1. Who is the father of modern genetics?
(a) Gregor Johann Mendel
(b) Hugo De Vries
(c) Charles Darwin
(d) Thomas Hunt Morgan
[Chhattisgarh P.C.S. (Pre) 2011]
Ans. (a) Gregor Johann Mendel
- Gregor Johann Mendel is credited as the founder of modern genetics for discovering the law of Inheritance.
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2. The classical Mendel’s work on his ‘laws of inheritance’ was performed on the organism –
(a) Drosophila
(b) Snapdragon
(c) Garden pea
(d) Sweet Pea
[U.P.P.C.S. (Mains) 2002]
Ans. (c) Garden pea
- Gregor Mendel was the first person to try hybridization with garden pea plants.
- He studied seven different characteristics of peas and came up with three laws:
- the Law of Dominance
- the Law of Segregation
- the Law of Independent Assortment.
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3. Mendel’s principle of inheritance is based on-
(a) Vegetative reproduction
(b) Asexual reproduction
(c) Sexual reproduction
(d) All of the above
[53rd to 55th B.P.S.C. (Pre) 2011]
Ans. (c) Sexual reproduction
- Mendel’s theory of passing on traits is based on how animals and plants reproduce sexually.
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4. Genome mapping relates to :
(a) Blood grouping
(b) Mapping of genes
(c) Mapping of nerve centers
(d) Mapping of brain
[U.P.P.C.S. (Pre) 2002]
Ans. (b) Mapping of genes
- Gene mapping is a technique used to find out where genes are located and how far apart they are on a chromosome.
- This is done by putting various types of markers, including genes, in their spots on the genome.
- All of these markers are then used to make a map of the genome.
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5. The unit of heredity in our body is called
(a) Chromosome
(b) DNA
(c) Gene
(d) Nucleus
[U.P.P.S.C. (GIC) 2010]
Ans. (c) Gene
- A gene is a unit of heredity that is made up of DNA.
- In humans, genes range in size from a few hundred to over two million DNA bases.
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6. Gene is
(a) A segment of DNA
(b) A segment of DNA and histone
(c) A segment of DNA, RNA, and histone
(d) All of the above
[Uttarakhand P.C.S. (Pre) 2016]
Ans. (a) A segment of DNA
- Each chromosome has a long and coiled DNA molecule, with small sections of it called genes.
- Usually, each gene has between 5000 and 100000 pairs of DNA molecules.
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7. The characteristics features of the genetic code are :
i. It is always universal
ii. It is a triplet of nucleotide bases corresponding to 20 amino acids
iii. It is non-overlapping, non-ambiguous, and commaless.
iv. It has a start and stop codon
Which of the statements given above are true?
(a) i, ii, and iv only
(b) i, iii, and iv only
(c) i, ii, and iii only
(d) All of the above
[M.P. P.C.S. (Pre) 2020]
Ans. (d) All of the above
- Living cells use the genetic code to turn information from DNA or mRNA into proteins.
- This code is made up of 64 combinations of 3-letter words (codons) that tell the cells which amino acids to use when making proteins.
- 61 of the codons code for amino acids and the other 4 tell the cells when to start and stop making the protein.
- The genetic code is always the same for all living things and is made up of codons that don’t overlap, are clear, and are repeated.
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8. Change in the base sequence within a gene is called:
(a) Mutation
(b) Cloning
(c) Fusion
(d) Breeding
[U.P.P.C.S. (Pre) 2020]
Ans. (a) Mutation
- A gene is the building block that is responsible for how we are inherited. When the sequence inside the gene changes, this is called a mutation.
- This mutation causes different forms of the gene which can be passed down to future generations.
- Mutations are the reason why we have genetic differences in the world, and they are also the driving force behind evolution.
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9. Hereditary symptoms are moved in the descendant of creatures by
(a) Ribosome
(b) Chromosome
(c) Plasma
(d) Lysosome
[R.A.S./R.T.S. (Pre) 1992]
Ans. (b) Chromosome
- The traits that are passed down from one generation to the next are carried by chromosomes.
- Chromosomes are made of nucleoproteins. The term “chromosome” was first used by Waldeyer.
- Chromosomes are small pieces of chromatin found in cells, and they contain genes.
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10. Which of the following is responsible for controlling the hereditary characteristics of the living cells?
