Science 6 Diagnostic

Yeast is used to bake bread and rolls. When dry, yeast looks like a light brown powder. When mixed with water and sugar, yeast grows and reproduces, producing gases that make dough rise.

A student is given a beaker containing a sample of dry yeast.

Which investigation will produce data to best support the claim that yeast is a living thing?

• Keep the dry yeast in sunlight for several days, and see if more yeast appears.

• Combine dry yeast with water, and measure the heat released from the mixture.

• Mix dry yeast with water and sugar, and measure the mixture’s change in volume.

• Mix dry yeast with water and sugar, and use a microscope to observe if cells are visible.

Answer explanation

The one thing all living things have in common is that we are made out of cells.

A spore is a small structure, usually a single cell, produced by plants, fungi, and some microorganisms. In the right environment, a single spore can develop into a new, individual organism.

During observations of soil samples, scientists find tiny structures that appear to be spores.

Which experiment could the scientists use that would best determine if these tiny structures are spores?

• Test them for chemicals normally found in living cells.

• Place them in water and see if they change in shape or mass.

• Observe whether they go through the steps of cell division to form new cells.

• Observe whether they are made of atoms by using a high-powered microscope.

Answer explanation

Living cells come from existing cells.

A group of students design a model to explain how the different parts of a cell function. They choose a grocery store as a model for a cell. They place a map of a grocery store and a cell diagram side by side to compare the parts of each.

Which part of a grocery store functions similarly to a cell membrane?

• a time clock recording employee hours in the office

• a sliding glass door opening and closing at the entrance

• the bricks in the outer wall providing support for the roof

• the aisles allowing customers to move between shelves of products

Answer explanation

The door allows people and groceries to move into and out of the store.

A teacher shared the model in the picture with her class. Which statement is best explained by the model?

• how the cell membrane controls what enters and exits the cell

• how the cell membrane protects the cell from harmful chemicals

• how oxygen is important for body cells to survive and reproduce

• how oxygen concentration is always different inside and outside of cells

Answer explanation

The diagram shows oxygen moving passively across the cell membrane because the structure allows some materials to move and not others.

A group of students used classroom materials to build a model of cellular structures. Which statement describes the best way materials were used to model mitochondria?

• a beaker with water, to model how the cell gets its shape

• a battery with wires, to model energy for cellular processes

• a cloth bag, to model how the cell lets materials into and out of it

• a computer mouse, to model how the cell controls cellular processes

Answer explanation

This choice correctly interprets the model as a function of mitochondria.

A group of students makes a claim that body systems work together to maintain the human body. To support their claim, the students present evidence comparing cells and tissues in the muscular system with those in the skeletal system. They say that the movement of arms and legs is caused by the contraction of muscles connected to bones. This is evidence that body systems work together to maintain the human body.

Which statement can be used as evidence to further support the group’s claim?

• Cells in the nose and mouth filter air breathed into the lungs.

• Cells in the brain produce signals that control the movement of the eyes.

• Cells in the mouth, stomach, and small intestine chemically break down food.

• Cells in the walls of the heart and blood vessels allow blood to pass throughout the body

Answer explanation

This is evidence that the nervous and muscular systems work together to move the eyes.

This organ is part of the digestive system.

• lung

• heart

• brain

• stomach

What is the function of the respiratory system?

• To digest your food

• To remove waste from the body

• To take in oxygen and remove carbon dioxide

• To fight disease

Which statement best describes the relationship between the nervous system and the muscular system?

• The nervous system controls the muscular system.

• The muscular system controls the nervous system.

• The nervous system provides nutrients for the muscular system.

• The muscular system provides nutrients for the nervous system.

In what way are the digestive and circulatory systems alike?

• Both protect organs in the body.

• Both control movement of the body.

• Both absorb gases or nutrients into the body.

• Both provide structural support for the body.