Birds have a four-chambered heart (четырёхкамерное сердце) and separate blood flows (arterial and venous).
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. rabochaia tetrad po biologii 7 klass stranitsa 87 zadanie
Could you provide the or the topic heading at the top of page 87? This will allow me to give you the exact text and diagram labels required. there are several popular versions
Comparing the skeletons or organ systems of different vertebrates. rabochaia tetrad po biologii 7 klass stranitsa 87 zadanie
They lack a urinary bladder (to reduce weight for flight). 2. Workbook by V.V. Latyushin and V.A. Shapkin