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CONTENTS:
UNIT I DIVERSITY IN THE LIVING WORLD
Chapter 2 : Biological Classification
UNIT II STRUCTURAL ORGANISATION IN PLANTS AND ANIMALS
Chapter 5 : Morphology of Flowering Plants
Chapter 6 : Anatomy of Flowering Plants
Chapter 7 : Structural Organisation in Animals
UNIT III CELL : STRUCTURE AND FUNCTIONS
Chapter 8 : Cell : The Unit of Life
Chapter 10 : Cell Cycle and Cell Division
UNIT IV PLANT PHYSIOLOGY
Chapter 11 : Photosynthesis in Higher Plants
Chapter 12 : Respiration in Plants
Chapter 13 : Plant Growth and Development
UNIT V HUMAN PHYSIOLOGY
Chapter 14 : Breathing and Exchange of Gases
Chapter 15 : Body Fluids and Circulation
Chapter 16 : Excretory Products and their Elimination
Chapter 17 : Locomotion and Movement
Animals are multicellular and heterotrophic. Animal kingdom is most diverse than the plant kingdom.
BASIS OF CLASSIFICATION
Levels of organization
3 levels (based on organization of cells):
Cellular level of organization: Here the cells are arranged as loose cell aggregates. E.g. Poriferans.
Tissue level of organization: Here the cells are arranged into tissues. E.g. Cnidarians and Ctenophores.
level of organization: Here the tissues are arranged into organs and the organs are associated to form organ systems. Each system performs a specific physiological function. E.g. All higher animals (from Platyhelminthes to chordates). Organ systems of different animals show complexities.
Digestive system of cnidarians and Platyhelminthes is incomplete (i.e. it has only a single opening which serves as both mouth and anus). Complete digestive system has 2 openings (mouth & anus).
Circulatory system is 2 types (open and closed).
Body symmetry
It is the arrangement of similar body parts on 2 sides of main axis of body. Based on symmetry animals are 2 types: Asymmetrical and Symmetrical.
Asymmetrical: Here, body cannot be divided into 2 similar parts. E.g. Certain Poriferans, Snails etc.
Symmetrical: Here, body can be divided into 2 similar parts. It is 2 types.
Radial symmetry: Body can be divided into 2 similar parts by any plane along oral aboral axis of body. E.g. some Poriferans, Cnidarians, Ctenophores and Echinoderms.
Bilateral symmetry: Body can be divided into 2 right and left halves by a section passing through the longitudinal axis. E.g. All vertebrates and many invertebrates. The body of bilaterally symmetrical animal has an upper or vertebral dorsal side, a lower ventral side, left and right lateral sides, anterior (cephalic) side and posterior (anal) side.
Germ layers
These are layers of gastrula from which all the body organs are formed. Based on the number of germ layers, animals are 2 types- Diploblastic and Triploblastic.
Diploblastic animals: 2 germ layers- outer ectoderm and inner endoderm. E.g. Sponges and Coelenterates.
Triploblastic animals: 3 germ layers- Outer ectoderm, middle mesoderm and inner endoderm. E.g. Flat worms to mammals.
Coelom (body cavity)
It is the space between body wall and gut wall. Coelom separates the muscles of gut and body wall. Based on nature of coelom animals are 3 types.
Acoelomate: No coelom. The space between body wall and digestive cavity is filled with matrix (parenchyma). E.g. Poriferans to Platyhelminthes.
Pseudocoelomate: Here, blastocoel becomes the coelom. It is not lined by peritoneal layer. E.g. Aschelminthes.
Eucoelomate (True coelomate): Here, the coelom arises from the mesoderm. Coelom is lined by peritoneal layer and filled with coelomic fluid. E.g. Annelids to mammals.
Haemocoelomates: In Arthropods and mollusks, true coelom is reduced and filled with blood.
Functions of coelom:
It accommodates visceral organs. Coelomic fluid gives moist environment to visceral organs. Thus, friction is minimized.
Acts as shock absorber.
Metamerism (segmentation)
In some animals, the body is formed of similar parts (segments or metameres). This segmentation is called metamerism. E.g. Annelids, Arthropods.
In vertebrates: only internal metamerism.
