STAAR TEST 2018 GRADE 8 SCIENCE

A partial grassland food web is shown. Which of the following best describes a relationship in this grassland?

• A. Badgers are top predators because they eat upland sandpipers and beetles.

• B. A producer–consumer relationship exists between lupines and ants.

• C. A predator–prey relationship exists between beetles and ground squirrels.

• D. Upland sandpipers are primary and secondary consumers because they eat grasses and grasshoppers.

  Science

Which statement about stars is correct?

• F. Star formation begins in a nebula.

• G. White dwarfs become main-sequence stars when they gain mass.

• H. Supergiants are stars that can absorb black holes.

• J. Main-sequence stars are formed by comets.

For a laboratory investigation some students put a strip of shiny metal into a beaker of blue solution and then stored the beaker on a shelf overnight. The next morning, the students recorded observations about the metal and the solution in the box below. Based on their observations, can the students correctly conclude that a chemical reaction occurred?

• A. No, because the metal strip was still visible

• B. Yes, because a new material of a different color formed on part of the metal strip

• C. No, because the solution stayed blue

• D. Yes, because the volume of the blue solution stayed the same

Which statement describes the energy changes that occur when water in a tea kettle is heated on a stove that uses natural gas?

• F. Some of the chemical energy in the natural gas transforms into thermal energy, which heats the water. Then some of the thermal energy changes into sound energy when the water forms steam and the steam leaves the kettle.

• G. Some of the thermal energy in the natural gas transforms into sound energy when the water becomes hot. Then some of the sound energy changes into light energy when the kettle becomes warm.

• H. Some of the electrical energy in the natural gas transforms into thermal energy, which causes the water to form steam. Then some of the thermal energy changes into sound energy and light energy when the steam leaves the kettle.

• J. Some of the light energy in the natural gas transforms into chemical energy in the water. Then some of the chemical energy changes into kinetic energy when steam leaves the kettle and into sound energy when the water boils.

  Science

To fight a bacterial infection, a patient was given an antibiotic to take for 10 days. After the patient finished taking the antibiotics as directed, almost all the bacteria were killed. After another 10 days, the patient was sick again with the same type of infection. What most likely happened?

• A. A few bacteria survived the antibiotics and stopped reproducing.

• B. The patient’s high fever inactivated the antibiotic, allowing the surviving bacteria to grow rapidly.

• C. The antibiotic slowed the life cycle of the bacteria.

• D. Some of the bacteria were resistant to the antibiotic, and they reproduced.

A 1,100 kg car comes uniformly to a stop. If the vehicle is accelerating at -1.2 m/s , which force is closest to the net force acting on the vehicle?

• F. -9,600 N

• G. -1,300 N

• H. -900 N

• J. -94 N

The beginning of autumn in North America is in September, but the beginning of autumn in South America is in March. The diagram shows the positions of Earth, the moon, and the sun on one day in September and one day in March. Why does autumn start in different months of the year in North America and South America?

• A. Earth’s orbit around the sun is not a perfect circle.

• B. North America has a larger landmass than South America.

• C. The moon has a greater pull on South America than on North America.

• D. Earth’s axis has a 23.5° tilt.

This drawing shows a human body system. What is the primary function of this body system?

• F. The protection of vital organs from injury

• G. The chemical breakdown of food into smaller pieces

• H. The transport of nutrients, water, and oxygen to body cells

• J. The production of hormones that regulate growth and metabolism

The diagram of Situation 1 shows one person failing to move a refrigerator up a ramp, while the diagram of Situation 2 shows two people successfully pushing a refrigerator up a ramp. What comparison can be made about the work done in the two situations?

• A. In Situation 1, no work was done, while 12,000 J of work was done in Situation 2.

• B.In Situation 1, 1,600 J of work was done, while 3,000 J of work was done in Situation 2.

• C. In Situation 1, no work was done, while 8,000 J of work was done in Situation 2.

• D. In Situation 1, 400 J of work was done, while 1,300 J of work was done in Situation 2.

An ecosystem that is not sustainable can break down when a natural disaster occurs. This can lead to organisms in the ecosystem either leaving the area or dying off.

Increased biodiversity results in a more sustainable ecosystem because —

• F. a greater number of plant species means that there is less barren land

• G. a greater variety of species present allows more organisms to adapt after changes occur

• H. the transition area between two ecosystems is narrower

• J. there are fewer species to be affected by environmental stresses