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Clover Through the Seasons: One Gene, Three Effects

Grade 8 gene mutation practice: use a park's year-long clover survey and leaf tests to explain how a changed enzyme can be harmful, helpful or neutral.

Grade 8ScienceInteractive · Printable

Aligned toMS-LS3-1

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Single worksheet
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1 NGSS standard
Printable answer key
10 questions
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Details

Format: Interactive · Printable
Grade: Grade 8
Subject: Science
Question types: Fill in the blank, Multiple choice, Matching, Circle the answer, Short answer

About this worksheet

What students practice

Students explain how a change in a gene can stop a protein from working and change a trait.
Students use seasonal data to decide when one mutation is harmful, helpful or neutral.
Students use test evidence to link a gene, an enzyme and a plant's trait.

How to use

Use after introducing genes as instructions for proteins. Read paragraphs 2 and 3 together and have students draw the gene–enzyme–trait chain before they start Part 2.

Curriculum

NGSS standard covered

MS-LS3-1

Explain how gene mutations can change proteins and have harmful, helpful or neutral effects on an organism.

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Name Date

Clover Through the Seasons: One Gene, Three Effects

Use a city park's clover survey to see how one gene change can harm, help or do nothing.

Part 1: From gene to trait

Read the survey notes. Then answer the questions.

The Clover Survey in Linden Square Park

1White clover grows in the lawns of almost every city park, including Linden Square Park, where eighth grader Keziah Moreno-Hart volunteers with park naturalist Mr. Tobias Ekwueme. For one year they surveyed two kinds of clover plants that look the same but differ in one gene. They marked 50 plants of each kind in the same lawn and checked them in every season.

2Every clover plant in the survey stores a harmless chemical in its leaves. Typical plants also have a gene with the instructions for building an enzyme, a protein that breaks the stored chemical apart. The enzyme and the chemical are kept in separate parts of the leaf cells. When a slug or snail chews a leaf and crushes its cells, the two mix, and the leaf gives off a tiny amount of cyanide, a bitter poison. Many slugs and snails avoid leaves that do this. The amount is far too small to harm people who touch the clover.

3The other plants have a mutation, a changed version of the same gene, so they build no working enzyme. To check this, Mr. Ekwueme crushed leaves from each plant on a test paper that turns blue when cyanide is given off. Leaves from typical plants turned the paper blue. Leaves from the changed plants left it white. When he added a drop of the working enzyme, taken from typical leaves, to the crushed changed leaves, the paper turned blue.

4In winter, hard freezes can burst leaf cells, too. After a January freeze, Keziah thawed frozen leaves from typical plants on test paper without crushing them, and the paper turned blue. Leaves from the changed plants stayed white. Biologists think that cyanide given off inside frozen leaves may damage the plant's own tissue.

5In each season, Keziah checked 20 leaves on every marked plant and counted the share of leaves with slug or snail bites. After freezes, she also recorded the share of leaves that were brown and dead from frost. The spring and fall were rainy, when slugs and snails were active. July was hot and dry, when few were out. Table 1 shows the results.

Use paragraphs 2 and 3. Fill in each blank with a word from the word bank. Two words are left over.

Word bank: gene · enzyme · trait · soil · season

In the changed plants, the has different instructions, so the plant builds no working . As a result, crushed leaves give off no cyanide, which is a different from the typical plants.

Use paragraph 3. What does the test with the added drop of enzyme show about the changed plants?

A. Their leaves fixed the changed gene once the drop of enzyme touched the cells.
B. Their leaves have the stored chemical but lack a working enzyme to break it apart.
C. Their enzyme works normally but is kept too far from the stored chemical to mix.
D. Their leaves lack the stored chemical, and the drop of enzyme supplied it.