Notochord
It is a supporting rod formed on the dorsal side during embryonic development in some animals. Animals with notochord are called chordates and those without notochord are called non-chordates.
CLASSIFICATION OF ANIMALS:
Phylum - Porifera
- Ex. Sponges.
Marine, asymmetrical, cellular level of organization
Have water canal system
Ostia, Spongocoel, Osculum
Choanocytes/ collar cells line in the spongocoel
Digestion is intracellular
Skeleton made up of spicules/ sponging fibres
Hermaphrodite –male and female organs present on the same body.
Reproduce asexually by fragmentation
Sexually by gametes
Fragmentation is internal and development is indirect
E.g. Sycon, Spongilla.
Phylum Coelenterata (Cnidaria)
- Ex. Hydra
Aquatic / marine
Sessile (fixed) / free swimming
Radially symmetrical
Have cnidoblasts / cnidocytes, stinging capsule on tentacles
Used for defense, anchorage and to capture the prey
Tissue level of organization diploblastic
Mouth on hypostome.
Digestion extracellular and intracellular
Corals have skeleton made of calcium carbonate.
Exhibit 2 basic forms called polyp and medusa.
Polyp is sessile cylindrical (hydra)
Medusa is umbrella shaped free living (jelly fish)
They show alternation of generation (metagenesis) where polyp forms medusa asexually and medusa forms polyp sexually. Ex. Obelia
Ex. - Hydra, Physalia, Sea anemone, Sea pen, Sea fan, Brain coral
Phylum - Ctenophora (sea walnuts/comb jellies)
Marine, radially symmetrical diploblastic
Tissue level of organization
Body bears 8 rows ciliated comb plates help in locomotion
Digestion by intra and extra cellular
Bioluminescence is well developed
Sexes are not separate (monoecious)
Reproduce by sexual reproduction
Fertilization is external and indirect development.
Phylum – Platyhelminthes (flat worms)
Dorso-ventrally flattened body
Endoparasites, bilaterally symmetrical
Organ level of organization
Triploblastic - acoelomate
Hooks and suckers are present
Flame cells for excretions
Sexes are not separate - fertilization is internal and development is through many larval stages
Have high regeneration capacity
Phylum - Aschelminthes (round worms)
Free living, aquatic, terrestrial parasitic
Organ system level of body organization
Bilaterally symmetrical and triploblastic
Pseudocoelomate
Digestive system is complete (mouth and anus)
Sexes are separate (dioecious)
Fertilization is internal and development is direct.
Ex. Ascaris, Wuchereria (filarial worm) and Ancylostoma (hookworm)
Phylum – Annelida (annulus little ring)
Aquatic/terrestrial
Free-living/ parasites
Organ system level of body organization
Bilaterally symmetrical
Triploblastic
Metamerically segmented – coelomate
Metameres/body is segmented
Marine Nereis possess parapodia
Possess longitudinal and circular muscles help in locomotion
Closed circulatory system
Nephridia help in osmoregulation and excretion
Dioecious (sexes are separate)
Earthworm and leeches are monoecious
Reproduction is sexual
E.g. Nereis, Pheretima (earth worm) and Hirudinaria (blood sucking leech)
Phylum – Arthropoda – (jointed legs)
Largest phylum 2/3 are insects
Organ system level of body organization
Bilaterally symmetrical
Segmented and coelomate
Chitinous exoskeleton.
Body has head thorax and abdomen.
Have jointed appendages (organs for locomotion) respiratory organs are gills/book gills/Book lungs / tracheal system
Open circulatory system.
Sense organs are antennae, eye, statocysts (balance organs)
Fertilization is internal.
Excretion by malpighian tubules.
Sexes are separate (Dioecious)
Oviparous
Development may be direct/ indirect
Economic importance- Honey bees (Apis), Silkworm worm (Bombyx), Vectors. Mosquito, Housefly, Aquatic –crab, prawn, lobster
Phylum - Mollusca: (soft bodied and shelled)
Second largest phylum
Terrestrial and aquatic
Organ system level of body organization
Bilaterally symmetrical
Triploblastic and Coelomate
Calcareous shell and unsegmented body with head muscular foot and visceral hump
Soft spongy layer of skin forms a mantle over the visceral hump
Gills for respiration and excretion
Head has sensory tentacles
Mouth has file like rasping organ for feeding radula
Sexes are separate (Dioecious)
Oviparous
Indirect development
E.g. Oyster, snail, squid, devil fish
Phylum - Echinodermata: (spiny skinned)
Spiny skin has exoskeleton which is calcareous ossicles
Marine organ level of body organization
Radially symmetrical
Coelomate
Triploblastic
Mouth of the lower side and anus on the upper side.
