Genetics and DNA Quiz
Double helix, Mendel's peas, Dolly the sheep and CRISPR: 15 questions on the code of life.
What does the abbreviation DNA stand for?
Got a hunch? Pick the answer that feels right.
Deoxyribonucleic acid
DNA is short for deoxyribonucleic acid, named for its deoxyribose sugar and its location in the nucleus of cells, where it stores the instructions for building and running an organism.
Swiss chemist Friedrich Miescher first isolated DNA in 1869 from the pus in used surgical bandages, calling it nuclein.
What is the name of the twisted ladder shape of a DNA molecule?
Got a hunch? Pick the answer that feels right.
Double helix
DNA consists of two strands wound around each other in a double helix, with the sugar-phosphate backbones on the outside and paired bases forming the rungs of the ladder.
The double helix makes one complete turn roughly every ten base pairs, a distance of about 3.4 nanometres.
Which monk worked out the basic laws of inheritance by breeding pea plants in the 1860s?
Got a hunch? Pick the answer that feels right.
Gregor Mendel
Gregor Mendel grew and crossed around 28,000 pea plants in the garden of his monastery in Brno, tracking traits like seed colour to reveal that inheritance follows predictable ratios.
Mendel's 1866 paper was ignored for over 30 years and only rediscovered in 1900, long after his death.
In DNA, the base adenine always pairs with which other base?
Got a hunch? Pick the answer that feels right.
Thymine
Adenine forms two hydrogen bonds with thymine, while guanine pairs with cytosine using three. This strict complementary pairing is what lets DNA copy itself accurately.
In RNA, thymine is replaced by uracil, which is one of the quickest ways to tell the two molecules apart.
Which pair of sex chromosomes does a typical human male carry?
Got a hunch? Pick the answer that feels right.
XY
Humans typically have two sex chromosomes: females carry two X chromosomes while males carry one X and one Y, with the Y chromosome triggering male development in the embryo.
The Y chromosome is one of the smallest human chromosomes and carries only a few dozen protein-coding genes.
What kind of animal was Dolly, the first mammal cloned from an adult cell?
Got a hunch? Pick the answer that feels right.
Sheep
Dolly the sheep was born at the Roslin Institute in Scotland in July 1996, cloned from a mammary gland cell of an adult ewe, and her existence was announced to the world in 1997.
Dolly was named after the singer Dolly Parton, a nod to the type of cell she was cloned from.
Which two scientists published the double helix model of DNA in the journal Nature in 1953?
Got a hunch? Pick the answer that feels right.
Watson and Crick
James Watson and Francis Crick published their one page paper in April 1953, building their model with help from Rosalind Franklin's X-ray data and Maurice Wilkins at King's College London.
Watson, Crick and Wilkins shared the 1962 Nobel Prize in Physiology or Medicine; Franklin had died in 1958 and prizes are not awarded posthumously.
What is the term for the different versions of the same gene, such as those for blue or brown eyes?
Got a hunch? Pick the answer that feels right.
Alleles
Alleles are alternative forms of a gene found at the same position on paired chromosomes, and you inherit one allele of each gene from each parent.
Eye colour is actually controlled by many genes, which is why two blue-eyed parents can occasionally have a brown-eyed child.
Down syndrome is caused by an extra copy of which chromosome?
Got a hunch? Pick the answer that feels right.
21
Down syndrome, also called trisomy 21, occurs when a person has three copies of chromosome 21 instead of two, usually because the chromosomes failed to separate when an egg or sperm formed.
Chromosome 21 is the smallest human chromosome, which is partly why an extra copy is survivable while trisomies of larger chromosomes usually are not.
How many DNA bases make up one codon, the unit that specifies a single amino acid?
Got a hunch? Pick the answer that feels right.
Three
A codon is a sequence of three bases, and with four possible bases there are 64 possible codons to code for 20 amino acids plus the start and stop signals.
Because several codons specify the same amino acid, the genetic code is described as degenerate, which cushions the effect of many mutations.
Mitochondrial DNA is inherited from which parent?
Got a hunch? Pick the answer that feels right.
The mother only
Mitochondria, and the small loop of DNA inside them, come almost entirely from the egg cell, so mitochondrial DNA passes down the maternal line with very little change over generations.
