5. NC 8th Grade Science EOG Review

After a chemical reaction occurs in an open test tube, measurements indicate that the mass of the reactants is greater than the mass of the products remaining in the test tube.  What MOST LIKELY explains the measurements?

• A gas was produced.
• A solid was produced.
• The salinity of the reactants was high.
• The temperature of the reactants was low.

A layer of marine fossils is discovered in a desert environment. Which hypothesis BEST explains the discovery?

• The area was once covered by water.
• Volcanic activity once occurred in the area.
• A catastrophic event once occurred in the area.
• Erosion turned most of the limestone in the area into sand.

Which theory BEST describes how an asteroid striking Earth may have caused the extinction of dinosaurs?

• Heat from the asteroid caused massive fires that reduced the food supply.
• Dense clouds formed following the collision, causing a global drop in temperature.
• Land masses were altered by the collision, reducing the space where dinosaurs could roam for food.
• Glaciers melted rapidly from heat produced by the asteroid, causing floods that destroyed dinosaurs' habitats.

Which statements BEST explains the reason muscle cells have more mitochondria than skin cells?

• Muscle cells use more energy than skin cells.
• Muscle cells have fewer proteins than skin cells.
• Muscle cells have a smaller nucleus than skin cells.
• Muscle cells have more excess water than skin cells.

How are parasites and viruses similar?

• Both are contagious diseases.
• Both infect host organisms.
• Both reproduce using host cells.
• Both break down food using oxygen.

Which describes a nonpoint source of pollution?

• accumulation of oil in a stream next to a gas station
• chemical spill in a river next to a manufacturing complex
• runoff from a road into a nearby stream
• liquid fertilizer flowing from a barrel into a stream

Which statement BEST explains the reason some insects can walk across the surface of a lake?

• Water is a polar molecule, and its adhesiveness causes good capillary action.
• Water is a non-polar molecule, and its cohesiveness causes good capillary action.
• Water is a non-polar molecule, and its adhesiveness provides high surface tension.
• Water is a polar molecule, and its adhesiveness causes high surface tension.

Which of these BEST illustrates natural selection?

• An organism with favorable genetic variation will tend to survive and breed successfully.
• A population monopolizes all of the resources in its habitat, forcing other species to migrate.
• A community whose members work together utilizes all existing resources and migratory routes. 
• The largest organisms in a species receive the only breeding opportunities.

Complete burning of plant material returns carbon primarily to the:

• herbivores
• water
• vegetation
• atmosphere

Earth has undergone some catastrophic changes from time to time. Which of these MOST LIKELY explains why life on Earth continued following these catastrophes?

• Dominant species had a slow mutation rate.
• Many species filled the same niche.
• A strong species had many different characteristics.
• A wide diversity of species existed.