A-Level (7402)
Biology
Paper 2
Updated Version 2024
QNS & ANS
1. Question: Describe how the process of photosynthesis in
plants contributes to energy transfer in ecosystems.
Answer: Photosynthesis converts solar energy into
chemical energy by synthesizing glucose from carbon dioxide
and water using chlorophyll, forming the base for energy
transfer to consumers in the ecosystem.
2. Question: Name one adaptation of ectotherms that helps
them survive in fluctuating temperatures.
Answer: Ectotherms, like reptiles, often bask in the sun to
absorb heat which raises their body temperature, allowing their
metabolic processes to function adequately.
3. Question: Explain the significance of the Hardy-Weinberg
principle in population genetics.
Answer: The Hardy-Weinberg principle provides a
mathematical model that describes how allele frequencies in a
population remain constant from generation to generation in the
absence of evolutionary influences.
4. Question: What is the role of operons in prokaryotic gene
regulation?
Answer: Operons are clusters of genes transcribed
together under the control of a single promoter, enabling
,coordinated regulation of gene expression in response to
environmental changes.
5. Question: Give two examples of internal environments an
organism might respond to and the corresponding response
mechanism.
Answer: 1) Internal pH levels: organisms can regulate
enzyme activity to maintain optimal pH. 2) Blood glucose levels:
organisms utilize insulin to lower blood glucose when levels are
high.
6. Question: List the three main components of the cell
theory.
Answer: 1) All living organisms are composed of cells. 2)
Cells are the basic unit of life. 3) All cells arise from pre-existing
cells.
7. Question: What is the effect of temperature on enzyme
activity?
Answer: Temperature affects the kinetic energy of
molecules; as temperature increases, enzyme activity typically
increases until an optimum is reached, after which denaturation
occurs.
8. Question: Describe the difference between mutations and
polymorphisms.
Answer: Mutations are changes in DNA sequences that
can lead to variations in traits, while polymorphisms refer to
variations in a population that are common and may not affect
fitness.
9. Question: Explain the concept of ecological succession.
Answer: Ecological succession is the process where one
community replaces another over time, often after a
disturbance, leading to a more stable ecosystem.
10. Question: What is the function of RNA polymerase in
transcription?
Answer: RNA polymerase synthesizes RNA by unwinding
the DNA and adding complementary RNA nucleotides to form a
primary transcript.
, ---
### Long Answer Questions
11. Question: Discuss the impact of climate change on
energy transfer within an ecosystem, referencing specific
examples.
Answer: Climate change can disrupt energy transfer by
altering plant growth patterns, leading to reduced
photosynthesis and nutrient availability. For instance, rising
temperatures can shift species distributions, affecting predator-
prey dynamics. Additionally, increased CO2 levels may
enhance plant growth initially (carbon fertilization), but extreme
weather can lead to habitat loss, thus reducing the biomass and
energy flow through food webs.
12. Question: Analyze the mechanisms of gene expression
control in eukaryotic cells, including the roles of transcription
factors and epigenetic modifications.
Answer: In eukaryotic cells, gene expression is controlled
at multiple levels. Transcription factors bind to specific DNA
sequences to activate or repress transcription. Additionally,
epigenetic modifications, such as DNA methylation and histone
acetylation, alter chromatin structure, influencing gene
accessibility. These mechanisms allow cells to respond to
internal signals or environmental cues, ultimately directing
development and adaptation.
13. Question: Evaluate the role of essential nutrients in
energy transfers within living organisms, emphasizing ATP
synthesis.
Answer: Essential nutrients, such as carbohydrates, lipids,
and proteins, serve as substrates for ATP synthesis. In cellular
respiration, glucose is broken down through glycolysis and the
Krebs cycle, producing intermediates that feed into the electron
transport chain, ultimately leading to ATP production.
Macromolecules also play roles in energy storage and transfer
(e.g., fats store more energy per gram than carbohydrates),
facilitating metabolic processes across the body's systems.
