Which is the respiratory organ of a silkworm?

Which animal performs respiration but does not possess a specialized respiratory organ?

Match List-$I$ with List-$II$ regarding the respiratory organs/mechanisms in different organisms:

List-$I$	List-$II$
$A$. Molluscs	$I$. Pulmonary respiration
$B$. Reptiles	$II$. Branchial respiration
$C$. Adult amphibians	$III$. Cellular respiration
$D$. Amoeba	$IV$. Pulmonary and Cutaneous respiration

Choose the correct answer from the options given below:

In insects,respiratory gas exchange occurs through

Which of the following organisms obtain dissolved oxygen from water by diffusion through their body surface during respiration?

$A$ hatching egg of a chick is covered by plaster of paris. It is harmful for