Movement Of Molecules In And Out Of Cells Flashcards Preview

Biology > Movement Of Molecules In And Out Of Cells > Flashcards

Flashcards in Movement Of Molecules In And Out Of Cells Deck (26):

Dissolved substances move by ? and ?

Active transport and diffusion


What is osmosis?

Osmosis is the diffusion of water from a dilute to a more concentrated solution through a partially permeable membrane that allows the passage of water molecules.


What do most soft drinks contain?

Water, sugar and ions.


What do sports drinks contain?

Sugars to replace the sugar used in energy release during the activity. They also contain water and ions to replace the water and ions lost during sweating.


What happens if water and ions are not replaced after exercise?

The balance of the body is disturbed and the cells do not work as efficiently.


What is active transport?

Active transport is the process of substances being absorbed against a concentration gradient using energy from respiration.


What does active transport allow?

Active transport enables cells to absorb ions from very dilute solutions.


What 4 things can increase the effectiveness of an exchange surface?

1. Having a large surface area
2. Being thin, to provide a short diffusion path
3. (In animals) having an efficient blood supply
4. (In animals, for gaseous exchange) being ventilated


Why are gas and solute exchange surfaces in humans and other organisms adapted?

To maximise effectiveness!!


What increases the difficulty of exchanging materials?

The size and complexity of an organism.


What is the surface area of the lungs increased by?

The alveoli.


What is the surface area of the small intestine increased by?



How are the villi specialised to absorb the products of digestion by diffusion and active transport?

They provide a large surface area with an extensive network of capillaries.


Where are the lungs and how are they protected?

The lungs are in the upper part of the body (thorax) protected by the ribcage and separated from the lower part of the body (abdomen) by the diaphragm.


How does the breathing system work?

The breathing system takes air into and out of the body so that oxygen from the air can diffuse into the bloodstream and carbon dioxide can diffuse out of the bloodstream into the air.


What is ventilation?

The movement of air into and out of the lungs.


Describe the process of ventilation.

To make air move into the lungs the ribcage moves out and up and the diaphragm becomes flatter. These changes are reversed to make air move out of the lungs.


In plants, how does carbon dioxide enter leaves?

By diffusion.


In plants, what is absorbed by the roots?

Most of the water and mineral ions.


How is the surface area of the roots increased?

By root hairs.


How are the surface area of leaves increased?

By the flattened shape and internal air spaces.


Why do plants have stomata?

To obtain carbon dioxide from the atmosphere and to remove oxygen produced in photosynthesis.


Where do plants lose most of their water vapour?

Through the stomata in their leaves.


What conditions speed up evaporation?

Hot, dry and windy conditions.


Why would the stomata need to close to prevent wilting?

Because plants may lose water faster than it is replaced by the roots.


What controls the size of stomata?

Guard cells, which surround them.