Practice 4.1 Species, communities and ecosystems with authentic IB Biology exam questions for both SL and HL students. This question bank mirrors Paper 1A, 1B, 2 structure, covering key topics like cell biology, genetics, and ecology. Get instant solutions, detailed explanations, and build exam confidence with questions in the style of IB examiners.
Paper
Level
Question 1
SLPaper 1A
Which is not essential in a viable mesocosm?
Question 2
SLPaper 2
1.[4]
Define habitat, population, community and ecosystem.
2.[6]
Outline how energy flows through an ecosystem.
3.[5]
Discuss the benefits and possible harmful effects of altering species by one example of genetic modification.
Question 3
SLPaper 2
The diagrams below show different organisms (not drawn to scale). 
1.[3]
State all the organisms shown above that belong to the following phyla.
Filicinophyta:
Arthropoda:
Mollusca:
2.[2]
Construct a possible food chain using three of the organisms shown opposite, stating the trophic level to which they belong.
3.[1]
State the initial energy source of the food chain constructed in (i).
Question 4
SLPaper 1A
The diagram below shows a population growth curve.
At which time in the population growth curve does the population size begin to decline?
Question 5
SLPaper 1A
How can a chi-squared test be used in ecological research?
Question 6
SLPaper 1A
In an area of forest measuring 100 m by 100 m , samples were taken to estimate the number of silver maple (Acer saccharinum) trees in the forest. The number of trees counted in each of five areas of was recorded.
Approximately how many silver maple trees are in the area of forest?
Question 7
SLPaper 1A
What is the classification of an organism that is able to make organic compounds from inorganic nutrients?
Question 8
SLPaper 1A
What is exchanged between a sealed mesocosm and the surrounding external environment?
Question 9
HLPaper 1A
The three-toed sloth, Bradypus variegatus, lives in tree tops where it feeds on leaves. It also feeds on algae and fungi which live in its fur.
[Source: Image from https://commons.wikimedia.org/wiki/File:Bradypus_variegatus.jpg. Christian Mehlführer Licensed under CC by 2.5 https://creativecommons.org/licenses/by/2.5/deed.en]
In which trophic group should the three-toed sloth be classified?
Question 10
HLPaper 1A
What is the trophic level of the Leopard seal?
[Source: adapted from http://amurdoch.tripod.com/yr4/AntFoodWeb.JPG]
I. Secondary consumer II. Tertiary consumer III. Quaternary consumer