IB Biology SL (Standard level)- 2024 – Practice Questions- All Topics
Topic 4.4 Climate change
Topic 4 Weightage : 10%
All Questions for Topic 4.4 – Greenhouse Gases, Greenhouse Effect, CO2 Concentrations, Climate Changes, Ocean Acidification, Greenhouse Debate, Water Cycle, Precautionary Principle, Carbon Footprint, Greenhouse Impacts
Question
Which gases have made the most significant contributions to global warming?
Water and carbon dioxide
Carbon dioxide and methane
Methane and nitrous oxide
Carbon dioxide and ozone
▶️Answer/Explanation
Ans: A
Euglena is a unicellular organism that feeds on bacteria and uses CO2 as a carbon source. Which describes the nutrition of this organism?
A. Autotrophic only
B. Heterotrophic only
C. Saprotrophic only
D. Autotrophic and heterotrophic
Answer/Explanation
Markscheme
D
Euglena is a mixotrophic unicellular organism that can produce its own food through photosynthesis and also feed on other organisms, such as bacteria, for nutrition. Euglena uses CO2 as a carbon source during photosynthesis, which allows it to convert light energy into organic compounds, such as sugars and starches, that it can use for energy. When light is not available, Euglena can also feed on other organisms, such as bacteria, to obtain the nutrients it needs to survive. This mixotrophic mode of nutrition (autotrophic and heterotrophic) allows Euglena to survive in a wide range of environments, from freshwater to marine habitats, where light and nutrients may be limiting.
The table shows the monthly CO2 concentrations in mg L–1 taken at two monitoring stations.
What is directly indicated by the data?
A. CO2 concentration in the atmosphere varies from place to place.
B. Cape Grim is less affected by global warming than Mauna Loa.
C. CO2 creates a greenhouse effect at both locations.
D. The standard deviation for Cape Grim is higher than standard deviation for Mauna Loa.
▶️Answer/Explanation
Markscheme
A
The concentration of $\text{CO}_{2}$ in the atmosphere varies from place to place due to a variety of factors, including natural processes and human activities.
Natural processes that influence $\text{CO}_{2}$ concentrations include photosynthesis, respiration, and the exchange of $\text{CO}_{2}$ between the atmosphere and oceans. Photosynthesis removes $\text{CO}_{2}$ from the atmosphere, while respiration and decomposition release $\text{CO}_{2}$ back into the atmosphere. The exchange of \textup{CO}_{2} between the atmosphere and oceans is influenced by factors such as ocean temperature, salinity, and circulation patterns.
Human activities, such as burning fossil fuels and deforestation, have also contributed to the increase in atmospheric $\text{CO}_{2}$ concentrations over the past century. Burning fossil fuels releases \textup{CO}_{2} that has been stored underground for millions of years, while deforestation reduces the number of trees that can absorb $ \text{CO}_{2}$ through photosynthesis.
The concentration of $\text{CO}_{2}$ in the atmosphere is also influenced by local factors, such as the proximity to sources of $\text{CO}_{2}$ emissions, the presence of vegetation, and weather patterns. For example, urban areas may have higher $\text{CO}_{2}$ concentrations than rural areas due to the concentration of human activities and emissions.
What contributes to the enhanced greenhouse effect?
A. Ozone from violent thunderstorms
B. Carbon particles in diesel engine exhaust
C. Methane from agricultural sources
D. Carbon dioxide from active volcanoes around the world
▶️Answer/Explanation
Markscheme
Ans: C
Question
Which gases have made the most significant contributions to global warming?
Water and carbon dioxide
Carbon dioxide and methane
Methane and nitrous oxide
Carbon dioxide and ozone
Answer/Explanation
Ans: A
Water and carbon dioxide have made the most significant contributions to global warming because they are the two most abundant greenhouse gases in the Earth’s atmosphere. Water vapor is the most abundant greenhouse gas, and it is responsible for about 60% of the greenhouse effect. Carbon dioxide is the second most abundant greenhouse gas, and it is responsible for about 20% of the greenhouse effect. Both water vapor and carbon dioxide trap heat in the Earth’s atmosphere, preventing it from escaping into space. The increase in atmospheric concentrations of carbon dioxide due to human activities, such as burning fossil fuels and deforestation, has led to an increase in global temperatures, resulting in climate change.
By which mechanism do greenhouse gases contribute to global warming?
A. Their higher concentration absorbs more long wave radiation coming from the Sun.
B. Short wave radiation emitted from the Earth’s surface increases with their concentration.
C. They absorb higher amounts of long wave radiation emitted from the Earth’s surface as their concentration increases.
D. They absorb higher amounts of short wave radiation caused by increased combustion of fossilized organic matter.
Answer/Explanation
Markscheme
C
Greenhouse gases contribute to global warming through a mechanism known as the greenhouse effect. When the Earth’s surface absorbs energy from the sun, it emits longwave radiation back into the atmosphere. Greenhouse gases, such as carbon dioxide, water vapor, and methane, absorb some of this longwave radiation and re-emit it in all directions, including back to the Earth’s surface. This process traps heat in the Earth’s atmosphere, preventing it from escaping into space. As the concentration of greenhouse gases in the atmosphere increases, more longwave radiation is absorbed and trapped, leading to an increase in global temperatures. This is known as the enhanced greenhouse effect, which is responsible for the observed increase in global temperatures over the past century.
Euglena is a unicellular organism that feeds on bacteria and uses CO2 as a carbon source. Which describes the nutrition of this organism?
A. Autotrophic only
B. Heterotrophic only
C. Saprotrophic only
D. Autotrophic and heterotrophic
▶️Answer/Explanation
Markscheme
D
What contributes to the enhanced greenhouse effect?
A. Ozone from violent thunderstorms
B. Carbon particles in diesel engine exhaust
C. Methane from agricultural sources
D. Carbon dioxide from active volcanoes around the world
▶️Answer/Explanation
Markscheme
C