Give reasons : (a) Ventricles have thicker muscular walls than atria. (b) Transport system in plants is slow. (c) Circulation of blood in aquatic vertebrates differs from that in terrestrial vertebrates. (d) During the daytime, water and minerals travel faster through xylem as compared to the night. (e) Veins have valves whereas arteries do not.
a) because ventricles have to pump blood out of the heart.
b) because plants are not motile and have a large proportion of dead cells in many tissues and due to which their energy needs are low and have a slow transport system.
c) because the terrestrial vertebrates take oxygen from the air through their lungs and the aquatic invertebrates take oxygen from the water through their gills.
d) because the rate of transpiration is higher during the daytime as compared to night.
e) because arteries don't require valves, as the pressure from the heart is so strong that blood is only able to flow in one direction.