Question

1.

Which statement about sponges is correct?

		Sponges have two germ layers, which give rise to well-organized tissues.
		Sponges can only reproduce asexually by fragmentation or budding.
		Most sponges have bilateral symmetry.
		Sponges belong to the group of invertebrates known as cnidarians.
		Sponges are filter feeders.

2.  

Which are invertebrate chordates?

		tunicates only
		lancelets only
		jawless fishes only
		tunicates and lancelets but not jawless fishes
		tunicates, lancelets, and jawless fishes

Answer 1

1:

Sponges are filter feeders option is correct.

Rest options are incorrect.

• Sponges have a single germ layer and do not exhibit tissue-layer organization. But have specialized cells, as choanocytes, porocytes, amoebocytes, and pinacocytes for specialized functions.
• Sponges have no body symmetry, and are sessile.
• Sponges belong to phylum Porifera. While phylum Cnidaria is one of the oldest groups of eumetazoans and exhibit a simple diploblastic, radial body plan.
• Sponges reproduce by both sexual and asexual methods.

2:

Option “tunicates and lancelets but not jawless fishes” is correct.

Phylum Chordata contains two subphylums of invertebrates:

1. Urochordata (tunicates)
2. Cephalochordata (lancelets).

They are invertebrates as they lack a backone.

• Jawless fishes belongs to the subphylum Vertebrata of phylum Chordata.

In this the notochord developed into a bony backbone.