Pennsylvania Science Review

A student was unable to lift a rock using the lever setup shown. The student moved the location of the fulcrum closer to the rock until he was able to lift the rock. The student concluded that as the length of the effort arm increased, less effort force was needed to lift the rock. Which graph best represents the student's conclusion?

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A scientific technique can be used to determine the presence and concentration of a chemical compound in a sample. A light source is directed at samples of known concentrations and the amount of light each absorbs is measured. Based on the graph, which statement best

describes the relationship between concentration and light absorption?

• The light absorption of a sample is independent of the concentration of the chemical compound.

• The concentration of the chemical compound in a sample remains steady as the light absorption increases.

• An increase in the concentration of the chemical compound in a sample is accompanied

  by an increase in the light absorption.

• A decrease in the light absorption of a sample is accompanied by an increase in the concentration of the chemical compound.

Tags

NGSS.MS-PS1-2

A scientist examined a colorless gas, which had a density between 1.30 and 1.60 g/L and a boiling point between −190 and −180°C. The gas reacted with sodium (Na) metal. Based on the data in the table, what is the most likely identity of the gas?

• argon (Ar)

• fluorine (F2)

• hydrochloric acid (HCl)

• oxygen (O2)

Tags

NGSS.MS-PS1-2

A student is roasting marshmallows on a stick above the flames of a campfire. How does convection transfer heat from the fire to the marshmallows?

• by direct contact between the fire and the marshmallows

• by currents of warm air molecules flowing upward from the fire

• by the collision of warm air and cool air molecules above the fire

• by the movement of heat through empty spaces between air molecules

Which statement best describes wood and coal in terms of renewability and formation time?

• Wood is nonrenewable and forms in a few years, unlike coal, which is renewable and takes millions of years to form.

• Wood is renewable and forms in a few years, unlike coal, which is nonrenewable and takes millions of years to form.

• Wood is nonrenewable and takes millions of years to form, unlike coal, which is renewable and forms in a few years.

• Wood is renewable and takes millions of years to form, unlike coal, which is nonrenewable and forms in a few years.

The acidity of the water in a stream is indicated by its pH. Historically, a certain stream has had a pH of 6.0. Acid rain has caused the stream’s pH to become 4.8. Which statement

predicts how the stream’s ecosystem will most likely be impacted?

• The flow rate of the stream will increase.

• The flow rate of the stream will decrease.

• The number of fish in the stream will increase.

• The number of fish in the stream will decrease.

Tags

NGSS.MS-LS2-4

Making Maple Syrup

In forested regions of Pennsylvania where maple trees are plentiful, making maple syrup is a

time-honored tradition. When air temperatures are below freezing at night but above freezing during the day, the sap in maple trees begins to flow. This means that water, sugar, and minerals from the soil move upward through the xylem inside the trees. Xylem is a tissue in plants through which

water and minerals move. Xylem also provides some structural support. Maple syrup makers

access the sap by making a hole through the tree bark and into the outer area of xylem, commonly known as sapwood. They insert a spout, also called a spile, into this hole. This is called tapping the tree.

Traditionally, maple tree sap was collected from buckets attached to the spiles. Maple syrup makers would visit each tree, sometimes several times a day, to empty the sap from each bucket into a larger collection container. Today, some maple syrup makers use a tubing system that allows sap to move from each tapped tree to a collection tank located where the sap processing occurs.Processing the sap into maple syrup typically involves reducing water content by heating the sap in large pans. Once the liquid reaches a precise finishing temperature and density, it is maple syrup. It takes nearly 40 gallons of sap from maple trees to make 1 gallon of maple syrup.

Approximate Boiling Points of Three Substances

Substance Boiling Point (°C)

water 100

sap 104

maple syrup 107

Which inference about the process of making maple syrup from maple tree sap is best supported by the data above?

• As the concentration of sugar in the liquid increases, the boiling point increases.

• As the concentration of sugar in the liquid increases, the boiling point decreases.

• A decrease in the boiling point of the liquid causes a decrease in sugar concentration.

• A decrease in the boiling point of the liquid causes an increase in sugar concentration.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

What is the approximate percent change in water content after maple tree sap becomes

maple syrup?

• Maple tree sap has 2% less water than maple syrup.

• Maple tree sap has 34% less water than maple syrup.

• Maple tree sap has 31% more water than maple syrup.

• Maple tree sap has 65% more water than maple syrup.

Tags

NGSS.MS-PS1-2

Tapholes for collecting maple syrup can scar the tree’s trunk. Why do the offspring of tapped maple trees, called saplings, have unscarred trunks?

• Scars are inherited traits, and saplings will develop scars as they age.

• Scars are acquired traits, and saplings are unable to inherit acquired traits.

• Scars are dominant traits, so a mutation must have occurred in saplings with

  unscarred trunks.

• Scars are recessive traits, so a sapling must receive the traits from both parents

  to exhibit the trait.

Tags

NGSS.MS-LS1-5

Which internal structures in humans have the most similar functions to that of xylem in

maple trees?

• lungs and skin, since they are involved in gas exchange

• nerves and brain, since they respond to environmental stimuli

• bones and muscles, since they are responsible for movement

• veins and arteries, since they transport blood throughout the body