Chapter 7 – Diversity in Living Organisms
Question 1:
Why do we classify organisms?
Solution:
As there are many organisms on the earth, it is important to know them. Diversity is not only between different organisms but also between different individuals of the same species. So, it will be very difficult to study each of the 30 million species one by one. Scientists, therefore, felt the need of grouping different species based on some observable similar characters. Classification of related organisms helps in the identification and study of their evolutionary relationships.
Question 2:
Give three examples of the range of variations that you see in life-forms around you.
Solution:
Examples observed in daily life are:
● Size of the different organisms which is seen from bacteria to giant trees.
● Colour, texture of the skin, size, shape and other characteristics in animals are completely different from each other.
● Mode of nutrition in animals and plants are completely different
Question 3:
Which do you think is a more basic characteristic for classifying organisms? (a) The place where they live.
(b) The kind of cells they are made of. Why?
Solution:
The kind of cells that living organisms are made up of is a more basic characteristic for classifying organisms, rather than based on their habitat. Organisms can be classified into - Prokaryotes and Eukaryotes A eukaryotic cell has membrane-bound organelles, including a nucleus, which allows cellular processes to be carried out efficiently in isolation from each other. Organisms which do not have a clearly demarcated nucleus and other organelles would need to have their biochemical pathways organised in very different ways.
Question 2:
What is the primary characteristic on which the broad division of organisms is made?
Solution:
The primary characteristic on which the broad division of organisms is made is the nature of the cell. It is considered to be the basic characteristic for dividing all living organisms. Nature of the cell includes the presence or absence of membrane-bound organelles. Therefore, on the basis of this fundamental characteristic, we can classify all living organisms into two broad
categories of eukaryotes and prokaryotes. Then, further classification is made on the basis of cellularity or modes of nutrition.
Question 3:
On what basis are plants and animals put into different categories?
Solution:
Plants and animals differ in many features such as the absence of chloroplasts, the presence of cell wall, etc. But, mode of nutrition is considered as the characteristic feature that separates animals from plants. They can be classified into - Heterotrophs (Animals) and Autotrophs (plants). Being able to produce one’s own food versus having to get food from outside would make very different body designs.
Qustion 1:
Which organisms are called primitive and how are they different from the so-called advanced organisms?
Solution:
When we connect the idea of evolution to classification, we find two groups of organisms. The first group has few organisms that have not changed much for e.g., lice and the duck- billed platypus. Whereas the second group has organisms which have acquired particular body designs by accumulating changes over a period of time. Those in the first group are frequently referred to as primitive or lower organisms, while those in the second group are called advanced or higher organisms.
Question 2:
Will advanced organisms be the same as complex organisms? Why?
Solution:
There might be a possibility that complexity in design will increase over evolutionary time, it may not be wrong to say that older organisms are simpler, while younger organisms are more complex.
Question 1:
What is the criterion for classification of organisms as belonging to kingdom Monera or
Protista?
Solution:
The criterion for the classification of organisms belonging to kingdom Monera or Protista is the presence or absence of a well-defined nucleus or membrane-bound organelles. Kingdom Monera includes organisms that do not have a well-defined nucleus or membrane-bound organelles and these are known as prokaryotes. Kingdom Protista, on the other hand, includes organisms with a well-defined nucleus and membrane-bound organelles and these organisms are called eukaryotes.
Question 2:
In which kingdom will you place an organism which is single-celled, eukaryotic and photosynthetic?
Solution:
Kingdom Protista
Question 3:
In the hierarchy of classification, which grouping will have the smallest number of organisms with a maximum of characteristics in common and which will have the largest number of organisms?
Solution:
A species will have the smallest number of organisms with a maximum of characteristics in common, whereas the kingdom will have the largest number of organisms.
Question 1:
Which division among plants has the simplest organisms?
Solution:
Thallophyta has the simplest organisms as this includes plants, which do not contain a well- differentiated plant body. Their body is not differentiated into roots, stems, and leaves
Question 2:
How are pteridophytes different from the phanerogams?
Solution:
Pteridophyta Phanerogams
Less differentiated reproductive organs. Well developed reproductive organs.
They produce naked embryos called spores. They produce seeds.
