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Biology (NCERT) - Class XII > XII Chap 13 Organisms & Populations > Flashcards

XII Chap 13 Organisms & Populations Flashcards

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1
Q

__________ is the Father of Ecology in India and founded the first postgraduate course in ecology in India

A

Ramdeo Misra

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2
Q

What is ecology?

A

Subject that studies the interactions among organisms (biotic environment) and between the organism and its physical (abiotic) environment

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3
Q

What are the 4 levels of biological organisation?

A
  1. Organisms
  2. Populations
  3. Communities
  4. Biomes
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4
Q

Even our intestine is a unique habitat for hundreds of species of microbes. T or F?

A

True

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5
Q

What are the major biomes of India?

A
  1. Tropical rain forest
  2. Deciduous forest
  3. Desert
  4. Sea coast
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6
Q

Key elements that lead to variation in different habitats?

A

Temperature, water, light and soil

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7
Q

Habitat of an organism only consists of the abiotic (physio-chemical) components like temperature, water, etc.

T or F?

A

False, also comprises of the biotic components - pathogens, parasites, predators and competitors

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8
Q

What is a niche?

A

Defined range of conditions that an organism can tolerate, diversity in the resources it utilises,
distinct functional role in the ecological system

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9
Q

Temperatures range from _________ in polar areas/high altitudes to ______ in tropical deserts in the summer

A

sub-zero

> 50°C

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10
Q

What are places where temperatures exceed 100°C?

A

Thermal springs and deep-sea hydrothermal vents

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11
Q

Tuna fish are rarely caught within tropical latitudes in the ocean. T or F?

A

False, they are ONLY caught within tropical latitudes, rarely BEYOND tropical latitudes

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12
Q

How does temperature affect organisms?

A

Affects kinetics of enzymes => metabolic activity

and other physiological functions

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13
Q

What are eurythermal vs stenothermal organisms?

A

Eurythermal - can tolerate and thrive in WIDE temp ranges

Stenothermal - restricted to NARROW temp range

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14
Q

What aspects of water are important for aquatic organims?

A

Quality (chemical composition, pH) and salinity

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15
Q

What is the salinity in:

  1. inland waters
  2. sea
  3. hypersaline lagoons?
A
  1. inland waters - 5 parts per thousand
  2. sea - 30-35 parts per thousand
  3. hypersaline lagoons - >100 parts per thousand
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16
Q

What are euryhaline vs stenohaline organisms?

A

Eury - WIDE range of salinities

Steno - NARROW range

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17
Q

Many freshwater organisms cannot live for long in sea water and vice versa because of ________

A

osmotic problems

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18
Q

Small plants are optimized to photosynthesize in low light. Why?

A

Constantly overshadowed by tall trees

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19
Q

Flowers rely on sunlight to meet their ______ requirement for flowering.

A

Photoperiodic

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20
Q

How is light important for animals?

A

use the diurnal and seasonal variation in light as cues for timing their foraging, reproductive and migratory activities

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21
Q

________ quality of solar radiation is important for life

A

Spectral

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22
Q

UV component of spectrum is harmful to many organisms. T or F?

A

True

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23
Q

All colour components of visible spectrum are available for marine plants living at different depths of the ocean. T or F?

A

False, not all color components

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24
Q

Nature and properties of soil are dependent on:

A

climate
weathering process
whether soil is transported or sedimentary
how soil development occurred

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25
Q

What characteristics determine percolation & water holding capacity of soil?

A

Soil composition
Grain size
Aggregation

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26
Q

What characteristics determine the vegetation in any area?

A 
Soil composition
Grain size 
Aggregation
pH
mineral composition
topography
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27
Q

In the aquatic environment the _____ characteristics often determine the type of _____ animals that can thrive there

A

sediment;

benthic

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28
Q

What is homeostasis?

A

Regulatory Process;

Constancy of an organism’s internal environment

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29
Q

What are the various responses an organism may have to abiotic factors?

A

Regulate
Conform
Migrate
Suspend

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30
Q

__________________ are capable of thermoregulation and osmoregulation.

A

All birds and mammals

Few lower vertebrate & invertebrates

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31
Q

Humans maintain a constant body temperature of _____

A

37°C

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32
Q

Do plants thermoregulate?

A

No

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33
Q

Do 99% of animals and almost all plants conform or regulate?

A

Conform

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34
Q

What is ambient temperature?

A

External temperature

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35
Q

In aquatic animals, the osmotic concentration of the body fluids change with _______________

A

ambient air, water osmotic concentration

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36
Q

Thermoregulation is energetically inexpensive. T or F?

A

False, it is expensive

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37
Q

Why do small birds and shrews conform to ambient temperature?

A

Thermoregulation is energetically expensive. Smaller animals => larger surface area => lose body heat very fast => much more energy required to regulate

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38
Q

Why are small animals rarely found in polar regions?

A

Thermoregulation is energetically expensive. Smaller animals => larger surface area => lose body heat very fast => much more energy required to regulate

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39
Q

What options do organisms have if stressful external conditions are localised or only temporary?

A

Migrate or Suspend

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40
Q

________ in Rajasthan hosts thousands of migratory birds coming from Siberia every winter

A

Keolado National Park (Bharatpur)

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41
Q

Which plants/animals suspend?

A

Bears - hibernation
Snails and fish - aestivation
Zooplankton - diapause
Seeds - dormancy (reduced metabolic activity)

42
Q

Why do snails and fish go into aestivation?

A

To avoid summer-related problems - heat and dessication

43
Q

What is adaptation?

A

Any morphological, physiological, behavioural attribute of the organism that enables survival and reproduction in its habitat

44
Q

Adaptations can be genetically fixed after a long period of time. T or F?

A

True

45
Q

Describe adaptation in a kangaroo rat

A

internal fat oxidation (water is by product);

concentrate its urine

46
Q

Describe adaptation in desert plants

A

sunken stomata arranged in deep pits
special photosynthetic pathway (CAM) => stomata closed during day

Opuntia - no leaves, only spines; photosynthesis => flattened stem

47
Q

What is the Allen’s Rule?

A

Mammals - colder climate - shorter ears and limbs - minimal heat loss

48
Q

Describe adaptation in polar mammals

A

seals of fat (blubber) below skin - insulator

49
Q

How does the human body adapt to altitude sickness?

A

increasing RBC production,
decreasing binding affinity of hemoglobin,
increasing breathing rate

50
Q

Human body adaptation to high altitudes is what kind of adaptation?

A

Physiological

51
Q

Desert lizard adaptation to high temperatures is what kind of adaptation?

A

Behavioral, bask in sun vs. moving to shade

52
Q

A group of individuals resulting from asexual reproduction is also considered a population in ecological studies. T or F?

A

True

53
Q

Natural selection operates at the individual or population level to evolve desired traits?

A

Population level

54
Q

What are attributes of a population?

A

Death rate
Birth rate
Sex ratio
Age distribution (pyramid)

55
Q

What is population density?

A

Population size, N

measured in numbers, percent cover or biomass OR relatively (e.g. number of fish caught per trap)

56
Q

Four basic processes that affect population density?

A

Natality and immigration => increase

Mortality and emigration => decrease

57
Q

What is N at t+1 ?

A

Nt + [(B + I) - (D + E)]

58
Q

What is relative importance of 4 processes that affect population density?

A

in normal conditions, B + D matter more

in case of new habitat, I may matter more

59
Q

What is the equation for exponential population growth?

A

dN/dt = (b - d) x N

b - d = r = intrinsic rate of natural increase

OR, integral form:

Nt = N0 * e^rt

60
Q

What is another name for exponential growth?

A

Geometric growth

61
Q

What is the shape of curve in geometric growth?

A

J - shape

62
Q

What is logistic growth?

A

Population growing in habitat with limited resources
Lag phase => acceleration => deceleration => asymptote

Verhulst-Pearl Logistic Growth

63
Q

What kind of curve for logistic growth?

A

Sigmoid curve

64
Q

What is “K” in logistic growth?

A

Nature’s carrying capacity - maximum possible number that resources in habitat can support

65
Q

Equation for logistic growth?

A

dN/dt = rN (K - N / K)

66
Q

What is Darwinian fitness?

A

Reproductive fitness, “r” value

67
Q

What are organisms that breed only once in a lifetime?

A

Pacific salmon fish, bamboo

68
Q

What are some organisms that produce large number of small-sized offspring?

A

Oysters, pelagic fish

69
Q

There is no natural habitat on earth that is inhabited by just one species. T or F?

A

True

70
Q

What are the different inter-species population interactions?

A

Mutualism - both gain
Competition - both lose
Predation - one gains, one loses
Parasitism - one gains, one loses
Commensalism - one gains, no effect on other
Amensalism - one loses, no effect on other

71
Q

In competition, one species loses and the other wins. T or F?

A

False, both lose

72
Q

In which types of species interaction do the species live close together?

A

Predation
Parasitism
Commensalism

73
Q

What important roles do predators play?

A
  1. Keeping prey populations under control

2. Reducing competition among competing prey => species diversity maintained

74
Q

What defenses have prey animal species evolved?

A
  1. Camouflage
  2. Poisonous
  3. Distastefulness (Monarch butterfly)
75
Q

What defenses have prey plant species evolved?

A
  1. Thorns (Acacia, Cactus)
  2. Chemicals that make animals sick
  3. Poison
76
Q

How does the weed Calotropis defend against herbivores?

A

Produces highly poisonous cardia glycosides

77
Q

Totally unrelated species can also compete for the same resources. T or F?

A

True

78
Q

What is interference competition?

A

Feeding efficiency of one species reduced due to interfering presence of other species

79
Q

Define competition

A

Fitness of one species ( ‘r’ ) is significantly lower in presence of another species

80
Q

Carnivores are more adversely affected by competition than herbivores and plants. T or F?

A

False, other way around

81
Q

What is the ‘Competitive Exclusion Principle?

A

Gause;
2 closely related species competing for same resources cannot co-exist indefinitely; competitively inferior will be eventually eliminated

82
Q

The Competitive Exclusion Principle always holds true?

A

No, only if resources are limiting;

Also species may evolve to co-exist e.g. resource partitioning

83
Q

What is resource partitioning?

A

If 2 species compete for same resource, they could avoid competition by choosing different feeding times or patterns

(e.g. five closely related species of warblers on same tree)

84
Q

Parasites are often host-specific and both parasite and hosts tend to co-evolve. T or F?

A

True

85
Q

What are some evolved characteristics of parasites?

A
  1. Loss of unnecessary sense organs
  2. Adhesive organs / suckers
  3. Loss of digestive system
  4. High reproductive capacity
86
Q

Life cycles of parasites are complex, how?

A

Usually involve one or 2 intermediate hosts or vectors

87
Q

What does lifecycle of human liver fluke depend on?

A

Depends on snail and fish

88
Q

Ectoparasites vs endoparasites?

A

Ecto - feed on external surface of host
e.g. lice, ticks (dogs), copepods (marine fish), Cuscuta plant (other plants)

Endo - live inside host

89
Q

Female mosquito is a parasite. T or F?

A

False, vector. Plasmodium is the parasite

90
Q

Ectoparasite lifecycles are more complex. T or F?

A

False, endo because they’re inside the body => extreme specialization

91
Q

What is brood parasitism?

A

parasitic bird lays eggs in host nest

92
Q

Examples of commensalism?

A

Orchid (epiphyte) growing on mango plant
barnacles on back of whale
cattle egret + grazing cattle (flesh out insects)
Sea anemone (stinging tentacles) + clown fish

93
Q

Examples of mutualism?

A

Lichens - fungus and photosynthesizing algae/cyanobacteria
Mycorrhizae - fungi and roots of higher plants
Pollinators and plants

94
Q

How does a fig tree exemplify mutualism?

A

pollinator - wasp,
every fig species is specific to a ‘partner’ wasp species
Female wasp uses fruit for nourishment + to lay eggs (oviposition)

95
Q

How does the Mediterranean orchid exemplify mutualism?

A

Sexual deceit, one flower petal resembles female bee

male bee pseudocopulates

96
Q

Only regulators are capable of homeostatis. T or F?

A

True

97
Q

Define population

A

Group of individuals
same species
sharing / competing for resources
defined geographical area

98
Q

When resources become limiting growth pattern turns _________

A

Logistic

99
Q

Population growth is limited by __________

A

K - carrying capacity of the environment

100
Q

________ is an important process through which trophic energy transfer is facilitated

A

Predation

101
Q

Why do snails and fish go into aestivation?

A

To avoid summer-related problems - heat and dessication

Biology (NCERT) - Class XII (18 decks)

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