Every card in Evolution and inheritance, Year 9
The whole deck, in order — so you can read it through before your child ever sees it.
- The passing of genetic information from one generation to the next
Heredity (inheritance)
HintIt is the reason features run in families.
WhyParents pass genes to their offspring in the egg and the sperm, which is why children resemble their parents and why features run in families. Features gained during life, such as a scar or a suntan, are not passed on, because they do not change the genes.
- A baby receives genes from both parents: ____ come from the mother's egg and the rest from the father's sperm.
half
HintThe two parents contribute equally.
WhyAn egg and a sperm each carry one set of genes, half the number found in a normal body cell. At fertilisation the two sets join, so the baby has a full set, with an equal share from each parent.
- Two sisters have the same mother and father, yet they look different from each other. Why did they not inherit exactly the same genes?
Every egg and every sperm carries a different mix of the parents' genes
HintMum and Dad hand on only half of what they hold, and not the same half twice.
WhyEach parent passes on only half of their genes, and which half is different every time an egg or sperm is made. Each child is therefore a new combination. Only identical twins, who grow from a single fertilised egg, share all their genes.
- In natural selection, the individuals best suited to their environment are more likely to ____ and ____, so their useful features are passed on to their ____.
survive; reproduce; offspring
HintStaying alive comes first, then having young, then what those young inherit.
WhyThese steps, repeated over many generations, make a useful feature more common in a population. Individuals without it are more likely to die before breeding, so their features become rarer. Nothing is chosen on purpose: the environment decides who lives long enough to breed.
- A few rabbits in a population have thicker fur than the rest. After a long run of very cold winters, almost all the rabbits have thick fur. Did individual rabbits grow thicker fur because they needed it?
No — the thick-furred ones survived and bred more, so the feature spread
HintAsk which rabbits were still alive each spring to have young.
WhyNatural selection works on differences that are already there. The thin-furred rabbits were more likely to die before breeding, so each generation contained a larger share of thick-furred ones. The population changed; no single rabbit did.
- On the Galapagos Islands, Darwin collected finches whose beaks differed from island to island. He later realised that each beak shape suited the type of ____ found on that island.
food
HintA thick, strong beak cracks hard seeds; a thin one picks out insects.
WhyThe finches had descended from one kind that reached the islands long before. On each island, the birds whose beaks happened to suit the local seeds, fruit or insects fed best and left more offspring. This variation was part of the evidence Darwin used when he worked out natural selection.
- Before Darwin, most people in Britain believed that each species had been created separately and had never changed. What did Darwin claim instead?
Species change gradually over many generations, by natural selection
HintHe pictured living things as branches growing from one shared tree.
WhyDarwin argued that living species have descended from earlier ones, and that the fit between an organism and its surroundings is produced by natural selection acting on variation over a very long time. Many people found the idea shocking because it challenged what they had been taught.
- Which flightless bird, found only on the island of Mauritius, died out in the 1600s within a century of sailors first landing there? (one word)
Dodo
HintIts name survives in the saying "as dead as a …".
WhyThe dodo had no natural predators and nested on the ground. It was first recorded by Dutch sailors in 1598, and the last widely accepted sighting was in 1662. It is the best-known example of a species driven to extinction by human activity.
- Sailors hunted the dodo, but hunting alone did not wipe it out. What else that arrived with the ships did more damage?
Introduced animals such as pigs, which ate its eggs
HintThe dodo nested on the ground, and the settlers brought livestock and pets.
WhyPigs, dogs, cats, rats and monkeys brought to Mauritius raided dodo nests and competed with the birds for food, while forest was cleared for farming. A change in the environment that a species is not adapted to cope with is the usual cause of extinction.
- Why can an extinct species never come back?
No individuals are left to reproduce
HintNew animals only ever come from parents.
WhyEvery organism is built from the genes of its parents. Once the last member of a species dies, its particular set of genes is gone and there is nothing to breed from. That is why extinction is final, and why endangered species are protected while some still survive.
- In the 1840s, most Irish farmers grew a single variety of potato. Why was one disease, potato blight, able to destroy almost the whole crop?
The plants were genetically alike, so none could resist it
HintIf one plant had no defence, ask what was true of its neighbours.
WhyWith little genetic variety, a disease that can attack one plant can attack them all. A crop or a wild population with plenty of variation is far more likely to contain some individuals that survive. Loss of variety makes living systems fragile.
- Pond A holds 100 animals, all of one species. Pond B holds 100 animals, ten each of ten species. Which pond has the higher biodiversity? (A or B)
B
HintCount the kinds of animal, not the individuals.
WhyBiodiversity is about variety. Both ponds hold the same number of animals, but the second contains ten times as many species, each with its own part to play in the food web.
- Aspirin was developed from a substance found in willow bark, and many other medicines began as chemicals in wild plants. How is this an argument for protecting biodiversity?
Species lost before they are studied may take useful substances with them
HintThink about the plants nobody has tested yet.
WhyWild species are a source of medicines, foods and materials, many of them still undiscovered. Each extinction removes possibilities for good. This is one of the practical reasons, alongside keeping ecosystems stable, for maintaining biodiversity.
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Keep what you learn
Here, nothing is saved. In your child’s own sky every card is scheduled — it comes back just before they’d forget it — and the professor who wrote it is one tap away.