Have water vascular system, help in locomotion, to capture and transport of food and for respiration
Excretory system is absent
Dioecious and fertilization is external, development is indirect with free swimming larva
Ex. Starfish, sea urchin, sea lily, sea cucumber
Phylum – Hermichordata
Under non-chordate
Worm like marine animals
Organ system level of organization
Bilaterally symmetrical, triploblstic
Coclomate – body has anterior proboscis, a collar and a long trunk
Circulatory system is open type
Respiration is through gills
Excretory organ is proboscis gland
Sexes are separate
Fertilization is external
Development is indirect Ex. Balanoglossus
Phylum – Chordata
Presence of notochord dorsal hollow spinal cord –nerve cord and paired pharyngeal gill slits
Bilaterally symmetrical and triploblastic
Coelomate organ system level of organization
Have post and tail
Closed circulatory system
Chordata -Urochordata, Cephalochordate and Vertebrata
Urochordata – notochord present in larval tail e.g. Ascidia, Salpa
Cephalochordate – notochord extends from head to tail e.g. Amphioxus
Subphylum – Vertebrata:
Possess notochord (replaced by vertebral column)
All vertebrates are chordates but not all chordates are vertebrates (all vertebrates have vertebral column, but all chordates do not have vertebral chord).
Fins and limbs for locomotion
Super class – Agnatha (without jaw) Class – Cyclostomata
Ectoparasites on some fishes.
Elongated body with 6-15 pairs of gill slits
Sucking circular mouth without jaw
Body is devoid of scales – paired fins
Cranium and vertebral column are cartilaginous
Circulation is closed –marine but migrate to fresh water for spawning
After spawning they die
Larvae, metamorphosis and return to the ocean
Super class - Gnathostomata (with jaw)
Jaws are present
Paired lateral appendages
There are six classes:
Class – Chondrichthyes:
Cartilage fish, endoskeleton is cartilage
Body is stream lined
Pelvic fins in male with claspers
5-7 pairs of gills.
No operculum
Mouth in ventral with teeth.
Jaws are powerful
Air bladder is absent
Heart is 2 chambered (I auricle and one ventricle)
Some possess electric /poison stings
Poikilothermous (cold blooded)
Body has placoid scales
Unisexual
Viviparous and fertilization is internal
Class – Osteichthyes - boney fish
Endoskeleton is bone. Skin is covered by cycloid scales.
Four pairs of gill slits with operculum, mouth is terminal, air bladder is present and help in buoyancy.
Heart is two chambered (I auricle and I ventricle)
Poikilotherms (cold blooded)
Sexes are separate, fertilization is external and oviparous
Ex. Angel fish, Clown fish,
Class – Amphibia - dual life
Live on land and move to water for breeding
Body has head and trunk
Tail is in larval stage – two pairs of limbs
Digits without claws.
Poikilotherms – eyes are with nictitating membranes
Skin is smooth and moist with mucous glands
Tympanum is ear drum
Heart is three chambered (two auricles and one ventricle)
Respiration by gills in larva and by lungs and skin in adults
Digestive system complete
Urinary tract and reproductive tract open in to a common cloacal chamber and the
Opening is called cloacal aperture.
Sexes are separate
Oviparous
Fertilization is external and development is indirect with tadpole larva Ex. Toad, Frog
Class – Reptilia
Skin is dry without glands.
Covered by horny epidermal scales (scutes)
Tympanum is small no external opening
12 pairs of cranial nerves
Trunk bears two pairs of pentadactyl limbs with claws.
Heart with three and half chambered (two auricles, one which is incompletely partitioned ventricle)
Only Crocodiles have four chambered heart
Respiration is by lungs.
Fertilization is internal.
