Turner often saw woodpeckers perched in trees in his backyard, but he never saw
them at his bird feeders. Turner usually
filled his feeders with sunflower seeds. He
wondered if he could attract woodpeckers
by adding a different type of food to the
feeders.
To test this idea, Turner gathered eight
identical bird feeders. He filled four with
sunflower seeds. He filled the remaining
four feeders with crushed peanuts. Turner
then placed the bird feeders in his
backyard. Over the next five days, he
counted the number of woodpeckers that
visited each bird feeder each morning.
a woodpecker at a bird feeder
Which of the following was an independent variable in this experiment?
the type of food used in the bird feeders
the number of woodpeckers that visited the bird
feeders

How can you tell the difference between rough er from smooth er?

Hormones are chemical molecules produced by endocrine glands. one such endocrine gland is the thyroid gland, which synthesizes the thyroid hormone, which in turn affects the heart muscles. which two statements describe the probable reason for the function of the hormone? the cells in the heart have specific receptors that allow for the intake of hormones. the heart and the endocrine glands have the exact same types of cells. all cells make the same types of hormones. thyroid hormones show their effect on the heart by means of specialized cells. thyroid cells and cardiac cells have different dna.

80 points pls brainliest 1. what does a red shift mean? blue shift? 2. describe the big bang theory. according to this theory, how old is the universe? 3. scientists believe the universe is expanding. what is the evidence that supports this? 4. describe a nebula. 5. describe the 3 types of galaxies. what is a barred spiral galaxy? 6. what is a light year? how far is alpha centauri from earth? 7. describe the universal law of gravitation. be sure to include gravitational force between two objects. 8. describe the planets’ orbits around the sun. 9. what is the asteroid belt? where is it located? 10. describe rotation and revolution of earth. what determines an earth day and year? 11. how do galaxies exist? 12. compare and contrast the inner and outer planets. 13. what causes the seasons?