Diversity in living organisms

Important terms:

1)Biodiversity :  the variety of life forms found in a region

2)Classification: arranging organisms into various groups on the basis of similarities and differences is called classification

3)Kingdom : a group of all organism sharing a set of distinguished common characters

4)Species : a group of similar individuals with similar morphological characters that are capable of interbreeding and produce their own kind

5)Bilateral symmetry : body organization in which one medium plane can divide an organism into two halves, each being a mirror image of the other

6)Radial symmetry : arrangement of similar parts around a central body as in a wheel is known as radial symmetry. Any longitudinal plane along the diameter can divide the animal into exact halves

7)Coelom : body cavity in which various body organs are placed in triploblastic animals is termed as coelom

8)Haemocoel : a reduced body cavity which is filled with blood

9)Diploblastic : animals having a body made of two layers of cells

10)Triploblastic : animals having a body made of three layers of cells ectoderm, mesoderm and endoderm

11)Ectoderm : outermost layer formed in the development of a multicellular animal from which skin and nervous system is derived

12)Mesoderm : middle layer formed in the early development of a multicellular animal from which muscles are derivd

13)Endoderm : innermost layer formed in the early development of a multicellular animal from which the gut and digestive organs are derived

14)Endoskeleton : the bony and cartilaginous supporting structure within the animal body

15)Exoskeleton : chitinous ,or other hard material covering the body surface and providing protection and support

16)Operculum : a structure serving as lid or cover in certain animals

17)Ostia : holes leading to a canal system in sponges

18)Notochord : a flexible rod of turgid cells located along the back of the animals separting the nervous tissue from the gut. It is replaced by the vertebral column in adult vertebrates. It is a part of skeleton system

19)Nerve cord : a solid strand of nervous tissue forming part of central nervous system in vertebrates. Nerve cord is a part of nervous system

Short Answer Questions

Q1 What are the criteria on which Whittaker based his system of classification

A  1) cell structure----prokaryotic or eukaryotic

     2) body organization----unicellular or multicellular

     3) modes of nutrition--- autotrophs or heterotrophs

Q 2 Enlist the main features of organisms placed under Protista

A  1) most of the members are unicellular and primarily aquatic

     2) euokaryotic cell organelles and nucleus

     3) bear flagella or cilia for movement

     4) mode of nutrition is absorptive, ingestive or photo autotrophic

     5) reproduction may be asexual or sexual

Q 3 Main features of kingdom Fungi

A  i) non green due to absence of chlorophyll

    ii) heterotrophs , obtaining food from dead and decaying organisms by absorption

   iii) cell wall is chitinous and cellulosic

   iv) asexual reproduction is by spore formation. Some also exhibits sexual reproduction

Q4 Main characteristics of kingdom Plantae

A  i) all complex multicellular plants that prepare their own food by photosynthesis

    ii) possess cell wall made up of cellulose

    iii) immobile and donot show locomotion

    iv) unlimited growth and grow throughout their lives

Q5 On which basis is the plant kingdom classified

A   i) evolution

     ii) presence or absence of vascular tissues for transport of food and water

    iii) presence or absence of seeds

    iv) presence or absence of fruits

Q6  Main features of Algae

A  i) autotrophs as they possess chlorophyll

    ii) mainly aquatic but some also grow in moist places

 iii) body is not divided into root, stem and leaves

Q7 Main features of division Bryophyta

A  i) Bryophytes are called amphibians of plant kingdom

    ii) The plant body is commonly differentiated to form stem and leaf like structures. But there is no specific tissue for conduction of water and food

     iii) vegetative reproduction is very common

     iv) sexual reproduction is of oogamous typei.e. the male gamete is small and motile and female gamete is non motile and large

    v) e.g. moss, Funaria and Marchantia  

Q8 Main features of Pteridophytes

A  i) plant body is divided into root, stem and leaves

    ii) they have a well developed vascular system(xylem and phloem)

   iii) multicellular reproductive system. The fertilized egg form embryo

Q9 Main features of kingdom Monera

A   i) unicellular, microscopic prokaryotes living in moist conditions

    ii) cell wall may or may not be present

   iii) nucleus is not enclosed in nuclear membrane

   iv) cell organelles are also not covered with a membrane

   v) mode of nutrition may be autotrophic or heterotrophic

  vi) reproduction is asexual by binary fission or budding

Q10 How are phanerogams classified?