Oviparous and egg is covered by hard calcareous shells
Ex. Snake, Tortoise, Turtle, Viper, Lizard
Class-Aves
Forelimbs into wings and hind limbs modified for perching, swimming, running, etc.
Voice box called syrinx is present
Respiration is by lungs.
Skin is dry with oil glands, at the base of tail.
Bones are pneumatic bones (air cavities) helps to make the body light.
Homeiothermous
Heart is 4 chambered
Oviparous and egg is with calcareous shells.
Fertilization is internal.
Ex. Pigeon, Crow, Sparrow, Ostrich.
Class- Mammalia
Aquatic/aerial/terrestrial
Body has head, neck, trunk and tail Have mammary glands in females’ External ear (pinna) is present
Skin has sweat glands and sebaceous glands
Heart is 4 chambered Respiration is by lungs. Body has hair
Excretion is by kidneys (ureotelic – urea) Sexes are separate
Viviparous (give birth young ones)
Few are ovoviviparous – egg laying mammals (Platypus)
Few are marsupials – pouched mammals with brood pouches (Kangaroo) Ex. Canis macaca, Camelus, Dolphin
NCERT Solutions
Kingdom Animalia is the most important kingdom in this chapter. Despite disparities in form and structure, there are essential characteristics that allow us to easily categorise them. The phyla of Porifera, Coelenterata (Cnidaria), Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata, and Chordata are discussed. Animal survival strategies, physiology, environment, and anatomy are all thoroughly discussed. This chapter brings Unit 1: Diversity in Living Organisms to a close. It is worth 14% of the NEET test and 7 marks in the final exam.
1. What are the difficulties that you would face in classification of animals, if common fundamental features are not taken into account?
Solution
Animals are classified based on common features such as the arrangement of cells, body symmetry, nature of coelom, patterns of digestive, circulatory or reproductive systems. Without these common features it is very difficult to deal with every living thing separately, also without common features it is impossible to include new species discovered daily. In order to study the diversity in animals, classification has to be based on the common basic features.
Some other difficulties are:
Tracing of interdependence amongst various animals will become difficult
Difficulty in developing new species of animals
2. If you are given a specimen, what are the steps that you would follow to classify it?
Solution:
Following are the steps to be taken to classify a specimen:
Classify level of organization: Classify the arrangement of cells in cellular and tissue level organization.
Symmetry: Classify the organism as radial or bilateral symmetry.
Classify Diploblastic or triploblastic organization
Presence or absence of body cavity
Type of coelom development
Classify segmentation
Differentiate the presence or absence of notochord.
3. How useful is the study of the nature of body cavity and coelom in the classification of animals?
Solution:
The coelom is the body cavity or fluid filled space lined by the mesoderm, and animals possessing coelom are called coelomates. In some animals, the body cavity is not lined by mesoderm; instead, the mesoderm is present as scattered pouches in between the ectoderm and endoderm. Such a body cavity is called pseudocoelom and the animals possessing them are called pseudocoelomates, example – Aschelminthes. In some animals body cavity is absent, they are referred to as acoelomates, example – Platyhelminthes.
Classification of body cavity and coelom are important to decide the complexity of an organism at organ level.
4. Distinguish between intracellular and extracellular digestion?
Solution:
Intracellular digestion
Extracellular digestion
Occurs within cells
Occurs within cavity of the ailmentry canal, outside the cell
It occurs in lower organisms
Occurs in multicellular organisms
Enzymes associated are very few
Large number of digestive glands and enzymes are required
It is less efficient with no regional differentiation
Highly efficient with regional differentiation
5. What is the difference between direct and indirect development?
Solution:
Direct development
Indirect development
In direct development, the embryo develops into a well-grown individual without involving in a larval stage.
It involves a sexually immature larval stage
Metamorphosis is absent
Metamorphosis is present
Occurs in fish, reptile birds and mammals
Occurs in in vertebrate amphibians
Ex: Hydra, earthworm
Ex: Frog, butterfly
6. What are the peculiar features that you find in parasitic platyhelminthes?
Solution:
Peculiar features found in parasitic Platyhelminthes are as follows:
Free-living parasitic forms
Body organization observed is of tissue organ grade
Mostly hermaphrodites
Three-layered body wall – epidermis (outermost covering) often ciliated and covered by cuticle.
