03. Evolution and Diversity of Organisms Flashcards

Question

Write examples for artifical classfication

Answer 1

Plants can be classiﬁed as cereals, ornamental plants, medicinal plants, poisonous plants etc. Animals can be classiﬁ ed as two legged, four legged, six legged, eight legged etc

Answer 2

• Represent s evolutionary relationships based on phylogeny- evolutionary history of a species or groups of species • Systems developed after then study of evolution. • Based on many characteristics. ( Characteristics used can be morphological, anatomical, cytological or molecular biological such as DNA and RNA base sequences)

Answer 3

Plants can be classiﬁ ed into phyla; Bryophyta, Lycophyta, Pterophyta, Cycadophyta, Coniferophyta and Anthophyta etc. Animals can be classiﬁed into Cnidaria, Platyhelminthes etc.

Answer 4

they were all artiﬁcial systems and were mostly based on human uses.

Answer 5

He divided organisms into plants and animals. Animals were further classiﬁed according to criteria such as mode of locomotion, reproduction and presence or absence of red blood cells. Aristotle’s pupil Theophrastus classiﬁed plants according to habit. e.g. trees, shrubs and herbs, and according to lifespan e.g. annuals, biennials and perennials.

Answer 6

Carolus Linnaeus introduced binomial nomenclature

Answer 7

He classiﬁed about 6,000 plants into a hierarchical order of taxa, classiﬁcation level such as; Species, genus, order, and class. His classiﬁcation of ﬂowering plants was based on the number of stamens and styles of ﬂower. He identiﬁed two kingdoms of organisms; plants and animals.

Answer 8

He introduced a third kingdom: Protista. He also introduced the taxon Phylum and classiﬁed many organisms

Answer 9

With the discovery of the electron microscope

Answer 10

He introduced the ﬁve kingdom system of biological classiﬁcation; Monera, Protista, Fungi, Plantae and Animalia. His classiﬁcation was based on the nature of cellular organization, unicellular or multicellular and mode of nutrition.

Answer 11

Carl Woese

Answer 12

In this tree of life the ﬁrst major split in the history of life occurred when bacteria diverged from others Eukarya and Archea are mostly related to each other than bacteria.

Answer 13

The present system of classiﬁcation is mainly based on the rapid advance of molecular biology and the new information on the evolutionary relationships of organisms.

Answer 14

• the sequence of bases of DNA of important genes • the sequences of bases of DNA of mitochondria and chloroplasts • the base sequence of ribosomal RNA • the sequence of amino acids in common proteins • the molecular structure of cellular components

Answer 15

Kingdom Protista

Answer 16

Viruses do not have cellular organization, and therefore do not belong to any of the kingdoms

Answer 17

Panthera is a taxon at the Genus level/ rank Mammalia is a taxon at the Class level/ rank

Answer 18

Each Domain is divided into kingdoms. A Kingdom is divided into phyla (singular phylum), phylum into classes .etc. Many of these categories may also be subdivided. (e.g. Super class, Sub-family, Subspecies, etc.)

Answer 19

From domain to species

Answer 20

From species to domain

Answer 21

Jelly ﬁsh (a Cnidarian) Cray ﬁsh (a Crustacean) Silver ﬁsh (an insect) Star ﬁsh (an Echinoderm)

Answer 22

First is the generic name, to which the species belongs and the second is a speciﬁc epithet, the unique for each species within the genus. Generic name is usually a noun and the speciﬁc epithet an adjective describing a particular feature. e.g. Homo sapiens- Homo means man, sapiens means intelligent Related species have the same generic name with different speciﬁ c epithets. e.g. Dipterocarpus zeylanicus and Dipterocarpus grandiﬂ orus Dipterocarpus zeylanicus means fruit with two wings, and endemic to Sri Lanka. Dipterocarpus grandiﬂorus means fruit with two wings and having large ﬂ owers.