A  Phanerogams are classified depending on the presence or absence of fruits. They are of two types

i)                   Gymnosperms possess naked seeds i.e.not enclosed by fruits

ii)                 Angiosperms , in which the seeds are enclosed within the fruit

Angiosperms are further divided into two types

i)                   Monocotyledons, which have single cotyledon in their seeds e.g. wheat, rice etc.

ii)                 Dicotyledons, which have two cotyledons in their seeds e.g. gram, pea etc.

Q11 Name the five kingdoms of organisms and the types of organisms present in them

A  i) Monera : containing bacteria and cyanobacteria

    ii)Protista : having unicellular organisms

iii)               Plantae : contains all the photosynthetic plants

iv)               Fungi : contains the organisms in which chlorophyll is absent and the food is obtained through absorption

v)                 Animalia : contains all the multicellular consumers i.e. the animals which depend on plants or other animals for food

Q12 What are Lichens?

A  Lichens are called compound plants as algae and fungi live together in close association, as a result of which both are benefitted. This relationship is called symbiosis. They occur as greyish green growths on rocks, bark of the tree or on the ground

Q13 What are mycoplasma?

A  Mycoplasmas are the smallest and the simplest organisms . they are prokaryotes having nucleoid. They are heterotrophs  and their body can change forms easily. They are also called MLO,i.e. Mycoplasma Like Organisms

Q14 What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?

A  Prokaryotes belong to the kingdom Monera and single celled eukaryotes belong to the kingdom Protista

Q15 How are gymnosperms different from angiosperms

A  Gymnosperms : plants of this group are usually evergreen, perennial and woody. The plants bear naked seeds. Ovules are not enclosed in ovary. Xylem lacks vessels and phloem does not contain companion cells

  Angiosperms : plants of this group may be annual, biennial or perennial. They may be woody or non woody. Seeds are enclosed in fruits. Reproductive organs are flowers. Xylem contains vessels and phloem contains companion cells

Q16 How are the criteria for deciding divisions in plants different from the criteria for deciding the sub groups among the animals?

A The criteria for dividing the plants include

1)     Differentiation of the plant body

2)     Vascular tissues

3)     Seed producing ability

4)     The seeds enclosed within the 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.

Diversity (2)

Animal kingdom:- salient features of various phylum

1.    Phylum Porifera

i)            Found in marine or fresh water

ii)           Multicellular, do not form tissues

iii)         Radial symmetry

iv)         Sessile(attached to surface),can’t move

v)           Pores all over the body,osculum on the top

vi)         Reproduction,asexual by budding and sexual by fertilization

vii)        Commonly called sponges

viii)      E.g. Sycon,Spongilla

2.   Coelenterata

i)            Found in aquatic (fresh water or marine)

ii)           Radial symmetry

iii)         Live either in colonies e.g. corals or solitary

iv)         E.g. Hydra, Jelly fish, Sea anemone

3.   Platyhelminthes (flat worm)

i)            Parasitic, ribbon like

ii)           Bilateral symmetry

iii)         Triploblastic

iv)         Hermaphrodite(both sex organs , male and female present in one animal)

v)           E.g. Tape worm, Liver fluke

   4. Nematoda (aschelminthes)

      i) parasitic

      ii) bilateral symmetry

      iii) cylindrical body

       iv)triploblastic

       v)Sexes are separate

vi)         E.g. Round worm, Pin worm (Ascaris)

4.   Annelida

5.   Annelida

i)            Found in fresh water, marine water or even on land

ii)           Body is elongated and segmented

iii)         Bilateral symmetry

iv)         True body cavity

v)           Sexes may be separated or united

vi)         E.g. Earthworm, Leech

6.   Arthopoda

i)            Found everywhere

ii)           Arthropod (jointed legs)

iii)         Open circulatory systemi.e. blood doesn’t flow in blood vessels

iv)         Body divided into head ,thorax and abdomen

v)           Bilateral symmetry and segmented

vi)         Body covered with chitinous exoskeleton

vii)        Body cavity is blood filled and called haemocoel

viii)      E.g. Cockroach, Butterfly

7.   Mollusca

i)            Soft, little segmented

ii)           Bilateral symmetry

iii)         Open circulatory system

iv)         Kidney like organs for excretion

v)           Bilateral symmetry

vi)         E.g. Pila (snail) , octopus

8.   Echinodermata

i)            Free living marine animals

ii)           Triploblastic and have coelomic cavitry

iii)         Water driven tube system used for moving around

iv)         Body surface is covered with calcareous spines so they are also called spiny skinned animals