Digestive tract is incomplete or absent
Presence of well-defined excretory structures such as flame cells
Presence of anti-toxins and a thick tegument which is resistant to the digestive enzymes of host
Anaerobic respiration. No special respiratory structure observed
Anterior body part contains suckers, hooks, eye spots and auricles for attachment to the host
Highly developed reproductive system of parasitic forms
7. What are the reasons that you can think of for the arthropods to constitute the largest group of the animal kingdom?
Solution:
Reasons for arthropods constituting the largest group of the animal kingdom are as follows
They have jointed legs which allow them to be motile, and perform many other functions because of these jointed appendages
Hard skeleton made of chitin protect their body
The hard skeleton also reduces the water loss from the body.
Exhibit distinct system for locomotion, respiration and reproduction
Capability to survive in diverse conditions and varied habitats
In comparison to other phyla, they tend to develop early
Better developed sense organs and nervous system
Some insects exhibit pheromones which enable communication
8. Water vascular system is the characteristic of which group of the following:
(a) Porifera (b) Ctenophora (c) Echinodermata (d) Chordata
Solution:
The answer is (c) Echinodermata
It is their characteristic feature. The perforate plate known as madreporite in them, allow water to percolate into their systems.
9. “All vertebrates are chordates but all chordates are not vertebrates”. Justify the statement.
Solution
Presence of notochord and paired pharyngeal gill slits are the characteristic feature of phylum chordate. But, in subphylum Vertebrata notochord present in the embryo gets replaced by bony vertebral columns in adults. Hence it is said, “All vertebrates are chordates, but all chordates are not vertebrates.”
10. How important is the presence of air bladder in Pisces?
Solution:
Air bladder in Pisces regulates Buoyancy which prevents fishes from sinking.
11. What are the modifications that are observed in birds that help them fly?
Solution:
Modifications that are observed in birds that help them fly are as follows:
Presence of feathers
Forelimbs are modified into wings, assisting them to take a flight
Hind limbs have scales
They have pneumatic or hollow bones which make the skeleton lightweight
Absence of urinary bladder, causes the net body weight to be reduced, facilitating them to fly
Their streamlined body offers lesser resistance enabling a smooth flight furthermore
12. Could the number of eggs or young ones produced by an oviparous and viviparous mother be equal? Why?
Solution:
No, the number of eggs or young ones produced by an oviparous and viviparous mother are not equal, the number of eggs produced by oviparous mothers is more comparatively because in oviparous animals, fertilization talks place outside the uterus whereas in viviparous animals’ development takes place inside the uterus which makes successful incubation of young animals lesser.
When eggs are present outside, there is a risk of getting eaten by predators due to their immobility. Therefore, in order to sustain the progeny, there is a requirement for more of eggs.
13. Segmentation in the body is first observed in which of the following:
(a) Platyhelminthes (b) Aschelminthes (c) Annelida (d) Arthropoda
Solution:
The answer is (c) Annelida
14. Match the following:
Column I
Column II
(a) Operculum
(i) Ctenophora
(b) Parapodia
(ii) Mollusca
(c) Scales
(iii) Porifera
(d) Comb plates
(iv) Reptilia
(e) Radula
(v) Annelida
(f ) Hairs
(vi) Cyclostomata and Chondrichthyes
(g) Choanocytes
(vii) Mammalia
(h) Gill slits
(viii) Osteichthyes
Solution:
Column I
Column II
(a) Operculum
(viii) Osteichthyes
(b) Parapodia
(v) Annelida
(c) Scales
(iv) Reptilia
(d) Comb plates
(i) Ctenophora
(e) Radula
(ii) Mollusca
(f ) Hairs
(vii) Mammalia
(g) Choanocytes
(iii) Porifera
(h) Gill slits
(vi) Cyclostomata and Chondrichthyes
15. Prepare a list of some animals that are found parasitic on human beings.
Solution:
Some animals that are found parasitic in humans are as follows:
i. Taenia (Tapeworm)
ii. Ascaris (Roundworm)
iii. Ancylostoma (Hookworm)
iv. Enterobius (Pinworm)
v. Wuchereria (Filarial worm)
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