Answer 23

• Two species of organisms cannot have the same name. • Each species has a generic name and a speciﬁc epithet, both together forming the species name or scientiﬁc name. • The Name should be made up of Latinized words written in the Roman script. • It should be underlined when hand written and italicized when printed. • The ﬁrst letter of the generic name must be capitalized the and speciﬁc epithet must be in simple letters In scientiﬁc writing, the name of the author who gave the name is indicated by a capital letter, an abbreviation or full word at the end of the name, which is not Latinized. A third word can be used to represent a subspecies or a variety

Answer 24

• Used to group organisms and identify them • Keys do not show the evolutionary relationships • The Commonly used key is the dichotomous key • Some examples are given below

Answer 25

a) Domain – Bacteria b) Domain –Archaea c) Domain –Eukarya

Answer 26

Kingdom - Protista Kingdom - Fungi Kingdom - Plantae Kingdom - Animalia

Answer 27

kingdom bacteria

Answer 28

Kingdom Archaebacteria

Answer 29

• They are prokaryotic • They are unicellular, colonial, ﬁlamentous • Most of them are found in size between 0.5 to 5µm • Well adapted to most of the ‘normal’ habitats (both land and water) • Most of them contain peptidoglycan in their cell walls • According to the amount of peptidoglycan present in the cell wall they are classiﬁed as Gram positive and Gram negative bacteria • Most of their cell walls are surrounded by a sticky layer of polysaccharides or proteins called capsule • Most of them have ﬂagella for motility. Bacterial ﬂagellum differs from eukaryotic ﬂagellum as they are not covered by a plasma membrane and absence of 9+2 structure of microtubules. • Possess diverse nutritional modes-Autotrophs, heterotrophs • Posses diverse metabolic modes- obligate aerobes, obligate anaerobes, facultative anaerobes, etc. • Some are capable of performing nitrogen ﬁxation- e.g. Rhizobium sp., some cyanobacteria • Rapid reproduction by binary ﬁssion. Some perform conjugation as a sexual method. • Certain bacteria use bacterial chlorophyll as a photosynthetic pigment

Answer 30

• Prokaryotic organisms • Photosynthetic • Most are unicellular and oxygen generating and solitary. But some are linked to form ﬁlaments or colonies sheathed in mucous • Some have the ability of ﬁxing atmospheric nitrogen

Answer 31

They are prokaryotic and unicellular. • They lack peptidoglycan in their cell walls which are made up of proteins and polysaccharides • The size of most of them is between 0.5-5 m • They include extreme halophiles and extreme thermophiles • Some Archaebacteria live in more moderate environments-Methanogens • Other species inhabits the anaerobic guts of cattle, termites and other herbivores

Answer 32

• They are Eukaryotic • Vary in size • Most of them are multicellular • Habitats are diverse • Diverse in nutrition • Mostly aerobes • Most of them exhibit sexual reproduction (some protists are only known to reproduce asexually)

Answer 33

• Most of them are unicellular, although there are some colonial and multi cellular species • It is a polyphyletic group (originated from more than one ancestor) and an artiﬁcial group in classiﬁcation. • Found in freshwater, marine and damp soil, some are symbionts. • Unicellular, colonial or multicellular. • Some are photoautotrophs, some are heterotrophs and some are mixotrophs (combination of photoautotrophic and heterotrophic nutrition)

Answer 34

• Unicellular, lack cell wall and pellicle present. • Chloroplasts are present. • They have one or two ﬂagella • They have eye spot • Contractile vacuole is present • They have a pocket at one end of the cell from which one or two ﬂagella emerged

Answer 35

• Habitat is freshwater • Lack cell wall but pellicle is present, unicellular • Cilia may completely cover the cell surface • They have two types of nuclei- mega nucleus and micronucleus • Contractile and food vacuoles are present • Oral groove is present

