DP Biology (first assessment 2025)

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Question 23M.1A.SL.TZ1.20

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Date May 2023 Marks available [Maximum mark: 1] Reference code 23M.1A.SL.TZ1.20
Level SL Paper 1A Time zone TZ1
Command term Question number 20 Adapted from N/A
20.
[Maximum mark: 1]
23M.1A.SL.TZ1.20

Humans have persecuted predators such as coyotes (Canis latrans), causing severe reduction in the number of large carnivores throughout the world. The diagram represents part of a food web in Texas, USA.

[Source: Coyote: https://commons.wikimedia.org/wiki/File:2009-Coyote-Yosemite.jpg. CC-BY-SA 3.0; Yathin S. Krishnappa, Jan.
2009, Coyote from Yosemite National Park, California in snow.]
[Source: Fox: https://commons.wikimedia.org/wiki/File:Foxes_of_Island_Beach_State_Park_New_Jersey_(16324545492).jpg.
CC-Attribution 2.0; Anthony Quintano, Jan. 2015, Foxes of Island Beach State Park New Jersey.]
[Source: Rodent/Brown Rat: https://commons.wikimedia.org/wiki/File:Rattus_norvegicus_-_Brown_rat_02.jpg. CC-BY-SA-4.0
Zeynel Cebeci, May 2020; Brown Rat, Adana, Turkey.]
[Source: Lagomorph: https://commons.wikimedia.org/wiki/File:Eastern_Cottontail.JPG. CC 3.0. Taken by Gareth Rasberry,
Huntington Beach State Park, Murrells Inlet, South Carolina, USA.]
[Source: Nest Eggs: https://commons.wikimedia.org/wiki/File:Eastern_Phoebe-nest-Brown-headed-Cowbird-egg.jpg. CC 3.0.
Galawebdesign, June 2007, Eastern Phoebe (Sayornis phoebe) nest with one Brown-headed Cowbird (Molothrus ater)
egg.]


What is a possible outcome for the lagomorph population in this ecosystem if coyote numbers were controlled by killing them to reduce losses of domestic livestock?


A.  Decrease because there are fewer predators

B.  Increase because there are fewer foxes to eat them

C.  Decrease because there are more rodents for foxes to eat

D.  Increase because, although there are more foxes, there are also more rodents

[1]

Markscheme

D