NCERT Solutions for Chapter 7 Diversity in Living Organisms Class 9 Science
Book Solutions1
Answer
There are millions of organisms on this earth. So, it is harder to study them one by one. Therefore, we look for similarities among them and classify them into different classes to study these different classes as a whole. Classification makes our study easier.2
Answer
Examples of range of variations observed in daily life are:→ Organisms vary greatly in size-from microscopic bacteria to elephants, whales and large trees.
→ The colour of various animals is quite different. Some worms are even colourless or transparent. Various types of pigments are found in plants.
→ The life span of different organisms is also quite varied. For example, a crow lives for only 15 years, whereas a parrot lives for about 140 years.
1
(a) The place where they live.
(b) The kind of cells they are made of. Why ?
Answer
The more basic characteristic for classifying organisms is the kind of cells they are made of because different organisms may share same habitat but may have entirely different form and structure. So, the place where they live cannot be a basis of classification.2
Answer
The primary characteristic on which the first division of organisms is made is the nature of the cell – prokaryotic or eukaryotic cell.3
Answer
Plants and animals are put into different categories on the basis of Mode of nutrition.Plants are autotrophs. They can make their food own while animas are heterotrophs which are dependent on others for food. Also, locomotion, absence of chloroplasts etc. make them different.1
Answer
A primitive organism is the one which has a simple body structure and ancient body design or features that have not changed much over a period of time. As per the body design, the primitve organisms which have simple structures are different from those so-called advanced organisms which have complex body structure and organization.2
Answer
Yes, because the advanced organisms also were like the primitive ones once. They have acquired their complexity relatively recently. There is a possibility that these advanced or 'younger' organisms acquire more complex structures during evolutionary time to compete and survive in the changing environment.1
Answer
The organisms belonging to Kingdom Monera are unicellular and prokaryotic whereas the organisms belonging to Kingdom Protista are unicellular and eukaryotic.2
Answer
Kingdom Protista3
Answer
In the hierarchy of classification,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.1
Answer
Division Thallophyta2
Answer
|
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. |
3
Answer
|
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. |
1
How do poriferan animals differ from coelenterate animals ?
Answer
|
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. |
2
Answer
|
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. |
3
Answer
|
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. |
4
Answer
|
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. |
1
Answer
Following are the advantages of classifying organisms:
→ It makes us aware of and gives us information regarding the diversity of plants and animals.
→ It makes the study of different kinds of organisms much easier.
→ It tells us about the inter-relationship among the various organisms.
→ It helps us understanding the evolution of organisms.
→ It helps in the development of other life sciences easy.
→ It helps environmentalists to develop new methods of conservation of plants and animals.
2
Answer
We choose that characteristics which depends on the first characteristics and determines the rest variety.3
Answer
The basis for grouping organisms into five kingdoms are:
→ Complexity of cell structure: There are two broad categories of cell structure: Prokaryotic and Eukaryotic. Thus, two broad groups can be formed, one having prokaryotic cell structure and the other having eukaryotic cell structure. Presence or absence of cell wall is another important characteristic.
→ Unicellular and multicellular organisms: This characteristic makes a very basic distinction in the body designs of organisms and helps in their broad categorizations.
→ Cell Wall: Presence and absence of cell wall leads into grouping.
→ Mode of nutrition: Organisms basically have two types of nutritions - autotrophic who can manufacture their own food and heterotrophic who obtain their food from external environment, i.e., from other organisms). Thus, organisms can be broadly classified into different groups on the basis of their mode of nutrition.
4
Answer
The major divisions in Kingdom Plantae are:→Thallophyta
→ Bryophyta
→ Pteridophyta
→ Gymnosperms
5
Answer
The characteristics used to classify plants is different from animals because the basic design are different, based on the need to make their own food (plants) or acquire food (animals).
Criteria for deciding divisions in plants are:
→ Differentiated/ Undifferentiated plant body
→ Presence/ absence of vascular tissues
→With/without seeds
→ Naked seeds/ seeds inside fruits
But the animals can't be divided into groups on these criteria. It is because the basic designs of animals are very different from plants. They are divided on the basis of their body structure.
6
Answer
Animals in Vertebrata are classified into five classes:(i) Class Pisces: This class includes fish such as Scoliodon, tuna, rohu, shark, etc. These animals mostly live in water. Hence, they have special adaptive features such as a streamlined body, presence of a tail for movement, gills, etc. to live in water.
(ii) Class Amphibia: It includes frogs, toads, and salamanders. These animals have a dual mode of life. In the larval stage, the respiratory organs are gills, but in the adult stage, respiration occurs through the lungs or skin. They lay eggs in water.
(iii) Class Reptilia: It includes reptiles such as lizards, snakes, turtles, etc. They usually creep or crawl on land. The body of a reptile is covered with dry and cornified skin to prevent water loss. They lay eggs on land.
(iv) Class Aves: It includes all birds such as sparrow, pigeon, crow, etc. Most of them have feathers. Their forelimbs are modified into wings for flight, while hind limbs are modified for walking and clasping. They lay eggs.
(v) Class Mammalia: It includes a variety of animals which have milk producing glands to nourish their young ones. Some lay eggs and some give birth to young ones. Their skin has hair as well as sweat glands to regulate their body temperature.