Mitochondrial DNA
1 card- 01
Mitochondrial DNA is inherited only from the mother. Why?
- A
Mitochondrial genes are on the X chromosome
- B
The egg contributes the cytoplasm — and all the mitochondria — of the embryo; the sperm's few mitochondria are destroyed after fertilisation
- C
Sperm have no mitochondria
- D
The father's mitochondria are recessive
- A
Cell membrane
1 card- 02
Why can oxygen and carbon dioxide pass straight through a cell membrane, while glucose and sodium ions cannot?
- A
Glucose and sodium are too heavy
- B
The membrane is made of protein that repels sugar
- C
Oxygen and CO₂ are smaller than the pores in the membrane
- D
The membrane's core is a double layer of lipids; small non-polar molecules dissolve through it, but polar or charged particles need a protein channel or carrier
- A
Osmosis
1 card- 03
A red blood cell is placed in pure water. What happens, and why?
- A
Nothing: the membrane blocks water
- B
It shrivels: water leaves the cell to dilute the surrounding water
- C
It swells slightly and stops: the cell wall resists
- D
It swells and bursts: water moves into the cell, where the solute concentration is higher
- A
Mitochondrion
1 card- 04
Why do heart muscle cells contain thousands of mitochondria, while a skin cell has far fewer?
- A
Mitochondria produce ATP by aerobic respiration, and cells that work continuously need a far greater energy supply
- B
Heart cells are larger and need more organelles to fill them
- C
Mitochondria store the oxygen that the heart needs
- D
Skin cells do not need energy
- A
Cellular respiration
1 card- 05
Where does most of the mass of a growing tree come from?
- A
Minerals absorbed from the soil
- B
Organic matter decomposing in the soil
- C
Water absorbed by the roots, which is retained
- D
Carbon dioxide from the air, fixed by photosynthesis
- A
Photosynthesis
1 card- 06
Where does the oxygen released by photosynthesis come from?
- A
From splitting carbon dioxide molecules
- B
From splitting water molecules
- C
From the chlorophyll
- D
From the air, which the leaf passes through
- A
Enzyme
2 cards- 07
An enzyme works well at 37 °C, poorly at 10 °C, and not at all at 70 °C. Why is the effect of heat not symmetrical?
- A
Cold merely slows molecular motion, which is reversible; heat unfolds the protein's shape, which is usually permanent
- B
Heat removes the enzyme's water
- C
Enzymes are only made at body temperature
- D
Cold enzymes stop working too, but more slowly
- A
- 08
What does an enzyme do to a reaction?
- A
Lowers the activation energy, so the reaction happens faster at body temperature; it is not used up
- B
Provides the energy the reaction needs
- C
Changes the products that the reaction makes
- D
Is consumed as the reaction proceeds
- A
Prokaryote
1 card- 09
Bacteria are prokaryotes; a yeast cell is a eukaryote. What is the defining difference?
- A
Eukaryotes are always multicellular
- B
Prokaryotes have no DNA
- C
Eukaryotic cells keep their DNA inside a nucleus and have membrane-bound organelles; prokaryotic cells have neither
- D
Prokaryotes have no cell membrane
- A
Virus
1 card- 10
Why are viruses often described as being on the border between living and non-living?
- A
They are too small to be alive
- B
They are made only of protein
- C
They contain no genetic material
- D
They have genes and evolve, but cannot metabolise or reproduce outside a host cell
- A
Antibiotic
1 card- 11
Why do antibiotics have no effect on a cold or flu?
- A
Viruses are too small for the antibiotic to reach
- B
Colds and flu are caused by viruses, and antibiotics target structures — such as cell walls — that only bacteria have
- C
Antibiotics only work on infections of the gut
- D
Cold viruses are resistant to all antibiotics
- A
Stem cell
1 card- 12
Every cell in your body carries the same DNA. Why, then, is a nerve cell so different from a liver cell?
- A
The DNA mutates differently in each tissue
- B
Different genes are switched on in each cell type; the rest of the genome is present but silent
- C
Each cell type has lost the genes it does not need
- D
Nerve cells have extra chromosomes
- A
Chromosome
1 card- 13
How many chromosomes does a normal human body cell contain, and how many does an egg or sperm contain?
- A
23 and 46
- B
46 and 46
- C
44 and 22
- D
46 and 23
- A
DNA replication
1 card- 14
Before a cell divides, it copies its DNA. How accurate is the copying?
- A
Perfect: DNA polymerase never makes mistakes
- B
About one error per hundred bases, corrected later by the immune system
- C
About one error per billion bases after proofreading — a handful of mutations per cell division across the whole genome
- D
Errors are common but only in non-coding DNA
- A
Genetic code
1 card- 15
DNA has four bases, and proteins are built from 20 amino acids. Why are amino acids encoded by groups of three bases?
- A
Three is the number of bonds a base can make
- B
Amino acids have three parts
- C
Two bases give only 16 combinations, too few for 20 amino acids; three give 64, which is enough with room for stop signals
- D
DNA strands come in threes
- A
Mutation
1 card- 16
Are mutations random?
