Practice questions
Section A: Multiple Choice Questions (10 marks) (Each question is worth 1 mark. Choose the
correct answer from the options provided.)
1. The term niche in ecology refers to:
a) The physical environment where an organism lives.
b) The role and position a species has in its environment.
c) The genetic diversity within a population.
d) The competition between species for resources.
2. Which of the following biomes has the highest biodiversity?
a) Tundra
b) Desert
c) Tropical Rainforest
d) Grassland
3. A keystone species is:
a) The most abundant species in an ecosystem.
b) A species that has a disproportionately large effect on its environment relative to its
abundance.
c) The top predator in an ecosystem.
d) A species that creates physical changes in the environment.
4. Primary succession occurs:
a) After a natural disaster like a fire or flood.
b) In an area that was previously uninhabited, such as bare rock.
c) When one species replaces another in an established ecosystem.
d) In marine ecosystems after pollution has been removed.
5. The relationship between a bee and a flowering plant, where both benefit, is an example
of:
a) Parasitism
b) Commensalism
c) Competition
d) Mutualism
6. Which process is responsible for removing carbon dioxide from the atmosphere?
a) Respiration
b) Decomposition
c) Photosynthesis
d) Combustion
7. Eutrophication is caused by:
a) Excess nutrients in water bodies leading to algal blooms.
b) A decrease in oxygen levels in the soil.
c) The introduction of invasive species.
d) The warming of the planet due to greenhouse gases.
8. The carrying capacity of an ecosystem is:
a) The total number of species it can support.
b) The maximum population size of a species that the environment can sustain indefinitely.
c) The minimum viable population size needed for a species to survive.
d) The total biomass of all organisms in an ecosystem.
9. Which of the following best describes biomagnification?
a) The increase in biodiversity over time.
b) The movement of toxins up the food chain, increasing in concentration in higher trophic
levels.
c) The accumulation of genetic mutations over generations.
d) The expansion of ecosystems due to global warming.
10. Trophic levels in an ecosystem refer to:
a) The diversity of species within a habitat.
b) The various levels of energy consumption, from producers to apex predators.
c) The depth of water in aquatic ecosystems.
d) The age structure of a population.
Section B:
Short Answer Questions (20 marks) (Each question is worth 5 marks. Answer any FOUR in
brief.)
1. Explain the concept of ecological succession and the difference between primary and
secondary succession.5mks
2. Describe the nitrogen cycle and explain the role of nitrogen-fixing bacteria in ecosystems.
5mks
3. What are invasive species, and how can they impact native ecosystems? 5mks
4. Explain the concept of habitat fragmentation and how it can affect biodiversity.5mks
5. What is the greenhouse effect, and how does it contribute to climate change?5mks
6. Discuss the importance of genetic diversity for the survival of species. 5mks
Section C:
Essay Questions (60 marks) (Each essay is worth 20 marks. Answer any three of the following
questions.)
QUESTION ONE
Part one (Ecosystem Dynamics)
a. Explain the concept of an ecosystem and describe the flow of energy through an
ecosystem. 10mks
b. Discuss the roles of producers, consumers, and decomposers, and explain how energy
transfer between trophic levels is governed by the 10% rule. 10mks
QUESTION TWO
(Biodiversity Conservation)
a. Discuss the importance of biodiversity and the threats it faces from human
activities.10mks
b. Propose strategies for conserving biodiversity, including habitat preservation, legal
protections, and sustainable resource use.10mks
QUESTION THREE
(Human Impact on Ecosystems )
a. Analyze the ways in which human activities such as deforestation, pollution, and
urbanization affect ecosystems.10mks
b. Use specific examples to highlight the consequences of these actions and suggest
solutions to mitigate negative impacts. 10mks
QUESTION FOUR
(Population Ecology )
a. Discuss the factors that influence population growth, including birth rates, death rates,
immigration, and emigration.10mks
b. Explain the concept of carrying capacity and how limiting factors such as food, water,
and shelter affect population dynamics. 10mks
QUESTION FIVE
(Climate Change and Ecosystems)
a. Explain how climate change is affecting ecosystems around the world. Discuss the effects
of rising temperatures, shifting weather patterns, and ocean acidification on species and
their habitats. 10mks
b. Suggest ways to mitigate the impact of climate change on ecosystems. 10mks
Section D:
Calculations (20 marks) (Attempt any ONE Question each question is worth 10 marks. Show all
workings.)
QUESTION ONE
a. In a particular grassland ecosystem, the biomass of producers is measured to be 5000 kg
per hectare. The biomass of primary consumers (herbivores) is 500 kg per hectare, and
the biomass of secondary consumers (carnivores) is 50 kg per hectare.
i. Calculate the efficiency of energy transfer between each trophic level and explain
your results.10mks
QUESTION TWO
a. A fish population in a lake was estimated to be 800 individuals. After one year, the
population grew to 1000 individuals.
i. Calculate the growth rate of the population over that year. If the lake's carrying capacity
is 1200 fish, discuss what might happen to the population if it continues to grow at the
same rate 10mks
END
