Question

Consider the following statements (A-C) each with two blanks.
A. Animals like Hydra and jellyfish depict (i)___ symmetry whereas earthworm and leech show (ii)____ symmetry.
B. In (iii)____ and (iv)_____ digestive tract has only a single opening (mouth) and is said to be incomplete.
C. Trichinella (Trichina worm) Is a cosmopolitan (v)_____ parasite whereas Fasciola, (liver fluke) lives in the bile ducts of the liver of (vi)____.
Which one of the following options, correctly fills any two statements?
A. (i)-Bilateral (ii)-Radial (iii)-Snail (iv)-Human
B. (i)-Porifera (ii)-Pisces (iii)-Human (iv)-Sheep
C. (i)-Radial (ii)-Bilateral (iii)-Coelenterata (iv)-Platyhelminthes
D. (i)-Amphibian (ii)-Annelida (iii)-Mosquito (iv)-Human

Answer 1

Hint:Symmetry mainly refers to the symmetry seen in organisms that include plants, animals, fungi, and bacteria.
Two types of symmetry are seen:
1.External and 2. Internal
External symmetry can be easily seen by just looking at an organism with the naked eye.
Internal symmetry is regarded as the internal features that also show internal symmetry.

Complete answer: In animals like Hydra, Jellyfish, starfish, the body is mainly divided into two equal halves by any plane passing through the certain from top to bottom and thus they exhibit radial symmetry.
In earthworm and leech, the body can be divided into two equal halves by a single plane only thus exhibiting bilateral symmetry.
In the blind sac body plan, the body has a single cavity with one opening to the outside.
This single opening functions as both mouth that is for ingestion and anus for the egestion.
It is commonly found in coelenterates and flatworms (Platyhelminthes).
So, In part A. the hydra and jellyfish depict radial symmetry, and the earthworm and leech depict the bilateral symmetry.
In Coelenterata and Platyhelminthes the digestive tract has only one opening and is said to be incomplete.

So, the correct option is option C. (i)-Radial (ii)-Bilateral (iii)-Coelenterata (iv)-Platyhelminthes.

Note: Platyhelminthes are triploblastic, bilaterally symmetrical, and acoelomate flatworms.
They don't have a definite anus, circulatory, skeletal and respiratory systems.
Their body is unsegmented and they are soft-bodied invertebrates.
The three main types of flatworms are:
1.Flucks
2.Planarians
3.Tapeworms