Chapter 15 (2nd year)

Chapter 15 (2nd year)

homeostasis

Environment

It can be defined as the surroundings or conditions in which a person, animal, or plant lives or operates.

Environment may be1: external environment2: internal environment

Homeostasis

It can be defined as the protection of internal environment from the harms of fluctuations in external environment is called as homeostasis

Osmoregulation

It can be defined as the mechanism of regulation , generally between organism and its environment , of solute and the gain and loss of water is osmoregulation

Thermoregulation

It can be defined as maintenance of internal temperature within a tolerable range is designated as thermoregulation.

Excretion

It can be defined as the process in which nitrogenous wastes are removed from the body is called as excretion

Control system

Water relations of cell

Osmoregulation in plants

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Distribution of plants according to different habitats

Hydrophytes Extensive stomata are present.They have very large leaves to transpire water excessively.Example: Water lilyMesophytes They have moderate water availabilityStomata are kept open to promote transpiration while in restricted supply of water, stomata are closed.Example. Brassica . Mango etc.xerophytes They have thick small leaves to reduce water lossThick waxy cuticle is present Stomata are on the lower surface of leaves, present in depressions.They have thick stem to store water, during rainy season.Some plants shed their leaves to restrict transpiration , completely.Example Cactus

Hydrophyte

Waterlily

Mesophytes

Rose Plant

Xerophytes

Cactus

Osmoregulation in animalsOsmoreconformers Osmoregulators

Osmoconformers

Their internal and outer water solute balance is isotonicSo they do not need to regulate it actively.Examples: invertebrates, including starfish and jelly fishAmong the vertebrates the osmoconformers are, hagfish , sharks, skates

Paramecium Contractile vacuole for osmoregulation

Terrestrial environment.

Kangroo rat

Excretion In plantsIn animals

Excretion in plantsBy:LeavesTrunkRootsBulbBy crystal formationEbony formation

Bulb of Blue bell flower

conifersRelease waste compounds in soil.

Rasins , latex, in trees

Excretophore

Excretory leaf and chlorosis in Leaves are different.

Nature of excretory products in animals

Urea cycle.

2 ammonia and 1 Carbon dioxide combine to form 1 urea molecule,

Excretion in planariaFlame cells.* protonephridium

Excretion in earthworm Metanephridium

Excretion in cockroach

Liver SynthesisStorageDetoxificationConversionrecycling

Skin as osmoregulatory organ

Sebaceous glandsSweat glands