The wheel organ is found in:

Statement-$1$ : Cephalochordata bears notochord all along the body throughout life.
Statement-$2$ : Urochordate bears vertebral column only in tail region throughout the life.
Then which is correct?

In which of the following is the notochord absent?

$A$ schematic representation of a chordate's embryo is shown in the figure. The structures marked $A, B, C$ and $D$ are respectively:

In which of the following is the post-anal tail present throughout life?

Give three major differences between chordates and non-chordates and draw a schematic sketch of a chordate showing those features.