Answer 36

• Aquatic (marine and freshwater) forms are free living others are parasitic. • Lack cell walls, unicellular organisms • They form pseudopodia which are used to locomote and feed • They do not have deﬁnite shape. • Food vacuoles are present

Answer 37

• Macroscopic marine forms. • Cell wall present • Multicellular thallus differentiated into leaf like blades and root like holdfast. • Green in colour (green algae)

Answer 38

• Marine. • Cell walls present • Multicellular thallus with hold fast. • It is greenish red in colour (red algae)

Answer 39

• Marine • Comparatively larger and complex • Thallus is plant- like; it consists of a root like holdfast ,stem like stipe and leaf like blade. • Multi cellular, thallus is supported by gas ﬁlled bulb shape ﬂoats. • Appear in olive green or brown colour (brown algae)

Answer 40

• It is aquatic (fresh water and marine) • Unicellular, having glass like, wall consists of two parts that overlap (presence of silica) • Highly diverse group regarding the shape and markings in the surface • Golden brown in colour (golden brown algae)

Answer 41

a group of chlorophytes/ green algae

Answer 42

walled spores produced in sporangia multicellular gametangia dependent embryo and apical meristem

Answer 43

Most of them are terrestrial organisms

Answer 44

Vascular Plants Non-vascular Plants

Answer 45

• Phylum Bryophyta • Phylum Hepatophyta- Marchantia • Phylum- Anthocerophyta- Anthoceros

Answer 46

- Mosses- Pogonatum

Answer 47

Marchantia

Answer 48

Anthoceros

Answer 49

• Phylum Lycophyta • Phylum Pterophyta

Answer 50

Selaginella

Answer 51

Nephrolepis

Answer 52

They are Gymnosperms Phylum – Cycadophyta (Cycas sp.) , Phylum- Coniferophyta (Pinus ) Phylum – Gnetophyta (Gnetum ) Angiosperms- Phylum Anthophyta (all ﬂowering plants)

Answer 53

(Cycas sp.)

Answer 54

Anthophyta (all ﬂowering plants)

Answer 55

One way to distinguish a group of plants is to see whether or not they have an extensive system of vascular tissue that transport water and nutrients throughout the plant body.

Answer 56

Bryophytes.

Answer 57

Marchantia Pogonatum Antheroceros

Answer 58

Bryophytes share some derived traits with vascular plants

Answer 59

Bryophytes lack many innovations of vascular plants such as presence of true stems, roots and leaves

Answer 60

• Especially common in moist terrestrial places. • Haploid gametophyte is dominant stage of the life cycle, photosynthetic and independent. • Gametophytes are differentiated into ‘leaves’, ‘stems’ and rhizoids. They have no vascular tissues. Archegonia and antheridia are typically carries on separate female and male gametophyte. Therefore gametophyte is dioecious. • Male plant produces ﬂagellated sperm which can swim through a ﬁ lm of water for fertilization. • Sporophytes are usually green and photosynthetic when young. However, they are not independent. They attach to their parental gametophytes and absorb nutrients and water from the female gametophyte. • Sporophytes have specialized pores called stomata which are also found in all vascular plants. • They are homosporous.

Answer 61

Vascular plants cover about 93% of the existing plant species.

Answer 62

pterophytes share a more recent common ancestor with seed plants.

Answer 63

Fossils and living seedless vascular plants provide evidence

Answer 64

The ancestors of vascular plants already have had some derived traits of modern vascular plants

Answer 65

they lack roots and some other adaptations.

Answer 66

Fossils suggest that, the ancestors of vascular plants had gametophyte and sporophytes that were about equal in size. However among the living vascular plants sporophyte generation is large and more complex. For example in ferns, leafy plants are the sporophytes

Answer 67

Xylem and Phloem

Answer 68

Xylem and Phloem

Answer 69

tracheids ﬁbers parenchyma cells

Answer 70

- conducting water and minerals.

