Cells and Cell Transport (2.1-2.6B), (2.15-2.17)

levels of organisation, cell structure, movement of substances

levels of organisation

organelles - cells - tissues - organs - systems

chloroplasts

site of photosynthesis in plant cells

nucleus

contains genetic information and controls cell activity

ribosomes

site of protein synthesis in cells

mitochondria

site of aerobic respiration in cells

cell wall

structural support

permanent vacuole

stores cell sap

cytoplasm

site of chemical reactions in cells

cell membrane

selectively permeable barrier that controls entry and exit of substances into the cell

similarities between plant/animal cells

• both eukaryotic

• have cell membrane, cytoplasm, mitochondria, ribosomes etc.

differences between plant/animal cells

• plant cells have cell walls; animal cells don’t

• plant cells have chloroplasts and a vacuole; animal cells don’t

definition of diffusion

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

definition of osmosis

the net movement of water particles from a dilute solution to a concentration across a selectively permeable membrane

definition of active transport

the movement of molecules from an area of lower concentration to an area of higher concentration against the concentration gradient using energy released from respiration

factors that affect the rate of diffusion

• temperature - warmth increases kinetic energy of particles

• distance - the greater the distance the longer it takes

• mass of particles - the heaver the particle, the slower it is

• surface area of membrane - larger surface area increases rate of diffusion

• surface are to volume ratio - diffusion takes longer when there is greater area needing to receive the diffusing substance but less area for it to actually enter

dilute solution

a solution with a high concentration of water and few solute molecules

concentrated solution

a solution with a lower concentration of water molecules and lots of solute molecules

selectively permeable

a membrane that allows water molecules through but not larger solute molecules such as sugar and salt

isotonic

balanced/equal concentration

hypertonic

more solute than water

hypotonic

more water than solute