Fish internal structure and nervous system
Answers are for parents and teachers.
1
Explain how fish gills work in 3 steps.
Water enters the mouth; in the gill filaments oxygen enters blood and carbon dioxide leaves; water exits through the gill slits.
2
Compare arterial and venous blood.
Arterial – oxygen-rich, bright red; venous – carbon-dioxide-rich, dark red.
3
List fish sense organs and their functions in a table.
Eye – sight; nostrils – smell; inner ear – hearing; lateral line – current; barbels – touch.
4
Give 2 examples of unconditioned reflexes.
Darting aside when poked; catching prey on sight; migrating to spawn.
5
What can protect a water body from oxygen depletion?
Reduce pollution, ensure water exchange, make holes in winter ice, do not overstock fish.