We can try to understand its complexity by investigating processes at various levels of biological organisation–macromolecules, cells, tissues, organs, individual organisms, population, communities, ecosystems and biomes. A

1. Organisms & populations

2. Biological organisation
• Macromolecules  cells tissues  organs 
individual organisms  population 
communities  ecosystems  biomes.

3. • ‘How does the bird sing?’
• By the operation of the voice box and vibrating bone in
bird …
• ‘Why does the bird sing ?’
• The bird’s need to communicate with its mate during
breeding season..

4. Why are night-blooming flowers generally white?
• Night white colour refract light which make them visible for
pollination..

5. Why does cactus have so many thorns?
• Spines also help prevent the cactus from losing water
through evaporation..
• And for Protection

6. How does the bee know which flower has nectar?
• Bees can sense electrical charge of flower having nectar.

7. What is Ecology
• Ecology is the studies the interactions among organisms
and interactions of organisms its physical (abiotic)
environment….

8. Ecology is basically concerned with four levels of biological
organisation
• Organisms
• populations,
• communities
• biomes.

9. • Organisms are adapted to their environments not only
survival but also reproduction.

10. Rotation of our planet around the Sun cause:
• Annual variations in the intensity of light
• duration of temperature,
• resulting in distinct seasons.
•

11. • Variations in the intensity and duration of temperature,
with annual variation in precipitation
• All variations together form major biomes such as :
• desert,
• rain forest
• tundra
• Precipitation includes both rain and snow..

12. Deciduous trees lose their leaves
seasonally

13. On planet Earth, life exists not only in favourable
habitats even in extreme and harsh habitats –
• Desert,
• rain-soaked Meghalaya forests,
• deep ocean
• polar regions,
• high mountain tops
• thermal springs,
• Even our intestine is a unique habitat for hundreds of
species of microbes.

14. Habitat of an organism
• Habitat of an organism do not characterise by only
abiotic factors..
• The Habitat also includes biotic factors:
• pathogens,
• parasites,
• predators
• competitors

15. Niche
• In ecology, a niche is the specific environmental condition
or Habitat.
• It describes how an organism or population responds to
the distribution of resources and competitors…

16. Biome distribution with respect to annual temperature and precipitation
Y

17. Major Abiotic Factors
• Temperature
• Water
• Light
• Soil

18. Temperature:
• Temperature is the most important ecologically relevant
factor.
• Temperature decreases from the equator towards the
poles..
• and from plains to the mountain tops.

19. Temperature
• Temperature is sub-zero levels in polar areas and high
altitudes..
• to > 50°C in tropical deserts in summer.
• Thermal springs and deep-sea hydrothermal vents:
• Where temperatures exceed > 100°C

20. • Mango trees do not and cannot grow in temperate
countries like canada and germany..
• Snow leopards are not found in kerala forests..
• Tuna fish are rarely caught beyond tropical latitudes in
the ocean

21. • Temperature to living organisms affects the kinetics of
enzymes
• and through metabolic activity
• and other physiological functions of the organism

22. Eurythermal Organisms
• A few organisms can tolerate and thrive in a wide range
of temperatures are called Eurythermal,..
• man, cow, sheep and monkeys.

23. Stenothermal Organisms
• A majority Organisms are restricted to a narrow range of
temperatures are called stenothermal.
• Penguin, Snow leopard, Tuna fish

24. WATER:

25. • life on earth originated in water and is unsustainable
without water.
• The productivity and distribution of plants is also heavily
dependent on water.
• . For aquatic organisms the quality (chemical
composition, pH) of water becomes important

26. The salt concentration measured as :
salinity in parts per thousand (ppt)
• Salt concentration is less than < 5 % in inland waters.
• 30-35 % in the sea
• > 100 % in some hypersaline lagoons.

27. Euryhaline & Stenohaline
• Euryhaline: Some organisms are tolerant of a wide range
of salinities.
• Stenohaline : Some organisms are restricted to a narrow
range of salinities
•

28. • Many freshwater animals cannot live for long in sea
water ..?
• because of the osmotic problems, they would face

29. Light:

30. • Many small plants (herbs and shrubs) growing in forests
are adapted to very low light conditions..
• because they are constantly overshadowed by tall,
canopied trees.
Sun light require for Photoperiodism:

31. Many animals use and seasonal variations in light intensity
and duration of light (photoperiod) as cues for ..
• timing their foraging,
• reproductive
• migratory activities
Foraging: searching for food resources

32. Deep (>500m) in the oceans, the environment is dark
• then What, is source of energy in deep oceans?
• Chemosynthesis (Chemical energy)

33. The UV component of the spectrum is harmful to many
organisms…
• All the colour components of the visible spectrum are
not available for marine plants living at different depths
of the ocean.

34. Among the red, green and brown algae
which is likely to be found in the deepest waters? Why?
• RED algae found deepest in ocean water..
• Red algae has phycoerythrin pigment absorb light even
in low intensity..

35. Soil:

36. The nature and properties of soil dependent on the?
• climate,
• weathering process,
• whether soil is transported or sedimentary

37. Various characteristics of the soil such as ..
• soil composition,
• grain size
• aggregation
Determine the percolation and
water holding capacity of the
soils.
Percolation :the slow movement of water through the pores in soil

38. Characteristics of the soil such as ..
• Soil composition,
• Grain size
• Aggregation
• pH,
• mineral composition
• topography
Determine
vegetation in any area.
Topography: is the
physical features of
soil such as
mountains, rivers,
lakes, and valleys.

39. In the aquatic environment,
• the sediment-characteristics often determine: the type of benthic
animals that can thrive there.

40. Ramdeo Misra
• Ramdeo Misra is revered as the Father of Ecology in
India…

42. Species would have evolved a relatively
constant internal environment
• constant internal environment permits all biochemical
reactions and physiological functions
• And Enhance the overall ‘fitness’ of the species

43. Homeostasis
• The ability of organism to maintain the constancy of its
internal environment is called homeostasis..
• air conditioner in summer
• heater in winter.

44. Organisms classified into 4 types:
• Regulators
• Conformers
• Migrates
• Suspenders
Based on responses to abiotic factors:

45. Regulators:
• Some organisms are able to maintain homeostasis.. i.e.
constant body temperature, constant osmotic
concentration..
•

46. Example for regulators
• All birds
• Mammals
• a very few lower vertebrate
• Few invertebrate species
• are capable of thermoregulation and osmoregulation..
• That’s why mammals thrive whether they live in
Antarctica or in the Sahara desert.

47. We maintain a constant body temperature of (37°C).
• In summer, when outside temperature is more than our
body temperature..
• we sweat profusely (Great).
• The resulting evaporative cooling: brings down the body
temperature..

48. • In winter when the temperature is much lower than
37°C,..
• we start to shiver, a kind of exercise..
• which produces heat and raises the body temperature
Plants: do not have such mechanisms to maintain
internal temperatures…

49. Conform:

50. • An majority (99 per cent) of animals and all plants
cannot maintain a constant internal environment.
• Their body temperature changes with the ambient
temperature.
Conformers:

51. • In aquatic animals, the osmotic concentration of the
body fluids change with ambient water osmotic
concentration.
• Aquatic animals and plants are simply conformers….

52. Why very small animals are rarely found in polar regions?
• Small animals lose body heat very fast when it is cold outside;
• They expend much energy to generate body heat through
metabolism..

53. Thermoregulation is energetically expensive for many
organisms
• This is particularly true for small animals like shrews and
humming birds.
• Heat loss or heat gain is a function of surface area.
• Since small animals have a larger surface area relative
to their volume..

55. Partial regulator:
• Partial regulator: changes their body temperature with
certain level of ambient temperature..
• but when outside temperature continues to increase
they are able to maintain constant body temperature.
• Example: squirrel, shrew etc.

56. Migrate :
• The organism can move away temporarily from the
stressful habitat to a more hospitable area..
• and return when stressful period is over.

57. Migrate:
• Persons moving from Delhi to Shimla for the duration of
summer.
• Every winter the famous Keolado National Park
(Bharatpur) in Rajasthan..
• host thousands of migratory birds coming from Siberia
and other extremely cold northern regions.

58. Suspend:

59. In bacteria, fungi and lower plants, form various kinds of
thick walled spores..
• which help them to survive unfavourable conditions…
• these germinate on availability of suitable environment.

60. In higher plants, seeds and some other vegetative reproductive
structures during stress coditions.
• Seeds reducing their metabolic activity and going into a
state of ‘dormancy’
• they germinate to form new plants under favourable
moisture and temperature conditions.

61. • Bears going into hibernation during winter..
• Some snails and fish going into aestivation to avoid
summer: heat and dessication.
• Under unfavourable conditions many zooplankton enter
into diapause..

62. Harinatha Reddy Aswartha
Assistant Professor
Department of Microbiology
biohari14@gmail.com