Free Biodiversity and Variety of Life MCQs with Answers

771. In contrast to annelids the platyhelminthes show :

• A. Absence of body cavity
• B. Bilateral symmetry
• C. Radial symmetry
• D. Presence of pseudocoel

Explanation: Platyhelminthes do not have body cavity so they are acoelomates. In annelids, the body cavity is true and schizocoelous. Both annelids and platyhelminthes have bilateral symmetry.

772. From the following statements select the wrong one:

• A. Prawn has two pairs of antennae
• B. Nematocysts are characteristics of the phylum cnidaria
• C. Millepedes have two pairs of appendages in each segment of the body
• D. Animals belonging to phylum porifera are marine and fresh water

Explanation: Prawns have one pair of antennae, one on either side, just below the antennules. They are sensory, excretory and balancing in function. Antennules are attached on either side, below the bases of eye stalks. They are tactile in function. Nematocysts are present in cnidoblasts that act as organs of offence and defence. Millipedes belong to class myriapoda. They are called thousand leggers because of possession of numerous walking legs. Their body is made up of a small head and 40 trunk segments, each with two pairs of jointed legs. Animals belonging to phylum porifera are mostly marine while a few are freshwater.

773. Which one of the following characters is not typical of the class mammalia?

• A. Thecodont dentition
• B. Alveolar lungs
• C. Ten pairs of cranial nerves
• D. Seven cervical vertebrae

Explanation: Mammals have twelve pairs of cranial nerves. Ten pairs of cranial nerves are present in fish and amphibians. Reptiles and birds also have 12 pairs of cranial nerves.

774. In Arthropoda, head and thorax are often used to form cephalothorax, but in which one of the following classes is the body divided into the head, thorax and abdomen?

• A. Insecta
• B. Myriapoda
• C. Crustacea
• D. Arachnida

Explanation: Class insecta is the largest group not only of Arthropoda but of all the animal kingdom and has great variety. Insects are found everywhere, many show social behaviour. The body in, insects has three distinct regions head, thorax and abdomen.

775. The animals with bilateral symmetry in young stage and radial pentamerous symmetry in the adult stage belong to the phylum:

• A. Annelida
• B. Mollusca
• C. Cnidaria
• D. Echinodermata

Explanation: The animals belonging to phylum echinodermata, have developed bilateral symmetry, as is evident, from the study of structure of their larvae. However, the adult Echinoderms, have secondarily developed radial symmetry, due to their special mode of life.

776. Presence of gills in the tadpole of frog indicates that:

• A. Fish were amphibians in the past
• B. Fish evolved from froglike ancestors
• C. Frogs will have gills in future
• D. Frogs evolved from gilled ancestors.

Explanation: Amphibians are on the border line between aquatic and true terrestrial animals. Fossil evidence from the Devonian period of earths history suggests that a large population of ish belonging to the group lobe-ins (dipnoi) came to live in shallow fresh water. Some of these crawled from one pool to another and therefore spent some time on land. This gave rise to the group that we recognize as amphibians which are the irst vertebrates to come on land. This suggests that frogs i.e amphibians a from gilled ancestors.

777. Sycon belongs to a group of animals which are best described as:

• A. Unicellular or acellular
• B. Multicellular without any tissue organization
• C. Multicellular with a gastrovascular system
• D. Multicellular having tissue organization but no body cavity.

Explanation: Sycon, belonging to the Phylum Porifera, are multicellular organisms with cellular level of body organisation. The constituent cells perform their functions more or less independently. No distinct tissue or organs are present in it.

778. During the lifecycle Fasciola hepatica(liver fluke) infects its intermediate host and primary host at the following larval stages respectively:

• A. Redia and miracidium
• B. Cercaria and redia
• C. Metacercaria and cercaria
• D. Miracidium and metacercaria

Explanation: The life cycle of F. hepatica is completed in two hosts. The primary host, in which the adult fluke lives, is a sheep, while the intermediate host, in which numerous larval stages are passed, is a snail (Lymnaea, Planorbis, etc.). This type of life cycle involving two different kinds of hosts is as termed digenetic. Miracidium larva is the larval stage involved in the life cycle. When suitable conditions become available, the encapsulated embryo differentiates into a miracidium larva in 415 days. It hatches out and swims in water. Metacercaria develops into adult fluke only inside its definitive host i.e sheep. The latter gets an infection by grazing on leaves and grass blades to which the cysts are attached. Metacercaria survives action of its host's gastric juices as its cysts are insoluble in them. The cyst wall finally dissolves in the proximal part of the intestine and liberates the larva.

779. Ommatidia serve the purpose of photoreception in:

• A. Cockroaches
• B. Frog
• C. Humans
• D. Sunflowers

Explanation: In cockroaches, the compound eyes are a pair of large, black, kidney shaped organs situated dorso-laterally on the head, one on either side. Their surface is marked by a large number of hexagonal areas, the facets. Each facet represents a visual unit named ommatidium. The eyes are the organs of sight (photoreception).In summary, ommatidia are specifically associated with the compound eyes of insects, such as cockroaches, for visual perception.

780. Which one of the following is a matching pair of an animal and a certain phenomenon it exhibits?

• A. Pheretima - Sexual dimorphism
• B. Musca - Complete metamorphosis
• C. Chameleon - Mimicry
• D. Taenia - Polymorphism

Explanation: In Musca, development is indirect with complete metamorphosis (holometaboly) including four stages i.e egg, larva, pupa and adult. In complete metamorphosis, larva moults several times after hatching to become a fully grown one. It later becomes a pupa within a secreted case, called the puparium. Pupa differentiates into the young adult that breaks the puparium open and emerges outside. Then it grows to a mature form.