A mutation question from the Indian National Biology Olympiad

A mutation question from the Indian National Biology Olympiad

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DNA was isolated from wild type (Gal+) and mutant (Gal-) E. coli cells and separated by density gradient centrifugation technique. DNA from Gal- strain acquired a lower position. This indicates that the mutation is caused by:

(a) deletion (b) insertion (c) mis-sense mutation (d) point mutation

Me and my friends had an extended discussion on this question and we all agreed that since the Gal- strain acquired a lower position, it was obviously more dense than Gal+ strain. Now, one of them claimed that if the volume were to remain constant, then mass is directly proportional to density hence the insertion mutation should cause increase in mass corresponding to a similar increase in density. I am not convinced by this explanation. They also said that, "Keeping the volume constant is a necessity since the experiment would lose its meaning otherwise". I am curious to know how far these assertions are correct.

After doing some research on this topic on the internet, I found a paper related to this question :

Mutations caused by the insertion of genetic material into the galactose operon of Escherichia coli

The answer given by the organizing committee of the 2nd Indian National Biology Olympiad was (b) insertion.

What could be the possible explanation for such an occurrence? Me and my friends are still unable to grasp the logic behind it even after going through different papers and books.

Now, one of them claimed that if the volume were to remain constant, then mass is directly proportional to density hence the insertion mutation should cause increase in mass corresponding to a similar increase in density.

I don't think that's quite how it works. You don't worry about the volumes being used. In those experiments (I don't know that anyone does them anymore) the DNA is in a solution of really salty water. Larger molecules get pushed more to the bottom of the tube, so the mutant DNA is larger, since it was close to the bottom.,molecules%20based%20on%20density%20alone.

Thus, centrifugal force pushes the larger components of a mixture farther from the rotor and closer to the bottom of the tube.

Larger DNA means an insertion. Point mutations are not detectable with this method.

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As the premier high school biology student competition worldwide, we aim to identify, inspire, empower and support the next generation of leaders in the life sciences and to develop their international network.


To value curiosity and to empower young biologists to develop their interest in life sciences.


To shape an international network of biology talents and future life science leaders.


To identify highly gifted biology students and to stimulate their talents further.


To encourage cross-cultural dialogue by bringing together biology students from around the world.


To set new standards in the education and assessment of highly gifted biology students.

IBO 2021 in Portugal

A virtual IBO Challenge 2021 is scheduled from 18-23 July 2021 by our wonderful hosts from Lisbon / Portugal. Find out more at or our news section.

Top Scholars

Congratulations to Kevin Fan (photo above) and Derrick Liang (photo below) for placing first in the 2019 competition, among schools in Canada and international schools, respectively. Both students are in Grade 11: Kevin at St. George's School (Vancouver, BC) and Derrick at Thomas Jefferson High School for Science and Technology (Alexandria, VA)

Congratulations to Albert Cheng (photo above) and Purab Patel (photo below) for placing tied for 1st of 3,433 eligible contestants from 277 schools within Canada in the 2018 competition. Albert, who also placed 1st in the 2017 competition, is in Grade 11 at University of Toronto Schools (Toronto, ON). Purab, also in Grade 11, placed tied for 19th in the 2017 competition and attends Marc Garneau Collegiate Institute (Toronto, ON), the Top School in Canada this year in the competition. Andrew Ding, from Adlai E. Stevenson High School (Lincolnshire, Illinois), placed 1st of 1,376 international students from 86 participating schools outside of Canada. Update (May 2019): Both Andrew and Purab will be studying Life Sciences at U of T in Sept. 2019 Andrew as a U of T National Scholar.

National Biology Competition
Department of Ecology & Evolutionary Biology
University of Toronto (St. George Campus)
25 Willcocks Street, Rm. 3055, Toronto, ON M5S 3B2
416.978.6178 | FAX: 416.978.5878 | contact via email | privacy policy

National Standard Examination in Biology (NSEB) Solved Paper 2016 Part-1

Get unlimited access to the best preparation resource for CTET-Hindi/Paper-1 : get questions, notes, tests, video lectures and more- for all subjects of CTET-Hindi/Paper-1.