(a) Enzyme
(b) Hormone
(c) RNA
(d) DNA
(e) None of the above/More than one of the above
[60th to 62nd B.P.S.C. (Pre) 2016]
Ans. (d) DNA
- DNA holds and moves genetic information, while RNA gives instructions to make proteins with the help of DNA and ribosomes.
- Some viruses, such as the Tobacco Mosaic virus and QB bacteriophage, use RNA instead of DNA as their inherited material.
- While DNA is usually the hereditary material in higher-level organisms, RNA usually acts as a messenger.
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11. Which of the following features of DNA makes it uniquely suited to store and transmit genetic information from generation to generation?
(a) Complementarity of the two strands
(b) Double helix
(c) Number of base pairs per turn
(d) Sugar-phosphate backbone
[I.A.S. (Pre) 2001]
Ans. (a) Complementarity of the two strands
- DNA consists of two strands that are connected together like a spiral.
- The outside of the DNA molecule is made up of sugar and phosphate, while the inside has chemicals called bases.
- These bases are paired up in a specific way: A always pairs with T, and G always pairs with C.
- There is also always the same amount of A as T and the same amount of G as C.
- This special pairing between the two strands of DNA helps store and pass on genetic information from generation to generation.
- It also helps cells copy and repair the information in the strands.
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12. Sexual reproduction causes genetic variation because of
(a) Blending of genes
(b) Chromosomal changes
(c) Shuffling of genes
(d) All of the above
[53rd to 55th B.P.S.C. (Pre) 2011]
Ans. (d) All of the above
- Sexual reproduction involves two parent cells that provide their traits to the offspring.
- This type of reproduction causes genetic variation due to the combination of genes, changes in chromosomes, and rearrangement of genes.
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13. Chromosomal theory of inheritance was given by
(a) Waldeiyer
(b) Mendel
(c) Sutton and Boveri
(d) Muller
[Jharkhand P.C.S. (Pre) 2021]
Ans. (c) Sutton and Boveri
- Walter Sutton and Theodor Boveri wrote papers in 1902 and 1903 suggesting that chromosomes are the carriers of genetic material.
- This theory was later proven by three scientists, de Vries, Correns, and von Tschermak, who found chromosomes in the nucleus.
- Thomas Hunt Morgan’s work on fruit flies in 1915 provided more evidence for the theory.
- Waldeyer coined the term “chromosome” to describe the stained filaments in the cell nucleus.
- This theory explains Mendel’s laws and puts forth the idea that genes are located at specific sites on chromosomes.
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14. Who first outlined the structure of the gene molecule (D.N.A.)?
(a) Dr. Maghnad Saha
(b) Dr. Stephan Hawking
(c) Dr. James Watson and Dr. Francis Crick
(d) Dr. Alexander Fleming
[M.P.P.C.S. (Pre) 1994]
Ans. (c) Dr. James Watson and Dr. Francis Crick
- James Dewey Watson (born April 6, 1928) was an American scientist who was known for discovering the double helix model of DNA with Francis Crick.
- In 1962, Watson, Crick, and Maurice Wilkins won the Nobel Prize in Physiology or Medicine for their work on the structure of nucleic acids and their impact on living things.
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15. James D. Watson and Francis Crick are associated with the discovery of
(a) Vaccine
(b) Structure of DNA
(c) Anti-malarial drugs
(d) Penicillin
[U.P.P.C.S. (Mains) 2012]
Ans. (b) Structure of DNA
- James Dewey Watson, born on April 6th, 1928, was an American scientist who is well-known for his research on DNA’s double helix structure.
- Along with Francis Crick and Maurice Wilkins, he was awarded the Nobel Prize in Physiology or Medicine in 1962 for this discovery, which had a large effect on life.
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16. Who has proposed for the first time the double helix model of DNA?
(a) Watson and Crick
(b) Fisher the Haldoni
(c) Lamark and Darwin
(d) Hugo de Vries
[U.P.P.C.S.(Pre) 2012]
Ans. (a) Watson and Crick
- James Dewey Watson, born on April 6th, 1928, was an American scientist who is famous for discovering the structure of DNA, a double helix.
- He, along with Francis Crick and Maurice Wilkins, was given the Nobel Prize in Physiology or Medicine in 1962 for this discovery, which had a huge impact on life.