Example: Ferns, Marsilea, Equisetum, etc. Example: Pinus, Cycas, fir, etc.
Question 3:
How do gymnosperms and angiosperms differ from each other?
Solution:
Gymnosperm Angiosperm
Non-flowering plants Flowering plants
Naked seeds are present Seeds are enclosed inside fruits.
Pinus, Cedar, fir, Cycas, etc. are some
examples of gymnosperms. Coconut, palm, mango, etc. are some
examples of angiosperms.
Questio 1:
How do poriferan animals differ from coelenterate animals?
Solution:
Porifera Coelenterate
Mostly marine, nonmotile, and found
attached to rocks. Exclusively marine animals which either
live in colonies or have a solitary lifespan.
Cellular level of organisation. Tissue level of organisation.
Examples: Spongilla, Euplectella, etc. Examples: Hydra, sea anemone, corals, etc.
Question 2:
How do annelid animals differ from arthropods?
Solution:
Annelids Arthropods
Annelids have closed circulatory system Arthropods have an open circulatory system
The body is divided into several identical
segments. The body is divided into a few specialized
segments.
Ring like segments Jointed legs
Question 3:
What are the differences between amphibians and reptiles?
Solution:
Amphibian Reptiles
They can live both on land and water. They are completely terrestrial.
Scales are absent. Skin is covered with scales.
They lay eggs in water. They lay eggs on land.
It includes frogs, toads, and salamanders. It includes lizards, snakes, turtles,
chameleons, etc.
Question 4:
What are the differences between animals belonging to the Aves group and those in the mammalia group?
Solution:
Aves Mammals
Most birds have feathers They do not have feathers
They possess beak or bill. The beak is absent.
They lay eggs. Hence, they are oviparous. Some of them lay eggs and some give birth
to young ones. Hence, they are both oviparous and viviparous.
Mammary glands are absent They have mammary glands
Question 1:
What are the advantages of classifying organisms?
Solution:
As there are many organisms on the earth, it is important to know them. The diversity is not only between different organisms but also between different individuals of the same organism. So, it will be very difficult to study each of the 30 million species one by one. Scientists, therefore, felt the need of grouping different species based on some observable similar characters. Classification of related organisms helps in the identification and study of their evolutionary relationships.
Question 2:
How would you choose between two characteristics to be used for developing a hierarchy in classification?
Solution:
For developing a hierarchy of classification, we choose the fundamental characteristic among several other characteristics. We can classify the organism based on different characteristics. Characteristics may be a particular form or function. The basic classification can be done based on the nucleus which is prokaryotes and eukaryotes. The second to be considered for classification can be a number of cells - unicellular and multicellular.
Question 3:
Explain the basis for grouping organisms into five kingdoms.
Solution:
There were many classifications done based on different characteristics of organisms. Out of all, the classification done by R.H Whittaker (1969) is accepted and widely used even today. The classification Whittaker proposed has five kingdoms: Monera, Protista, Fungi, Plantae and Animalia. The five-kingdom classification is done on cell structure, mode and source of nutrition and body organisation.
Question 4:
What are the major divisions in the Plantae? What is the basis for these divisions?
Solution:
The major divisions in kingdom Plantae are Thallophyta, Bryophyta, Pteridophyta, Gymnosperms, and Angiosperms.
The classification depends on the following criteria:
● Differentiated or undifferentiated plant body
● Presence or absence of vascular tissues
● With or without seeds
● Naked seeds or seeds inside fruits
Question 5:
How are the criteria for deciding divisions in plants different from the criteria for deciding the subgroups among animals?
Solution:
Criteria for deciding divisions in plants are based on - Differentiated or Undifferentiated plant body, presence or absence of vascular tissues, with or without seeds and naked seeds or seeds inside fruits whereas in animals it is broadly based on presence or absence of a notochord.
Question 6:
Explain how animals in Vertebrata are classified into further subgroups.
Solution:
Animals in Vertebrata are classified into six classes - Cyclostomata, Pisces, Amphibia, Reptilia, Aves and Mammalia. Vertebrata is further classified into subgroups based on the exoskeleton, nature of the heart, respiration organs, reproduction, mode of living etc.
