To provide an accurate answer for page 87 of your 7th-grade biology workbook, it is important to identify which specific author's workbook you are using. In the Russian curriculum, there are several popular versions, and the content on page 87 differs significantly between them.

Comparing the skeletons or organ systems of different vertebrates.

Describing food chains or the role of animals in a specific biocenosis. Key Answers: Producers (plants) →right arrow Primary Consumers (herbivores) →right arrow Secondary Consumers (predators). How to confirm your assignment:

Birds have a four-chambered heart (четырёхкамерное сердце) and separate blood flows (arterial and venous).

They lack a urinary bladder (to reduce weight for flight). 2. Workbook by V.V. Latyushin and V.A. Shapkin

, specifically focusing on their internal structure or diversity.