Attempt giving a clear definition of the term species
Solution and Explanation
Top Questions on Evolution
- (a) “The process of evolution of different species in a given geographical area starts from a point and literally radiates to other geographical areas.” Explain it with an example.
(b) Cite an example where more than one adaptive radiation has occurred in an isolated geographical area. Name the type of evolution your example depicts. - (a) "The process of evolution of different species in a given geographical area starts from a point and literally radiates to other geographical areas." Explain it with an example.
(b) Cite an example where more than one adaptive radiation has occurred in an isolated geographical area. Name the type of evolution your example depicts. - A few stages and their respective time period in the evolutionary history of human beings are mentioned in the flowchart given below:
- 15 mya — Primates walking like gorillas and chimpanzees existed.
- 3–4 mya — Man-like primates walked in Eastern Africa. Fossils of their bones were discovered.
- 2 mya — This ancestor lived in the East African grasslands and ate fruits.
- 1.5 mya — This hominid had a brain size of 900 cc and probably ate meat.
- [(a)] Name one primate about 15 mya.
- [(b)] Name one place where fossils of primates were discovered in Eastern Africa.
- [(c)] Name the ancestor that lived in the East African grasslands about 2 mya.
- [(d)] Name the hominid that was found around 1.5 mya.
The given graph shows the range of variation among population members, for a trait determined by multiple genes. If this population is subjected to disruptive selection for several generations, which of the following distributions is most likely to result?
Read the following passage and answer the questions that follow. According to evolutionary theory, every evolutionary change involves the substitution of a new gene for the old one and the new allele arises from the old one. Continuous accumulation of changes in the DNA coding for proteins leads to evolutionary differences. The chemical composition of DNA is basically the same in all living beings, except for differences in the sequence of nitrogenous bases. Given below are percentage relative similarities between human DNA and DNA of other vertebrates:
(a) What is the term used for the substitution of a new gene for the old one and the new allele arising from the old one during evolutionary process?
(b) Which one of the following holds true for the data provided in the above table?
- [(A)] Greater the evolutionary distance, greater are the differences in the nitrogenous bases.
- [(B)] Lesser the evolutionary distance, greater are the differences in the nitrogenous bases.
- [(C)] Greater the evolutionary distance, lesser are the differences in the nitrogenous bases.
- [(D)] Lesser the evolutionary distance, lesser are the differences in the nitrogenous bases.
(c) [(i)] To which category of evolution (divergent or convergent) does the following relationship belong? Justify your answer.
Human and Rhesus Monkey
OR[(ii)] Differentiate between Convergent and Divergent evolution.
Questions Asked in CBSE CLASS XII exam
- Analyse the role of Gandhiji after independence of India.
- CBSE CLASS XII - 2025
- Mahatma Gandhi and the Nationalist Movement
A current-carrying coil is placed in an external uniform magnetic field. The coil is free to turn in the magnetic field. What is the net force acting on the coil? Obtain the orientation of the coil in stable equilibrium. Show that in this orientation the flux of the total field (field produced by the loop + external field) through the coil is maximum.
- CBSE CLASS XII - 2025
- Magnetism and matter
- Sudha, Sudama and Sulochna were partners in a firm sharing profits equally. On 31st March, 2020, Sudha retired. On the date of retirement ₹ 2,40,000 became due to her. Sudama and Sulochana agreed to pay Sudha in four equal yearly instalments plus interest @ 10% p.a. on the unpaid balance starting from 31st March, 2021. The firm closes its books on 31st March every year.
Prepare Sudha’s loan account till it is fully paid.- CBSE CLASS XII - 2025
- Retirement and Death of a Partner
- Using integration, find the area of the region bounded by the line \[ y = 5x + 2, \] the \( x \)-axis, and the ordinates \( x = -2 \) and \( x = 2 \).
- CBSE CLASS XII - 2025
- Evaluation of Definite Integrals by Substitution
- Centurian Ltd. invited applications for issuing 2,00,000 equity shares of ₹ 10 each at a premium of ₹ 20 per share. The amount was payable as follows: On Application and Allotment – ₹ 20 per share (including premium ₹ 17 per share)
On First and Final call – ₹ 10 per share (including premium ₹ 3 per share)
Applications were received for 3,00,000 equity shares and allotment was made to the applicants as follows: (i) Applicants for 2,00,000 shares were allotted 1,50,000 shares.
(ii) Applicants for 1,00,000 shares were allotted 50,000 shares.
Excess money received on application and allotment was adjusted towards sums due on first and final call. Deepali, who had applied for 2,000 shares, failed to pay the first and final call money. Her shares were subsequently forfeited. Deepali belonged to Category (i).
Pass necessary journal entries for the above transactions in the Books of Centurian Ltd.
Open Calls-in-Arrears and Calls-in-Advance account, wherever necessary.- CBSE CLASS XII - 2025
- Accounting for Share Capital
Concepts Used:
Hardy-Weinberg Principle
Hardy Weinberg Law:
In a considerable size, random-mating population, the genotype and allele frequencies remain constant in the absence of any evolutionary influences from one generation to another. Influences include a choice of mate, natural selection, genetic drift, mutation, sexual selection, gene flow, genetic hitchhiking, founder effect, meiotic drive, population bottleneck, inbreeding, and assortative mating.
Assumptions for the Hardy Weinberg Principle
Following are a few assumptions for the law:
- Only sexual reproduction can take place.
- The mating process is random.
- The size of the population is indefinitely large.
- Entities are diploid.
- Generations do not overlap.
- Equality of allele frequencies in terms of sexes.
- No gene flow, selection, mutation, migration, or admixture.