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