XII Chap 13 Organisms & Populations Flashcards
__________ is the Father of Ecology in India and founded the first postgraduate course in ecology in India
Ramdeo Misra
What is ecology?
Subject that studies the interactions among organisms (biotic environment) and between the organism and its physical (abiotic) environment
What are the 4 levels of biological organisation?
- Organisms
- Populations
- Communities
- Biomes
Even our intestine is a unique habitat for hundreds of species of microbes. T or F?
True
What are the major biomes of India?
- Tropical rain forest
- Deciduous forest
- Desert
- Sea coast
Key elements that lead to variation in different habitats?
Temperature, water, light and soil
Habitat of an organism only consists of the abiotic (physio-chemical) components like temperature, water, etc.
T or F?
False, also comprises of the biotic components - pathogens, parasites, predators and competitors
What is a niche?
Defined range of conditions that an organism can tolerate, diversity in the resources it utilises,
distinct functional role in the ecological system
Temperatures range from _________ in polar areas/high altitudes to ______ in tropical deserts in the summer
sub-zero
> 50°C
What are places where temperatures exceed 100°C?
Thermal springs and deep-sea hydrothermal vents
Tuna fish are rarely caught within tropical latitudes in the ocean. T or F?
False, they are ONLY caught within tropical latitudes, rarely BEYOND tropical latitudes
How does temperature affect organisms?
Affects kinetics of enzymes => metabolic activity
and other physiological functions
What are eurythermal vs stenothermal organisms?
Eurythermal - can tolerate and thrive in WIDE temp ranges
Stenothermal - restricted to NARROW temp range
What aspects of water are important for aquatic organims?
Quality (chemical composition, pH) and salinity
What is the salinity in:
- inland waters
- sea
- hypersaline lagoons?
- inland waters - 5 parts per thousand
- sea - 30-35 parts per thousand
- hypersaline lagoons - >100 parts per thousand
What are euryhaline vs stenohaline organisms?
Eury - WIDE range of salinities
Steno - NARROW range
Many freshwater organisms cannot live for long in sea water and vice versa because of ________
osmotic problems
Small plants are optimized to photosynthesize in low light. Why?
Constantly overshadowed by tall trees
Flowers rely on sunlight to meet their ______ requirement for flowering.
Photoperiodic
How is light important for animals?
use the diurnal and seasonal variation in light as cues for timing their foraging, reproductive and migratory activities
________ quality of solar radiation is important for life
Spectral
UV component of spectrum is harmful to many organisms. T or F?
True
All colour components of visible spectrum are available for marine plants living at different depths of the ocean. T or F?
False, not all color components
Nature and properties of soil are dependent on:
climate
weathering process
whether soil is transported or sedimentary
how soil development occurred
What characteristics determine percolation & water holding capacity of soil?
Soil composition
Grain size
Aggregation
What characteristics determine the vegetation in any area?
Soil composition Grain size Aggregation pH mineral composition topography
In the aquatic environment the _____ characteristics often determine the type of _____ animals that can thrive there
sediment;
benthic
What is homeostasis?
Regulatory Process;
Constancy of an organism’s internal environment
What are the various responses an organism may have to abiotic factors?
Regulate
Conform
Migrate
Suspend
__________________ are capable of thermoregulation and osmoregulation.
All birds and mammals
Few lower vertebrate & invertebrates
Humans maintain a constant body temperature of _____
37°C
Do plants thermoregulate?
No
Do 99% of animals and almost all plants conform or regulate?
Conform
What is ambient temperature?
External temperature
In aquatic animals, the osmotic concentration of the body fluids change with _______________
ambient air, water osmotic concentration
Thermoregulation is energetically inexpensive. T or F?
False, it is expensive
Why do small birds and shrews conform to ambient temperature?
Thermoregulation is energetically expensive. Smaller animals => larger surface area => lose body heat very fast => much more energy required to regulate
Why are small animals rarely found in polar regions?
Thermoregulation is energetically expensive. Smaller animals => larger surface area => lose body heat very fast => much more energy required to regulate
What options do organisms have if stressful external conditions are localised or only temporary?
Migrate or Suspend
________ in Rajasthan hosts thousands of migratory birds coming from Siberia every winter
Keolado National Park (Bharatpur)
Which plants/animals suspend?
Bears - hibernation
Snails and fish - aestivation
Zooplankton - diapause
Seeds - dormancy (reduced metabolic activity)
Why do snails and fish go into aestivation?
To avoid summer-related problems - heat and dessication
What is adaptation?
Any morphological, physiological, behavioural attribute of the organism that enables survival and reproduction in its habitat
Adaptations can be genetically fixed after a long period of time. T or F?
True
Describe adaptation in a kangaroo rat
internal fat oxidation (water is by product);
concentrate its urine
Describe adaptation in desert plants
sunken stomata arranged in deep pits
special photosynthetic pathway (CAM) => stomata closed during day
Opuntia - no leaves, only spines; photosynthesis => flattened stem
What is the Allen’s Rule?
Mammals - colder climate - shorter ears and limbs - minimal heat loss
Describe adaptation in polar mammals
seals of fat (blubber) below skin - insulator
How does the human body adapt to altitude sickness?
increasing RBC production,
decreasing binding affinity of hemoglobin,
increasing breathing rate
Human body adaptation to high altitudes is what kind of adaptation?
Physiological
Desert lizard adaptation to high temperatures is what kind of adaptation?
Behavioral, bask in sun vs. moving to shade
A group of individuals resulting from asexual reproduction is also considered a population in ecological studies. T or F?
True
Natural selection operates at the individual or population level to evolve desired traits?
Population level
What are attributes of a population?
Death rate
Birth rate
Sex ratio
Age distribution (pyramid)
What is population density?
Population size, N
measured in numbers, percent cover or biomass OR relatively (e.g. number of fish caught per trap)
Four basic processes that affect population density?
Natality and immigration => increase
Mortality and emigration => decrease
What is N at t+1 ?
Nt + [(B + I) - (D + E)]
What is relative importance of 4 processes that affect population density?
in normal conditions, B + D matter more
in case of new habitat, I may matter more
What is the equation for exponential population growth?
dN/dt = (b - d) x N
b - d = r = intrinsic rate of natural increase
OR, integral form:
Nt = N0 * e^rt
What is another name for exponential growth?
Geometric growth
What is the shape of curve in geometric growth?
J - shape
What is logistic growth?
Population growing in habitat with limited resources
Lag phase => acceleration => deceleration => asymptote
Verhulst-Pearl Logistic Growth
What kind of curve for logistic growth?
Sigmoid curve
What is “K” in logistic growth?
Nature’s carrying capacity - maximum possible number that resources in habitat can support
Equation for logistic growth?
dN/dt = rN (K - N / K)
What is Darwinian fitness?
Reproductive fitness, “r” value
What are organisms that breed only once in a lifetime?
Pacific salmon fish, bamboo
What are some organisms that produce large number of small-sized offspring?
Oysters, pelagic fish
There is no natural habitat on earth that is inhabited by just one species. T or F?
True
What are the different inter-species population interactions?
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
In competition, one species loses and the other wins. T or F?
False, both lose
In which types of species interaction do the species live close together?
Predation
Parasitism
Commensalism
What important roles do predators play?
- Keeping prey populations under control
2. Reducing competition among competing prey => species diversity maintained
What defenses have prey animal species evolved?
- Camouflage
- Poisonous
- Distastefulness (Monarch butterfly)
What defenses have prey plant species evolved?
- Thorns (Acacia, Cactus)
- Chemicals that make animals sick
- Poison
How does the weed Calotropis defend against herbivores?
Produces highly poisonous cardia glycosides
Totally unrelated species can also compete for the same resources. T or F?
True
What is interference competition?
Feeding efficiency of one species reduced due to interfering presence of other species
Define competition
Fitness of one species ( ‘r’ ) is significantly lower in presence of another species
Carnivores are more adversely affected by competition than herbivores and plants. T or F?
False, other way around
What is the ‘Competitive Exclusion Principle?
Gause;
2 closely related species competing for same resources cannot co-exist indefinitely; competitively inferior will be eventually eliminated
The Competitive Exclusion Principle always holds true?
No, only if resources are limiting;
Also species may evolve to co-exist e.g. resource partitioning
What is resource partitioning?
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)
Parasites are often host-specific and both parasite and hosts tend to co-evolve. T or F?
True
What are some evolved characteristics of parasites?
- Loss of unnecessary sense organs
- Adhesive organs / suckers
- Loss of digestive system
- High reproductive capacity
Life cycles of parasites are complex, how?
Usually involve one or 2 intermediate hosts or vectors
What does lifecycle of human liver fluke depend on?
Depends on snail and fish
Ectoparasites vs endoparasites?
Ecto - feed on external surface of host
e.g. lice, ticks (dogs), copepods (marine fish), Cuscuta plant (other plants)
Endo - live inside host
Female mosquito is a parasite. T or F?
False, vector. Plasmodium is the parasite
Ectoparasite lifecycles are more complex. T or F?
False, endo because they’re inside the body => extreme specialization
What is brood parasitism?
parasitic bird lays eggs in host nest
Examples of commensalism?
Orchid (epiphyte) growing on mango plant
barnacles on back of whale
cattle egret + grazing cattle (flesh out insects)
Sea anemone (stinging tentacles) + clown fish
Examples of mutualism?
Lichens - fungus and photosynthesizing algae/cyanobacteria
Mycorrhizae - fungi and roots of higher plants
Pollinators and plants
How does a fig tree exemplify mutualism?
pollinator - wasp,
every fig species is specific to a ‘partner’ wasp species
Female wasp uses fruit for nourishment + to lay eggs (oviposition)
How does the Mediterranean orchid exemplify mutualism?
Sexual deceit, one flower petal resembles female bee
male bee pseudocopulates
Only regulators are capable of homeostatis. T or F?
True
Define population
Group of individuals
same species
sharing / competing for resources
defined geographical area
When resources become limiting growth pattern turns _________
Logistic
Population growth is limited by __________
K - carrying capacity of the environment
________ is an important process through which trophic energy transfer is facilitated
Predation
Why do snails and fish go into aestivation?
To avoid summer-related problems - heat and dessication
