B3 - Exchange of materials Flashcards
What is osmosis
The diffusion of water through a partially permeable membrane. From a high concentration of water to a low. So from a dilute to concentrated solution
What’s active transport
Cells use active transport to absorb substances over a concentration gradient. Usually by using energy from respiration
Give an example of active transport
Glucose reabsorbed by active transport in the kidney tubes
Why is glucose used during exercise
Glucose is used for respiration and when you exercise your muscles respire to release energy
What is lost from the body when you exercise
Ions, water through sweat and sugars through respiration
What’s an isotonic sports drink and it’s function
A drink that contains water and ions to rehydrate cells after exercise. Isotonic means the concentration of the drink matches the concentration of the body fluids.
Are isotonic drinks the best option
Not always, water works just as well
What is an exchange surface
Surfaces in the body that absorb the food and oxygen needed
How would an exchange path be efficient
Large surface area
Thin walls
Short diffusion pathway
What exchange happens in the lungs
Gaseous exchange, surface area is increased by the alveoli
What are alveoli and how are they well adapted
Air sacs in the lungs that help to ventilate the air and absorb required substances. They have thin walls, a large surface area and a good blood supply
Describe the gaseous exchange that goes on in the alveoli
Oxygen diffuses into the surrounding capillaries and carbon dioxide diffuses back into the lungs to be breathed out
Describe the movement of breathing in
Lungs - Move up and out
Volume - Increases
Diaphragm - Flattens
Pressure - Decreases, so the outside air is forced in
Describe the movement of breathing out
Lung - Move in and down
Volume - Decreases
Diaphragm - Arches
Pressure - Increases, so the air is forced out
Give 2 ways a person might not be able to get enough oxygen into their bloodstream
Paralysed so the muscles are unable to contract and move the ribcage
Alveoli are damaged, surface area for gas exchange is reduced
What are villi
Line the inside of the small intestine and exchange the material from the digestive system to the blood
Explain how villi are adapted to increase efficiency
Large surface area and thin walls. Many capillaries and can absorb via active transport or diffusion
Describe the structure of a leaf cell
Waxy cuticle - waterproof layer to stop water loss
Upper epidermis
Palisade
Mesophyll
Lower epidermis
Stomata - with guard cells that control water loss
Describe the exchange in a plant
Gases diffuse from the stomata at the bottom of the leaf, and the size is controlled by the size of the guard cells.
Oxygen needed for respiration and waste from photosynthesis, vice versa with carbon dioxide
Water vapour is also diffused from the stomata
What is the transpiration stream
The movement of water through a plant
Starting at the root where the water is taken by the root until it is wasted through evaporation from the stomata
What increases the rate of evaporation and what could this mean for the plant
Hot, dry, windy or bright conditions
Plant could dehydrate if more water is lost than is taken in