14. Question: Compare and contrast natural selection and
genetic drift as mechanisms of evolution, providing examples of
Biology
Paper 2
Updated Version 2024
QNS & ANS
1. Question: Describe how the process of photosynthesis in
plants contributes to energy transfer in ecosystems.
Answer: Photosynthesis converts solar energy into
chemical energy by synthesizing glucose from carbon dioxide
and water using chlorophyll, forming the base for energy
transfer to consumers in the ecosystem.
2. Question: Name one adaptation of ectotherms that helps
them survive in fluctuating temperatures.
Answer: Ectotherms, like reptiles, often bask in the sun to
absorb heat which raises their body temperature, allowing their
metabolic processes to function adequately.
3. Question: Explain the significance of the Hardy-Weinberg
principle in population genetics.
Answer: The Hardy-Weinberg principle provides a
mathematical model that describes how allele frequencies in a
population remain constant from generation to generation in the
absence of evolutionary influences.
4. Question: What is the role of operons in prokaryotic gene
regulation?
Answer: Operons are clusters of genes transcribed
together under the control of a single promoter, enabling
,coordinated regulation of gene expression in response to
environmental changes.
5. Question: Give two examples of internal environments an
organism might respond to and the corresponding response
mechanism.
Answer: 1) Internal pH levels: organisms can regulate
enzyme activity to maintain optimal pH. 2) Blood glucose levels:
organisms utilize insulin to lower blood glucose when levels are
high.
6. Question: List the three main components of the cell
theory.
Answer: 1) All living organisms are composed of cells. 2)
Cells are the basic unit of life. 3) All cells arise from pre-existing
cells.
7. Question: What is the effect of temperature on enzyme
activity?
Answer: Temperature affects the kinetic energy of
molecules; as temperature increases, enzyme activity typically
increases until an optimum is reached, after which denaturation
occurs.
8. Question: Describe the difference between mutations and
polymorphisms.
Answer: Mutations are changes in DNA sequences that
can lead to variations in traits, while polymorphisms refer to
variations in a population that are common and may not affect
fitness.
9. Question: Explain the concept of ecological succession.
Answer: Ecological succession is the process where one
community replaces another over time, often after a
disturbance, leading to a more stable ecosystem.
10. Question: What is the function of RNA polymerase in
transcription?
Answer: RNA polymerase synthesizes RNA by unwinding
the DNA and adding complementary RNA nucleotides to form a
primary transcript.
, ---
### Long Answer Questions
11. Question: Discuss the impact of climate change on
energy transfer within an ecosystem, referencing specific
examples.
Answer: Climate change can disrupt energy transfer by
altering plant growth patterns, leading to reduced
photosynthesis and nutrient availability. For instance, rising
temperatures can shift species distributions, affecting predator-
prey dynamics. Additionally, increased CO2 levels may
enhance plant growth initially (carbon fertilization), but extreme
weather can lead to habitat loss, thus reducing the biomass and
energy flow through food webs.
12. Question: Analyze the mechanisms of gene expression
control in eukaryotic cells, including the roles of transcription
factors and epigenetic modifications.
Answer: In eukaryotic cells, gene expression is controlled
at multiple levels. Transcription factors bind to specific DNA
sequences to activate or repress transcription. Additionally,
epigenetic modifications, such as DNA methylation and histone
acetylation, alter chromatin structure, influencing gene
accessibility. These mechanisms allow cells to respond to
internal signals or environmental cues, ultimately directing
development and adaptation.
13. Question: Evaluate the role of essential nutrients in
energy transfers within living organisms, emphasizing ATP
synthesis.
Answer: Essential nutrients, such as carbohydrates, lipids,
and proteins, serve as substrates for ATP synthesis. In cellular
respiration, glucose is broken down through glycolysis and the
Krebs cycle, producing intermediates that feed into the electron
transport chain, ultimately leading to ATP production.
Macromolecules also play roles in energy storage and transfer
(e.g., fats store more energy per gram than carbohydrates),
facilitating metabolic processes across the body's systems.
14. Question: Compare and contrast natural selection and
genetic drift as mechanisms of evolution, providing examples of
