Powdery mildew of crops are caused by from Biology Biological Cl

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 Multiple Choice QuestionsMultiple Choice Questions

201.

Red tide of sea is due to presence of

  • Gonyaulax

  • Cymbella

  • chlamydae

  • blue-green algae


202.

Which one of the following is a bacteria?

  • Pseudomonas

  • Clostridium

  • Actinomycetes

  • Azotobacter


203.

Consider the following statements about basis of classification.

I. Amphibians are classified on the basis of their habitat.

II. Reptiles are classified on the basis of the nature of their skulls.

III. Birds are classified on the basis of their bones.

IV. Mammals are classified on the basis of their mode of reproduction.

Choose the correct option

  • Only I

  • I and II

  • Only II

  • II and IV


204.

In biosystematics, the basis of classification is

  • major morphological characters

  • cytological characters

  • evolutionary history considering various parameters from different fields of studies

  • phenotypic relationships between species


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205.

The protein that reproduce within the living cells are termed as

  • plasmids

  • phages

  • prions

  • prophages


206.

The oldest fossil belongs to which of the following group of plants/ animals?

  • Asteriodae

  • Rhodophyceae

  • Blue- green algae

  • Phaeophyceae


207.

In Amoeba hyaline cap is formed by

  • around the food vacuole

  • around the contractile vacuole

  • around the nucleus

  • on pseudopodia


208.

The cell wall of fungi is formed by

  • chitin and mannose

  • cellulose

  • glucose

  • None of the above


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209.

The chief advantage of encystment of an Amoeba is

  • protection from parasites and predators

  • the chance to get rid of accumulated waste products

  • the ability to survive during adverse physical conditions

  • the ability to live for sometime without ingesting food


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210.

Powdery mildew of crops are caused by

  • bacteria

  • Ascomycetes

  • Basidiomycetes

  • Phycomycetes


B.

Ascomycetes

Mildew diseases are caused by a group of fungal parasites called Ascomycetes. It is of two types powdery mildew and downy mildew.

Powdery mildews are caused by external parasites which grow superficially on the leaves, green stems and fruits and form powdery or dusty patches which are filled with white conidia. Downy mildews are caused by internal obligate parasites which are characterised by downy growth.


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