Study the graph given below and answer the questions that follow:i Write the status of food and space in the curves a and b ii In the absence of predators, which one of the two curves would appropriately depict the prey population?iii Time has been shown on X-axis and there is a parallel dotted line above it Give the significance of this dotted line. from Biology Organisms and Populations Class 12 Nagaland Board

The organism will start synthesising the necessary proteins, co-enzymes and vitamins needed for their growth and hence there will be a subsequent increase in the lag phase. Bacteria enter into the human blood through the any injury of the body respiration food materials and mixed in blood streams so nutrition such as vitamin. The dotted line represents the carrying capacity of the environment. The carrying capacity represents the size of population that the environment can hold by providing necessary resources.

Exponential growth – When the resources in the habitat are unlimited, each species has the ability to realise its innate potential t grow in number fully. Explain any three different ways the population density can be measured, with the help of an example each. ​Developmental plasticity is a general term referring to changes in neural connections during development as a result of environmental interactions as well as neural changes induced by learning.

  • Individual bacteria begin to die due to the unfavourable conditions and the death is rapid and at uniform rate.
  • The highest temperature at which growth is maximum growth temperature .
  • Thermo word derived from Greek word ” thermolita ” meaning heat and philia meaning love .
  • The plants which adapt to extreme habitats such as dry and wet are called xerophytes and hydrophytes, respectively.

They bacteria are heat loving bacteria they are mostly found in hot places. There optimum temperature range is 80 ℃ to above 100 ℃ . The lowest temperature at which organisms growth is the minimum growth temperature. types of curves are obtained in the growth of organism In this phase bacterial size increase but not increase number of cell. For example, if the population is growing the policies can be made to increase the food resources to maintain the population.

The inherent capacity of a species to increase its maximum number under the ideal conditions is called biotic potential. Adaptation is an attribute that enables the organisms to survive and reproduce in its habitat. The need for adaptation arises when extremely unfavourable conditions persist in the environment.

Many adaptations have evolved over a long evolutionary time and genetically fixed through mutations. The study of ecology is divided into two branches, namely autecology and synecology.

Desert Adaptations

Age distribution plot for a given population is given by the age pyramid. State the basis for the difference in the shape of these curves. In the absence of predators, curve would appropriately depict the prey population.

types of curves are obtained in the growth of organism

Individual bacteria begin to die due to the unfavourable conditions and the death is rapid and at uniform rate. The number of dead cells exceeds the number of live cells. Some organisms which can resist this condition can survive in the environment by producing endospores. By plotting the size or weight of an organism against time, the growth curves can be obtained. In this phase bacteria death due to lack of nutrition and increase and decrease temperature. Finally after a variable period the entire population dies and culture medium sterile.

Physics Questions

Logistic growth – In nature, a given habitat has enough resources to support maximum possible number, beyond which no further growth is possible. • The living differentiated cells, that by now have lost the capacity to divide can regain the capacity of division under certain condition is dedifferentiation. Interactions between populations of two species are of various types such as ‘competition’, ‘predation’, ‘parasitism’ , ‘commensalism’ and ‘mutualism’. Populations have attributes, but the individual organisms do not have attributes like natality, mortality, sex ratio and age distribution.

It was invented in the early 20th century by Sir Jagadish Chandra Bose. Needs to review the security of your connection before proceeding. Biotic community is an assemblage of populations of different species present in an area exhibiting interdependence and interactions. The plants which adapt to extreme habitats such as dry and wet are called xerophytes and hydrophytes, respectively.

types of curves are obtained in the growth of organism

As the bacterial population continues to grow, all the nutrients in the growth medium are used up by the microorganism for their rapid multiplication. This result in the accumulation of waste materials, toxic metabolites and inhibitory compounds such as antibiotics in the medium. This shifts the conditions of the medium such as pH and temperature, thereby creating an unfavourable environment for the bacterial growth. The reproduction rate will slow down, the cells undergoing division is equal to the number of cell death, and finally bacterium stops its division completely. The cell number is not increased and thus the growth rate is stabilised.

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The dynamics of the bacterial growth can be studied by plotting the cell growth versus the incubation time or log of cell number versus time. The curve thus obtained is a sigmoid curve and is known as a standard growth curve. The increase in the cell mass of the organism is measured by using the Spectrophotometer. The Spectrophotometer measures the turbidity or Optical density which is the measure of the amount of light absorbed by a bacterial suspension. Thus the increasing the turbidity of the broth medium indicates increase of the microbial cell mass .The amount of transmitted light through turbid broth decreases with subsequent increase in the absorbance value.

types of curves are obtained in the growth of organism

List the different attributes that a population has and not an individual organism. Development is controlled by intrinsic as well as extrinsic factors. • Cells produced by the dedifferentiated tissues again loose the capacity to divide and mature to perform specific function is called redifferentiation. • Development of interfascicular cambium and cork cambium from fully differentiated parenchymatous cells is the example of dedifferentiation. • Differentiated tracheary element cells loose their protoplasm, develop a very strong, elastic lignocellulosic secondary cell walls.

Attitude scale the attitude scale is a spacial type of questionnaire designed to measure people opinion on any special issues or event th… The temperature at which rapid rate of multiplication occurs . A population can be composed of individuals of different age groups.

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The human population at present is represented by the logistic growth. State the basis for the difference in the shape of the growth curves. Thermo word derived from Greek word ” thermolita ” meaning heat and philia meaning love .

When a population reaches this line its population size is stabilized by various environmental factors. The graph shows two types of population growth curve. A Verhulst−pearl logistic curve is also known as an S-shaped growth curve. With the help of suitable diagram describe the logistic population growth curve. The depletion of nutrients and the subsequent accumulation of metabolic waste products and other toxic materials in the media will facilitates the bacterium to move on to the Death phase. During this, the bacterium completely loses its ability to reproduce.

Tourists visiting high altitude areas such as Rohtang Pass or Mansarovar, experience altitude sickness. Its symptoms include nausea, fatigue and heart palpitations. This is because in the low atmospheric pressure of high altitudes, the body does not get enough oxygen. But, gradually we get acclimatised and stop experiencing altitude sickness. The body compensates low oxygen availability by increasing red blood cell production, decreasing the binding affinity of hemoglobin and by increasing breathing rate. The increased growth per unit time is termed as growth rate.

The S-shaped growth curve is also called a logistic growth curve. It describes a situation in which the population density of an organism increases slowly establishing itself then increasing rapidly, approaching an exponential growth rate. Many population of micro-organisms broadly follow this basic sigmoidal pattern. For example, when a fresh culture medium is inoculated with bacteria, sigmoidal or S-shaped growth curve is observed. The S-shaped curve is generated when a population approaches the environmental’s carrying capacity.

If a cell taken from the stationary phase is introduced into a fresh medium, the cell can easily move on the exponential phase and is able to perform its metabolic activities as usual. They is lag phase, long phase, stationary phase , death phase. When a microorganism is introduced into the fresh medium, it takes some time to adjust with the new environment. This phase is termed as Lag phase, in which cellular metabolism is accelerated, cells are increasing in size, but the bacteria are not able to replicate and therefore no increase in cell mass. The length of the lag phase depends directly on the previous growth condition of the organism. When the microorganism growing in a rich medium is inoculated into nutritionally poor medium, the organism will take more time to adapt with the new environment.

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