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Write an essay on one of the topics below - AQA - A-Level Biology - Question 7 - 2020 - Paper 3
Question 7
Write an essay on one of the topics below. Either The functions of enzymes and their importance in organisms. or The causes and importance of variation and divers... show full transcript
Worked Solution & Example Answer:Write an essay on one of the topics below - AQA - A-Level Biology - Question 7 - 2020 - Paper 3
Step 1
The functions of enzymes and their importance in organisms.
Answer
Enzymes are biological catalysts that accelerate chemical reactions in living organisms. They are crucial for various metabolic processes and are composed of proteins.
Functions of Enzymes
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Catalysis: Enzymes speed up reactions by lowering the activation energy required, enabling biological processes to occur at rates necessary for life. For example, digestive enzymes break down macromolecules into absorbable units.
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Specificity: Each enzyme is specific to a particular substrate due to its unique active site. This specificity ensures that enzymes only catalyze the intended reactions, contributing to metabolic efficiency.
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Regulation: Enzymes can be regulated by factors such as temperature, pH, and substrate concentration. This regulation allows organisms to control metabolic pathways and respond to changes in their environment.
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Cofactors and Coenzymes: Many enzymes require additional non-protein molecules called cofactors (inorganic) or coenzymes (organic) to function properly. For example, the enzyme hexokinase requires the presence of magnesium ions to catalyze its reaction.
Importance of Enzymes
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Cellular Respiration: Enzymes play a pivotal role in cellular respiration by facilitating the breakdown of glucose to produce ATP, the energy currency of the cell. Key enzymes involved include hexokinase and phosphofructokinase.
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DNA Replication and Repair: Enzymes like DNA polymerases are essential for DNA replication and repair, ensuring genetic fidelity and stability.
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Metabolism: Enzymes are fundamental in metabolic pathways—both catabolic and anabolic processes. For instance, they help in the synthesis of proteins and other macromolecules from smaller building blocks.
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Homeostasis: Enzymatic reactions contribute to maintaining homeostasis within organisms by regulating metabolic processes responsive to internal and external stimuli.
Conclusion
In summary, enzymes are vital for facilitating biochemical reactions necessary for life. Their role as catalysts, specificity, and regulatory mechanisms underscore their importance in sustaining life and ensuring efficient metabolic functions.
Step 2
The causes and importance of variation and diversity in organisms.
Answer
Variation among organisms refers to the differences in traits within a species due to genetic and environmental factors. This diversity is crucial for the survival and evolution of species.
Causes of Variation
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Genetic Mutations: Changes in the DNA sequence can lead to new traits. Mutations can arise spontaneously or be induced by environmental factors such as radiation.
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Gene Flow: The movement of genes between populations can introduce new alleles into a gene pool, increasing genetic diversity.
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Sexual Reproduction: This process involves meiosis and fertilization, leading to offspring with combinations of traits from both parents, enhancing genetic variation.
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Environmental Factors: Different environments may select for different traits, leading to variation in phenotypic traits among populations of the same species.
Importance of Variation and Diversity
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Adaptation: Variation is essential for natural selection. Traits that improve survival and reproduction can be passed on, leading to populations that are well-adapted to their environments.
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Ecosystem Stability: Biodiversity contributes to ecosystem stability and resilience. Diverse ecosystems are better equipped to respond to environmental changes and disturbances.
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Evolution: Variability within populations fuels the process of evolution. Diverse genetic attributes allow populations to evolve over time in response to changing conditions.
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Human Agriculture and Medicine: Genetic diversity in crops and livestock can lead to improved yields and resistance to diseases. In medicine, understanding genetic variation helps in drug development and personalized medical approaches.
Conclusion
In conclusion, variation and diversity are vital components of biological systems. They foster resilience, adaptability, and evolutionary processes that ensure the long-term survival of species and ecosystems.