Gujarat Board GSEB Textbook Solutions Class 11 Biology Chapter 1 The Living World Textbook Questions and Answers.
Gujarat Board Textbook Solutions Class 11 Biology Chapter 1 The Living World
GSEB Class 11 Biology The Living World Text Book Questions and Answers
Why are living organisms classified?
Classification is necessary for the study of all living organisms by grouping them conveniently into categories based on some easily observable characters.
Why are the classification systems changing every now and then?
Reasons for changing the classification system can be listed as follows:
- Importance of classification in knowing bio-resources and their diversity.
- The taxonomic study is useful in agriculture and forestry.
- The actual account of habitat and distribution of organisms provide an index, which very much beneficial for knowing extinct and endangered species.
- Evolves a new branch of biology.
What different criteria would you choose to classify people that you meet often?
We would classify people we meet based on physique, colour, occupation, relation,’ gender, geographical location, etc.,
What do we learn from the identification of individuals and populations?
Identification of an individual and population categorized it into a species. It can be distinguished from other closely related species on the basis of distinct morphological differences.
Given below is the scientific name of Mango. Identify the correctly written name.
Mango has a biological/scientific name written as Mangifera indica.
Define a taxon. Give some examples of taxa at different hierarchical levels.
Viaxon is the unit of classification which represents a particular category of an organism with distinct biological entities. Taxonomists have developed some taxa like kingdom, phylum or division, class, order, family, genus, and species which forms a taxonomic hierarchy.
Can you identify the correct sequence of taxonomical categories?
Try to collect all the currently accepted meanings for the word ‘species’. Discuss with your teacher the meanings of species in the case of higher plants and animals on one hand, and bacteria on the other hand.
‘Species’ is a group of individuals with fundamental similarities. They can be distinguished from other closely related species on the basis of distinct morphological differences. In the case of higher plants and animals, one genus may have one or more than one specific epithets representing different organisms having similar morphological similarities
Ex. Panthera leo (lion)
Panthera tigris (Tiger)
But bacteria are grouped under four categories based on their shape spherical, cocus, rod-shaped, comma, and spiral-shaped. Thus the meaning of species in higher organisms and bacteria is different.
Define and understand the following terms
(1) Phylum: This includes different classes having some common
feature. The phylum Arthropoda have animals
- With jointed appendages,
- The body consists of the head, thorax, and abdomen.
- Tracheal system for respiration.
(2) Class: Taxonomic category representing organisms of related orders. Order Primata comprising monkey, gorilla, and gibbon is put along with order Carnivora representing tiger, cat, and dog. Both are placed in class Mammalia.
(3) Family: Family, has a group of related genera with still fewer similarities as compared to genus and species. Families are characterized on the basis of both vegetative and reproductive features of plant species. Among plants, for example, three different genera Solanum, Petunia, and Datura are placed in the family Solanaceae. Among animals, for example, genus Panthera, comprising lion, tiger, leopard is put along with genus, Felis (Cats) in the family Felidae.
(4) Order: Assemblage of families similar to one another in a few characters.
(5) Genus: Genus comprises a group of related species that has more characters in common in comparison to species of other genera.
For example, potato, tomato, and brinjal are three different species but all belong to the genus Solanum. Lion (Panthera leo), leopard (P. pardus), and tiger (P. Tigris) with several common features are all species of the genus Panthera.
How is a key helpful in the identification and classification of organisms?
(1) Key is another taxonomical aid used for the identification of unknown plants and animals based on the similarities and dissimilarities. The keys are taxonomic literature based on the contrasting characters generally a pair called a couplet.
(2) This results in acceptance of only one and rejection of other. Each statement in the key is called a lead. The joined leads of a pair are arranged. Separate taxonomic keys are required for each taxonomic category. Keys are generally analytical in nature.
(3) Manuals, monographs, catalogs, keys are some other means of recording descriptions of species that help incorrect identification.
(4) These provide an index to the plants known in the area. Manuals are useful in providing information for identification or names of species occurring in an area. Monographs in formation for reversionary work particularly for taxa like family and genus of the unknown.
(5) Being analytical in nature, two types of keys are commonly used- indented key (yolked key) and bracketed key,
- Indented key – Provides a sequence of choice between two or more statements of characters of species. The user has to make the correct choice for identification. Different genera in the family Ranunculaceae are identified by using the indented key by considering the characters of the carpel and fruit of the specimens. The first choice starts with carpel with single ovule and achene type of fruit in contrast to carpels being many ovulated and fruits are follicle.