CCEA A Level Biology
CCEA A Level Biology 2.2 The Adaptation of Organisms Exam Questions
Free CCEA A Level Biology revision for 2.2 The Adaptation of Organisms: what you need to know, common mistakes and exam-style questions with answers. Covers behavioural, physiological and morphological adaptations, climatic, edaphic and biotic factors, ecological niche, and sampling methods and measures of abundance.
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About CCEA A Level Biology 2.2 The Adaptation of Organisms
Section 2.2 of Unit AS 2 looks at how organisms are adapted to their environment and how ecologists study distribution. You need to classify adaptations as behavioural, physiological or morphological, and explain how climatic factors (temperature, water, light intensity, quality and day length), edaphic factors (soil pH, nutrients, aeration) and biotic factors (competition, predation, waste) affect where organisms live. The concept of ecological niche is key. A large part of the section is fieldwork: random sampling, line and belt transects, quadrats, pin frames, pitfall traps, sweep nets and pooters, and measuring abundance as density, frequency or percentage cover. It links to biodiversity (2.3) and ecosystems in A2 1.
What you need to know
- Types of adaptation Behavioural adaptations are actions (for example woodlice moving to damp areas); physiological adaptations are internal processes (for example producing concentrated urine); morphological adaptations are structures (for example sunken stomata in xerophytes).
- Climatic factors Temperature range, water availability, light intensity, light quality and day length all limit distribution.
- Edaphic factors Soil pH, macronutrients and micronutrients, and soil aeration (linked to waterlogging) affect plant distribution.
- Biotic factors and niche Competitors, predators and accumulation of waste affect distribution. A niche is the role of an organism in its community, including its habitat, feeding and interactions.
- Sampling methods Random sampling uses coordinates from random numbers to avoid bias. Line and belt transects are used where conditions change across an area (for example a shore or woodland edge). Pitfall traps, sweep nets and pooters sample animals.
- Measuring abundance Density is number per unit area; frequency is the percentage of quadrats in which a species is present; percentage cover is the proportion of a quadrat covered, often measured with a pin frame.
Common mistakes in 2.2 The Adaptation of Organisms
- Using random sampling across an environmental gradient. Use a transect when you want to link distribution to a changing factor.
- Confusing frequency and density. Frequency records presence or absence in each quadrat, not how many individuals there are.
- Calling an adaptation behavioural when it is a structure. Hairs and thick cuticles are morphological.
- Defining niche as the place where an organism lives. That is its habitat; the niche includes its role and interactions.
- Saying a larger number of quadrats makes results accurate. More quadrats make the result more representative and reliable.
Try three 2.2 The Adaptation of Organisms exam-style questions
1. Explain when a belt transect would be used instead of random sampling. (2 marks)
Show the mark scheme answer
Where there is a gradual change in an environmental factor across an area; to show how species distribution changes along the gradient.
2. Describe how to estimate the percentage cover of a plant in a field using random sampling. (4 marks)
Show the mark scheme answer
Lay out tape measures to make a grid; use random numbers to generate coordinates; place quadrats (or pin frames) at the coordinates; estimate percentage cover in each; use a large number of quadrats and calculate the mean.
3. A plant species was present in 18 out of 40 quadrats. Calculate its frequency. (1 mark)
Show the mark scheme answer
18 / 40 x 100 = 45%.
2.2 The Adaptation of Organisms FAQs
What does CCEA A Level Biology 2.2 The Adaptation of Organisms cover?
It covers types of adaptation, climatic, edaphic and biotic factors, ecological niche and field sampling methods.
Which unit is 2.2 The Adaptation of Organisms examined in?
It is examined in Unit AS 2: Organisms and Biodiversity, a 1 hour 30 minute written paper of structured questions and an essay. Related practical skills can also be tested in Unit AS 3.
Which sampling equipment do I need to know?
Quadrats, pin frames, line and belt transects, pitfall traps, sweep nets and pooters, and when each is appropriate.
