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Organisms And Populations

Question
CBSEENBI12001898
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(a) List any three ways of measuring population density of a habitat.

(b) Mention the essential information that can be obtained by studying the population of an organism. 

Solution

(a) Population density means number of individuals present per unit area. We can find out population density of a habitat by determining the population size. The different methods to study population size are as follows:-

(1) Total number: In this method the total number of organism in the population is counted. For example, in order to determine the number of bacteria growing in a Petri dish, their colonies are counted.

 (2) Relative densities- In this method relative density of the population is taken into account rather than counting the total number. For example - The number fish caught per trap gives the measure of their total population density in the given water body.

 

 

(3) Percent cover or biomass cover: For example in a population of 200 Parthenium plants and a single huge Banyan tree the percent cover of both are taken into account. 

(b) The study of population tells us a lot about the status of the species in the habitat. It tells us about -:

(i)The outcome of competition with another species.

(ii) The impact of a predator.

(iii) The effect of a pesticide application .

Some More Questions From Organisms and Populations Chapter

Fill in the blanks with suitable words :

1. The optimal capacity of the organism to produce offspring is called........................

2. Rapid increase in human population is called........................

3. Mathematical expression of the growth of population is called........................

4. Yeast cells grown in a culture medium show........................growth curve.

5. Main cause of population explosion is........................

State true or false :

Coin one word for the following statements :

1.Organism that can tolerate only a narrow range of salinity.

2. Plants that can survive a wide range of temperature.

3. Interaction of two species in which one is benefited while other is neither benefited nor harmed.

4. Number of births during a given period in the population that are added to the initial density.

5. the process of maintaing a constant body temperature.

A few organisms can tolerate and thrive in a wide range of temperature, they are called........................

Majority of organisms are restricted to a narrow range of temperature, such organisms are called ........................ 

The organisms ideally try to maintain the constancy of its internal environment by the process called........................

Mammals from colder climates have shorter ears and limbs to minimize heat loss. This rule is called........................ 

The parasites that feed on external surface of host organisms are called ........................

The parasites that live inside the body at different sites (liver, kidney, lungs, RBC etc.) are called........................

List two negative interactions between two species.

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