Question

23. Bilaterally symmetrical and acoelomate animals
are exemplified by:
(1) Platyhelminthes
(2) Aschelminthes
(3)
Annelida
Ctenophora​

Answer 1

Answer:

platehelminthes

Explanation:

neet 2020 question

Answer 2

Answer:

Platyhelminthes is the right answer.

Explanation:

BILATERAL SYMMETRY:

• When an organism can be divided into two equal halves in only one plane passing through the centre of symmetry is called bilateral symmetry.

• Majority of organisms of the phylum platyhelminthes to chordata are bilaterally symmetrical.

• In kingdom animalia, the phylum porifera , cnidaria , ctenophora are radially symmetrical.

• In radial symmetry , the organisms can be divided into two equal halves by cutting in any plane.

ACOELOMATE:

• The triploblastic organisms can be classified on the basis of presence or absence of body cavity or coelom in the body.

• When the coelom is absent , the organisms are called acoelomates.

• When the coelom is present and the mesoderm is scattered in pouches , the organisms are pseudo coelomates.

• The organisms in which the coelom is present and is completely lined by mesoderm is called eucoelomate.

OPTIONS:

PLATYHELMINTHES:

• These are bilaterally symmetrical and acoelomates.

• So this is the right answer.

ASCHELMINTHES:

• The members of aschelminthes are bilaterally symmetrical and pseudo coelomates.

ANNELIDA:

• These are bilaterally symmetrical and are eucoelomate.

CTENOPHORA:

• Ctenophores are radially symmetrical and are acoelomates.