AQA A2 Biology Student Unit Guide: Unit 4 Populations and Environment

Summary:
Student Unit Guides are perfect for revision. Each guide is written by an examiner and explains the unit requirements, summarises the relevant unit content and includes a series of specimen questions and answers.

There are three sections to each guide:

Introduction - includes advice on how to use the guide, an explanation of the skills being tested by the assessment objectives, an outline of the unit or module and, depending on the unit, suggestions for how to revise effectively and prepare for the examination questions.

Content Guidance - provides an examiner's overview of the module's key terms and concepts and identifies opportunities to exhibit the skills required by the unit. It is designed to help students to structure their revision and make them aware of the concepts they need to understand the exam and how they might analyse and evaluate topics.

Question and Answers - sample questions and with graded answers which have been carefully written to reflect the style of the unit. All responses are accompanied by commentaries which highlight their respective strengths and weaknesses, giving students an insight into the mind of the examiner.

• A revision guide specifically written to meet the requirements of the unit
  

• Written by an examiner with commentary on key points and concepts 
  

• Features specimen questions and answers, together with examiner's comments
  

Table of Contents:
Introduction
About this guide
Preparing for the Unit 4 test
Approaching the unit test
Content Guidance
About this section
Populations and the factors that affect them
The transfer of energy within organisms
Respiration: releasing energy from organic molecules
How elements are cycled in ecosystems
Succession: how ecosystems change over time
Inheritance: passing on genes from one generation to the next
Selection and speciation: the origin of new species
Questions and Answers
About this section
Q1 Food chains and food webs
Q2 Hardy–Weinberg
Q3 Aerobic respiration
Q4 Greenhouse effect
Q5 Nitrogen cycle
Q6 Inheritance
Q7 Energy and food production
Q8 Selection and speciation
Q9 Populations and succession
Q10 Photosynthesis and energy transfer

About the Author(s):
Steve Potter has been a chief/principal examiner for a number of awarding bodies and is the author of numerous A-level biology books.