paper 2 bio aqa

AQA Biology Paper 2 Overview

Suitable for:

• Higher Tier and Foundation Tier

• Double Combined, Trilogy, and Triple/Separate Biology

Topics Covered:

1. Homeostasis and Response

2. Inheritance

3. Variation and Evolution

4. Ecology

Homeostasis and Response

Definition of Homeostasis:

Homeostasis is the intricate process by which an organism maintains a stable internal environment despite fluctuations in external conditions. This regulation is crucial for sustaining life, as it impacts various physiological processes.

Importance:

Maintaining homeostasis is essential for ensuring optimum conditions for enzymatic reactions, which are vital for metabolic processes that support life functions such as respiration, digestion, and growth.

Regulation of Blood Glucose Concentration:

• Blood glucose levels must be carefully regulated to provide a consistent energy supply for cellular activities and maintain metabolic homeostasis.

• The pancreas plays a crucial role in this regulation by releasing insulin to lower blood glucose levels and glucagon to raise them, depending on the body's needs.

Feedback Mechanisms:

• Involves various components: sensors (detect changes), control centers (process information), and effectors (carry out responses).

• Predominantly utilize negative feedback loops, which act to counteract deviations from a set point, ensuring stability.

Inheritance

Basics of Genetics:

• Inheritance refers to the process by which genetic traits and information are passed from parents to offspring through their genes.

• This genetic transmission shapes the phenotype of individuals and influences their traits.

Mendelian Genetics:

• Key concepts include dominance (the trait that is expressed), recessiveness (the trait that is only expressed in the absence of a dominant allele), homozygous (having two identical alleles), and heterozygous (having two different alleles).

Punnett Squares:

• A valuable tool for predicting genetic variation in offspring based on parental genotypes. Allows for visual representation of potential genetic combinations and phenotypic ratios in the offspring.

Types of Alleles:

• Dominant alleles are expressed if present, while recessive alleles require both alleles to be recessive for expression.

Variation and Evolution

Key Concepts:

• Genetic variation arises from processes such as mutations, which introduce new traits, and sexual reproduction, which shuffles alleles.

Natural Selection:

• A foundational concept in evolution where organisms that are better adapted to their environments are more likely to survive and reproduce, leading to the gradual evolution of species.

Speciation:

• The evolutionary process that results in the formation of new and distinct species; can occur via mechanisms like geographic isolation or environmental changes, leading to reproductive isolation over time.

Ecology

Ecological Levels:

• Levels of biological organization include organisms, populations, communities, and ecosystems; each level interacts to create the complexity of life.

Ecosystem Interactions:

• Dynamics such as predator-prey relationships, symbiotic relationships (mutualism, commensalism, parasitism), and competition define how species coexist.

Energy Flow:

• Energy transfer within ecosystems is illustrated through food chains and food webs comprising various trophic levels: producers (autotrophs), primary consumers (herbivores), secondary consumers (carnivores), and tertiary consumers.

Human Impact on Ecosystems:

• Activities such as deforestation, pollution, and global warming significantly affect ecological balances and biodiversity, leading to threats like habitat loss and species extinction.

Study Tips

• Stay engaged with video materials, taking thorough notes of key concepts.

• Utilize diagrams and models, especially for complex processes like homeostasis and genetic inheritance, to visually reinforce your understanding.

• Regularly practice past exam questions to embed knowledge and identify areas needing further review.