In Text Questions:
Page No. 80
1. Why do we classify organisms?
• Classification helps in the study of wide variety of organisms in a simple way.
• It reveals interrelationship among organisms.
• It help in understanding the evolution of organisms.
2. Give three examples of the range of variations that you see in life forms around you.
Different forms in which life occurs on Earth:
• Size: Organisms vary greatly in size-from microscopic bacteria to elephants, whales and large trees.
• Life Span. Pine trees live for thousands of years while insects such as mosquitoes die within few days.
• Colour. Colourless or transparent worms to brightly coloured birds and flowers.
Page No. 82
1. 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.
The kind of cells is a more basic characteristic for classification of organisms. The cells may be prokaryotic or eukaryotic. The presence or absence of nucleus, or membrane bound organelles reflect every aspect of cell design and capacity to make a multicellular body.
2. What is the primary characteristic on which the first division of organism is made?
The primary characteristic on which the first division of organisms is made is the nature of the cell – prokaryotic or eukaryotic cell.
3. On what basis are plants and animals put into different categories?
• Mode of nutrition: Plants prepare their own food by photosynthesis due to the presence of chlorophyll, while animals depend on other organisms for food.
• Presence or absence of cell wall: Plant cells are surrounded by a cell wall, whereas animal cells lack cell wall.
• Locomotion: Plants are fixed, whereas animals are motile.
• Growth: Plants grow throughout their life, whereas animals stop growing after a certain period.
Page No. 83
1. Which organisms are called primitive and how are they different from the so called advanced organisms?
Primitive organisms are those which have ancient body designs and have not changed much. They are also called 'lower' organisms. The organisms that have acquired their particular body design relatively recently are called advanced organisms. They are also called 'higher' organisms.
2. Will advanced organisms be the same as complex organisms? Why?
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.
Page No. 85
1. What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?
Nature and number of cell are the criteria for classification of Monera and Protista. Prokaryotes belong to the kingdom Monera, while unicellular eukaryotes belong to the kingdom Protista.
2. In which kingdom will you place an organism which is single-celled, eukaryotic and photosynthetic?
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?
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.
Page No: 88
1. Which division among plants has the simplest organisms?
2. How are pteridophytes different from the 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. How do gymnosperms and angiosperms differ from each other?
|They are non-flowering plants.||They are flowering plants.|
|They are flowering plants.||Seeds are enclosed inside fruits.|
|Pinus, Cedar, fir, Cycas, etc. are some examples of gymnosperms.||Coconut, palm, mango, etc. are some examples of angiosperms.|
Page No: 94
1. How do poriferan animals differ from coelenterate animals?
|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. How do annelid animals differ from 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. What are the differences between amphibians and 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. What are the differences between animals belonging to the Aves group and those in the mammalia group?
|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.|