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Ants, Aphids and Basking Logs: Seasons of Interactions in a City Park

Grade 7 life science: analyze a city park's ant-blocking test, basking log counts and hawk visits to explain patterns of interactions among organisms.

Grade 7ScienceInteractive · Printable

Aligned toMS-LS2-2

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What’s included

Single worksheet
Auto-graded online
1 NGSS standard
Printable answer key
12 questions
Classroom-ready

Details

Format: Interactive · Printable
Grade: Grade 7
Subject: Science
Question types: Fill in the blank, Multiple choice, Sorting, Short answer

About this worksheet

What students practice

Students analyze an ant-blocking test to explain a mutually beneficial relationship and predation.
Students use basking log counts to explain competition for a limited resource.
Students compare the same kinds of interactions across different organisms in one ecosystem.

How to use

Read one season of the passage at a time with the matching section, so students connect each table to its paragraphs. Ask students to name who benefits and who is harmed before choosing answers.

Curriculum

NGSS standard covered

MS-LS2-2

Explain patterns of interactions among organisms in ecosystems: competition, predation and mutually beneficial relationships.

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Name Date

Ants, Aphids and Basking Logs: Seasons of Interactions in a City Park

Use a milkweed test, turtle counts and feeder counts to explain mutualism, competition and predation.

Late spring: the milkweed test

Read the passage and study Table 1. Then answer the questions.

A Year in Halsted Park

1Halsted Park is a city park with a pond, a meadow and a row of bird feeders by the nature center. Seventh grader Jun Watanabe joined the park's Junior Naturalist program, and from May to January he worked with the park naturalist, Ms. Beatrix Holloway, to study how the park's living things affect one another.

2In late spring, many milkweed stems in the meadow were covered with small yellow aphids. Aphids are insects that suck sugary sap from plants and give off a sweet liquid waste called honeydew. Black ants climbed the stems, stroked the aphids with their antennae and drank the honeydew. Ladybugs and their larvae, which eat aphids, also landed on the stems. Twice, Jun saw ants chase a ladybug larva off a stem.

3To test what the ants were doing, Ms. Holloway chose 20 milkweed stems of about the same size, each with 20 aphids. Around the base of 10 stems she wrapped a band of sticky paste that ants could not climb past. The paste did not touch the leaves or the aphids, and flying ladybugs could still land on those stems. The other 10 stems were left open to ants. Every week for 4 weeks, Jun counted the aphids on each stem and the ladybugs and larvae on each group of stems (Table 1).

4In summer, Jun turned to the pond. It is home to painted turtles and to red-eared sliders, larger turtles that were most likely released there as unwanted pets. A spring survey had found about 18 painted turtles and 16 sliders. Both kinds of turtles climb onto logs to bask in the sun, which warms their bodies so they can move and digest food well. The pond had only 3 basking logs. On sunny mornings, Jun counted the turtles on the logs and recorded each time a slider climbed onto a painted turtle's spot and pushed it into the water. In August, the park crew added 5 more logs (Table 2).

5In winter, a Cooper's hawk began hunting near the feeders. These hawks catch small birds in flight. On 6 mornings when the hawk was not seen, Jun counted an average of 32 small birds at the feeders in 10 minutes. On 4 mornings when the hawk perched nearby, the average was 9, and he watched sparrows dive into a thick hedge when it flew over. Once he saw it catch a sparrow.