Answer 71

by the polymer lignin

Answer 72

These tissues permit plants to grow tall. This may facilitate them to obtain a high amount of light for photosynthesis and ease the spore dispersal.

Answer 73

this tissue has cells arranged in tubes

Answer 74

They distribute sugars, amino acids and other organic products among different parts of the plant

Answer 75

Roots are organs that absorb water and nutrients from the soil. They anchor the plants and allow the shoot system to grow taller. They are to replace the rhizoids seen in bryophytes.

Answer 76

Root tissues of living plants resemble stem tissues of the early vascular plants preserved in fossils

Answer 77

microphylls megaphylls

Answer 78

Microphylls are single veined and smaller in size while megaphylls are large, ﬂattened with branched veins

Answer 79

Leaves with branched vascular tissues increase the surface area for efficient photosynthesis

Answer 80

Most seedless vascular plant species produce one type of sporangium and one type of spores. Therefore, they are known as homosporous.

Answer 81

Some plant species produce two types of sporangia and produce two kinds of spores called mega spores and microspores. This condition is known as heterosporous.

Answer 82

Mega spores develop into female gametophyte Microspores develop into male gametophyte

Answer 83

• Lycophytes are terrestrial and some are epiphytes. • The dominant plant is sporophyte. • They produce upright stems and ground hugging stems. • In upright stems small leaves can be found. • Ground hugging stems produce dichotomously branching roots. • They have strobili. In many club mosses and spike mosses sporophylls are clustered into club shaped cones/ strobili. • They are homosporous or heterosporous • Spike mosses are usually relatively smaller and often grow horizontally. • All Club mosses are homosporous; • All Spike mosses are heterosporous. • In some species the tiny gametophyte live above the ground and are photosynthetic. Others live below the ground and are nourished by symbiotic fungi.

Answer 84

Lycopodium sp.

Answer 85

e.g. Selaginella

Answer 86

• Most sporophytes have rhizome (an underground stem) • At the tip of the rhizome they produce leaves, called fronds • Many fronds are highly dissected and feathery. • All species are homosporous which develop into a bisexual gametophyte. • Sporophytes are dominant

Answer 87

e.g. Nephrolepis

Answer 88

Seed plants

Answer 89

1. Gymnosperms 2. Angiosperms

Answer 90

Gymnosperms are “naked seed” plants as their seeds are not enclosed in chambers.

Answer 91

Angiosperms are “seed plant” group accommodating all ﬂowering plants Angiosperm seeds develop inside chambers called ovaries; which originate within ﬂowers and mature into fruits.

Answer 92

1. Production of seed 2. Reduced gametophyte 3. Heterospory 4. Production of ovules and eggs 5. Production of pollen and sperms

Answer 93

A seed consists of an embryo and endosperm

Answer 94

Endosperms supply food to the embryo

Answer 95

This endosperm is surrounded by a protective coat which is known as seed coat

Answer 96

When seeds are mature they can be dispersed through various dispersal methods.

Answer 97

Seeds are key adaptations that help seed plants to become the dominant producers on land and to exhibit the vast plant diversity of today

Answer 98

The evolutionary trend of gametophyte reduction continued further in the vascular plants and led to seed plants

Answer 99

The gametophyte of seed vascular plants is not visible to the naked eye because they are mostly microscopic.

Answer 100

Tiny gametophytes develop from spores and are retained within the sporangia of sporophyte

Answer 101

This arrangement protects the gametophyte from environmental stresses

Answer 102

The moist reproductive tissues of the sporophyte shield the gametophyte from UV radiation and protect them from drying out This relationship also enables the dependent gametophyte to obtain nutrients from the sporophyte

Answer 103

Each megasporangium has a single functional megaspore and each microsporangium contains a large number of microspores.

Answer 104

Seed plants are unique in retaining the megasporangium within the parent sporophyte

Answer 105

A layer of sporophyte tissue called integument envelops which protects the megasporangium

Answer 106

Inside each ovule female gametophyte develops from a megaspore and produces one or more eggs.

