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CHEMISTRY/common core: vocabulary in context

SEPTEMBER 2, 2013

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CluEd InIn “Oil Bloom” (p. 18), you learned about a student’s research into plant-based fuels. The article may have contained words that were new to you. Context clues are words and phrases that come before or after unfamiliar words and can help you define them. Context clues may be in the same sentence or paragraph, or in a nearby paragraph. Use context clues to determine the meanings of the five words below from the article. (Hint: Reread the paragraphs to find the context clues.)

1. Word: viable (Introduction, last paragraph)Sentence: She’s come up with a solution that could make algae biofuels a viable alternative to petroleum-based fuels.Meaning: A. costly B. difficult C. adequate D. decreasing

Context Clue: __________________________________________________________________________________________

2. Word: downsides (Plant Problems section, first paragraph)Sentence: Through her research, Sara learned that crops like corn and soy can be used as biofuels, but these plants have downsides.Meaning: A. disadvantages B. benefits C. prices D. details

Context Clue: __________________________________________________________________________________________

3. Word: cultivated (Plant Problems section, first paragraph)Sentence: That means they can be cultivated just about anywhere.Meaning: A. found B. measured C. buried D. grown

Context Clue: __________________________________________________________________________________________

4. Word: yield (Plant Problems section, second paragraph) Sentence: That’s why researchers—including Sara—have been trying all sorts of methods to grow algae that yield more oil.Meaning: A. cost B. destroy C. feed on D. produce

Context Clue: __________________________________________________________________________________________

5. Word: enables (A Killer Idea section, first paragraph)Sentence: The trick was in how this herbicide kills: It interferes with an enzyme—a protein that accelerates a chemical reaction—that enables algae to make oil.Meaning: A. eats B. allows C. destroys D. prevents

Context Clue: __________________________________________________________________________________________

ExaMplE:Word: cringe (Introduction, first paragraph)Sentence: Most people would cringe at the sight of green slime growing under their beds.Meaning: A. talk B. look afraid or disgusted C. consider D. admireContext Clue: The sentence says it’s what most people would do when they see green slime.

Permission granted by Science World to reproduce for classroom use only. Copyright ©2013 by Scholastic Inc. SEPTEMBER 2, 2013

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biology: reading comprehension

CHooSIng TRaITSIn “Oil Bloom” (p. 18), you read about how Sara Volz is growing algae so it can one day be a viable biofuel source. She used the process of artificial selection to grow algae that produce more oil. Read the following passage to learn about other ways scientists have used artificial selection in plants and animals. Then answer the questions that follow.

beINg SeleCtIveIf nature were in charge, poodles wouldn’t exist! That’s because these pooches are the result of

artificial selection, a process by which humans choose the features they want in plants and animals.

In nature, the traits passed on to new generations of plants or animals are determined by environmental conditions. For example, in cold regions, wolves with thick fur may be more likely to survive than those with thin fur. The thick-furred wolves would pass on this characteristic to their offspring, eventually building a population of thick-coated wolves. This process is called natural selection.

People sometimes interfere with nature to create plants and animals with traits they feel are desirable. They do this by allowing only individuals with those desired characteristics to reproduce. Dog breeding is an example. Over time, people have chosen dogs with traits that they liked—such as the poodle’s curly fur, or a dachshund’s miniature legs—and bred those animals to create more dogs like them.

Humans were also the driving force behind many of the veggies on your dinner plate. Broccoli, cauliflower, cabbage, and Brussels sprouts—all derived from the wild mustard plant—were created through artificial selection.

QuESTIonS1. What do you think the author’s purpose was for writing this passage?

2. Use context clues to write a definition for trait.

3. According to the principle of natural selection, what determines which traits are passed on to new generations of plants or animals?

4. Name three organisms mentioned in the passage that are the result of artificial selection.

5. Suppose a dog breeder is known for her very gentle dogs. How might she have used artificial selection to bring out this trait in the animals she breeds?

Permission granted by Science World to reproduce for classroom use only. ©2013 by Scholastic Inc. SEPTEMBER 2, 2013

EaRTH: CHaRT REadIng

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duElIng FuElSIn “Oil Bloom” (p. 20), you learned about a student’s research into using algae to make biofuel. Plant-based biofuels release less greenhouse gases than petroleum-based fuels. But biofuels have their own drawbacks. The chart below shows some environmental impacts of different biofuels. Study the chart. Then answer the questions that follow.

analYZE IT1. Some biofuel production is carbon negative: The plants absorb more carbon dioxide when they grow than is released by burning the fuel. Which biofuels on the chart are carbon negative?

2. Processing and burning gasoline releases 94 kg of carbon dioxide per megajoule of energy. How much less carbon dioxide does soybean biofuel release per megajoule of energy?

3. Which biofuel requires the most resources to grow, harvest, and process?

4. Suppose the U.S. government decided to plant enough sugar cane to produce enough ethanol to meet half of U.S. energy needs. What percentage of cropland would be left to grow food? Do you think this would be a good idea?

5. Which biofuel in the chart above do you think shows the most promise as a fuel source? Explain your answer.

SOURCE: GROOM ET Al., Conservation Biology (JUNE 2008), 602-609.

environmental Impacts of biofuels

Crop biofuel

greenhouse emission

Carbon dioxide released (in kg) per megajoule

of energy

Resource UseRelative amount of resources used to grow,

harvest, and process crops into fuel

land UsePercent of U.S.

cropland needed to produce

enough fuel to meet half of U.S. energy demand

Water Fertilizer Pesticide energyCorn Ethanol 83 High High High High 210%

Sugar Cane Ethanol 8 High High Medium Medium 52%

Switch Grass Ethanol -24 Medium-

low low low low 84%

Soy-beans Biodiesel 49 High low-medium Medium Medium-low 210%

Canola Biodiesel 37 High Medium Medium Medium-low 30%

Algae Biodiesel -183 Medium low low High 2%

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Permission granted by Science World to reproduce for classroom use only. ©2013 by Scholastic Inc. SEPTEMBER 2, 2013

PHYSICS: MaTH SKIllS

algaE PoWERIn “Oil Bloom” (page 18), you learned about how a student is working toward improving the production of algae biofuel. Solve the following problems to learn more about biofuel energy.

QuESTIonS1. In 2011, the U.S. consumed 1.03 5 1020 joules (J) of energy. Nine percent of that came from renewable sources. How much energy, in J, is produced from renewable sources?

2. U.S. biodiesel energy consumption in 2011 was 1.82 5 1017 J. What percentage of the total U.S. energy consumption did biodiesel represent? (Hint: Refer to the previous question.)

3. It takes energy to make energy! The process of making algae biofuel uses energy for harvesting the algae and extracting its oil. One way to measure the efficiency of energy production is called energy return on investment (EROI).

eROI = energy produced ÷ energy used in the production process

One method of making algae biofuel creates 33,300 J of energy for every 10,000 J used in producing it. What is the EROI for this method?

4. The U.S. used 81.9 billion liters of oil in 2011. Each liter of oil produces 38.5 million J of energy. A liter of algae biofuel produces 33.7 million J of energy. a. How much oil energy, in J, was used in 2011?

b. How many liters of algae biofuel would it take to produce that much energy?

5. last year, the U.S. Navy paid $12 million for a shipment of 450,000 gallons of biofuel, some of which was sourced from algae. a. What was the price per gallon for this purchase?

b. How does this purchase price compare with current prices for gasoline in your area? Is algae biofuel ready to compete with conventional fossil fuels on price?