- A
Mutations arise randomly with respect to their usefulness; selection is the non-random part
- B
Yes, and so is natural selection
- C
No: organisms produce the mutations they need
- D
No: mutations are always harmful
- A
Dominance (genetics)
1 card- 17
Having six fingers (polydactyly) is caused by a dominant allele, yet almost everyone has five. How can a dominant trait be so rare?
- A
Most people carry it but it is switched off
- B
It is only dominant in some families
- C
The dominant allele is slowly disappearing
- D
Dominance describes what happens when both alleles are present, not how common an allele is in the population
- A
Punnett square
2 cards- 18
Two parents both carry one allele for cystic fibrosis (both are Ff; the condition is recessive). What is the chance that a given child has cystic fibrosis?
- A
3 in 4 (75%)
- B
1 in 3 (33%)
- C
1 in 2 (50%)
- D
1 in 4 (25%)
- A
- 19
A plant with purple flowers (Pp) is crossed with a white-flowered plant (pp). Purple is dominant. What proportion of the offspring is expected to be white?
- A
3/4
- B
1/2
- C
None
- D
1/4
- A
Dihybrid cross
1 card- 20
Two pea plants heterozygous for both seed shape and colour (RrYy × RrYy) are crossed. What ratio of phenotypes is expected among the offspring?
- A
1 : 2 : 1
- B
9 : 3 : 3 : 1
- C
3 : 1
- D
1 : 1 : 1 : 1
- A
Sex linkage
1 card- 21
Red–green colour blindness is far more common in men than in women. Why?
- A
Women are protected by oestrogen
- B
The gene is on the X chromosome; a man has only one X, so a single faulty copy shows, while a woman needs two
- C
The gene is on the Y chromosome
- D
Men's eyes have fewer cone cells
- A
ABO blood group system
1 card- 22
A mother has blood group A and a father has group B. Could their child have group O?
- A
Yes, but only if the child is a girl
- B
Yes, if both parents are heterozygous (AO and BO): the child inherits O from each
- C
No: the child must be AB
- D
No: O is only possible if a parent is O
- A
Twin
1 card- 23
Identical twins have identical DNA. Why are their fingerprints different?
- A
Fingerprint ridges are shaped by tiny differences in the womb — pressure, position, growth rate — not by genes alone
- B
Fingerprints are inherited from different parents
- C
Their DNA is not actually identical
- D
One twin's prints are a mirror image of the other's
- A
Heritability
1 card- 24
'Height is 80% heritable.' What does this mean?
- A
About 80% of the variation in height between people in that population is associated with genetic differences
- B
Genes explain 80% of the height of each individual
- C
A person's height is 80% determined before birth
- D
80% of your height comes from your genes and 20% from your diet
- A
Epigenetics
1 card- 25
A cloned cat was born with a different coat pattern from its genetic donor. How is this possible?
- A
The clone received DNA from the surrogate mother
- B
Cloning introduced mutations
- C
The coat-colour gene is on the X chromosome, and which X is silenced in each cell is decided randomly during development
- D
Coat colour is not genetic
- A
Telomere
1 card- 26
Why can most human cells divide only a limited number of times?
- A
The protective caps on chromosome ends shorten with each division, and the cell stops dividing when they get too short
- B
Each division uses up mitochondria
- C
Cells are programmed to die after exactly 50 divisions
- D
The cell runs out of DNA
- A
Human evolution
1 card- 27
'If humans evolved from monkeys, why are there still monkeys?' What is wrong with the question?
- A
There are no monkeys left, only apes
- B
Monkeys will eventually become human
- C
Evolution stopped once humans appeared
- D
Humans did not evolve from modern monkeys; humans and monkeys share a common ancestor, and both lineages have evolved since
- A
Survival of the fittest
1 card- 28
In 'survival of the fittest', what does 'fittest' mean?
- A
Most intelligent
- B
Healthiest and most athletic
- C
Strongest and most aggressive
- D
Best at surviving and reproducing in the current environment — which may mean smallest, slowest or most cooperative
- A
Natural selection
1 card- 29
A population of bacteria is exposed to an antibiotic, and within weeks most of them are resistant. Which describes what happened?
- A
The antibiotic caused resistance mutations
- B
A few bacteria already carried resistance by chance; the antibiotic killed the rest and the survivors multiplied
- C
Each bacterium gradually got used to the drug
- D
The bacteria sensed the antibiotic and altered their genes to resist it
- A
Lamarckism
1 card- 30
A bodybuilder develops large muscles. Will their children be born with a tendency to larger muscles because of the training?
- A
Yes, but only through the father
- B
Yes: exercise strengthens the genes for muscle
- C
Yes, if the training happened before puberty
- D
No: changes acquired during life are not written into the DNA of the eggs or sperm
- A
Vestigiality
1 card- 31
Why do humans have an appendix, a tailbone and goosebumps?
