Biological Classification
Biological Classification
Biological Classification
Grade: XI
Subject: Biology
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1. Discuss how classification system has undergone changes over a period of time?
Ans Linnaeus developed a two kingdom system of classification -Plantae and Animalia
which classified all organisms into these two kingdom but this type of classification was
inadequate as:
i)There are many organisms which cant be classified as plants or animals
ii)This classification did not distinguish between prokaryotes and eukaryotes, unicellular and
multicellular organisms, photosynthetic and non-photosynthetic organisms
Whittaker proposed a five kingdom classification based on – cell structure,nature of cell
wall,mode of nutrition, mode of reproduction,evolutionary relationships
The understanding of which groups to be included under Kingdom Animalia and Plantae has
been changing over time,even the nature of other kingdoms has been studied differently by
different scientists over time
Ans: Cell wall is made up of cellulose and impregnated with silica,which makes their cell
wall indestructible
Cell wall occurs in the form of two overlapping halves which fit together as in a soap case
4. Find out what the algal bloom and red tide signify?
Ans: Algal bloom refers to the excess growth of algae especially Cyanobacteria in water
polluted with inorganic nutrients;it depletes the dissolved oxygen content of the water body
Red tides are caused by Dinoflagellates like Gonyaulax which undergo rapid multiplication
that the sea appears red.The toxin secreted can kill the marine animals like fish
5. How are viroids different from viruses.
Ans:
Viroids Viruses
They are smaller than viruses Comparatively larger
They lack a protein coat They have a surface protein coat called
capsid
They are short segments of free RNA which
are infectious Their genetic material is DNA or RNA
7. Plants are autotrophic. Can you think of some plants which are partially heterotrophic?
Ans:
Insectivorous plants like Venus Flytrap are autotrophs but supplement their nitrogen
requirement by capturing and digesting insects. They normally grow in nitrogen deficient
soil
Parasitic plants like Cuscuta are also heterotrophic in nature
8. What do the terms phycobiont and mycobiont signify?
Ans: Lichen is a symbiotic association between algae and fungi.The algal component is
called phycobiont and the fungal component is called the mycobiont .The phycobiont is the
autotrophic partner preparing food whereas the fungi(heterotrophic) provide shelter and
absorb nutrients and water for its partner
9.Give a comparative account of the classes of Kingdom Fungi under the following:
a) Mode of nutrition b) Mode of reproduction
Ans: