NCERT Solutions for Class 9 Science Chapter 7 Diversity in Living Organisms

These NCERT Solutions for Class 9 Science Chapter 7 Diversity in Living Organisms Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.

Diversity in Living Organisms NCERT Solutions for Class 9 Science Chapter 7

Class 9 Science Chapter 7 Diversity in Living Organisms InText Questions and Answers

Question 1.
Why do we classify organisms?
Answer:
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 to study these different classes as a whole. Thus, classification makes our study easier.

Question 2.
Give three examples of the range of variations that you see in life-forms around you.
Answer:
Examples of range of variations observed in daily life are:

Variety of living organisms in terms of size ranges from microscopic bacteria to tall trees of 100 metres.
The colour, shape, and size of snakes are. completely different from those of lizards.
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.

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:
The kind of cells that living organisms
are made up of is a more basic characteristic for classifying organisms, than on the basis of their habitat. This is because on the basis of the kind of cells, we can classify all living organisms into eukaryotes and prokaryotes. On the other hand, a habitat or the place where an organism lives is a very broad characteristic to be used as the basis for classifying organisms. For example, animals that live on land include earthworms, mosquitoes, butterfly, rats, elephants, tigers, etc.

These animals do not resemble each other except for the fact that they share a common habitat. Therefore, the nature or kind of a cell is considered to be a fundamental characteristic for the classification of living organisms.

Question 4.
What is the primary characteristic on which the first division of organisms is made?
Answer:
The primary characteristic on which the first division of organisms is made is the nature of the cell. It is considered to be the fundamental characteristic for classifying 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 5.
On what basis are plants and animals put into different categories?
Answer:
Plants and animals differ in many features such as the absence of chloroplasts, presence of cell wall, etc. But, locomotion is considered as the characteristic feature that separates animals from plants.

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), the presence of chloroplasts (for photosynthesis) etc. Hence, locomotion is considered to be the basic characteristic as further differences arose because of this characteristic feature.

Question 6.
Which organisms are called primitive and how are they different from the so-called advanced organisms?
Answer:
A primitive organism or lower 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. An advanced organism or higher organism has a complex body structure and organization. For example, an Amoeba is more primitive as compared to a starfish. Amoeba has a simple body structure and primitive features as compared to a starfish. Hence, an Amoeba is considered more primitive than a starfish.

Question 7.
Will advanced organisms be the same as complex organisms? Why?
Answer:
It is not always true that an advanced organism will have a complex body structure. But, there is a possibility that over the evolutionary time, complexity in body design will increase. Therefore, at times, advanced organisms can be the same as complex organisms.

Question 8.
What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?
Answer:
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 9.
In which kingdom will you place an organism which is single-celled, eukaryotic and photosynthetic?
Answer:
Kingdom Protista includes single celled, eukaryotic, and photosynthetic organisms.

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:
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.

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

Pteridophyta	Phanerogams
1. They have inconspicuous or less differentiated reproductive organs.	1. They have well developed reproductive organs.
2. They produce naked embryos called spores.	2. They produce seeds.
3. Ferns, Marsilea, Equisetum, etc. are examples of Pteridophyta.	3. Pinus, Cycas, fir, etc. are examples of phanerogams.

Question 13.
How do gymnosperms and angiosperms differ from each other?
Answer:

Gymnosperm	Angiosperms
1. They are non-flowering plants.	1. They are flowering plants.
2. Naked seeds not enclosed inside fruits are produced.	2. Seeds are enclosed inside fruits.
3. Pinus, Cedar, fir, Cycas, etc. are some examples of gymnosperms.	3. Coconut, palm, mango, etc. are some examples of angiosperms.

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

Porifera	Coelenterate
1. They are mostly marine, non-motile, and .found attached to rocks.	1. They are exclusively marine animals that either live in colonies or have a solitary life-span.
2. They show cellular level of organisation.	2. They show tissue level of organisation.
3. Spongilla, Euplectella, etc. are poriferans.	3. Hydra, sea anemone, corals, etc. are coelenterates.

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

Annelids	Arthropoda
1. The circulatory system of annelids is closed.	1. Arthropods have an open circulatory system
2. The body is divided into several identical segments.	2. The body is divided into few specialized segments.

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

Amphibian	Reptiles
1. They have a dual mode of life.	1. They are completely terrestrial.
2. Scales are absent.	2. Skin is covered with scales.
3. They lay eggs in water.	3. They lay eggs on land.
4. It includes frogs, toads, and salamanders.	4. 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:

Aves	Mammalia
1. Most birds have feathers and they possess a beak.	1. They do not have feathers and the beak is also absent.
2. They lay eggs. Hence, they are oviparous.	2. Some of them lay eggs and some give birth to young ones. Hence, they are both oviparous and viviparous.
3. Their bones are light and pneumatic.	3. Their bones are hard and solid.
4. Example : Birds like sparrow, crow, parrot, etc.	4. Example: Animals like cow, deer, humans, lion, zebra and whale.

Class 9 Science Chapter 7 Diversity in Living Organisms Textbook Questions and Answers

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

It determines the methods of organising the diversity of life on Earth.
It helps in understanding millions of life forms in detail.
It also helps in predicting the line of evolution.

Question 2.
How would you choose between two characteristics to be used for developing a hierarchy in classification?
Answer:
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 3.
Explain the basis for grouping organisms into five kingdoms.
Answer:
RE 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 or
ganisms 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 a 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.

Question 4.
What are the major divisions in the Plantae? What is the basis for these divisions?
Answer:
The kingdom Plantae is divided into five main divisions: Thallophyta, Bryophyta, Pteridophyta, Gymnosperms, and Angiosperms.

The classification depends on the following criteria:

Differentiated/ Undifferentiated plant body
Presence /absence of vascular tissues
With/without seeds
Naked seeds/ seeds inside fruits

(i) The first level of classification depends on whether a plant body is well differentiated or not. A group of plants that do not have a well differentiated plant body are known as Thallophyta.

(ii) Plants that have well differentiated body parts are further divided on the basis of the presence or absence of vascular tissues. Plants without specialised vascular tissues are included in division Bryophyta, whereas plants with vascular tissues are known as Tracheophyta.

(iii) Tracheophyta is again sub-divided into division Pteridophyta, on the basis of the absence of seed formation.

(iv) The other group of plants having well developed reproductive organs that finally develop seeds are called Phanerogams. This group is further sub-divided on the basis of whether the seeds are naked or enclosed in fruits. This classifies them into gymnosperms and angiosperms. Gymnosperms are seed bearing, non-flowering plants, whereas angiosperms are flowering plants in which the seeds are enclosed inside the 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 divisions in plants different from the criteria for deciding the subgroups among animals because

plants are fixed at a specific position while the animals are motile.
plants are autotrophic while animals are heterotrophic therefore, their requirements and the circulation of the necessary substances in body is different.
plants lack nervous system but animals from the phylum cinidaria onwards posses nervous system.

Question 6.
Explain how animals in Vertebrata are classified into further subgroups.
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.

Class 9 Science Chapter 7 Diversity in Living Organisms Additional Important Questions and Answers

Question 1.
Find out incorrect sentence
(a) Protista includes unicellular eukaryotic organisms
(b) Whittaker considered cell structure, mode and source of nutrition for classifying the organisms in five kingdoms
(c) Both Monera and Protista may be autotrophic and heterotrophic
(d) Monerans have well defined nucleus
Answer:
(d) Monerans have well defined nucleus

Question 2.
Which among the following has specialised tissue for conduction of water?
(i) Thallophyta
(ii) Bryophyta
(iii) Pteridophyta
(iv) Gymnosperms
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)
Answer:
(c) (iii) and (iv)

Question 3.
Which among the following produce seeds?
(a) Thallophyta
(b) Bryophyta
(c) Pteridophyta
(d) Gymnosperms
Answer:
(d) Gymnosperms

Question 4.
Which one is a true fish?
(a) Jellyfish
(b) Starfish
(c) Dogfish
(d) Silverfish
Answer:
(c) Dogfish

Question 5.
Which among the following is exclusively marine?
(a) Porifera
(b) Echinodermata
(c)Mollusca
(d) Pisces
Answer:
(b) Echinodermata

Question 6.
Which among the following have open circulatory system?
(i) Arthropoda
(ii) Mollusca
(iii) Annelida
(iv) Coelenterata
(a) (i) and (ii)
(b) (iii) and (iv)
(c) (i) and (iii)
(d) (ii) and (iv)
Answer:
(a) (i) and (ii)

Question 7.
In which group of animals, coelom is filled with blood?
(a) Arthropoda
(b) Annelida
(c) Nematoda
(d) Echinodermata
Answer:
(a) Arthropoda

Question 8.
Elephantiasis is caused by
(a) Wuchereria
(b) Pinworm
(c) Planarians
(d) Liver flukes
Answer:
(a) Wuchereria

Question 9.
Which one is the most striking or (common) character of the vertebrates?
(a) Presence of notochord
(b) Presence of triploblastic condition
(c) Presence of gill pouches
(d) Presence of coelom
Answer:
(a) Presence of notochord

Question 10.
Which among the following have scales?
(i) Xmphibians
(ii) Pisces
(iii) Reptiles
(iv) Mammals
(a) (i) and (iii)
(b) (iii) and (iv)
(c) (ii) and (iii)
(d) (i) and (ii)
Answer:
(c) (ii) and (iii)

Question 11.
Find out the false statement
(a) Aves are warm blooded, egg laying and have four chambered heart
(b) Aves have feather covered body, fore limbs are modified as wing and breathe through lungs
(c) Most of the mammals are viviparous
(d) Fishes, amphibians and reptiles are oviparous
Answer:
(d) Fishes, amphibians and reptiles are oviparous

Question 12.
Pteridophyta do not have
(a) root
(b) stem
(c) flowers
(d) leaves
Answer:
(c) flowers

Question 13.
Identify a member of Porifera
(a) Spongilla
(b) Euglena
(c) Penicillium
(d) Hydra
Answer:
(a) Spongilla

Question 14.
Which is not an aquatic animal?
(a) Hydra
(b) Jellyfish
(c) Corals
(d) Filaria
Answer:
(d) Filaria

Question 15.
Amphibians do not have the following
(a) Three chambered heart
(b) Gills or lungs
(c) Scales
(d) Mucus glands
Answer:
(c) Scales

Question 16.
Organisms without nucleus and cell organelles belong to
(i) fungi
(ii) protista
(iii) cyano bacteria
(iv) archae bacteria
(a) (i) and (ii)
(b) (iii) and (iv)
(c) (i) and (iv)
(d) (ii) and (iii)
Answer:
(b) (iii) and (iv)

Question 17.
Which of the following is not a criterion for classification of living organisms?
(a) Body design of the organism
(b) Ability to produce one’s own food
(c) Membrane bound nucleus and cell organelles
(d) Height of the plant
Answer:
(d) Height of the plant

Question 18.
The feature that is not a characteristic of protochordata?
(a) Presence of notochord
(b) Bilateral symmetry and coelom
(c) Jointed legs
(d) Presence of circulatory system
Answer:
(c) Jointed legs

Question 19.
The locomotory organs of Echinoderms are
(a) tube feet
(b) muscular feet
(c) jointed legs
(d) parapodia
Answer:
(a) tube feet

Question 20.
Corals are
(a) Poriferans attached to some solid support
(b) Cnidarians, that are solitary living
(c) Poriferans present at the sea bed
(d) Cnidarians that live in colonies
Answer:
(d) Cnidarians that live in colonies

Very Short Answer Questions

Question 1.
Who is called as the father of taxonomy?
Answer:
Carious Linneaus

Question 2.
Which division of plants is also considered as amphibian of plant kingdom?
Answer:
Bryophytes having motile sperms are considered as amphibian of plant kingdom.

Question 3.
Which is the first division of plants to bear true shoot and root?
Answer:
Pteridophytes are the first to bear true root and shoot.

Question 4.
What are sporophylls in ferns?
Answer:
The leaves bearing the sporangia on their lower surface are called the sporophylls.

Question 5.
What are circinate leaves in a dryopteris?
Answer:
Circinate leaves are young leaves with the top margins folded inwardly.

Question 6.
Which part of pinus plant bears naked seeds?
Answer:
The female cone in pinus plant bears the seeds.

Question 7.
Which is the lateral appendage of shoot in angiosperms that acts as the reproductive organ?
Answer:
Flower is the lateral appendage of shoot that acts as the reproductive organ.

Question 8.
Which phase is dominant in a Funaria plant, gametophytic i sporophytic?
Answer:
In funaria, the gametophytic phase is dominant over the sporophytic phase.

Question 9.
Which type of spores are produced by the Funaria sporophyte?
Answer:
The sporophyte always produces the haploid spores that give rise gametophytic thallus.

Question 10.
In phanerogams, which plants bear the tap root system, gymnosperms or angiosperms?
Answer:
In phanerogams, the gymnosperms bear the tap roots.

Question 11.
In which plants the algae and fungi are present in the symbiotic relationship?
Answer:
Lichens consist of algae and fungi in the symbiotic relationship.

Question 12.
Which type of plants do you expect to observe in the artic regions?
Answer:
Bryophytes

Question 13.
Which division of plants consists mostly of ornamental plants?
Answer:
Pteridophytes, mostly ferns.

Question 14.
Name an aquatic pteridophyte that is capable of nitrogen fixation?
Answer:
Azolla

Question 15.
Name any two products of economical value that are obtained from algae.
Answer:
Iodine from kelps and silica from diatoms.

Question 16.
Which term is used to describe the network of hyphae in Rhizopus?
Answer:
Mycelium

Question 17.
Which nutrient medium is mostly used in laboratory for culturing microorganisms?
Answer:
Agar-agar, a product obtained from an algae is widely used as the culture medium.

Question 18.
What are the male and female reproductive organs in a moss or fern?
Answer:
In a moss or fern, the male and female reproductive organs are multicellular. They are called antheridum and archegonium respectively.

Question 19.
Name the division of plants whose members show a clearly distinct phases of alternation of generation.
Answer:
The members of bryophytes shows a clearly distinct alternation of generation with gametophytic phase being dominant over the sporophytic phase.

Question 20.
How is a protozoan different from a metazoan?
Answer:
A protozoan is unicellular but a metazoan is multicellular.

Question 21.
What is reproductive nature of an earthworm, unisexual or bisexual?
Answer:
An earthworm is bisexual, although the ovaries and testes mature at the different rimes.

Question 22.
Which cockroach has the larger antennae, male or female?
Answer:
The male cockroach has larger antennae than the female cockroach to perceive the odour in the surroundings.

Question 23.
Which phylum in animal kingdom has the largest and the second largest number of animals?
Answer:
The phylum arthropods has the largest and phylum mollusca has the second largest number of animals.

Question 24.
Which animal phylum is characterized by the presence of water canal system and water vascular system?
Answer:
Animals belonging to phylum Echinodermata have water vascular system, while the animals belonging to phylum Porifera have water canal system.

Question 25.
Which is the common physical feature in a bird and a fish?
Answer:
A bird and a fish both have streamlined body.

Question 26.
Name the animal that resembles both the reptiles and mammals.
Answer:
Duck billed platypus as it lays eggs like reptiles.

Question 27.
Name an aerial and an aquatic mammal.
Answer:
The only aerial mammal is bat and whale is an aquatic mammal.

Question 28.
Give an example of a parasitic annelida?
Answer:
Leech ( Hinidinaria) is the parasitic annelida. It is parasitic on cattle fronl whom it sucks the blood.

Question 29.
Name any three animals that show the generation of their body parts.
Answer:
Star fish regenerates it lost arm, frog regenerates its limb and a hous lizard regenerates it lost tail.

Question 30.
The animals of which phylum are characterized by the presence of protective hard shell?
Answer:
In the phylum Mollusca, all animals posses protective hard shell.

Question 31.
Sea horse is a vertebrate. In which class has it been placed li classification?
Answer:
Sea horse has been placed in the classes of Pisces under Oestiochythe

Question 32.
Name the three layers present in the embryo of a triploblastic animal.
Answer:
The three layers are ectoderm, mesoderm and endoderm.

Short Answer Questions

Question 1.
Who proposed binomial nomenclature? State its significance.
Answer:
The concept of binomial nomenclature was proposed by Carolus Linnaeus It was meant to give the scientific name to an organism for

easy identification of an organism because the first name refers to the gen while the second name is the specific epithet.
maintaining the uniformity of the names worldwide.

Question 2.
Draw a labelled diagram of a typical bacterium.
Answer:

Question 3.
How are prokaryotes different from eukaryotes?
Answer:
The organisms with the prokaryotic cell are characterized by the abs of well defined nucleus and membrane bound cell organelles while those with t eukaryotic cell, plant or animal cell are called eukaryotes.

In five kingdom system, prokaryotes have been placed in kingdom Me while the eukaryotic organisms have been placed in the rest of the four kingdoms.

Question 4.
Why are viruses considered to be at the border line of living and non-livings?
Answer:
Viruses are the obligate parasites, they are living only when in body of a living host otherwise, they act as non-living. They can be filtered and crystallized like chemicals.

Question 5.
What are protozoa? Give examples.
Answer:
Protozoa are the eukaryotic unicellular animals which belongs to the kingdom ‘Protista’. These animals are either free living or parasitic. The free living protozoa include amoeba and paramecium while the parasitic protozoa which are the cause of infectious disease to mankind include

Plasmodium, the causative agent of malaria.
Trypanosoma, the causative agent of sleeping sickness.
Entameoba histolytica, the causative agent of amoebiasis.

Question 6.
Why are the saprophytes called the natural cleaners of the environment?
Answer:
The saprophytes are called the natural cleaners of the environment because they decompose the dead organic matter of living organisms such as the agricultural wastes and animal excreta into simple inorganic form to allow the recycling of the different nutrients.

Question 7.
Name the unicellular fungi with its importance.
Answer:
One of the unicellular fungi is yeast. It is commercially an important gradient as it lays the foundation of brewery and bakery industry because of its ability of anaerobically breaking down of sugar, producing the alcohol, ethanol and carbon dioxide. The ethanol is the product used in brewery industries and produced carbon dioxide is used in bakery industry to make the bread or cake soft and spongy.

Question 8.
Differentiate in the followings:
(a) Monera and Protista
(b) Bryophytes and pteridophytes
(c) Monocots and dicots
(d) Mollusca and echinodermata
(e) Chordata and non-chordata
(f) Cartilaginous and bony fishes
(g) Platyhelminthes and nematoda
Answer:

Monera	Protista
1. They have prokaryotic cells.	They have eukaryotic cells.
2. They are autotrophic, parasitic or free living.	They are autotrophic, parasitic or free living.
3. Example: Bacteria, Mycoplasm	Example: Protozoa and algae like chlamydomonas.

(b) Bryophytes and pteridophytes

(d) Mollusca and echinodermata

(e) Chordata and non-chordata

Chordates	Nonchordates
1. They show the presence of notochord in any stage of their life.	1. They do not posses notochord in any stage of their life.
2. Central nervous system is hollow and dorsal.	2. Central nervous system is solid and ventral.
3. Heart is always ventral.	3. Heart if present is dorsal.
4. They have haemoglobin present in red blood cells.	4. They have haemoglobin or any other respiratory pigment present dissolved in blood plasma.

