i) 10-2= centi, so 6.35cL ii)10-6=micro, so 6.5s iii) 10-6=micro, so 95m iv) 10-9=nano, so 4.23nm v) 103=kilo, so 12.5*10-8*103g=12.5*10-5g, 10-6=micro, so 125g Solution i) 10-2= centi, so 6.35cL ii)10-6=micro, so 6.5s iii) 10-6=micro, so 95m iv) 10-9=nano, so 4.23nm v) 103=kilo, so 12.5*10-8*103g=12.5*10-5g, 10-6=micro, so 125g.

1. Structure: Hydra has a tubular body, with only one opening the mouth. The mouth is surrounded
by tentacles which are in turn provided with cnidoblasts. It remains attached to the substratum
with the help of adhesive foot called basal disc.
Feeding and digestion.
The hydra feed on small aquatic animals like cyclops with the help of its tentacles. The
cnidoblasts cell then inject a poison into its prey which paralyzes it. The food is then pushed
through the mouth to the gut. Inside the gut several enzymes break down the food into simpler
form. The undigested food is then released outside through the mouth of the hydra.
The green pigment of hydra is due to the unicellular algae, Chlorella that inhabits the
gastrodermis of the hydra.
Solution
Structure: Hydra has a tubular body, with only one opening the mouth. The mouth is surrounded
by tentacles which are in turn provided with cnidoblasts. It remains attached to the substratum
with the help of adhesive foot called basal disc.
Feeding and digestion.
The hydra feed on small aquatic animals like cyclops with the help of its tentacles. The
cnidoblasts cell then inject a poison into its prey which paralyzes it. The food is then pushed
through the mouth to the gut. Inside the gut several enzymes break down the food into simpler
form. The undigested food is then released outside through the mouth of the hydra.
The green pigment of hydra is due to the unicellular algae, Chlorella that inhabits the
gastrodermis of the hydra.