DP Biology (last assessment 2024)

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Question 22M.2.SL.TZ2.1b

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Date May 2022 Marks available [Maximum mark: 3] Reference code 22M.2.SL.TZ2.1b
Level SL Paper 2 Time zone TZ2
Command term Predict Question number b Adapted from N/A
b.
[Maximum mark: 3]
22M.2.SL.TZ2.1b

There is growing evidence of a decrease in bee populations. This decrease is a serious problem because of their valuable role as pollinators in the ecosystems where they live. Neonicotinoid pesticides have been implicated in this decrease because they have been found at trace levels in the nectar and pollen of crop plants and in the bee colonies.

Scientists placed colonies of a species of bumblebee, Bombus terrestris, in the laboratory to test the effects of different levels of a neonicotinoid on their development. They divided the colonies into three groups:

  • The control colonies were given a solution of water and sugar that resembled nectar produced by flowers.
  • A second group of colonies was given the same sugar solution containing a neonicotinoid dissolved in it at low concentrations, similar to those found in nature.
  • A third group of colonies was given the same sugar solution containing a neonicotinoid dissolved in it at high concentrations, similar to those found in nature.

After two weeks, all colonies were placed in the field to allow the bumblebees to feed naturally.

The mass of the colonies, including adult bumblebees, wax, honey and larvae, was recorded every week. The cumulative increase in mass was calculated and is shown on the graph.

[Source: Adapted from Whitehorn, P.R., O’Connor, S., Wackers, F.L. and Goulson, D., 2012.
Bumble Bee Colony Growth and Queen Production. Science, [e-journal] 336(6079), pp. 351–352.
http://dx.doi.org/10.1126/science.1215025.]

The number of queen bumblebees produced in each colony was recorded. New bumblebee colonies are started by a queen.

[Source: Adapted from Whitehorn, P.R., O’Connor, S., Wackers, F.L. and Goulson, D., 2012.
Bumble Bee Colony Growth and Queen Production. Science, [e-journal] 336(6079), pp. 351–352.
http://dx.doi.org/10.1126/science.1215025.]

(b)

Using the data in the graph, predict how the use of neonicotinoid pesticides will affect bumblebee populations.

[3]

Markscheme
  1. number of populations may/will decrease;
  2. both treatments decreased very significantly the number of queens;
  3. low treatment had (almost) the same effect as the high
    OR
    even low levels have as toxic/lethal effects as high levels;
  4. without new queens, new colonies cannot be founded;
  5. no/less/little reproduction (as only queens lay eggs);
  6. new colonies are essential to maintain bumblebee populations;

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