Because of this pattern, geneticists trace every living human's mitochondrial DNA back to a woman nicknamed Mitochondrial Eve who lived in Africa over 100,000 years ago.
In which year was the Human Genome Project declared complete?
Got a hunch? Pick the answer that feels right.
2003
The International Human Genome Sequencing Consortium announced the project's completion in April 2003, about 13 years after it began, with a sequence covering roughly 92 percent of the genome.
The final gaps were not closed until 2022, when the Telomere-to-Telomere consortium published the first truly complete human genome sequence.
Which gene editing tool earned Emmanuelle Charpentier and Jennifer Doudna the 2020 Nobel Prize in Chemistry?
Got a hunch? Pick the answer that feels right.
CRISPR
Charpentier and Doudna showed in 2012 that the bacterial CRISPR-Cas9 system could be programmed to cut DNA at any chosen sequence, turning it into a precise tool for editing genes.
It was the first time a science Nobel Prize had been shared by two women without a male co-winner.
When Mendel crossed two pea plants that each carried one dominant and one recessive allele, what ratio of dominant to recessive appearance did he find in the offspring?
Got a hunch? Pick the answer that feels right.
3 to 1
Crossing two heterozygous plants produces offspring in a 3 to 1 ratio, because three of the four possible allele combinations contain at least one dominant allele and only one is purely recessive.
Mendel's famous 9:3:3:1 ratio appears when two traits are tracked at once, showing that different genes are inherited independently.
Whose rules state that in any DNA sample the amount of adenine equals thymine and the amount of guanine equals cytosine?
Got a hunch? Pick the answer that feels right.
Erwin Chargaff
Austrian-born biochemist Erwin Chargaff published these base ratios in 1950, and they were a vital clue that led Watson and Crick to the idea of complementary base pairing.
Chargaff was openly bitter that his findings underpinned a Nobel Prize he did not share, and he became a sharp critic of genetic engineering.
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All Science quizzes →About the Genetics and DNA Quiz
Every cell in your body carries about three billion letters of DNA, and if you stretched out the DNA in a single cell it would reach roughly two metres. Gregor Mendel worked out the basic rules of inheritance in a monastery garden using pea plants, decades before anyone knew what a gene was made of.
These 15 questions move from the basics, including what DNA stands for, base pairing and the shape of the molecule, through chromosomes and inheritance to modern landmarks such as the Human Genome Project and CRISPR gene editing. It suits biology students, science fans and anyone who has wondered why they have their grandmother's eyes.
You will find 15 multiple choice questions here, each with four options. Difficulty: Hard. Most people finish in about 6 minutes, and every answer comes with a short explanation and one extra fact worth keeping.
How to play
Read the question and pick one of the four answers. The correct answer is revealed straight away with a short explanation, then press Next question to keep going. At the end you get your score out of 15 and a full review of your round. Play again any time and the questions arrive in a fresh order. There is no timer and no account.
Good to know before you play
What does DNA stand for?
DNA stands for deoxyribonucleic acid, the molecule that stores genetic instructions in almost every living thing.
Who discovered the structure of DNA?
James Watson and Francis Crick published the double helix model in 1953, drawing on X-ray work by Rosalind Franklin and Maurice Wilkins.
Is this genetics quiz suitable for high school students?
Yes. The first ten questions cover standard high school biology, and the final few stretch into university level topics such as Chargaff's rules.
Answer key: all 15 questions with explanations
- What does the abbreviation DNA stand for?
Deoxyribonucleic acid DNA is short for deoxyribonucleic acid, named for its deoxyribose sugar and its location in the nucleus of cells, where it stores the instructions for building and running an organism. Swiss chemist Friedrich Miescher first isolated DNA in 1869 from the pus in used surgical bandages, calling it nuclein. - What is the name of the twisted ladder shape of a DNA molecule?
Double helix DNA consists of two strands wound around each other in a double helix, with the sugar-phosphate backbones on the outside and paired bases forming the rungs of the ladder. The double helix makes one complete turn roughly every ten base pairs, a distance of about 3.4 nanometres. - Which monk worked out the basic laws of inheritance by breeding pea plants in the 1860s?
Gregor Mendel Gregor Mendel grew and crossed around 28,000 pea plants in the garden of his monastery in Brno, tracking traits like seed colour to reveal that inheritance follows predictable ratios. Mendel's 1866 paper was ignored for over 30 years and only rediscovered in 1900, long after his death. - In DNA, the base adenine always pairs with which other base?
