AQA GCSE Biology (8461), Higher tier · Inheritance, variation and evolution › Understanding of genetics and evolution
Practise Extinction. 11 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Many species that once lived on Earth are now extinct. What does extinct mean?
There are no living individuals of the species left
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Many species that once lived on Earth are now extinct.
(a) What does extinct mean?[1]
(b) Which two of the following could cause a species to become extinct? Tick (✓) two boxes.[2]
A new disease
A new predator
An increase in the food supply
A decrease in the number of competitors
An increase in the area of habitat
(c) Give one other factor that could cause a species to become extinct.[1]
Show the answer and mark scheme
(a)Answer: There are no living individuals of the species left
there are no living individuals of the species left (anywhere)
(b)Answer: A new disease; A new predator
(c)
new / more successful competitors
changes to the environment / climate over geological time
a single catastrophic event, e.g. an asteroid collision / massive volcanic eruption
habitat destruction (by humans)
hunting / overfishing by humans
Question 2Medium6 marks
A species of flightless bird lived only on one small island. The birds nested on the ground. In 1880, ships brought rats to the island for the first time. Rats eat eggs and chicks. {table} shows the number of breeding pairs of the bird on the island.
[object Object]
(a) Calculate the percentage decrease in the number of breeding pairs between 1870 and 1910.[2]
(b) Suggest why the arrival of rats caused this species of bird to become extinct.[3]
(c) Suggest one other factor that may have contributed to the extinction of this bird.[1]
Show the answer and mark scheme
(a)Answer: 74.2%
(1200 − 310) ÷ 1200 × 100
74.2 (%)
(b)
rats were a new predator (on the island)
the birds had no adaptations / defences against rats (e.g. they nested on the ground)
rats ate eggs / chicks, so fewer young survived to breed
(so) deaths were greater than births / the population kept falling
the birds could not fly away / lived only on this island, so they could not escape
(c)
rats may have competed with the birds for food
rats / people may have brought a new disease
habitat destruction by people who arrived on the ships
hunting by people
Question 3Hard8 marks
About 66 million years ago, a large asteroid hit the Earth. Scientists think that about three-quarters of all species on Earth became extinct soon afterwards, including most dinosaurs. The impact threw huge amounts of dust into the atmosphere, which blocked much of the sunlight for several years.
(a) Explain how blocking sunlight could cause large animals, such as plant-eating dinosaurs and the carnivores that ate them, to become extinct.[4]
(b) Many small animals that ate seeds, insects or dead material survived. Suggest why.[2]
(c) Explain how fossils could show that many species became extinct at about the same time.[2]
Show the answer and mark scheme
(a)
less light so less photosynthesis
(so) many plants / producers died / less plant biomass was produced
herbivores had less food so starved / died
carnivores had less prey / food so died
large animals need large amounts of food
temperatures fell, so many plants and animals could not survive
(b)
seeds can survive for a long time without light / seeds were still available after plants died
there was plenty of dead material (after many organisms died)
small animals need less food
small animals can shelter / burrow to avoid the cold
small animals reproduce quickly, so populations could recover
(c)
fossils of many species are found in rock layers older than 66 million years
but are not found in younger rock layers (above the 66-million-year layer)