Answer 107

into pollen grain that consists of a male gametophyte enclosed within the pollen wall

Answer 108

The wall of the pollen is tough as it is made up of the polymer sporopollenin, which protects the pollen grain during pollination.

Answer 109

it gives rise to a pollen tube that discharges sperm (male gametes) into the female gametophyte located within the ovule

Answer 110

Some gymnosperms retain the ancient ﬂ agellated condition, however ﬂ agella have been lost in the sperm of most gymnosperms and all angiosperms.

Answer 111

Some gymnosperms retain the ancient ﬂagellated condition, however ﬂagella have been lost in the sperm of most gymnosperms and all angiosperms.

Answer 112

Inside a pollen grain, a sperm producing male gametophyte is present.

Answer 113

The sperms of seed plants do not require motility as they are carried directly in to the eggs by pollen tubes.

Answer 114

The sperms of seed plants do not require motility as they are carried directly in to the eggs by pollen tubes.

Answer 115

Only gymnosperms have vessels in xylem • Leaves of gymnosperms look like those of the ﬂ owering plants. Their seeds, look like fruits of angiosperms.

Answer 116

They have palm like leaves and large cones • They have ﬂ agellated sperms similar to those of seedless vascular plants e.g. Cycas

Answer 117

e.g: Pinus • Large trees are included such as Cyperes and Red woods. • In conifers two types of spores are produced by separate cones.

Answer 118

• Stamens produce microspores and these microspores develop into pollen grains • These pollen grains contain male gametophyte/ gametes • Carpels produce megaspores and these megaspores produce female gametophytes/ embryo sac • Seeds are enclosed within the carpels • Production of fruit

Answer 119

Seeds are protected by fruits which help in their dispersal. This is one of the unique features of phylum Anthophyta

Answer 120

A fruit typically consists of a fertilized ovary and sometimes include other persistent ﬂ oral parts. After fertilization, the ovary wall thickens and develops into fruit. Ovules develop as seed of the fruit

Answer 121

A fruit typically consists of a fertilized ovary and sometimes include other persistent ﬂ oral parts. After fertilization, the ovary wall thickens and develops into fruit. Ovules develop as seed of the fruit

Answer 122

The fruit protects dormant seeds and aid in their dispersal.

Answer 123

The fruit protects dormant seeds and aid in their dispersal.

Answer 124

1. Monocotyledons- species with one cotyledons 2. Dicotyledons- species with two cotyledons

Answer 125

The embryos have only one cotyledon in Monocotydonae whereas Embryos have two cotyledons in class Dicotyledonae Fibrous root system in Monocotydonae where as tap root system is found in class Dicotyledonae Parallel veins in leaves in Monocotydonae class and reticulate veins in leaves can be seen in class Dicotyledonae Flower parts are trimerous in Monocotydonae class and flower parts are pentamerous/tetramerous Perianth present in ﬂowers (No distinct calyx and corolla) in Monocotydonae class and Distinct calyx and corolla present in ﬂowers in Dicotyledonae class Pollen grains are with one opening/ aperture in Monocotydonae class and Pollen grains are with three openings/ apertures in Dicotyledonae class Vascular bundles in the stem do not have cambia and are scattered (grasses, coconut, rice) in Monocotydonae plants and Vascular bundles in the stem have cambia and arranged in a ring (e.g. Rose, shoe ﬂower, cucurbits) in Dicotyledonae class

Answer 126

• Eukaryotic • Cell walls are made up of chitin a strong but ﬂ exible polysaccharide. • They are absorptive and heterotrophs - many of them secrete extra cellular enzymes which aid in the breaking down of complex molecules into small molecules. • Different species live as decomposers, parasites or mutualistics. • Few are unicellular, others forming multicellular ﬁ laments called hyphae . • Septa can be found in hyphae. (division of hyphae into cells by septa – cross walls). • Septum has a hole which enables the movement of mitochondria, ribosomes, nuclei etc. • Fungi lack septa are known as coenocytic fungi (with many nuclei) • Fungal hyphae produce mycelium • Some fungi produce haustoria ( to penetrate and absorb or exchange nutrients between plants and the fungi) • Multicellular fungi produce mycelia. ( a network of branched hyphae adapted for absorption of nutrition) • They show sexual and asexual reproduction. • They produce spores.