Q: 1. Nitrogen bend ′ avoided by diving mammals like whales because

(A) Their blood has low partial pressure of Nitrogen at all time

(B) Their lungs are filled with nitrogenous air before diving

(C) Peripheral circulation is minimal while diving

(D) They have very low metabolic rate while diving

Q: 2. A frog ′ egg is centrifuged to disturb its contents. Which of the following is correct

(A) Abnormal development may occur since the animal pole and vegetal pole are reversed

(B) Abnormal development may occur since the grey crescent is shifted vertically

(C) Abnormal development may occur since the grey crescent is shifted horizontally

(D) Abnormal development may occur since the heavier proteins are shifted to the vegetal pole

Q: 3. The predator population in a habitat is an indicator of health becauses

(A) Predator keep a check on the population of tertiary consumers

(B) Predators control the consumption of primary consumers

(C) Predators selectively hunt the weaker members of consumers

(D) Predators enhances population of decomposers

Q: 4. The key events in embryo development are given below. Which is the correct order of sequences

Q: 5. The molecules absorbed and secreted in the lumen by the cells of malpighain bodies of cockroach are respectively

Q: 6. The least percentage of water is encountered in the

(A) Fluid in convoluted tubule

(B) Filtrate in Bowman՚s capsule

(C) Blood plasma in glomerulus

(D) Filtrate in renal capsule

Q: 7. Some animals have adapted specific niche. In this specialization, some organs become well

Developed at the expense of others that become vestigial

Select the correct match of the animals

Q: 8. Which of the following statements is incorrect

(A) cDNA is synthesized from mRNA

(C) cDNA cannot be expressed outside a eukaryotic cell

(D) Size of cDNA is shorter than the original DNA in a eukaryotic cell

Q: 9. The Km value of an enzyme substrate reaction is a measure affinity of the enzyme for its substrate. In presence of a competitive inhibitor, which of the following is true?

(A) The Km and Vmax will increase

(B) The Km will increase but Vmax will remain unaltered

(C) The Km will remain same but Vmax increase

(D) The Km will remain same but Vmax will decrease

For detailed explanations and answers visit - NSEB Answers with detailed explanations

Exam Content

The exam questions will cover material that a senior high school biology student is likely to have come across in their studies. The content of the exam will reflect the similarities in the secondary school biology curricula among the provinces. The major topics covered on the exam include:

  • General biochemistry: basic chemical concepts, chemical bonds, biochemical reactions, biologically important organic molecules
  • Cell structure and processes: cell structure and function, membrane structure, transport across membranes
  • Cell metabolism: energy in the cell, enzymes, cellular respiration, photosynthesis, mitosis, cell cycle
  • Genetics: meiosis, sexual and asexual reproduction, Mendelian inheritance, DNA, genes and chromosomes, protein synthesis, mutation, genetic disorders in humans, gene expression and manipulation
  • Evolution: historical context for evolutionary theory, evidence for evolution, population genetics, evolutionary mechanisms, adaptation, speciation, extinction
  • Biological diversity: taxonomy, phylogeny, origin of life, microbial, fungal, plant, and animal diversity
  • Plant structure and function: structure, growth, and reproduction, transport mechanisms, growth regulators
  • Vertebrate structure and function: digestion, circulation, gas-exchange, reproduction, development, homeostasis, excretion, and nervous, endocrine, and immune systems
  • Ecology: species interactions, matter exchange and energy flow, population dynamics, human ecology, conservation biology
  • "Hot" biology topics in the news

National Biology Competition
Department of Ecology & Evolutionary Biology
University of Toronto (St. George Campus)
25 Willcocks Street, Rm. 3055, Toronto, ON M5S 3B2
416.978.6178 | FAX: 416.978.5878 | contact via email | privacy policy

Conduction of the examination

The National Science Olympiad is executed at two levels.

