Practise Biotic factors. 14 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.
Ash dieback is a disease of ash trees caused by a fungus. The disease was first found in the UK in 2012. In some woodlands, most of the ash trees have now died.
(a) Is ash dieback a biotic factor or an abiotic factor? Give a reason for your answer.[1]
(b) Some species of insect and lichen live only on ash trees. Explain why these species could become extinct in the UK.[2]
(c) When ash trees die, more light reaches the woodland floor. Suggest how this could affect the plants growing on the woodland floor.[2]
(d) A small number of ash trees are not affected by the disease. Suggest how scientists could use these trees to help restore ash woodlands.[2]
Show the answer and mark scheme
(a)Answer: Biotic — caused by a living organism (a fungus)
biotic, because it is caused by a living organism / pathogen / fungus
(b)
ash trees provide food / shelter / a habitat for these species
(when the ash trees die) these species lose their only food / habitat, so they cannot survive or breed
(c)
more photosynthesis, so some plants grow more
(so) some species may increase in number / new species may grow / competition between ground plants may change
(d)
collect seeds from / breed from the unaffected trees (selective breeding)
plant their offspring, which are likely to inherit the alleles for resistance
Question 3Hard6 marks
A non-native shrub was planted in gardens and escaped into a nearby woodland. The shrub:
grows quickly, forming dense thickets up to 4 m tall
keeps its leaves all year round
has leaves that are not eaten by any native animals
produces flowers that provide nectar for bees in spring.
Explain how the arrival of the shrub could affect the woodland community.[6]
Show the answer and mark scheme
the shrub is a new competitor (a biotic factor)
its dense leaves shade the woodland floor all year, so native plants get less light and photosynthesise less
it also competes with native plants for space, water and mineral ions, so some native plants may die out locally
no native animals eat it, so nothing controls its spread
animals that feed on the native plants, e.g. insects, lose food and shelter, so their numbers fall
predators that feed on those animals then have less food
tree seedlings are shaded, so the woodland may not regenerate
bees gain nectar in spring, so some species may benefit
overall, biodiversity falls and the community becomes less stable
Marked with levels of response: the full level descriptors are in the app.