8th Grade STAAR Practice Test

Based on these observations, which ecosystem is likely the most sustainable over time?

• Ecosystem 1, because it has the fewest species.

• Ecosystem 2, because it includes both fish and birds.

• Ecosystem 3, because it has the greatest amount of insects.

• Ecosystem 4, because it supports the greatest amount of organisms

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-2

NGSS.MS-LS2-3

NGSS.MS-LS2-5

Humans have been selectively breeding corn for generations. During the process of domestication, the wild form of corn was eventually changed into a form that has more favorable traits. Early farmers most likely used corn seed that had –

• thin stalks to withstand stronger wind.

• a darker color so that they would blend with the field and be protected from predators.

• larger leaves that could be used for compost.

• the ability to grow in a large number of climates, soil types, and produced the largest amount of kernels.

Tags

NGSS.MS-LS1-5

NGSS.MS-LS4-4

Which organelle stores the information that determines an individual's hair color?

• Organelle 1

• Organelle 2

• Organelle 3

• Organelle 4

Tags

NGSS.MS-LS1-5

NGSS.MS-LS3-1

A scientist added bacteria to a sterile petri dish with a growth medium called agar. No other materials were added. The graph shows the growth of bacteria over time. Which of these most likely explains why the bacteria population stopped growing?

• The bacteria came in contact with a virus that killed off the population.

• The bacteria could not produce any longer because the population was too large.

• The bacteria competed for nutrients and died after all of the nutrients were consumed.

• The bacteria evolved into another organism.

Tags

NGSS.MS-LS1-5

NGSS.MS-LS2-1

NGSS.MS-LS2-4

Secondary succession occurs after a major disturbance to an existing ecosystem. Even though the area is altered, it is not completely lifeless. Which organisms would you most likely see return to the ecosystem first?

• small grasses and insects

• tertiary consumers like bears and eagles

• large hardwood trees

• secondary consumers like skunks and foxes

Tags

NGSS.MS-LS2-4

Decommissioned oil rigs are sometimes converted to artificial reefs in the Gulf of Mexico. What is the likely impact to the ecosystem by creating artificial reefs around these retired oil rigs?

• The large fish population will increase, but the small fish population will decrease.

• Biodiversity is increased throughout the ecosystem.

• Biodiversity remains the same because organisms do not like man-made structures.

• Invasive species of fish move into the ecosystem because there are no natural predators.

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-2

NGSS.MS-LS2-4

NGSS.MS-LS2-5

The graph shows the distance an object traveled in 20 seconds. Which answer choice best describes the movement of the object between 8 and 12 seconds?

• Moving at a constant speed

• Stopped

• Moving sideways

• Accelerating

Tags

NGSS.MS-PS3-1

A car accelerates away from the starting line at 3.6 m/s² and has the mass of 2400 kg. What is the net force acting on the vehicle?

• 8640 N

• 7200 N

• 9600 N

• 8400 N

Tags

NGSS.MS-PS2-2

A man pulled a food cart 4.5 m to the right for 15 seconds. What is the average speed of the food cart to the nearest tenth of a m/s?

• 0.3 m/s

• 0.2 m/s

• 0.4 m/s

• 0.5 m/s

Tags

NGSS.3-PS2-1

NGSS.3-PS2-2

A baseball sits motionless near first base on a baseball diamond. What statement best explains why the baseball remains motionless?

• The forces acting on the baseball are all balanced.

• There are no forces acting on the baseball.

• The dirt is placing an unbalanced force on the baseball.

• The force on the baseball is unbalanced due to gravity.

Tags

NGSS.3-PS2-1