Cells & Systems
What is a multicellular organism?
organism made up of one or more cells
What is the term for a substance that has no definite shape but has a definite volume?
What does the term “transparent” mean?
allows all light to pass through
Which simple machine is used in a staircase?
inclined plane
Why is it unsafe to drink untreated river water?
It may contain harmful microorganisms or pollutants.
What is the basic unit of life?
a cell
What is the substance that is dissolved in a solution?
A solute
What part of the eye controls how much light enters?
the iris (controls the size of the pupil)
What is mechanical advantage?
The ratio of output force to input force. (how much a machine increases your force)
What is salinity?
the amount of salt dissolved in water
Name two organelles found in plant cells but not in animal cells.
chloroplasts and cell walls
Name two ways to increase the rate at which a solute dissolves in a solvent.
Stirring and heating it up
What happens when light passes from air into water?
it bends or refracts
Name the six simple machines.
lever, inclined plane, wedge, screw, pulley, and wheel and axle
What causes tides in the ocean?
the gravitational force of the moon
Compare arteries and veins.
Arteries carry blood away from the heart; veins carry blood toward the heart.
What is the difference between a pure substance and a mixture?
A pure substance has only one type of particle; a mixture contains two or more.
How do regular reflection and diffuse reflection differ?
Regular reflection occurs on smooth surfaces; diffuse reflection on rough ones.
Why are gears used in a bicycle?
To change the force and speed of motion.
What is the largest source of freshwater on Earth?
glaciers/ icecaps
Explain the role of the small intestine in digestion.
It absorbs nutrients from digested food into the bloodstream.
A fluid's internal resistance to flow is called _______
viscosity
What is the retina’s function in the eye?
It detects light and sends signals to the brain.
What does efficiency measure in a machine?
How well a machine converts input energy into useful output.
How does fertilizer runoff affect lakes and rivers?
It causes algae blooms that can harm aquatic life.