State whether the following statement is true or false:
Seeds consist of the embryo along with stored food,which serves for the initial growth of the embryo during germination.

$X, Y$ and $Z$ are living organisms.
$(a)$ Identify the group to which they belong on the basis of following features:
$(i)$ $X -$ Microscopic,unicellular,prokaryotic.
$(ii)$ $Y -$ Microscopic,unicellular,eukaryotic and shows locomotion with the help of pseudopodia/flagella.
$(iii)$ $Z -$ Multicellular,filamentous,eukaryotic,autotrophic and aquatic.
$(b)$ Which amongst the above is most advanced?
$(c)$ Name one organism each belonging to the groups of $X, Y$ and $Z$.

Give reasons for the following:
$(a)$ Echidna and Platypus lay eggs but are considered as mammals.
$(b)$ Birds have pneumatic bones.

Define the following terms and give one example of each:
$(a)$ Bilateral symmetry
$(b)$ Coelom
$(c)$ Triploblastic

An animal is dorsoventrally flattened,has three embryonic germ layers,and is acoelomate. Which phylum does it belong to? What are they commonly called? Give one example.

The locomotory organs of $Echinodermata$ are: