NEET Biology – Organisms and Populations – Study Notes

Organisms and Populations

Table of Content

• Organism and its Environment
• Major Abiotic Components
  • Temperature
  • Water
  • Light
  • Soil
• Response to Abiotic Factors
• How does organism cope with the changing environment?
  • Regulate
  • Conform
  • Migrate
  • Suspend
• Adaptation
  • Adaptation of animal in desert
  • Adaptation of plant in desert (xerophytes)
  • Adaptation of animal in cold climate
  • Adaptation in high altitude
  • How our bodies respond to the problem?
  • Behavioral adaptation
• Population
  • Population Attributes
  • Methods for measurement of population density
  • Population Growth
  • Exponential Growth
  • Logistic Growth Model
  • Logistic Growth (Sigmoid curve is obtained)
• Population Interactions
  • Predation
  • Competition
  • Parasitism
  • Commensalism
  • Mutualism
  • Sexual Deceit

Organism and its Environment

• Sun’s rotation and the tilt of its pivot cause yearly variations in the force and span of temperature, bringing forth the various seasons.
• These variations alongside yearly variations in precipitation, frames significant biomes, for example, tundra, rainforest, and desert.
• Temperature, soil, light, and water are the key components that prompt to such a great amount of variation in the physical and synthetic states of living spaces.
• Both abiotic (physic-synthetic) and biotic parts (competitions, pathogen, predators, parasites) describe the environment of a life form.

Fig: Abiotic and Biotic factors that influence ecosystems

Major Abiotic Components

Temperature

• Temperature diminishes dynamically from equator moving towards the pole and high heights to > 50° C during summer in the tropical desert
• Thermal springs and remote ocean hydrothermal vents are exceptional with >100° C
• Temperature influences the BMR, the kinetics of enzymes, and other physiological activities
• Eurythermals: creatures which can endure an extensive variety of temperatures
• Stenothermals: creatures which can endure limited scope of temperatures

Fig: Steno-species exhibit a narrow tolerance zone while Eury- species exhibit a wide tolerance zone.

Water

• Water is additionally a vital component that impacts the life of a living being
• The efficiency and conveyance of plants likewise rely on water
• The saltiness fluctuates in the oceanic environment:
  • 5% in inland waters (new water)
  • 30-35 percent in ocean water
  • More than 100 percent in hyper saline tidal ponds
• Euryhaline: life forms which can endure extensive variety of saltiness
• Stenohaline: life forms which can endure limited scope of saltiness

Fig: A euryhaline fish

Fig: Yellow fin Tuna: A Stenohaline species

Light

• Plants deliver sustenance by photosynthesis, which is conceivable only in light. Consequently, it is imperative for autotrophs.
• Plant species (bushes and herbs) adjusted for photosynthesis under shade.
• Sunlight is required for a photoperiodic reaction like blooming.
• Animals utilize diurnal and regular variations in light force and photoperiod as prompts for timing their migration, reproduction, and foraging.

Soil

• Properties of soil change as per the atmosphere, the weathering procedure.
• Aggregation, grain size, and soil composition decide the permeation and water holding limit of the soil.
• These trademarks alongside pH, mineral organization and geography decide to a huge degree the vegetation in any range.
• The silt trademark frequently decides the kind of benthic creature in oceanic environment.

Response to Abiotic Factors

Homeostasis; the procedure by which the creature keeps up a steady inner environment in regard to changing outside environment.

Fig: Homeostasis

How does organism cope with the changing Environment?

Regulate

• Some life forms can keep up homeostasis physiological (occasionally behavioral too) meaning which guarantees steady body temperature, consistent osmotic focus.
• All mammals and birds and few lower spineless creatures are prepared to do such regulation i.e. osmoregulation and thermoregulation.
• Success of warm-blooded creatures is because of thermoregulation.
• We keep up a consistent body temperature of 37^oC.
• When outside temperature is high we sweat abundantly and evaporative cooling happens to cut the body temperature down.
• In winter, because of low temperature outside our body, temperature falls underneath 37^oC, we begin to shudder to create warmth to raise body temperature.

Fig: Regulators

Conform

• Majority (99%) of creatures and plants can’t keep up a steady interior environment; their body temperature differs as indicated by surrounding temperature.
• In sea-going creatures the osmotic convergence of body liquid differs with surrounding water osmotic focus.
• All the above creatures and plants are just called as conformer.

Fig: Conformers

Why the conformers are not evolved to become regulators?

• Thermoregulation is vigorously costly for some creatures.
• Humming birds and small creature like shrews can’t bear the cost of such a great amount of vitality for thermoregulation.
• Heat gain or heat loss is a component of surface range.
• Small creatures have bigger surface range with respect to their volume, they have a tendency to lose body warmth quickly when it is chilly outside; they then need to use much vitality to produce body warmth through digestion system.
• This is the reason little creatures are seldom found in Polar Regions.

Alternate response for difficult conditions is limited or stays for brief term.

Migrate

• The creatures move away briefly from the distressing territory to a more affable zone and return when the unpleasant condition is over
• Birds move from the colder locale to hotter area

Suspend

• Spores with thick walls are shaped in organisms to defeat unpleasant outside environment. Spores sprout in ideal condition.
• In higher plants, seeds and other vegetative conceptive structures are intended to hold over the stress. They diminish their metabolic movement and going into a condition of ‘dormancy’.
• Hibernation: amid winter creatures like bears escape in time
• Aestivation: creatures like snail and fish keep away from summer related issue like warmth and parching.
• Diapauses: numerous zooplanktons experience a phase of suspended advancement in unpleasant conditions.

Adaptation

• Adaptation: is any quality of the living being (behavioral, morphological, and physiological) that empowers the living being to survive and replicate in its living space.

Adaptation of animal in desert

• Kangaroo rat meets their water prerequisite from oxidation of fat
• Excrete extremely concentrated urine to save water

Fig: Adaptations of Kangaroo rat

Adaptation of plant in desert (xerophytes)

• Leaf surfaces having thick cuticle
• Sunken stomata, both to decrease transpiration
• Have exceptional photosynthetic pathway (CAM), stomata shut amid daytime and stayed open amid night
• Opuntia has no leaf- they are diminished to spines
• Photosynthesis happens in flattened green stems

Fig: Desert Ground Plants

Adaptation of animal in cold climate

• Allen’s Rule: warm-blooded creatures from colder atmospheres, for the most part, have shorter ears and appendages to minimize warmth loss.
• Seals of polar oceanic oceans have blubber, a thick layer of fat underneath their skin that goes about as an insulator and decreases loss of body warmth.

Fig: Adaptations of Polar Bear in cold region

Adaptation in high altitude

• An individual moving to high height (>3,500 meter), suffers from altitude sickness
• Symptoms created are heart palpitations, fatigue and nausea
• This is because of low air weight of high heights; the body is not able to get enough oxygen

How our bodies respond to the problem?

• The body repays low oxygen accessibility by expanding the production of red blood cells
• The body repays by diminishing binding capacity of hemoglobin to oxygen by expanding rate of respiration

Behavioral Adaptation

• Desert reptiles are conformers thus they adapt to the distressing environment by their behavioral adjustments:
  • They lounge in the sun and assimilate warmth when their body temperature drops beneath the safe place in winter
  • Move towards shade when the surrounding temperature increases
  • Some species tunnel into the soil to conceal and escape from over the ground warmth

Population

Population Attributes

• Population: a gathering of individual living in a very much characterized topographical range, share or go after comparable assets, possibly interbreed.
• Birth rate refers to per capita births and death rate alludes to per deaths.
• Another property is sex proportion. The proportion between the male- female in a population.
• If the age conveyance is plotted for a population the subsequent structure is called age pyramid.
• The state of the pyramids mirrors the development status of the population like developing, stable or declining.
• The population size is all the more in fact called as population density.

Fig: Diagram depicts the stage of Growth

Methods for measurement of population density

• Percent cover
• Counting the number
• Pug marks and fecal pellets for tiger census
• Biomass

Population Growth

• The population size changes relying upon food accessibility, predation force and lessen climate.
• Population estimate vacillated because of changes in four fundamental procedures, two of which (Natality and immigration) contribute an expansion in population density and two (mortality and emigration) to a diminishing.
• Natality: number of birth in given period in the population.
• Mortality: number of deaths in the population in a given timeframe.
• Immigration is the quantity of people of same species that have come into the territory from somewhere else amid a given timeframe.
• Emigration: number of people of the population who left the territory and gone somewhere else amid a given timeframe and age.
• If “N” is the population density at time ‘t’, then its density at time t + 1 is:

N1+t = Nt + [( B+1) – (D + E)]

Fig: Verhulst Pearl Logistic Growth

dN/dt = rN [(K – N)/K]
Where B = the number of births

D = the number of deaths

I = the number of immigrants

E = the number of Emigrants

K = Carrying capacity (The maximum population size that an environment can sustain)

N = Population Density

t = Time period

r = Intrinsic rate of natural increase

Exponential Growth

• The Exponential growth equation is N_t = N₀e^rt
• N0 = Population density at time zero
• Nt = Population density after time t
• e = the base of natural logarithms (2.71828)
• r = intrinsic rate of natural increase
• Exponential growth (‘J’ shape curve is obtained)
  At the point when assets are not constraining the development
• Any species development exponentially under boundless assets conditions can achieve gigantic population densities in a brief span
• Growth is not all that sensible and realistic

Logistic growth model

• Verhulst-Pearl Logistic Growth is described by the following equation

dN/dt = rN (K–N / N)

• WhereK = Carrying capacity
• r = Intrinsic rate of natural increase
• N = Population density at time t

Fig: Exponential vs Logistic Growth

Logistic Growth (Sigmoid curve is obtained)

• When reactions are restricting the Growth.
• Resources for development for most creature populations are limited and get to be distinctly restricting.
• The logistic growth model is a more practical one.

Fig: Logistic Growth Curve

Population Interactions

Predation

• Higher trophic level organisms (predator) sustains on the creature of lower trophic level (prey) is known as the predation
• Even the herbivores are not altogether different from the predator
• Predator goes about as a section for the exchange of vitality crosswise over the trophic level
• Predators monitor prey populations
• Exotic species have no normal predator subsequently they grow quickly. (thorny pear prickly plant presented in Australia made issue)
• Predators additionally help in keeping up species assorted qualities in a group, by lessening the force of rivalry among contending prey species. (Pisaster starfish field experiment)

Defense developed by prey against predators

Animals:

• Insects and frogs are obscurely shaded (camouflaged) to abstain from being recognized by the predator
• Some are noxious and in this way maintained a strategic distance from by the predators
• Monarch butterfly is exceptionally disagreeable to its predator (flying creature) because of the nearness of unique concoction in its body. The substance procured by nourishing a harmful weed amid caterpillar stage.

Plants:

• Thorns in Cactus and Acacia are a morphological method for protection
• Many plants create and store some substance which makes the herbivore wiped out if eaten, distress reproduction, digestion, and interferes feeding even slaughter the predators
• Calotropis produces noxious cardiovascular glycosides against herbivores
• Nicotine, opium, caffeine, strychnine, quinine, and so on are created by plant as resistances against the nibblers and browsers

Competition

• Interspecific rivalry is a powerful drive in natural development.
• Competition, for the most part, happens when firmly related species go after similar assets that are restricting, yet this not by any stretch true or genuine:
• Firstly: absolutely random species could likewise go after similar assets.
  • American lakes going by flamingoes and inhabitant angles have their normal food, zooplanktons.
• Secondly: assets need not be restricting for a rivalry to happen.
  • Abingdon tortoise in Galapagos Islands got to be distinctly wiped out within 10 years after goats were presented on the island, because of more prominent perusing capacity.

Parasitism

• Parasitic method of life guarantees free space and food
• Some parasites are host-particular (one parasite has a solitary host) in a manner that both host and parasite tend to co-develop

Parasitic Adaptation

• Loss of superfluous sense organs
• Presence of sucker or organs to stick on to the host
• Loss of stomach related framework
• High reproductive limit
• Parasites having at least one intermediate host or vectors to encourage parasitisation of its essential host
• Liver fluke has two hosts (snail and a fish) to finish its life cycle

Effects on the host:

• Parasite dependably harms the host
• Reduce its population density
• They diminish the survival, development and generation of the host
• They make the host more defenseless against the predators, by making it physically frail

• Ectoparasite: sustains on the outer surface of the host.

• Lice on human
• Marine fish pervaded with copepods
• Ticks on dogs
• Cuscutaa parasitic plant develop on hedge plants

• Endoparasites: are those that live inside the host body at various locales:

• Life cycle is much complex
• Highly created reproductive framework
• Morphological and anatomical components are extraordinarily disentangled

• Brood parasitism:

• Special sort of parasitism found in birds
• The egg of the parasite is fundamentally the same as with the egg of the host
• The parasitic winged creatures lay its eggs in the home of its host and let the host hatch them
• Cuckoo lays eggs in the nest of the crow

Fig: Parasitism versus Predation

Commensalism

• This is the association in which one species benefits and the other is neither profited nor hurt
• Clown fish living in the tentacles of the sea anemone
• Orchids developing as an epiphyte on a mango branch
• Cattle Egret and nibbling steers
• Barnacles on the back of whales

Mutualism

communication between two living being, both are similarly profited, nobody is hurt.

• Lichen: a mycobiont and a Phycobiont
• Mycorrhiza: relationship amongst fungi and base of the higher plant
• Fig trees and its pollinating specialist wasp
• Pollinating bugs and blossoming plants

Fig: The most commonly known mutualistic relationship is the honey bee and the flower though there are many different types of mutualistic relationships.

Sexual Deceit

Sexual Deceit is a type of pseudo copulation. Pseudo copulation describes behaviors similar to copulation that serve a reproductive function for one or both participants but do not involve actual sexual union between the individuals.

• Mediterranean orchid Ophrys utilizes ‘sexual deceit’
• The male honey bee pulled into what it sees as a female, “pseudo copulates” with the bloom, however, does not get any advantages
• Petal of the bloom looks like the female honey bee

Fig: Sexual Deception by Ophrys apifera