For Level 1, three dates are allowed. Each school is allowed to select a date of own choice for NSO. Set of questions varies on different dates. After selecting a date, changing of date is not allowed.

The exam is conducted during school hours.

Exam Pattern

1 to 4Logical Reasoning, Science, Achievers Section
5 to 10Logical Reasoning, Science, Achievers Section
11 & 12Physics & Chemistry, Mathematics/Biology, Achievers Section

Level 1 is taken as an objective-type question test of 60 minutes consisting of 35 multiple choice questions (For Class 1 – 4) and 50 multiple choice questions (For Class 5 – 12).

Different question papers are set for different classes. The medium of exam is English. Generally, CBSE, ICSE, ISC and State Board Syllabuses are followed during setting the questions.

Selected Olympiads of Class 3 to 12, who appeared at the Level 1 test is allowed to appear at the Level 2 test.

Eligibility of appearing at Level 2 Test

Here is the list the eligibility to appear National Science Olympiad 2019 Level 2 Exam conducted by Science Olympiad Foundation (SFO).

1. Top 5% Level 1 succeeded Olympiads of each class may appear at the Level 2 test. Each section of the question papers has different weightage.

2. Top 25 rankers of Level 1 from every class from every zone.

3. A class topper of Level 1 may qualify for the Level 2 test if minimum 10 students appear from that class of that school at the Level 1 and that topper must have scored at least 50% marks at the Level 1. For section wise registration, the topper will be considered irrespective of sections, but respective of classes. Section topper will win a gold medal, but wouldn’t qualify for Level 2, if he/she don’t be the class topper.

NSEB (National Standard Examination in Biology) Offical Previous Years (Past) Papers All Sets|Shifts|Slots|Days (Free/Without Login PDF Download) from 2009-2021

1 Olympiad Topper Best Preparation Platform [ Olympiad Upd. ]

The Olympiad Topper was introduced as a common platform for all students who wish to participate in the Olympiad exams conducted across the world. It aims to aid students in preparing for the exams. It is a one-stop destination for students to find everything that they need to su…

2 Why Should We Include Olympiad in Academics and Their Benefits? [ Olympiad Upd. ]

Olympiad exams promote the learning of life skills in students by boosting confidence, enhance problem-solving and reasoning skills based on the fundamental concept. The method of questions set for Olympiads driven to increase the knowledge and application of concepts in an integ…

3 IMO Results 2019-20 Declared [ Olympiad Upd. ]

IMO was conducted on 5 th Dec and 17 th Dec 2019. IMO Results 2019 - 20 Are Declared. Enter Your Roll No. to Check IMO Results. IMO Results for students of classes 1 to 12.

4 NSO Results Declared 2019-20 [ Olympiad Upd. ]

NSO Result 2019 - 20 - SOF has declared the level 1 result of NSO 2019 - 20 in online mode at sofworld. org on December 27,2019. SOF NSO 2019 Level 1 result for classes 1 to 12 can be accessed through roll number.

5 IEO Results Declared 2019-20 [ Olympiad Upd. ]

IEO Result 2019 - SOF has declared IEO 2019 result on December 3,2019 on results. sofworld. org. Students need to visit the SOF official website to check the result of IEO 2019. They will have to enter their roll number to access the SOF IEO result 2019.

IEO Results 2019 - 20 Declared

6 NSO Result 2019-20 [ Olympiad Upd. ]

SOF has declared the level 1 result of NSO 2019 - 20 in online mode at sofworld. org on December 27,2019. SOF NSO 2019 Level 1 result for classes 1 to 12 can be accessed through roll number. National Science olympiad result 2019 for level exam contains the students՚ details, mark…

Stage I: National Stan d ar d Examination in Biology (NSEB)

All In d ian stu d ents who are born on or after July 1, 1993 an d , in a d d ition, are in Class XII or lower as of November 30, 2012, are eligible to appear for NSEB 2012 -- 2013. A stu d ent may appear for more than one subject provi d e d the examination sche d ule allows it. See information about the examination sche d ule un d er various subjects. Stu d ents who have passe d Class XII are not eligible to enroll for NSEB.