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17. Nobel Prize-winning scientist James D. Watson is known for his work in which area?
(a) Metallurgy
(b) Meteorology
(c) Environmental protection
(d) Genetics
[I.A.S. (Pre) 2008]
Ans. (d) Genetics
- James Dewey Watson, born on April 6th, 1928, was an American scientist who became famous for his discovery of the double helix structure of DNA.
- He, alongside Francis Crick and Maurice Wilkins, was awarded the Nobel Prize in Physiology or Medicine in 1962 for this groundbreaking discovery, which greatly influenced life.
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18. Double-helical structure of DNA was given by whom?
(a) Jacob and Monod
(b) Watson and Crick
(c) H.G. Khorana
(d) None of the above
[U.P. P.C.S. (Pre) 2018]
Ans. (b) Watson and Crick
- In 1869, Friedrich Miescher discovered and separated DNA.
- Then in 1953, James Watson and Francis Crick gave us the double helix model of DNA.
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19. Who discovered DNA?
(a) James Watson and Francis Crick
(b) Gregor Mendel
(c) Johannsen
(d) Hargovind Khorana
(e) None of the above/More than one of the above
[64th B.P.S.C. (Pre) 2018]
Ans. (e) None of the above/More than one of the above
- In 1869, Friedrich Miescher found and separated the parts of DNA.
- Then in 1953, James Watson and Francis Crick showed us how DNA is shaped like a double helix.
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20. Har Gobind Khorana is credited for the discovery of
(a) Synthesis of Protein
(b) Synthesis of gene
(c) Synthesis of Nitrogenous
(d) None of these
[39th B.P.S.C. (Pre) 1994]
Ans. (a) Synthesis of Protein
- Robert W. Holley, Har Gobind Khorana, and Marshall W.
- Nirenberg was all given the Nobel Prize in Physiology or Medicine in 1968 for discovering the genetic code and how DNA helps create proteins.
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21. In the laboratory, who did the synthesis of DNA –
(a) Miller
(b) Khorana
(c) D. Weris
(d) Kelvin
[43rd B.P.S.C. (Pre) 1999]
Ans. (b) Khorana
- Robert W. Holley, Har Gobind Khorana, and Marshall W. Nirenberg were all awarded the Nobel Prize in Physiology or Medicine in 1968 for uncovering the genetic code and the role DNA plays in generating proteins.
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22. Who delivered the principle of ‘jumping genes’?
(a) Gregor Johann Mendel
(b) Tomas Hunt Morgan
(c) Barbara McClintock
(d) Watson and Crick
[I.A.S. (Pre) 1993]
Ans. (c) Barbara McClintock
- Barbara McClintock won the Nobel Prize in 1983 for her work on heredity in corn plants.
- She discovered that some parts of the DNA (transposons) can move from one chromosome to another, which she referred to as “jumping genes”.
- Her research also showed that these changes could lead to changes in the appearance of the corn grains.
- This work was important in understanding how development works.
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23. Which compound present in D.N.A. does not form an amino acid?
(a) Adenine
(b) Tyrosine
(c) Guanine
(d) Cytosine
[U.P.P.C.S. (Pre) 1994]
Ans. (b) Tyrosine
- Tyrosine is one of the 22 amino acids that help cells build proteins. Its code is UAC and UAU.
- It is not essential and has a polar side group. German chemist Justus von Liebig first found it in 1846 in cheese’s protein called casein.
- It is also known as tyrosyl when it is a side chain or a functional group.
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24. The sugar present in DNA is :
(a) Glucose
(b) Fructose
(c) Deoxyribose
(d) Ribose
[U.P. P.C.S. (Mains) 2016]
Ans. (c) Deoxyribose
- The sugar found in DNA is called deoxyribose.
- It is a type of five-carbon sugar called ribose.
- DNA is a molecule that carries important information and is mainly located in the nucleus of the cell.
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25. Ribozymes are :
(a) DNA
(b) RNA
(c) Proteins
(d) None of these
[Jharkhand P.C.S. (Pre) 2016]
Ans. (b) RNA
- Ribozyme is an enzyme made of RNA that helps to speed up chemical reactions, similar to protein enzymes.
- They are found in the ribosome, which links amino acids together to create proteins.
- Thomas R. Cech and Sidney Altman won the Nobel Prize in 1989 for discovering that RNA can act as a catalyst.
