c) chapter 3 - movement in and out of cells

diffusion

the net movement of particles from an area of high concentration to low concentration

the energy for diffusion comes from

the kinetic energy of random movement of molecules and ions

some substances move in and out using the

cell membrane

factors influencing diffusion

temperature, surface area, thickness of diffusion surface, concentration gradient, ph level, size of particles

osmosis

the net movement of water molecules from an area of high water potential to low water potential through a partially-permeable membrane

why is water a crucial solvent?

• aids digestion by helping enzymes break down food and facilitating nutrient absorption

• in excretion, it helps dissolve the waste products of metabolism

• in transport, is a key part of plasma, carries substances through the body

• maintains cell structure, supports cellular processes and regulates body temperature

turgid cells

• vacuole is pushing all the space and pushing at the cell wall to give the cell its shape

• plant is stiff and upright

flaccid cells

• not putting enough pressure on the cell wall to hold the shape

• plant is not stiff

plasmolysed

cell membrane and cell wall have detached from each other

hypertonic

low concentration compared to the cell

hypotonic

high concentration compared to the cell

isotonic

almost equal concentration compared to the cell

active transport

• low to high concentration

• using ATP which is released during aerobic respiration

• through a protein channel in the cell membran

active transport in the root cells

allows plants to absorb mineral ions, which are necessary for healthy growth, even though the concentration of minerals is usually lower in the soil than in the root hair