- A
They are all essential for survival
- B
They develop only in people with certain diets
- C
They are inherited from ancestors in which they had a fuller function; evolution modifies what exists rather than designing from scratch
- D
They are recent mutations that have not yet been removed
- A
Convergent evolution
1 card- 32
Dolphins and sharks have strikingly similar streamlined bodies and fins. Are they closely related?
- A
No, but they share a recent common ancestor
- B
No: similar environments select for similar shapes in unrelated lineages — convergent evolution
- C
Yes: sharks evolved from dolphins
- D
Yes: dolphins are a kind of fish
- A
Speciation
1 card- 33
Horses and donkeys can mate and produce mules, yet they are considered separate species. Why?
- A
They have different numbers of legs
- B
Mules are not real animals
- C
Species are defined by appearance, and they look different
- D
Mules are almost always sterile, so the two populations cannot exchange genes over generations
- A
Common descent
1 card- 34
Humans share about 98.8% of their DNA sequence with chimpanzees. What does this figure mean?
- A
Only 1.2% of human genes are unique
- B
Humans are 98.8% chimpanzee
- C
Comparing the aligned sequences, about 1.2% of bases differ — around 35 million single-letter differences, plus larger insertions and deletions
- D
Chimpanzees and humans could interbreed
- A
Genetic drift
1 card- 35
An island is colonised by five birds from a mainland population, and after many generations the island birds all have an unusual beak colour that is rare on the mainland. What is the most likely explanation?
- A
The birds mutated to match the island
- B
Island birds are always more colourful
- C
The founder effect: the five colonists happened to carry the rare allele, so it started common on the island and drifted to fixation
- D
The island's food selected for that beak colour
- A
Lactose intolerance
1 card- 36
Most adults in the world cannot digest milk comfortably; most adults of northern European descent can. Which is the 'normal' human condition?
- A
Losing the ability after weaning is the ancestral state; keeping it is a mutation that spread in populations that kept dairy animals
- B
Both are equally common worldwide
- C
Being able to digest milk; intolerance is a disorder
- D
Neither: it depends entirely on childhood diet
- A
Sickle cell disease
1 card- 37
Sickle cell disease is severe and often fatal without treatment. Why has the allele that causes it remained common in parts of Africa?
- A
The mutation keeps re-occurring
- B
Sickle cells are better at carrying oxygen
- C
People with one copy are largely protected against malaria, so the allele is favoured where malaria is common
- D
The allele is dominant, so it spreads
- A
Cancer
1 card- 38
What is cancer, in cellular terms?
- A
Cells that have accumulated mutations letting them ignore the signals that limit growth, division and location
- B
An infection by foreign cells
- C
A failure of the immune system to make antibodies
- D
Cells that have lost their DNA
- A
Antibody
1 card- 39
Why does having had chickenpox usually protect you for life, while you can catch a cold again and again?
- A
Colds attack the immune system so it cannot remember them
- B
Chickenpox is only caught in childhood
- C
Memory cells remember the chickenpox virus, which barely changes; 'the cold' is over 200 different viruses that also mutate
- D
Chickenpox is a bacterium and colds are viruses
- A
Vaccine
1 card- 40
How does a vaccine protect against a disease?
- A
It presents a harmless version or piece of the pathogen so the immune system builds memory cells before the real infection
- B
It contains antibiotics that stay in the blood
- C
It strengthens the immune system in general
- D
It kills the pathogen if you later catch it
- A
Homeostasis
1 card- 41
Why do you shiver when cold and sweat when hot?
- A
They are negative-feedback responses: the body detects a deviation from 37 °C and acts to reverse it
- B
Shivering and sweating are side effects of illness
- C
The body cannot control its temperature
- D
They release excess energy
- A
Gene
1 card- 42
Is there a single gene for eye colour?
- A
No: at least eight genes contribute, with two (OCA2 and HERC2) accounting for most of the variation
- B
Yes: brown is dominant over blue, exactly as in a Punnett square
- C
No: eye colour is not inherited
- D
Yes, but it is on the Y chromosome
- A
Neuron
1 card- 43
Do we use only 10% of our brains?
- A
Yes: the other 90% is reserve capacity
- B
No: brain imaging shows activity throughout the brain, and damage to almost any region causes some deficit
- C
Yes: most of the brain is unused glial tissue
- D
No: we use exactly 50%
- A
Genome
1 card- 44
Which of these has the largest genome?
- A
A human (about 3 billion base pairs)
- B
A chimpanzee (about 3 billion base pairs)
- C
A fruit fly (about 140 million base pairs)
- D
A marbled lungfish (about 130 billion base pairs)
- A
Cell (biology)
1 card- 45
Roughly how many bacterial cells live on and in a human body, compared with the body's own cells?
- A
About a thousand times as many human cells
- B
Almost none: a healthy body is sterile inside
- C
About ten times as many bacteria as human cells
- D
About the same number — tens of trillions of each
- A
End of deck · 45 cards