How do ecologists estimate the total number of species present in the world?
Solution and Explanation
The diversity of living organisms present on the Earth is very vast. According to an estimate by researchers it is about seven millions.
The total number of species present in the world is calculated by ecologists by statistical comparison between a species richness of a well studied group of insects of temperate and tropical regions. Then these ratios are extrapolated with other groups of plants and animals to calculate the total species richness present on the Earth.
Top Questions on Biodiversity and Conservation
A biologist surveyed islands of different sizes and consolidated the results in the form of the data given below. Study the data carefully and answer the questions that follow.
- ICSE Class XII - 2026
- Biology
- Biodiversity and Conservation
Based on data (Birds decline, Plants % decline, Area decline), interpret two reasons for change in the population of migratory birds.
- ICSE Class XII - 2026
- Biology
- Biodiversity and Conservation
- Describe the In-situ and Ex-situ methods of biodiversity conservation.
- RBSE Class XII Exam - 2026
- Biology
- Biodiversity and Conservation
- Which of the following is not an alien species in India?
- AP EAPCET - 2025
- Zoology
- Biodiversity and Conservation
- Find the mismatched pair:
- AP EAPCET - 2025
- Zoology
- Biodiversity and Conservation
Questions Asked in CBSE CLASS XII exam
- The rate for the following reaction is given by: \[ A + B \rightarrow C, \quad \text{Rate} = k[A][B]^2 \] How is the rate affected if we double the concentration of B?
- CBSE CLASS XII - 2026
- Chemical Kinetics
- Find the general solution of the differential equation \[ y\log y\,\frac{dx}{dy}+x=\frac{2}{y}. \]
- CBSE CLASS XII - 2026
- Differential Equations
- A square loop of side 0.50 m is placed in a uniform magnetic field of 0.4 T perpendicular to the plane of the loop. The loop is rotated through an angle of 60° in 0.2 s. The value of emf induced in the loop will be:
- CBSE CLASS XII - 2026
- Electromagnetic induction
A racing track is built around an elliptical ground whose equation is given by \[ 9x^2 + 16y^2 = 144 \] The width of the track is \(3\) m as shown. Based on the given information answer the following:
(i) Express \(y\) as a function of \(x\) from the given equation of ellipse.
(ii) Integrate the function obtained in (i) with respect to \(x\).
(iii)(a) Find the area of the region enclosed within the elliptical ground excluding the track using integration.
OR
(iii)(b) Write the coordinates of the points \(P\) and \(Q\) where the outer edge of the track cuts \(x\)-axis and \(y\)-axis in first quadrant and find the area of triangle formed by points \(P,O,Q\).
- CBSE CLASS XII - 2026
- Integration
- Consider a cylindrical conductor of length \( l \) and area of cross-section \( A \). Current \( I \) is maintained in the conductor and electrons drift with velocity \( \vec{v}_d \, (|\vec{v}_d| = \frac{eE}{m} \tau) \), where symbols have their usual meanings. Show that the conductivity of the material of the conductor is given by \[ \sigma = \frac{n e^2 \tau}{m}. \]
- CBSE CLASS XII - 2026
- Current Density
Concepts Used:
Biodiversity and Conservation
The term ‘biodiversity’ is derived from the two words- ‘bios' which means life and ‘diversity’ i.e, differentiation or variation. Edward Wilson, the sociobiologist was the first to popularise the term ‘biodiversity’ in the year 1992. The term implies the occurrence of various plants and animals along with their variants such as biotypes, ecotypes and genes on earth. In our biosphere, the immense diversity or heterogeneity remains not only at the species level but also, at every level of biological organization that ranges from macromolecules in the cells to biomes.
Biodiversity and Conservation is a topic covered under the fifteenth chapter and Unit 5 of NCERT class 12 biology.