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26. Chromosome number in any species :
(a) increase by age
(b) decrease by age
(c) is constant
(d) increase with the weight
[Chhattisgarh P.C.S. (Pre) 2019]
Ans. (c) is constant
- The amount of chromosomes differs across species but is the same for each species.
- This number stays the same, no matter how old or heavy the animal is.
- In most animals, any change in the usual chromosome amount for that species is usually caused by a genetic disorder.
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27. Which of the following does not have a sex chromosome?
(a) Monkey
(b) Tiger
(c) Butterfly
(d) Lizard
[U.P.P.C.S. (Spl) (Mains) 2004]
Ans. (d) Lizard
- The karyotypes of different types of lizards in the Sceloporus genus show that it is not possible to tell the difference between male and female lizards just by looking.
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28. How many chromosomes are there in humans?
(a) 36
(b) 46
(c) 56
(d) 25
[U.P.P.C.S. (Pre) 1992 , U.P.P.C.S. (Pre) 1991]
Ans. (b) 46
- In humans, each cell usually has 46 chromosomes in total, which are split into 23 pairs.
- 22 of these pairs are the same in males and females and are called autosomes.
- The 23rd pair, the sex chromosomes, differ between males and females.
- Females have two X chromosomes (XX) and males have one X and one Y chromosome (XY).
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29. The number of chromosome pairs, found in the cells of the human body is –
(a) 21
(b) 22
(c) 23
(d) 24
[Uttarakhand P.C.S. (Pre) 2003]
Ans. (c) 23
- In humans, each cell usually has 46 total chromosomes, with 22 pairs being identical in both males and females.
- The 23rd pair, the sex chromosomes, differ between males and females.
- Females have 2 X chromosomes (XX), and males have one X and one Y chromosome (XY).
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30. Assertion (A): In human beings, the females play a major role in determining the sex of the offspring.
Reason (R): Women have two `X’ chromosomes.
Code :
(a) Both (A) and (R) are true and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true but (R) is not a correct explanation of (A).
(c) (A) is true but (R) is false.
(d) (A) is false but (R) is true.
[I.A.S. (Pre) 2000]
Ans. (d) (A) is false but (R) is true.
- The X chromosome is responsible for deciding the sex of an animal, like humans, and is present in all males and females.
- Females have two X chromosomes (XX) while males have one X and one Y chromosome (XY).
- A female baby is created when the male and female both have an X chromosome (44+XX), whereas a male baby is created when the male has an X and a Y chromosome (44+XY). So, in humans, it is the male that determines the sex of the baby.
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31. Male’s gene constituent is –
(a) XX
(b) XY
(c) X
(d) Y
[43rd B.P.S.C. (Pre) 1999]
Ans. (b) XY
- The X chromosome is part of the two chromosomes that control the biological sex of many animals, including humans.
- Males and females both have one pair of these chromosomes.
- Females have two X chromosomes (XX) and males have one X and one Y chromosome (XY).
- When a male and female reproduce, they can create either a male child (44+XY) or a female child (44+XX).
- Therefore, males are the main factor in deciding the gender of the offspring.
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32. Which combination of chromosomes in mankind gives birth to a male child?
(a) X of male and X of female
(b) X of male and Y of female
(c) Y of male and X of female
(d) Y of male and Y of female
[M.P.P.C.S. (Pre) 2005]
Ans. (c) Y of male and X of female
- The X chromosome is found in both males and females and is one of the two chromosomes that determine a person’s sex.
- Females have two X chromosomes (XX) while males have one X and one Y chromosome (XY).
- To have a female child, both the male and female must have at least one X chromosome (44+XX).
- To have a male child, the male must have a Y chromosome and the female must have an X chromosome (44+XY).
- In humans, it is usually the male who decides the sex of the baby
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33. Which of the following professional(s) are more likely to run the risk of a permanent change in their cell’s DNA?
1. Researchers using carbon 14 isotope
2. X-ray technician
3. Coal miner
4. Dyer and painter
Select the correct answer by using the codes given below :
Code :
(a) 2 only
(b) 1, 2, and 3
(c) 1, 2 and 4
(d) 1, 3, and 4
[I.A.S. (Pre) 1996]
Ans. (a) 2 only
- X-ray technicians are more likely than other people to have changes in their cells’ DNA that will stay permanent.
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