Answer 127

e.g.: Chytridium • Aquatic or terrestrial . • Some are decomposers while others are parasitic. • Multicellular or unicellular when multicellular it is coenocytic. • They produce zoospores which are ﬂ agellated. • Cell walls are made up of chitin. • Some of them form colonies with hyphae while others exit as single spherical cell.

Answer 128

e.g. Mucor , Rhizopus • Most of them are saprotrophs and some of them are parasites or commensals. • Mycelium is coenocytic and aseptate. Septa found only where reproductive cells are formed. • Asexual reproduction: Produce sporangia in which genetically identical haploid spores are produced. Also by endospores produced in sporangia. • Sexual reproduction: A Zygosporangium is produced which is a sturdy structure produced by plasmogamy and karyogamy. Zygosporangium is resistant to unfavorable environmental conditions. o Zygosporangium is a multinucleated structure which is resistant to drying and freezing. o They are metabolically inactive in adverse environmental conditions. • Zygosporangium produces genetically diverse haploid spores when environmental conditions are favourable.

Answer 129

e.g. Aspergillus, Saccharomyces, Penicillium • Marine or freshwater or terrestrial • Parasitic or symbiotic. • Most of them are decomposers. • Unicellular or ﬁ lamentous, multicellular. • In asexual reproduction conidia are produced at the tip of the conidiphores which are specialized hyphae. (Exospores in clusters or chains) • In sexual reproduction fusion of sexually differentiated gametangia takes place and produce sac like structure called asci. • Ascospores are produced within asci. Generally there are eight ascospores are produced in each ascus. • Most of these fungi produce ascocarps enclosing asci.

Answer 130

e.g. Agaricus, Puffballs, Shell fungi • They are Terrestrial. • They are major decomposers and some are symbionts. • Filamentous with septae and dikaryotic. • Mycelium is the dominant stage of the life cycle. • They produce fruiting bodies called basidiocarps during sexual reproduction. Produce basidia on the gills of the basidiocarp. • Produce basidiospores on basidium and exogenous.

Answer 131

Multicellular • Heterotrophic eukaryotes- they ingest food and digest them in the body using enzymes • Cells of the animals are organized into tissues. • Most of them reproduce by sexually. • Some show radial symmetry and some others show bilateral symmetry.

Answer 132

e.g. Hydra, Sea anemone, Obelia, Corals and Jelly fish • Majority of them are marine, except a few fresh water species. Some are macroscopic. • Simple organization: diploblastic or just 2 body cell layers- an outer layers of ectoderm and inner layer of endoderm sandwitched between these two layers is a acellular layer of mesoglea • They have a simple gastrovascular cavity which is a sac with a central digestive compartment. This cavity is lined by endodermis with a single opening (mouth) only. • They show radial symmetry with two body forms polyp and medusa. Polyps are cylindrical forms attached to the substrate by the aboral end of the body. Tentacles are found around the mouth. • Medusa resembles a ﬂ attened mouth down version of the polyps and they are free living. • Some cnidarians exist only as polyps or only as medusa. Others have both polyp and medusa forms in their lifecycles. • Tentacles are armed with cnidocytes which functioning defense and capturing prey. • They have nematocysts which contain stinging thread

