Chapter 7 Diversity in Living Organisms Solutions
Question - 11 : - Which division among plants has the simplest organisms?
Answer - 11 : -
Thallophyta is the division of plants that has the simplest organisms. This group includes plants, which do not contain a well differentiated plant body. Their body is not differentiated into roots, stems, and leaves. They are commonly known as algae.
Question - 12 : - How are pteridophytes different from the phanerogams?
Answer - 12 : -
| Pteridophyta | Phanerogams |
| They have inconspicuous or less differentiated reproductive organs. | They have well developed reproductive organs. |
| They produce naked embryos called spores. | They produce seeds. |
| Ferns, Marsilea, Equisetum, etc. are examples of pteridophyta. | Pinus, Cycas, fir, etc. are examples of phanerogams. |
Question - 13 : - How do gymnosperms and angiosperms differ from each other?
Answer - 13 : -
| Gymnosperm | Angiosperm |
| They are non-flowering plants. | They are flowering plants. |
| Naked seeds not enclosed inside fruits are produced. | Seeds are enclosed inside fruits. |
| Pinus, Cedar, fir, Cycas, etc. are some examples of gymnosperms. | Coconut, palm, mango, etc. are some examples of angiosperms. |
Question - 14 : - How do poriferan animals differ from coelenterate animals?
Answer - 14 : -
| Porifera | Coelenterate |
| They are mostly marine, non-motile, and found attached to rocks. | They are exclusively marine animals that either live in colonies or have a solitary life-span. |
| They show cellular level of organisation. | They show tissue level of organisation. |
| Spongilla, Euplectella, etc. are poriferans. | Hydra, sea anemone, corals, etc. are coelenterates. |
Question - 15 : - How do annelid animals differ from arthropods?
Answer - 15 : -
| Annelids | Arthropods |
| The circulatory system of annelids is closed. | Arthropods have an open circulatory system. |
| The body is divided into several identical segments. | The body is divided into few specialized segments. |
Question - 16 : - What are the differences between amphibians and reptiles?
Answer - 16 : -
| Amphibian | Reptiles |
| They have a dual mode of life. | 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 - 17 : - What are the differences between animals belonging to the Aves group and those in the mammalia group?
Answer - 17 : -
| Aves | Mammals |
| Most birds have feathers and they possess a beak. | They do not have feathers and the beak is also 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. |
Question - 18 : - What are the advantages of classifying organisms?
Answer - 18 : -
There are a wide range of life forms (about 10 million-13 million species) around us. These life forms have existed and evolved on the Earth over millions of years ago. The huge range of these life forms makes it very difficult to study them one by one. Therefore, we look for similarities among them and classify them into different classes so that we can study these different classes as a whole. This makes our study easier.
Therefore, classification serves the following advantages:
(i) It determines the methods of organising the diversity of life on Earth.
(ii) It helps in understanding millions of life forms in detail.
(iii) It also helps in predicting the line of evolution.
Question - 19 : - How would you choose between two characteristics to be used for developing a hierarchy in classification?
Answer - 19 : -
For developing a hierarchy of classification, we choose the fundamental characteristic among several other characteristics. For example, plants differ from animals in the absence of locomotion, chloroplasts, cell wall, etc. But, only locomotion is considered as the basic or fundamental feature that is used to distinguish between plants and animals. This is because the absence of locomotion in plants gave rise to many structural changes such as the presence of a cell wall for protection, and the presence of chloroplast for photosynthesis (as they cannot move around in search of food like animals). Thus, all these features are a result of locomotion. Therefore, locomotion is considered to be a fundamental characteristic. By choosing the basic or fundamental characteristic, we can make broad divisions in living organisms as the next level of characteristic is dependent on these. This goes on to form a hierarchy of characteristics.
Question - 20 : - Explain the basis for grouping organisms into five kingdoms.
Answer - 20 : -
R.H. Whittaker proposed a five kingdom classification of living organisms on the basis of Linnaeus’ system of classification. The five kingdoms proposed by Whittaker are Monera, Protista, Fungi, Plantae, and Animalia.
The basis for grouping organisms into five kingdoms is as follows:
(i) On the basis of the presence or absence of membrane-bound organelles, all living organisms are divided into two broad categories of eukaryotes and prokaryotes. This division lead to the formation of kingdom Monera, which includes all prokaryotes.
(ii) Then, eukaryotes are divided as unicellular and multicellular, on the basis of cellularity. Unicellular eukaryotes form kingdom Protista, and multicellular eukaryotes form kingdom Fungi, Plantae, and Animalia.
(iii) Animals are then separated on the basis of the absence of a cell wall.
(iv) Since fungi and plants both contain a cell wall, they are separated into different kingdoms on the basis of their modes of nutrition. Fungi have saprophytic mode of nutrition, whereas plants have autotrophic mode of nutrition. This results in the formation of the five kingdoms.