Gujarat Board Textbook Solutions Class 9 Science Chapter 7 Diversity in Living Organisms

Gujarat Board Textbook Solutions Class 9 Science Chapter 7 Diversity in Living Organisms

GSEB Solutions Class 9 Science Chapter 7 Diversity in Living Organisms

Gujarat Board Class 9 Science Diversity in Living Organisms Textbook Questions and Answers

Question 1.
What are the advantages of classifying organisms?
Answer:
The advantages of classifying organisms is that:

1. Their identification and study becomes easier.
2. Gives a better organised structure to the vast amount of diversity of organism present on Earth.
3. Helps in understanding the interrelationships and the evolutionary trends among organisms.
4. Helps to predict the properties or the characteristics of the organisms on the basis of the group to which they belong.

Question 2.
How would you choose between two characteristics to be used for developing a hierarchy in classification?
Answer:
The characteristics chosen should start with the characteristic which forms the broadest division and then the next characteristic chosen should be dependent on the previous characteristic and division, besides having its own new characteristic features.

This process should be continued for the next levels in order to build a hierarchy in classification. For example, the classification of organisms into two broad categories-prokaryotes and eukaryotes forms the basis of the further characteristics on which their classification is based.

Question 3.
Explain the basis for grouping organisms into five kingdoms.
Answer:
The grouping of organisms into five kingdoms by R.H. Whittaker has been done on the basis of four main factors:
(i) Cell structure: On the basis of this the two groups are prokaryotes and eukaryotes which are distinguished on the basis of absence or presence of well-defined nuclear membrane.

(ii) Thallus organisation: The organisms are grouped as unicellular or multicellular organisms on the basis of their being composed of a single cell or of many cells respectively.

(iii) Mode of nutrition: The organisms are grouped as autotrophs or heterotrophs on the basis of their ability to synthesise their own food or being dependent on other organisms for their food.

(iv) Phylogenetic relationship: Evolutionary history of an organism is called its phylogeny. It groups organisms as simple organisms with primitive features and complex organisms with more recent and advanced features.

Question 4.
What are the major divisions in the Plantae? What is the basis for these divisions?
Answer:
The Kingdom Plantae has the following major divisions:
(i) Thallophyta
(ii) Bryophyta
(iii) Pteridophyta
(iv) Gymnosperms
(v) Angiosperms

The basis for these divisions are –
(i) Presence or absence of well differentiated parts/components of the body. Algae, the members of Thallophyta do not have well differentiated components in their body.

(ii) Presence or absence of the vascular tissues (i.e., xylem and phloem). Vascular tissues are absent in bryophytes.

(iii) Presence or absence of the ability to bear seeds. Pteridophytes do not have the ability to bear seeds.

(iv) Seeds enclosed within the fruit or not. Naked seeds are produced in gymnosperms as their seeds are not enclosed in fruit.

Question 5.
How are the criteria for deciding divisions in plants different from the criteria for deciding the subgroups among animals?
Answer:
The criteria for deciding the divisions in plants is different from the criteria for deciding the subgroups among animals because animals do not show the characteristics exhibited by plants. This is due to their different body designs and organisation of components.

Plants are classified on the basis of differentiation of body, vascular tissues, ability to bear seeds and the ability to form seeds enclosed in fruits. In animals, the criteria used are the organisation of body into cells, tissues and organs, embryonic layers, symmetry, metamerism, coelom, presence or absence of notochord, etc.

Question 6.
Explain how animals in Vertebrata are classified into further subgroups.
Answer:
The vertebrates are classified into different groups in the order of their growing complexity starting from the organisms with simple body design. The criteria used are –

(i) Kind of skeleton present: Skeleton made of cartilage in cartilaginous fishes and of bones in bony fishes (Pisces).

(ii) Kind of respiration: Skin slimy to touch and respiration occurs through gills in larvae only in the case of Amphibians.

(iii) Presence of dry scales on the body in the case of Reptilia.

(iv) Presence of beak, forelimbs modified into wings, covered by feathers and egg laying group called Aves.

(v) Presence of mammary glands, hair on body, external ears and ability to give birth to young ones in the case of Mammalia.

Gujarat Board Class 9 Science Diversity in Living Organisms InText Questions and Answers

Page – 80
Question 1.
Why do we classify organisms?
Answer:
We classify organisms as it becomes easier to –

1. Study them properly
2. Organise them in various groups
3. Understand them and their inter-relationship in a better way
4. Predict the properties of a member on the basis of the group to which it belongs.

Question 2.
Give three examples of the range of variations that you see in life forms around you.
Answer:
The range of variations which we see in life forms around us are:

1. The organisms appear of various colours (flowers, birds, etc.) and some of them are white, transparent or colourless (cow, Amoeba, etc.).
2. The life span of different organisms also varies. Some live for only a few days (example mosquitoes) and some live for years (example banyan tree).
3. The size of the organisms also varies from a few micrometres (example bacteria) to large plants and animals (example redwood trees of California, blue whale, etc.).

Page – 82

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?
Answer:
(a) The more basic characteristic for classifying organisms is the kind of cells they are made of.

(b) The reason for this is that different kinds of organisms can live or colonise the same habitat even though they do not belong to the same group. For example, forests are colonised by different types of plants and animals. Thus, habitat cannot be the more basic characteristic for classifying organisms.

Question 4.
What is the primary characteristic on which the first division of organisms is made?
Answer:
The primary characteristic on the basis of which the first division of different organisms is made is the presence or the absence of a well-defined nuclear membrane in them i.e., whether they are prokaryotic or eukaryotic.