v)           E.g,. Star fish, Sea urchin

9.   Chordate

(A)       Protochordata

i)            Marine animals

ii)           Bilateral symmetry, triploblastic, have coelom

iii)         Notochord is present

iv)         E.g. Balanoglossus, Herdemania

(B)        Vertebrata

i)            possess a solid notochord

ii)           bilateral symmetry

iii)         true vertebral column

iv)         dorsal hollow nerve cord

v)           triploblastic

vi)         respire through lungs and aquatic forms through gills

vii)        there are five classes of vertebrates—Pisces, Amphibians, Reptiles, Aves, Mammalia

Q give the point of differences between non chordates and chordates

A

Non chordates	chordates
1.    vertebral column is absent 2.   central nervous system is solid and ventral 3.   if heart is present,it is dorsal 4.   haemoglobin,if present is dissolved in plasma 5.   the anus is posterior,so no post anal tail 6.   e.g. protozoa, arthopoda	1.    vertebral column is present 2.   central nervous system is hollow and dorsal 3.   heart is ventral 4.   haemoglobin is present in red blood corpuscles 5.   a post anal tail is present 6.   e.g. Pisces, Aves, reptiles etc.

Salient features of classes:-

1)   Pisces

i)            Water living animals

ii)           Skin covered by plates or scales

iii)         Respiration by gills

iv)         Streamlined body with muscular tail

v)           Cold blooded

vi)         Two chambered heart

vii)        Lay eggs

viii)      E.g. Rohu, Sharks, Scolidon

2)  Amphibia:

i)            Found both in water and land

ii)           Moist body without scales

iii)         2 pairs of limbs

iv)         3 chambered heart

v)           Respiration by lungs,gills and skin

vi)         E.g. Frog (Rana tigrina), Toad

3)  Reptillia:

i)            cold blooded

ii)           covered by scales

iii)         respiration by lungs only

iv)         3 chambered heart except crocodile that has 4 chambred heart

v)           E.g. snakes, lizards,crocodile

4)  Aves:

i)            Warm blooded

ii)           4 chambered heart

iii)         Breathe through lungs

iv)         Lay eggs

v)           Body covered by feathers

vi)         Fore limbs modified for flight

vii)        Hollow bones

viii)      Beak is present

ix)         E.g. Pigeon, sppparrow

5)  Mammalia:

i)            Warm blooded

ii)           4 chambered heart

iii)         Skin has hair,sweat glands and oil glands

iv)         Give birth to young ones except Platypus which lay eggs

v)           Presence of mammary glands for production of milk to nourish the young ones

vi)         E.g. rat, whale, man

Q List out some common features in cat,rat and bat

A Bat,cat and rat belong to the class mammalian and all have following common features:

i)            Have notochord at some stages of life cycle

ii)           Are warm blooded

iii)         Have four chambered heart

iv)         Have skin covered with hair and sweat and oil glands

Q Why do we keep snake and turtle in the same class?

A  Both snake and turtle are kept in the same class because both are : i) cold blooded, ii) have scales,iii) breathe through lungs, iv) 3 chambered heart, v) lay eggs without covering

Q Distinguish between the 5 classes of vertebrates on the basis of characters like habitat, kind of exoskeleton, respiratory organs and other distinct features

A Differences b/w  Pisces, Amphibia,Reptilia, Aves and Mammals are as follows

character	Pisces	Amphibia	Reptilia	Aves	Mammals
Habitat	Aquatic	Terrestrial& aquatic	Terrestrial	Arboreal	Terrestrial Aquatic& arboreal
Exoskeleton	Slimy scales	absent	Dry and scaly	Feathers and claws	Hair and nails etc.
Respiratory organs	Gills	Gills ,lungs and skin	Lungs	Lungs	Lungs
Body temperature	Cold blooded	Cold	Cold	Warm	Warm
Heart	2 chambered	3 chambered	3 chambered	4 chambered	4 chambered
Locomotary organs	Fins	Limbs	Limbs but absent in snakes	Wings and limbs	Limbs
Others	Body is streamlined. They are oviparous	They have webbed feet, eggs are laid in water and larvae are aquatic	They are oviparous and some are viviparous e.g. lizard and snake.	Body is covered by feathers and forelimbs are modified into wings. Their bones are hollow	Presence of mammary glands. There are hair on the body. They are viviparous