(f) Cartilaginous and bony fishes

(g) Platyhelminthes and Nematoda

Question 9.
List some of the important characteristics of protochordates.
Answer:
The protochordates are primitive to chordates.

They are triploblastic and bilaterally symmetrical with a coelom.
They are exclusively marine animals.
They posses a notochord at some stage of their life that separates nervous tissue with gut.
They have muscles attached to notochord for easy movement.
Example: Herdmania, Amphixous and Balanglossus.

Question 10.
Write the characteristic adaptive features in the followings:
(a) Fishes for swimming in water.
(b) Birds for flying in air.
Answer:
(a) Fishes are well adapted for swimming in water because they have

streamlined body to reduce friction when swimming in water.
scales to prevent the rotting action of water on body.
have fins to swim and tail fin to steer their motion in water.
have gills for the gaseous exchange.
have swim bladder to change their buoyancy i.e. the depth in water.

(b) Birds are well adapted for flying because of the presence of

streamlined body with kneeled chest to reduce the air friction in air.
forelimbs modified in form of wings to help bird fly in air.
pneumatic bones to keep the body weight light.
air bladder to change their height in air.

Question 11.
Do all birds fly? If not, give examples.
Answer:
No, all birds do not fly. They are few non-flying birds such as

Ostrich of Africa,
Kiwi of Newzealand
Penguin of Antarctica region

Long Answer Questions

Question 1.
How have the organisms being classified on the basis of their mode of nutrition?
Answer:
The organisms on the basis of their mode of nutrition have been basically classified into two types, autotrophs and heterotrophs. Autotrophs can synthesize their own food like green plants but heterotrophs are organisms that are dependent on others for their nutrition. These organisms based on that how they obtain their food have been further categorized into different types such as:

Saprophytes: Organisms who obtain their nourishment from other living organisms called host. They cause serious damage to the host as they obtain their nourishment such as malaria parasite, leech, ticks, etc.

Symbiotic: Organisms which while living together help each other in gaining the nourishment such as lichen. They are composed of algae and fungi, the fungi absorbs water and minerals while green algae synthesize the food that is equally shared by the both algae and fungi.

Question 2.
State the different characteristic features of monera.
Answer:
All members of Monera have the following characteristics:

They lack multicellular body design.
The body cell lack well defined nucleus and membrane bound cell organelles.
Some posses cell wall like bacteria and cyanobacteria while others like mycoplasm lack it.
They can be autotrophic, heterotrophic or symbiotic in their mode of nutrition.
Example: Bacteria, mycoplasma and cyanobacteria like nostoc, anabena and oscillatoria.

Question 3.
State the different characteristic features of protista.
Answer:
The kingdom Protista include number of eukaryotic unicellular organisms.

They vary in their structure, some have locomotory organs like cila or flagella while others don’t like amoeba.
They vary in their mode of nutrition, some are autotrophic while others are heterotrophic from holozoic to parasitic. Euglena is the only Protista that shows both autotrophic and heterotrophic mode of nutrition.

Question 4.
State the chief characteristics of the division Thallophyta with examples.
Answer:
The chief characteristics of thallophytes include:

The plant body is in form of individual thallus ire. not differentiated between stem, root and leaf.
They lack vascular system and tissues for conduction of water and food.
They are predominantly aquatic.
Their reproductive organs are single celled.
They are autotrophic like algae, symbiotic like lichens or saprophytic like fungi in their mode of nutrition.

Question 5.
Which conventions are followed when writing the scientific name of organism?
Answer:
When writing the scientific name of an organism, the sign conventions followed are:

The name of genus is written first followed by the name of species.
The name of genus starts with capital alphabet while that of species starts with small alphabet.
When printed, it is always written in italics and if written by hand, it is underlined.