Cells
This organelle contains DNA and controls cell activities
Nucleus
Movement of particles from high → low concentration
Diffusion
Variable that is changed
Independent Variable
What is pressure?
Force per unit area
Found ONLY in plant cells and provides support
Cell Wall
Movement of water across a membrane
Osmosis
Variable that is measured
Dependent Variable
What happens when surface area increases?
Pressure Decreases
Difference between a tissue and an organ
Tissue = group of similar cells working together
Organ = group of different tissues working together
A cell shrinks in salt water
Osmosis — water moves out of the cell (higher water inside → lower water outside), causing the cell to shrink
Why repeat experiments?
To ensure results are reliable and accurate
Why do sharp knives cut better?
Smaller surface area → greater pressure → easier to cut
Which cell has a cell has chloroplasts, a cell wall, and a large vacuole?
Plant Cell
2 differences between diffusion and osmosis
Diffusion: any particles move; Osmosis: only water moves
Diffusion does not require a membrane; Osmosis requires a selectively permeable membrane
What is off about this: Student changes light AND water
Not a fair test — more than one variable is changed, so results are unreliable
Pascal’s Law
Pressure applied to a fluid is distributed equally in all directions
Why is cellular differentiation important? + example
Cells become specialized to perform specific functions, allowing multicellular organisms to function efficiently.
Example: muscle cells contract, nerve cells transmit signals
What is the concentration in and outside of a red blood cell in distilled water
Outside = high water concentration
Inside = lower water concentration
Water moves into the cell by osmosis
Cell swells and may burst
Find the variables: Design experiment (temperature vs dissolving rate)
Independent variable: temperature of water
Dependent variable: rate of dissolving
Control variable: amount of substance (or volume of water)
What are the differences between Hydraulic and Pneumatic
Hydraulic = uses liquids (e.g., car brakes)
Pneumatic = uses gases (e.g., air compressor)
Liquids are not compressible; gases are compressible