NEET-XI-Biology
01: The Living World
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- Qstn #9-iiClassAns : Class
Class is a taxonomic group consisting of one or more related orders. For example, the class, Mammalia, includes many orders.
- Qstn #9-iiiFamilyAns : Family
Family is a taxonomic group containing one or more related genera. In plants, families are categorized on the basis of vegetative and reproductive features.
- Qstn #9-ivOrderAns : Order
Order is a taxonomic group containing one or more families. For example, the order, carnivore, includes many families.
- Qstn #9-vGenusAns : Genus
Genus is a taxonomic group including closely related species. For example, the genus, Solanum, includes many species such as nigrum, melongena, tuberosum,etc.
- Qstn #10How is a key helpful in the identification and classification of an organism?
Ans : Key is another taxonomical aid that helps in identification of plant and animal species. These keys are based on similarities and dissimilarities in characters, generally in a pair called couplet.
Each statement in a taxonomic key is referred to as a lead. For categorizing each taxonomic rank, such as family, genus, species, etc., different keys are used. It is also useful in identification of unknown organisms.
Keys are of two types- indented and bracketed keys. Indented key provides a sequence of choices between two or more statements while in bracketed key, a pair of contrasting characters are used.
(i) Indented key to identify different species of Rhododendron.
1. Leaves evergreen
2. leaves densely hairy below, orange or white hair; flower
appears to have separate petals
............................ Rhododendron groenlandicum
2. hair absent on leaves, flower has five petals fused in a shallow
tube
............................ Rhododendron maximus
1. Leaves deciduous
3. pink flowers with two free petals and three fused petals
............................ Rhododendron canadense
3. white to pink flowers with all petals fused together
(ii) Bracketed key to identify different species of Rhododendron.
- Leaves evergreen———————————————-2
1. Leaves deciduous———————————————-3
2. Leaves densely hairy below, orange or white hair; flower
appears to have separate petals
...................................... Rhododendron groenlandicum
2. Hair absent on leaves, flower has five petals fused in shallow
tube
......................................Rhododendron maximus
3. Pink flowers with two free petals and three fused petals
.................................... Rhododendron canadense
3. White to pink flowers with all petals fused together—-4
- Qstn #11Illustrate the taxonomical hierarchy with suitable examples of a plant and an animal.
Ans : The arrangement of various taxa in a hierarchical order is called taxonomic hierarchy.
In this hierarchy, species is present at the lowest level whereas kingdom is present at the highest level.
Kingdom
↑
Phylum or division
↑
Class
↑
Order
↑
Family
↑
Genus
↑
Species
A Taxonomic hierarchy
Classification of a plant
As an example, let us classify Solanum melongena (Brinjal).
Kingdom - Plantae
Division - Angiospermae
Class - Dicotyledonae
Order - Solanales
Family - Solanaceae
Genus - Solanum
Species - melongena
Classification of an animal
As an example, let us classify Columba livia (Blue rock Dove).
Kingdom - Animalia
Phylum - Chordata
Class - Aves
Order - Columbiformes
Family - Columbidae
Genus - Columba
Species - livia