Question 5.
On what bases are plants and animals put into different categories?
Answer:
The plants and animals have been put into different categories on the basis of their –

1. nutrition: autotrophic or heterotrophic and
2. body design: presence or absence of cell wall.

Page – 83

Question 6.
Which organisms are called primitive and how are they different from the so-called advanced organisms?
Answer:
The organisms having ancient body design (i.e., came into existence earlier) are called as primitive whereas the organisms who have very recent body design (i.e., came into existence later/recently) are called as advanced organisms. For example, Prokaryotes are primitive as they do not have well-defined (nucleus and the eukaryotes are advanced as they have a well-defined nucleus.

Question 7.
Will advanced organisms be the same as complex organisms? Why?
Answer:
The complexity of organisms has increased over the evolutionary time. More advanced organisms have acquired a more complex body design than the primitive organisms which may have occurred to increase their survival rate. So, we can say that advanced organisms will be the same as complex organisms.

Page – 85

Question 8.
What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?
Answer:
All the unicellular prokaryotes which do not have well-defined nucleus and are devoid of membrane bound cell organelles have been kept under kingdom Monera. All the unicellular eukaryotes having well-defined nucleus and membrane bound organelles have been kept under kingdom Protista.

Question 9.
In which kingdom will you place an organism, which is single-celled, eukaryotic and photosynthetic?
Answer:
Kingdom Protista.

Question 10.
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?
Answer:
Species will have the smallest number of organisms with a maximum of characteristics in common and Kingdom will have the largest number of organisms.

Page – 88

Question 11.
Which division among plants has the simplest organisms?
Answer:
Thallophyta

Question 12.
How are pteridophytes different from the phanerogams?
Answer:
Pteridophytes are cryptogams as they have inconspicuous and hidden reproductive organs. They bear naked embryos called spores. Phanerogams have well differentiated reproductive organs and bear embryos inside the seed.

Question 13.
How do gymnosperms and angiosperms differ from each other?
Answer:
Gymnosperms are non-flowering plants having reproductive organs in cones. They bear naked seeds i.e., the seeds are not enclosed in the fruit. Angiosperms are flowering plants having reproductive organs in flowers and bear seeds which are enclosed within a fruit.

Page – 94

Question 14.
How do poriferan animals differ from coelenterate animals?
Answer:
Poriferan:

• Have cellular level organisation.
• Have pores called ostia all over their body.
• Do not have tentacles.
• Have an external skeleton.
• Have a canal system to circulate water throughout their body.

Coelenterate:

• Have tissue level organisation.
• Do not have pores.
• Have tentacles.
• No skeleton is present.
• Do not have canal system to circulate water.

Question 15.
How do annelid animals differ from arthropods?
Answer:
Annelids:

• Body is segmented both externally and internally.
• Do not have an exoskeleton of chitin.
• Bear setae or parapodia for locomotion.
• Coelomic cavity is not filled with blood.

Arthropoda:

• Body is segmented externally but no internal segmentation.
• Have an exoskeleton made up of chitin.
• Bear jointed legs for locomotion.
• Coelomic cavity is blood-filled.

Question 16.
What are the differences between amphibians and reptiles?
Answer:
Amphibians:

• Can live both in land as well as water.
• Lack scales on body and have slimy skin.
• Lay eggs in water.
• Eggs are devoid of tough covering.

Reptiles:

• Most of them are terrestrial animals.
• Have dry scales on body.
• Lay their eggs mostly on land.
• Eggs have a tough covering to protect from drying.

Question 17.
What are the differences between animals belonging to the Aves group and those in the mammalia group?
Answer:
Aves:

• They do not have mammary glands to produce milk for their young ones.
• Are oviparous i.e., lay eggs.
• Forelimbs are modified as wings covered by feathers.
• Have beak.

Mammalia:

• Have mammary glands to produce milk for their young ones.
• Are viviparous i.e., give birth to young ones.
• Body covered with hair and has sweat and oil glands.
• No beak is present.

In-Text Activities Solved

(Textbook Page 80)

Activity 7.1
Answer:
No, a desi cow does not look like a Jersey cow.
No, all desi cows do not look alike.
Yes, we can identify Jersey cow in a crowd of desi cows that don’t look like each other.
The basis of our identification would be the length, height, built of the body, shape and size of its horns, colour and markings on body, shape and size of tail, etc.

(Textbook Page 88)

Activity 7.2
Answer:
1. No, all the seeds do not break into two nearly equal halves.

2. Tap roots are present in dicots and the monocots have fibrous roots.

3. Reticulate venation is present in dicots whereas the monocots have parallel venation.

4. Dicots have pentamerous flowers which means their petals are 5 or in multiple of 5. Monocots have trimerous flowers which means the petals are 3 or in multiples of 3.

(i) Coleoptile protects plumule and coleorrhiza protects radicle in the case of monocots, but no such
structure is seen in the dicot embryo.

(ii) The dicots usually have non-endospermous seeds whereas the monocots generally have endo- spermous seeds.

(iii) The seed coat is separated from the fruit in dicots whereas in the monocots like maize, wheat, etc., the seed coat is fused with the wall of the fruit.

(Textbook Page 96)

Activity 7.3
Answer:

(Textbook Page 96)

Activity 7.4
Answer:

The scientific names are in Latin or are Latinised. So, the common names of plants and animals are different from their scientific names.

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