why is the excess tissue fluid drained into and where does it go once there?
It is drained into the lymphatic system which transports the excess fluid back into the circulatory systems
Label the diagram of the main blood vessel in the body?
See flash card
What in the roots of the plants increase their surface area for the absorption of water?
Root hair cells
What four things does the water have to go through after being absorbed by the root hair cell before it reaches the xylem?
Epidermis, cortex, endodermis and then the pericycle
What is the epidermis?
The outer layer of cells surrounding the roots
What is the cortex?
A tissue of unspecialised cells
What is the endodermis?
The inner layer of cells between the cortex and the pericycle
What is the pericycle?
The cylinder of cells between the cortex and then xylem
How is water absorbed into the root hair cell?
By osmosis from the area of high water potential in the soil to the are of low water potential in the cell
Why is there a maintained concentration gradient
The water is constantly evaporating from the leaves so they constantly have a low water potential and so this maintains the concentration gradient
What is the water potential gradient?
The difference in water potential
What two ways can water move through the cortex?
Through the symplast pathway and through the apoplast pathway
What is the symplast pathway?
Through the cytoplasm of the cell
What is the apoplast pathway?
Through the cell walls of the cells
What is the casparian strip?
A waxy strip in the endodermis cell layer
What does the casprain strip prevent?
Water movement along the cell walls and backflow during dry seasons
What happens to water in the apoplast pathway when it reaches the casprain strip?
It is redirected through the cytoplasm along the symplast pathway
What is transpiration?
The loss of water from a plants surface due to evaporation
What happens when the spongey mesophyll cells lose water?
It accumulates in air spaces between cells in the leafs and when the stomata is open it moves out of the leaf down the water potential gradient
What four factors affect the transpiration rate?
Light intensity, temperature, humidity and air movement
How does light intensity affect transpiration rate?
The lighter it is the faster the rate of transpiration of the stomata will be open when it is light allowing water to be lost
How does temperature affect transpiration rate?
The higher the temperature the faster the rate of transpiration because the molecules will have more energy so will evaporate out of the leafs faster, increasing the water potential inside the leaf and so increasing the water potential gradient so more water will be lost
How does humidity affect transpiration rate
The lower the humidity the faster the transpiration rate this is because the air around the plants is dry and so the water potential gradient will be bigger and so more water will be lost
How does wind movement affect transpiration rate?
The windier it is the faster the transpiration rate this is because the wind blows away the water molecules from the stomata increasing the water potential gradient and so more water is lost
What are the three reasons water moves up the xylem?
Root pressure, cohesion tension theory and capillarity
How does capillarity allow water to move up the xylem?
There is adhesive forces between the molecules and the walls of the xylem which pulls the water molecules up when water is lost from the lead by evaporation
How does the cohesion tension theory mean water moves up the xylem?
Water evaporates from the leaves at the top of the xylem
Then creates tension (suction) which pulls more water into the lead to replace the water lost
As water molecules are cohesive and stick together when one molecule is pulled up the rest follow and so the while column of water in the xylem moves upwards
How does root pressure mean water moves up the xylem?
When water is transported into the xylem in the roots it creates pressure shoving water already in the xylem further upwards
