Free Biodiversity and Variety of Life MCQs with Answers

871. Photoreceptors of the earthworm occur on their:

• A. Clitellum
• B. Many eyes
• C. Dorsal surface
• D. Lateral sides

Explanation: Photoreceptors are restricted only to the dorsal surface. They are more numerous on the prostomium and peristomium of the earthworm and gradually reduce in number towards the posterior end of the body. They are totally absent in the clitellum. Each photoreceptor consists of a single ovoid cell, with a nucleus and clear cytoplasm containing a network of neurofibrillae and a small transparent L shaped lens or optic organelle made up of a hyaline substance. Photoreceptors enable worms to judge the intensity and duration of light.

872. All are the features of kingdom animalia except:

• A. Heterotroph
• B. Organic synthesis
• C. Eukaryotes
• D. Multicellular

Explanation: Organic synthesis is referred to as photosynthesis in which inorganic molecules (water and carbon dioxide) are converted into organic molecule (Glucose). This process takes place in Autotrophs.

873. Animals of grade radiata are:

• A. Diploblastic
• B. Acoelomate
• C. Triploblastic
• D. Pscudococlomate

Explanation: Grade radiata includes only one phylum; Cnidaria. These animals are always diploblastic and have gastrovascular cavity with sac type digestive system.

874. Reproductive system arises from:

• A. Germlayer
• B. Ectoderm
• C. Mesoderm
• D. Endoderm

Explanation: Ectoderm form skin and nervous system. Endoderm form digestive system and rest of the systems in triploblastic animals are formed from mesoderm including reproductive system.

875. Reproductive system, excretory system, circulatory system and respiratory system developed from:

• A. Ectoderm
• B. Endoderm
• C. Mesoderm
• D. Ectoderm and endoderm

Explanation: Ectoderm forms skin and nervous system. Endoderm forms lining of digestive system and rest of the systems in triploblastic animals originate from mesoderm.

876. Bilaterally symmetrical animals are:

• A. Lesser developed
• B. Lacking mesoderm
• C. Placed in one phylum only
• D. Triploblastic

Explanation: All bilaterally symmetrical animals are triploblastic.

877. In coelomate the layer that surround endoderm is:

• A. Coelomic Epithelium
• B. Ectoderm
• C. Visceral mesoderm
• D. Parictal Mesoderm

Explanation: All bilateral symmetrical animals are triploblastic. Coelom (body cavity) is formed due to splitting of mesoderm at embryonic stages. Its outer layer is called parietal layer which underlines the body wall, while inner layer of mesoderm is called visceral layer that surrounds the endoderm.

878. All are correct about acoelomates except:

• A. Sac type digestive system
• B. Well-developed respiratory system
• C. Parenchyma till the body space
• D. Well-developed excretory system

Explanation: Acoelomate includes animals of Phylum Platyhelminthes in which respiratory and circulatory system is absent. Gaseous exchange takes place directly through body surface

879. Which of the following are pseudocoelomates?

• A. Platyhelminthes
• B. Echinoderms
• C. Molluscs
• D. Aschelminthes

Explanation: Aschelminthes or nematodes are pseudocoelomates.

880. A fluid filled cavity which is mesodermal in origin but absent in nematodes is:

• A. Coelom
• B. Gastrocoel
• C. Pseudocoelum
• D. Sponogocoel

Explanation: Coelom is true body cavity, which is always fonned from mesoderm. Nematodes are Pseudocoelomates