Investigating populationsAQA A-Level Biology: Flashcards
What these 14 flashcards ask
- Why are quadrats unsuitable for estimating the size of a population of beetles?
- How can quadrat positions be chosen randomly?
- Why must quadrat positions be random?
- How do you estimate a population from quadrat counts?
- What is a belt transect?
- When is a belt transect more useful than random sampling?
- State the mark-release-recapture formula.
- Which type of organism is mark-release-recapture used for?
- State two assumptions of mark-release-recapture.
- Why must the mark not harm the animal?
- Effect on the estimate if the marks wear off.
- A sample of 30 animals is marked. A second sample of 24 contains 6 marked. Estimate the population.
- Which statistical test could be used for the relationship between an abiotic factor and species abundance?
- Why does a significant correlation not prove that an abiotic factor causes a distribution?
Exam questions on Investigating populations
- An ecologist wants to estimate the number of dandelion plants in a meadow of area 2000 m². She places a 0.5 m × 0.5 m quadrat at 20 positions in the meadow and counts a total of 130 dandelion plants in the 20 quadrats.Calculate an estimate of the total number of dandelion plants in the meadow. Show your working.2 marks
- A student investigates how the percentage cover of a moss species changes along a 20 m line running from the edge of a woodland into an open field. She suspects that light intensity affects the distribution of the moss.Suggest two other abiotic factors that the student should measure or control to be confident that light intensity is responsible for the distribution of the moss.2 marks
- Ground beetles in a field were sampled using pitfall traps. On day 1, 86 beetles were caught, marked with a small dot of non-toxic paint on the underside of the body and released where they were caught. Three days later, 74 beetles were caught, of which 19 were marked.Calculate an estimate of the population size of the beetles. Show your working.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).