NCERT Class 11-Biology: Chapter –1 the Living World Part 3

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Question 3:

International Code of Botanical nomenclature (ICBN) has provided a code for classification of plants. Give hierarchy of units of classification botanists follow while classifying plants and mention different ‘Suffixes’ used for the units.

Answer:

As per the ICBN, various hierarchies of units for classifying plants and suffixes used for such hierarchies are as follows:

Hierarchy Suffix
Hierarchy Suffix

Hierarchy

Suffix

Kingdom

-Plantae

Division

Class

Order

-Ales

Family

Genus

It is the first term of scientific name of organism which usually has Latin origin and written in italics.

Species

It is the second term of the scientific name which usually has Latin Origin and written in italics.

Question 4:

A plant species shows several morphological variations in response to altitudinal gradient. When grown under similar conditions of growth, the morphological variations disappear and all the variants have common morphology. What are these variants called?

Answer:

These variants are called biotypes. All biotypes are similar genetically but they are different morphologically. The morphological difference happens because of the differences in abiotic factors like temperature, of soil, climate etc. The difference in abiotic factors is the result of different altitudinal gradients.

Question 5:

How do you prepare your own herbarium sheets? What are the different tools you carry with you while collecting plants for the preparation of a herbarium? What information should a preserved plant material on the herbarium sheet provide for taxonomical studies?

Answer:

Following are the various steps of preparing herbarium:

(a) Collection: This step involves collection of a particular species.

(b) Pressing: This step involves spreading the specimen and pressing it between two sheets of paper so as to preserve most of the parts.

(c) Drying: This step usually involves drying under the sun.

(d) Poisoning: Sometimes, antifungal treatment needs to be given to the specimen to preserve it for longer duration.

(e) Mounting: This step involves mounting the specimen over a herbarium sheet.

(f) Labeling: This step involves writing full information and classification of the specimen.

Different tools which need to be carried while collecting plants for the preparation of a herbarium are; digger and pruning knife, sickle, vasculum, , polythene bags, old newspaper or magazine, blotting paper, plant press, field notebooks, herbarium sheets, glue, labels, etc.

The preserved material should have through information and classification. This should include the name of division, order, family, genus and species.

Question 6:

What is the difference between flora, fauna and vegetation? Eichornia crassipes is called as an exotic species while Rauvolfia serpentina is an endemic species in India. What do these terms exotic and endemic refer to?

Answer:

The sum of plant species in a given geographical area is called flora of that area. The sum of animal species in a given geographical area is called fauna of that area. The term ‘ vegetation’ has wider scope than the term ‘flora’. Vegetation is often used for much wider geographical area than a particular ecosystem. In many cases, the term ‘vegetation’ is used for all the plants on the global scale.

Endemic Species:

A species which is found only in a particular geographical area is called the endemic species for that area. For example; Rauvolfia serpentina is found only in India.

So, it is an endemic species in India.

Exotic Species:

A species which is not naturally found in a particular area but may be living because of careful selection and breeding or because of being imported called an exotic species. For example, Eichhornia crassipes is native of other country but it was introduced in India. So, it is an exotic species in India.

Question 7:

A plant may have different names in different regions of the country or world. How do botanists solve this problem?

Answer:

There are many languages and even more dialects being spoken in different parts of the world. This means a plant may have different names in different regions of the country or world. This compounds the problem for anybody because nobody can remember all those names. To solve this problem, botanists have devised the system of binomial nomenclature so that a particular species can have unique name for the purpose of scientific study. A botanical name is usually composed of two terms, viz. genus name and species name. Care is taken to make a unique name for a particular species.

Question 8:

Brinjal and potato belong to the same genus Solanum, but to two different species. What defines them as separate species?

Answer:

Brinjal and potato belong to the same genus Solanum because of certain common characters in them. Phyllotaxy, venation, inflorescence, etc. are some of the common characters in these plants which make them the member of the same genus. But breeding between a Brinjal plant and a potato plant is not possible. Since capability to interbreed is the most defining criterion for members of a particular species; hence brinjal and potato are kept under separate species although they belong to the same genus.

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