Open Responses, Grade 5
Answer Key
Sample Student Response: Plant Cells
a. Chloroplasts make food for the plant. Chloroplasts contain a chemical called
chlorophyll that uses the energy in sunlight to make food from carbon dioxide and
water. This is called photosynthesis. The sugar is then transported throughout the
plant. Without chloroplasts, plants could not make food and they would die.
b. Another structure that is found in plant cells but not in animal cells is a cell wall.
The cell wall is a stiff structure that surrounds the outside of the cell. It gives the
cell strength and support.
.
Sample Student Response: Avoiding Competition
a. The main structural difference in these birds is the shape of their beaks:
 The akiapolaau’s upper beak is long, slender, and curved downward.
 Both parts of the iiwi’s beak are long and curved.
 The Maui parrotbill has a short beak with a sharp point. Its beak is broader
than the other beaks and looks like it is strong.
 The Maui creeper has a short, narrow, pointed beak.
 The apapane’s beak is also narrow and pointed, but it is longer the Maui
creeper’s beak.
b. Because each bird’s beak has a different shape, the birds are able to eat different
types of food or get their food from different parts of the habitat. They do not
have to compete for the same food, even though they live in the same area. For
example, both the akiapolaau and the Maui creeper eat insects, but the akiapolaau
can use its curved upper beak to get insects from under tree bark. The Maui
creeper has a much shorter pointed beak that cannot get behind tree bark.
However it can get insects from other parts of the tree. It eats insects it finds on
leaves, branches, and bark. Even though both birds eat insects, they get them from
different places and avoid competition.
Sample Student Response: The Water Cycle
A. Heat from the Sun causes water particles in bodies of water, such as oceans and
lakes, to absorb energy and change from a liquid to a gas (evaporation). The water
vapor rises into the atmosphere. When the water vapor cools, it condenses into a
water droplet. Water droplets gather with dust to form clouds. When clouds
become too heavy with droplets, or ice, the water falls back to Earth’s surface.
Some of this water collects on land and flows downhill. It can flow into rivers,
lakes, and streams. Most water will flow from rivers to the ocean. Some of the
water soaks into the ground, settling into the spaces between rocks and soil. The
cycle continues when water from Earth’s surface evaporates.
B. Earth’s water is conserved in this process because water that rises due to
evaporation does not leave Earth’s atmosphere. When it rises into the atmosphere,
the water vapor cools and condenses back to a liquid. It then falls back to Earth as
precipitation to continue the same cycle.
Sample Student Response: Comparing Planets
a. The inner planets are Mercury, Venus, Earth, and Mars. The outer planets are
Jupiter, Saturn, Uranus, and Neptune.
b. Three examples of how the inner planets and outer planets are different:
Temperature
Surface Material
Size
Inner Planets
Hotter—Venus is the
hottest planet with a mean
temperature of 482°C, and
Mars is the coolest inner
planet with a temperature
of –63 °C.
The inner planets are made
of mostly rock.
The inner planets are
smaller. Their radii at the
Equators range between
2,440 km on Mercury to
6,378 km on Earth.
Outer Planets
Colder—The outer planet
with the highest
temperature is Jupiter at –
121°C and the coldest are
Uranus and Neptune at –
193°C
The outer planets are
mostly gases.
The outer planets are
larger. Their radii at the
Equator range between
24,746 km on Neptune to
71,492 km on Jupiter.
Sample Student Response: Comparing Density and Buoyancy
a. The illustration shows the molecules of the rubber ball are arranged so that there
are large spaces of air between some of them. The molecules in the marble are
more tightly packed together. How tightly molecules are packed in a space
determines an object’s density. The marble and the rubber ball are the same size.
However, the marble’s molecules are more tightly packed. It has a greater density
than that of the rubber ball.
b. Reasons for the floating ball and sinking marble:


The rubber ball is floating in the water because its density is less than that of
water. Because the water has a greater density, it can push harder on the ball than
the ball can push on it.
The marble has a greater density than that of water. Because the marble has a
greater density, it can push harder on the water than the water pushing on it.
Therefore, it sinks to the bottom of the aquarium.
c. If each object were cut in half, the marble would still sink and the ball would still
float. This is because the density for each cm3 doesn’t change. The ½ ball still
has less density per cm3 than the water. The ½ marble still has greater density per
cm3 than the water.
Sample Student Response: Using Energy
a. Each photo demonstrates kinetic energy. Kinetic energy is the energy of a moving
object. Each photo shows that the ball is moving.
b. To increase the potential energy of the ball in the first photo, the boy could have
held the ball higher above his head before dropping it. By holding it higher, he
would increase the distance gravity could pull it. This increased energy is then
stored until the boy drops the ball.