It is the stu d ent's res ponsibility to ensure that the eligibility criteria are satisfie d . In case at any stage of the program it is foun d that the stu d ent d oes not satisfy the eligibility criteria, he/she may be d isqualifie d from the program.

The syllabus for NSEB is broa d ly equivalent to the senior se co n d ary level (Class XI an d Class XII) of CBSE Biology. This is only a rough gui d eline, an d there is no d etaile d syllabus given for NSEB.

Question Paper:
NSEB emphasizes co mprehension of the subject, not rote memory. Its format will be as follows:
The question paper will co nsist of 80 multiple choice questions, each with only one of the four options co rrect.
Language : English.

    Eligibility Clause: A can d i d ate must secure a s co re equal to or greater than a Minimum A d missible S co re (MAS) to be eligible for the Stage II INO exam lea d ing to the International Olympia d . The MAS for a given subject will be 40% of the maximum s co re in that subject.

For any queries or clarifications an d for any d ifficulties regar d ing enrollment for NSEB, please co ntact:
Prof. M. L. Oglapurkar
Co -or d inator (NSE)
IAPT Office, I.I.E. Campus,
128/2, J. P. Naik Marg, Kothru d , Pune - 411 038.
Tel : (Off.) 020 - 25420163.
(9:00 AM to 7:00 PM)
Email: [email protected]
Prof. R.M. D harkar
Chief Co -or d inator (IAPT Examinations)
Email: rm d [email protected] co m

What to Look for in High School Science Research Competitions

The above list certainly doesn't include every science competition for high schoolers, and if you don't find one that quite fits what you're looking for, feel free to do some additional research of your own. However, use judgement when considering unknown competitions, especially if they are new or you can't find much information about them beyond a website or their social media. Also be wary of those that charge large fees to participate.

Quality science competitions will have a clear and detailed website that explains what the competition is, who is eligible, how you can participate, and who you can contact to learn more. It's not required for them to be backed by an academic or government entity (such as the Department of Energy) or a well-known corporation (such as Toshiba), but having that name recognition can help solidify their legitimacy. Additionally, older competitions, and those that are national (rather than just local or regional) typically are better known and can stand out more on college applications. While some competitions offer significant prize money, just because a certain competition has smaller/no prizes doesn't mean they're not worth your time. Winners may receive other benefits, such as mentorship or invitations to conferences where they can network.

If you're ever unsure about a science competition, ask your science teacher or guidance counselor about it they often know a lot about these things and can advise you if you should participate or focus your efforts elsewhere.

Importance of Olympiad Exams

Olympiad Exams aims to provide a unique competitive platform, identify young geniuses, and create a future talent pool.

  • Olympiad Exams are not just an exam it does a lot more to bring out students' best. Giving at least one Olympiad Exam motivates students to strive for better.
  • A rank in any Olympiad Exams will develop confidence and motivate the students & their parents. Most importantly, Olympiad Exams help parents in identifying the real talent and interests of their children.
  • Olympiad Exam problems are being tricky and more conceptual, so it helps students understand the topic well. It ultimately improves routine class results.
  • Olympiad Exams help cultivate a kind of analytical thinking that is very helpful in an entrance examination such as IIT-JEE or any other high-level competitive entrance exam.

Benefits of Olympiad Exams

Olympiads Exam not only improves logical thinking but also gives a career path to young minds. Given below are the significant benefits of giving Olympiad Exams.

  • It will always help you to learn , assess , and improve .
  • It help school students to test the conceptual understanding, logical thinking, and potential of reasoning.
  • It also enhances logical thinking, analytical skills, and speed working and gives a career-oriented path to young students.
  • Olympiad Exams, as conducted by various government and private foundations for students from primary to senior secondary levels, can show their talent at the international, national, or state level.