BELLWORK #138 4-11-11
Some species of bacteria are harmful. Antibiotics are chemicals that kill
bacteria. Some bacteria are resistant to antibiotics and are not killed by
these chemicals. Over time, the resistant bacteria can reproduce and create
populations that are not affected by antibiotics. The graphs below show the
results of a controlled experiment that measured thepopulation of one
species of bacteria that had been grown in four containers under identical
conditions. Different antibiotics were added to three of the four containers.
The control in this experiment is represented by the container with
(4) no antibiotic added
BELLWORK #139 4-12-11
Some species of bacteria are harmful. Antibiotics are chemicals that
kill bacteria. Some bacteria are resistant to antibiotics and are not killed
by these chemicals. Over time, theresistant bacteria can reproduce and
create populations that are not affected by antibiotics. The graphs below
show the results of a controlled experiment that measured thepopulation of
one species of bacteria that had been grown in four containers under
identical conditions. Different antibiotics were added to three of the four
containers. Which conclusion about this species of bacteria is best supported
by the information in the graphs?
(3) Antibiotic C was most effective in controlling the growth.
BELLWORK #140 4-13-11
Which object represents a simple machine? 2
BELLWORK #141 4-14-11
The diagram below shows a student using a spring scale to pull a wooden block
up a ramp that is resting on a stack of books. Which change would require
more force to pull the wooden block up the ramp?
(4) Glue sandpaper to the surface of the ramp.
BELLWORK #142 4-15-11
Base your answer to the question on the information below and on your
knowledge of science. A baseball strikes the roof of a car and dents it. The
paint on the roof begins to crack and chip, exposing the metal. The exposed
metal on the roof rusts, eventually causing a small hole in the roof. Which
event is a chemical change?
(4) The exposed metal rusts.
BELLWORK #143 4-18-11
Animals are made up of many atoms. What happens to the atoms after an animal
has died? B) The atoms recycle back into the environment.
BELLWORK #144 4-19-11
If a neutral atom loses an electron, what is formed? B) An ion.
BELLWORK #145 4-20-11
A tight metal lid on a jar of pickles may loosen when it has been held in hot
water. This is because the hot water causes the
D) metal lid to expand more than the glass jar expands.
BELLWORK #146 4-21-11
In an electron dot diagram, the element symbol and dot(s) is used to represent
C. the nucleus and valence electrons.
BELLWORK #147 4-25-11
During which phase change is heat energy absorbed by a substance?
(1) liquid to gas
BELLWORK #148 4-26-11
When carbon and oxygen combine chemically, the mass of the product is
(1) greater than the mass of the carbon plus the mass of the oxygen
BELLWORK #149 4-27-11
Which example best demonstrates the process of conduction?
(3) A metal spoon gets warm when used to stir hot soup.
BELLWORK #150 4-28-11
The graph below shows the heating curve for substance X. At approximately
which temperature does a phase change begin? (2) -10°C
BELLWORK #151 4-29-11
Which statement best describes the energy changes that occur while a child is
riding on a sled down a steep, snow-covered hill?
(2) Kinetic energy increases and potential energy decreases.
BELLWORK #152 5-2-11
Early space flights were unmanned because -
B. reliable life-support systems were not yet developed
BELLWORK #153 5-3-11
The force that holds the planets in orbit around the sun is called -
D. gravity
BELLWORK #154 5-4-11
The Moon orbits Earth at a speed of approximately one kilometer per second.
The Moon affects which of the following on Earth? D. ocean tides
BELLWORK #155 5-5-11
Which of these would be different for an object if measured on the Earth and
on the moon? D. Weight
BELLWORK #156 5-6-11
Which statement about particles in an atom is true?
d. Protons and neutrons have far more mass than an electron.
BELLWORK #157 5-9-11
The graph below relates distance to time for a rolling ball. Draw the line
for an average speed of the ball of 2 m/s.
Distance (m)
10
8
6
4
2
0 1 2 3 4 5
Time (s)
BELLWORK #158 5-10-11
According to the chart, on which planet would a ball fall the fastest?
D. Jupiter
BELLWORK #159 5-11-11
The drawing below shows part of a graduated cylinder containing liquid. Based
on the sensitivity of the graduated cylinder, what is the volume of the
liquid? C. 76.0 mL
BELLWORK #160 5-12-11
Two beakers contain pure water. A 100mL beaker is filled to the 50mL level. A
50mL beaker is filled to the 50mL level. Which of the following properties
is the same for both of these samples? C. volume
BELLWORK #161 5-13-11
A glass is partially filled with water. Five ice cubes are placed in the
glass, causing the level of the water to reach the rim of the glass. Which of
the following statements best explains the increase in water level?
A. The volume of the submerged ice is equal to the volume of water displaced.
BELLWORK #162 5-16-11
A can of diet soda and a can of regular soda were dropped into a container of
water. The can of regular soda sank to the bottom but the can of diet soda
floated. Which of the following statements best explains this observation?
B. The can of regular soda is more dense than the can of diet soda.
BELLWORK #163 5-17-11
A student in a laboratory transfers a beaker containing a hot solution from
the lab table to a cool water bath. Which of the following parts of the
system experiences an increase in heat energy? D. Water bath
BELLWORK #164 5-18-11
The density of an object is dependent upon the object's mass and -
B. volume
BELLWORK #165 5-19-11
A balance measures a burning candle in a sealed glass ball before and after
burning. The size of the candle decreases, but the balance reading does not
change. Which of the following is demonstrated by this experiment?
A. The total mass of the system is constant.
BELLWORK #166 5-20-11
A Cartesian diver is made from a plastic bottle filled with water and an
inverted test tube partially filled with water. What causes the diver to sink
as the bottle is squeezed?
B. Volume of air in the diver decreases.
BELLWORK #167 5-23-11
Which of these have a positive charge and are found in the nucleus of an atom?
D. Protons
BELLWORK #168 5-24-11
Which of these elements has the greatest average atomis mass? B. Al
BELLWORK #169 5-25-11
A substance made up of two or more elements that have been chemically
combined is called C. compound
BELLWORK #170 5-26-11
In the chemical formula for ammonia, NH3, what does the subscript 3 represent?
B. number of hydrogen atoms in each molecule of ammonia
BELLWORK #171 5-27-11
Between points 4 and 5, energy is being used to change water from a -
D. liquid to a gas
BELLWORK #172 5-31-11
A mixture of iron filings and sulfur can easily be separated by -
B. using a magnet
BELLWORK #173 6-1-11
A science class is studying physical and chemical changes. The student puts a
beaker of water onto a hot plate and heats it until bubbles appear.
Physical change: the bubbles are evidence that a liquid is changing to a gas.
This change is a phase change. The form of the substance is changing but the
composition is not.
BELLWORK #174 6-2-11
The teacher puts a sugar cube into a container of warm water. Eventually the
sugar cube is no longer visible.
Physical change: the sugar dissolves into the water forming a solution. Since
you can get the sugar back out of the solution by boiling it, the change is a
physical change.
BELLWORK #175 6-3-11
The teacher pours vinegar into a small container of baking soda. The combined
substances begin to fizz and bubble as a gas is released.
Chemical change: the 2 substances combine to form a new substance and give
off gas as evidence of the change.
