Movement in and out of cells

Question 1

Diffusion

rate of diffusion, active or passive

Answer 1

Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient until it is evenly distributed. It is a passive process meaning no energy is needed.
The rate of diffusion depends on the distance the particles have to travel and the difference in concentration.
Oxygen, food and waste products move by diffusion.

Question 2

What are alveoli? (and their adaptations)

Answer 2

The tiny air sacs at the end of the bronchioles in which gas exchange occurs.
Alveoli have several adaptations that help make gas exchange efficient.
1. They are very thin
2. Covered by a network of fine capillaries enabling gas bas between the lungs and blood stream.
3. Moist, encouraging gas molecules to dissolve
4. Large surface area allowing large amounts of gases to be exchanged with each breath.

Question 3

Diffusion and Digestion (mainly digestion tbf)

+(small food molecules)

Answer 3

Digestion breaks down large food molecules into smaller molecules such as fatty acids, amino acids and glucose that can be easily absorbed.
Small food molecules are usually absorbed in the small intestine diffusing across the intestine wall and into the bloodstream.
The wall of the small intestine is lined w many tiny finger like projections called villi. These are v thin and increase the surface.a of the small.i, increasing the rate of diffusion.

Question 4

Diffusion and Placenta

Answer 4

The placenta enables nutrients and oxygen to pass from the mother to the fetus by diffusion and waste products to diffuse from the fetus back to the mother.

The placenta can filter out certain molecules and bacteria but not harmful substances like alcohol, chemicals and some types of viruses from reaching the fetus.

Question 5

Diffusion and Nerve Cells

Answer 5

A synapse is a junction between 2 neurons across which electrical signals must pass

Neurotransmitter molecules diffuse from vesicles towards the neurotransmitter receptors from an area of high to low concentration

Question 6

Active Transport

Answer 6

Movement of particles from a region of lower concentration to a region of higher concentration using energy.

Question 7

Osmosis

Answer 7

Movement of water particles from a region of higher water potential to a region of lower water potential.

A partially permeable membrane has holes in it that permit water molecules through but are too small to allow larger molecules through. (irrelevant)

Question 8

Hypertonic and Hypotonic

Answer 8

Hypertonic means that the environment outside of the cell has a higher concentration of solutes than the cell itself.

A hypotonic solution is one in which the concentration of solutes is greater inside the cell than outside of it.