Answer 133

e.g. Planaria, Taenia , Fasciola • Commonly known as ﬂ atworms. • Free living (Planaria) or parasitic (ﬂ ukes and tapeworms). • They are found in marine, fresh water and in damp terrestrial habitats. • Body is dorsoventrally ﬂ attened. Some have elongated tape like body forms without true segmentation. • Triploblastic with all three germ layers (ectoderm, mesoderm and endoderm). Signs of cephalization present but are not distinct. • No body cavities, circulatory, respiratory and skeletal systems.The gaseous exchange is by simple diffusion through body wall. • Sensory organs are found only in free living examples. Eye spots are found in the head. • First appearance of little complex nervous and sensory system. A pair of anterior ganglion and two longitudinal nerve cords on central nervous system. • Appearance of separate organs for excretion: Nitrogenous excretory system consists of protonephridia. These are a network of tubules with ciliated structures called ﬂ ame bulb. These are used to maintain the osmotic balance. • They have incomplete digestive system only with mouth without anus. Branched gastrovascular cavity is present for digestion. Some are having eversible pharynx. • Free living examples have cilia for the locomotion. • Some show asexual reproduction by regeneration. All are bisexual. Except tape worms (Taenia). Others have cross fertilization which is internal. In parasitic forms there are several larval stages, direct development in free living examples without larval stages.

Answer 134

e.g. round worms, hook worms, pin worms • Most of them are free living in marine, few are fresh water and damp soil environments and parasitic in plants and animals. • They are bilateral symmetrical. Triploblastic with pseudocoelomic .Their body forms are cylindrical with tapered ends. Body size varies from microscopic to macroscopic. They do not show distinct cephalization and segmentation. The sensory papillae are found on the anterior end of the body. Body is covered by tough cuticle and undergoes ecdysis. • No circulatory and respiratory systems. Gaseous exchange is by simple diffusion through body wall. They have an Alimentary canal. • Body wall is composed only of longitudinal muscles. They do not have special locomotary structures. Longitudinal muscles in the body wall are involved in locomotion. • The Sexual reproduction is by internal fertilization. Sexes are separated and females are larger than males.

Answer 135

e.g. Earthworms, Leeches and regworms. • They can be marine, freshwater or in damp soil. • They are segmented worms with cylindrical bodies • They are Triploblastic. • Coelom (true body cavity) is present for the ﬁ rst time. • The ﬁ rst animals to show cephalization. • Nervous system well developed; dorsal cerebral ganglion, ventral nerve chord, circumenteric connectives. • Clitellum, Parapodia, setae and suckers are found in some examples. Clitellum is for external fertilization. Parapodia is used for locomotion and respiration. Seate are present for locomotion and suckers for locomotion and ingestion in ecto parasitic forms.

Answer 136

e.g. Oysters, Clams, Slugs, Snails, Octupus, Squids, Chitons and tusks shells • Majority are marine. Some inhabit freshwater and land. Some are bilateral symmetrical and few are asymmetrical. • They are soft bodied and non-segmented. Calcareous shell is secreted as a protective exoskeleton. Coelomic. • Body is divided into three parts: o muscular foot is used for locomotion o visceral mass contains most of the internal organs o mantale is to secrete the shell • Shell could be internal or external. • Many molluscs possess radula (a minutely toothed, chitinous ribbon) in the mouth for feeding. • Most molluscs have separated sexes and their gonads are located in visceral mass.

Answer 137

e.g. Insects, Spiders, Prawns, Crabs, Scorpions, Ticks, Mites, Millipedes and Centipedes • One of the most successful animal groups on earth with the highest number of species. They live everywhere – air, water, soil • They have segmented bodies with “jointed legs” • They have a chitinous exoskeleton (skeleton on the outside) Because of exoskeleton these animals can’t grow continuously and needs periodic molting • The nervous system is well developed with primitive dorsal brain. • The nerve cord is solid, segmented and ventrally located. • They have many and varied sense organs. • They have an open blood circulatory system; Blood is pumped by a heart into the body cavities (haemocoel), where tissues are surrounded by the blood. No capillaries. • Respiration • In aquatic animals- Gills • In terrestrial animals- Tracheal system of chitinous tubes • In arachnids - Book lungs • Excretion is by Malphigian tubules They excrete uric acids • Reproduction: Sexes separate [Dioecious]

