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Answering Exam Questions ` Exams require you to demonstrate your understanding of a particular concept by providing a written paragraph or essay. ` Open answer questions (meaning there is no definitive answer) are designed so that you can demonstrate your level of understanding. The question may give you some guidance as to what you should include in your answer, such as definitions of certain terms or to provide specific examples.
` In order to gain the highest possible mark in these questions, you need to lay out your answer in a clear and logical way so that the examiner can easily see how you have demonstrated your understanding of the topic.
` The difference between you obtaining a low, mid, or high grade depends on how well you demonstrate your understanding
PR E O V N IE LY W
of a concept.
• Defining, drawing, annotating, or giving a description demonstrates a basic understanding of the material.
• Explaining how a process works, why it works, and how changes to it may affect an outcome shows a deeper understanding of how the system works in that situation. • Linking biological ideas, comparing and contrasting, analysing, or justifying ideas shows both a deep understanding and an ability to translate that understanding to a new situation.
` The following example shows how an answer can be built up from a simple definition, through explanation, to comparisons and linking of ideas.
The human digestive system consists of specialised cells, tissues, and organs. Provide an overview of the digestive system and use a specific example to discuss how the specialisation and organisation of the cells, tissues, and organs contributes to its overall function and efficiency.
A brief description of the overall function of the digestive system is provided.
The main components of the digestive system are identified.
The digestive system is a collection of specialised cells, tissues, and organs.
The stomach is used as an example to show how specialisation contributes to functionality and efficiency. Other examples (e.g. alkaline environment and increased surface area of the small intestine) could also be used.
Specialisation improves efficiency (food molecules, especially protein, are partially digested before moving to the small intestine).
The digestive system is responsible for the ingestion and breakdown of food, nutrient absorption, and elimination of undigested material The main components of the digestive system are the teeth and digestive glands in the mouth, stomach, small and large intestines and associated organs (pancreas, gall bladder and liver). Each is specialised to carry out a specific role. The human digestive system is essentially a one-way tube divided into regions. Each region is specialised to perform a particular task (or group of tasks) associated with digestion. A hierarchy of organisation (cells form tissues and tissues form organs) and specialised roles of the system's components improve the overall efficiency of the digestive process.
This is illustrated by the stomach. In the stomach, ingested food is mixed with HCl in a very acidic environment (pH 1.5 - 2.0). The low pH has two purposes: 1) it begins the chemical breakdown of some food particles into smaller molecules, 2) the main digestive enzyme in the stomach (pepsin) is activated This enables pepsin to digest (break down) protein molecules in the ingested food. Several specialisations allow the stomach to carry out this role. - Muscular layers allow efficient mixing of the stomach contents with the acid to maximise chemical pre-digestion. - Goblet cells secrete mucus to protect the stomach lining from being digested and damaged by the highly acidic HCl.
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Gastric glands in the stomach contain specialised cells to aid digestion: Specialised cells in the stomach (and their roles) are clearly stated.
- Chief cells secrete pepsinogen (a precursor to pepsin) into the stomach - Parietal cells, produce HCl (allows for some chemical digestion and also converts pepsinogen into the active enzyme pepsin)l
- Endocrine cells secrete the hormone gastrin (gastrin promotes HCl production) Regional specialisation and sequential digestion in the digestive system enable the most is gained from the nutrients contained in the food eaten.
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A concluding statement summarises the role of regional specialisation and sequential processing of food.