Thymine Adenine forms two hydrogen bonds with thymine, while guanine pairs with cytosine using three. This strict complementary pairing is what lets DNA copy itself accurately. In RNA, thymine is replaced by uracil, which is one of the quickest ways to tell the two molecules apart. - Which pair of sex chromosomes does a typical human male carry?
XY Humans typically have two sex chromosomes: females carry two X chromosomes while males carry one X and one Y, with the Y chromosome triggering male development in the embryo. The Y chromosome is one of the smallest human chromosomes and carries only a few dozen protein-coding genes. - What kind of animal was Dolly, the first mammal cloned from an adult cell?
Sheep Dolly the sheep was born at the Roslin Institute in Scotland in July 1996, cloned from a mammary gland cell of an adult ewe, and her existence was announced to the world in 1997. Dolly was named after the singer Dolly Parton, a nod to the type of cell she was cloned from. - Which two scientists published the double helix model of DNA in the journal Nature in 1953?
Watson and Crick James Watson and Francis Crick published their one page paper in April 1953, building their model with help from Rosalind Franklin's X-ray data and Maurice Wilkins at King's College London. Watson, Crick and Wilkins shared the 1962 Nobel Prize in Physiology or Medicine; Franklin had died in 1958 and prizes are not awarded posthumously. - What is the term for the different versions of the same gene, such as those for blue or brown eyes?
Alleles Alleles are alternative forms of a gene found at the same position on paired chromosomes, and you inherit one allele of each gene from each parent. Eye colour is actually controlled by many genes, which is why two blue-eyed parents can occasionally have a brown-eyed child. - Down syndrome is caused by an extra copy of which chromosome?
21 Down syndrome, also called trisomy 21, occurs when a person has three copies of chromosome 21 instead of two, usually because the chromosomes failed to separate when an egg or sperm formed. Chromosome 21 is the smallest human chromosome, which is partly why an extra copy is survivable while trisomies of larger chromosomes usually are not. - How many DNA bases make up one codon, the unit that specifies a single amino acid?
Three A codon is a sequence of three bases, and with four possible bases there are 64 possible codons to code for 20 amino acids plus the start and stop signals. Because several codons specify the same amino acid, the genetic code is described as degenerate, which cushions the effect of many mutations. - Mitochondrial DNA is inherited from which parent?
The mother only Mitochondria, and the small loop of DNA inside them, come almost entirely from the egg cell, so mitochondrial DNA passes down the maternal line with very little change over generations. Because of this pattern, geneticists trace every living human's mitochondrial DNA back to a woman nicknamed Mitochondrial Eve who lived in Africa over 100,000 years ago. - In which year was the Human Genome Project declared complete?
2003 The International Human Genome Sequencing Consortium announced the project's completion in April 2003, about 13 years after it began, with a sequence covering roughly 92 percent of the genome. The final gaps were not closed until 2022, when the Telomere-to-Telomere consortium published the first truly complete human genome sequence. - Which gene editing tool earned Emmanuelle Charpentier and Jennifer Doudna the 2020 Nobel Prize in Chemistry?
CRISPR Charpentier and Doudna showed in 2012 that the bacterial CRISPR-Cas9 system could be programmed to cut DNA at any chosen sequence, turning it into a precise tool for editing genes. It was the first time a science Nobel Prize had been shared by two women without a male co-winner. - When Mendel crossed two pea plants that each carried one dominant and one recessive allele, what ratio of dominant to recessive appearance did he find in the offspring?
3 to 1 Crossing two heterozygous plants produces offspring in a 3 to 1 ratio, because three of the four possible allele combinations contain at least one dominant allele and only one is purely recessive. Mendel's famous 9:3:3:1 ratio appears when two traits are tracked at once, showing that different genes are inherited independently. - Whose rules state that in any DNA sample the amount of adenine equals thymine and the amount of guanine equals cytosine?
Erwin Chargaff Austrian-born biochemist Erwin Chargaff published these base ratios in 1950, and they were a vital clue that led Watson and Crick to the idea of complementary base pairing. Chargaff was openly bitter that his findings underpinned a Nobel Prize he did not share, and he became a sharp critic of genetic engineering.
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