Answer 138

• They are exclusively marine. Triploblastic and coelomic, slow moving or sessile. • Adults are penta radial symmetrical without head and segmentation. • Deuterostomes. • Thin epidermis covers the endoskeleton of hard calcareous plates. • Water vascular system is a network by hydraulic canals branching into tube feet which function in locomotion and feeding. • Digestive system is usually complete, but the mouth is on the underside and the anus on the top surface of the animal. • Circulatory system is reduced and closed without a heart. Sexes are separated with external fertilization. Larval forms are bilaterally symmetrical. • Well developed nervous system. Intelligent animals.

Answer 139

• Longitudinal, ﬂ exible rod called notochord located between digestive tube and nerve cord. It is extending from anterior to posterior providing support in at least embryonic stage. • Dorsal, hollow, single nerve cord located dorsal to the notochord. • In all chordate embryos there are slits or clefts in pairs either side of pharynx (pharyngeal sits) that opens to the outside of body. In terrestrial, adult chordates it disappears and remains in the aquatic adults and larval forms of terrestrial chordates as respiratory structures. • Muscular tail that extends posterior to the anus present in the embryonic stages. In some terrestrial adult it is reduced.

Answer 140

e.g. Skates, Sharks • All are aquatic • Skeleton composed predominantly of cartilage • Fins for locomotion • Caudal ﬁ n is heterocercal. • Gills without operculum. • Body is covered with placcoid scales. • Eggs are fertilized internally. Some are ovoviviparous and others are oviparous or viviparous. • Reproductive tract, excretory duct and digestive tract empty into the cloaca, a common chamber that has a single opening to the outside

Answer 141

• All are aquatic • Having a skeleton composed of bones. • Gills are covered by a bony ﬂ ap called operculum. • Swim bladder for control the buoyancy. • Caudal ﬁ n is homocercal. • Body is covered by ﬂ atten bony scales called ctenoid and cycloid scales. • Most are fertilized externally some have internal fertilization. • Most species are oviparous. e.g. Carp, Tuna,

Answer 142

• First animals to invade land but need water to complete life cycle, live in both water and on land. • They are found only on land or fresh waters. No marine species. • First species to poses limbs, body is somewhat elevated by these limbs to help locomotion in terrestrial environment. • Some are limbless but some are tetrapods. • Ectothermic- changes body temperature according to environmental temperature. This restricts metabolism. • Body is covered with thin, moist skin. No scales. Sensitive to environmental changes. • Nictitating membrane covers the eye and tympanic membrane is found behind the eye. • Most amphibians show external fertilization. Eggs without shells. e.g. Toad, Frog, Ichthyophis

Answer 143

• They are the ﬁrst animal to live a complete terrestrial life. • Possess limbs for locomotion and digits. • Body is covered with keratinized scales to prevent from desiccation and abrasion. • Poses lungs for aerial respiration. • They are ectothermic (cold blooded) • Live in terrestrial and aquatic habitats. • Internal fertilization. They lay shelled eggs (calcareous) on land. e.g. Lizards, Snakes, Turtles, Crocodiles and Alligators

Answer 144

• Body is covered by keratinized feathers. • Hind limbs are converted to ﬂ ight. • Many adaptations to help ﬂ ying: light body, wings, bones with air cavities, high metabolism, restrictions in body size • They are having a beak without teeth. • They are endothermic. • Birds have colour vision and excellent eye sight. • Internal fertilization, lay shelled eggs e.g. Crow, Parrot, Humming birds, Eagles etc.

03. Evolution and Diversity of Organisms Flashcards

(170 cards)