Countercurrent exchange in the fish gills helps to maximize

• blood pressure

• diffusion

• active transport

• osmosis

In the countercurrent exchange in a fish's gills, the oxygen concentration is always _______ in the blood than the water along the entire pathway of each lamella.

• the same

• higher

• lower

• varies depending on the time of the year

Which of the following statements comparing respiration in fish and in mammals is correct?

• The respiratory medium for fish carries more oxygen than the respiratory medium of mammals.

• A countercurrent exchange mechanism between the respiratory medium and blood flow is seen in mammals but not in fish.

• In blood, oxygen is primarily transported by plasma in fish, but by red blood cells in mammals.
  

• The movement of the respiratory medium in mammals is bidirectional, but in fish it is unidirectional.

Which of the following is not a common adaptation for respiratory gas exchange?

• Countercurrent flow

• Minimizing the diffusion path length through an aqueous medium

• Maximizing partial pressure gradients

• Mechanisms to adjust the temperature of the medium to increase diffusion

• Increasing the surface area over which diffusion of gases can occur

Tags

NGSS.HS-LS4-4

The respiratory system of insects consists of

• Trachea that supply O2 to cells

• Branched gills that end in trachea

• Branched gills that end in spiracles

• Layers of gas exchange material just under the exoskeleton

Tags

NGSS.HS-LS2-3

Bird and fish respiratory systems are similar in that both

• employ a countercurrent exchanger

• have air sacs

• function by means of unidirectional flow of the environmental medium over the gas exchange membranes

• consist of tidal flow of air

A major disadvantage for O2 exchange in mammal lungs is

• one-way air flow

• two-way air flow

• dry surfaces

• positive pressure breathing

Organisms with a circulating body fluid that is distinct from the fluid that directly surrounds the body's cells are likely to have _____.

• a closed circulatory system

• an open circulatory system

• a gastrovascular cavity

• branched tracheae

Mammalian, bird, and crocodile hearts have four chambers with two separate atria and ventricles to ensure _____ distinct circuits for blood flow.

• 1

• 2

• 3

• 4

The only vertebrates in which blood flows directly from respiratory organs to body tissues without first returning to the heart are the _____.

• amphibians

• mammals

• fishes

• reptiles