B2.2 The challenges of size
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B2.2 The challenges of size
Mathematical learning outcomes:
BM2.2i calculate surface area:volume ratios
BM2.2ii use simple compound measures such as rate
BM2.2iii carry out rate calculations
BM2.2iv plot, draw and interpret appropriate graphs
Assessable content statements:
B2.2a explain the need for exchange surfaces and a transport system in multicellular organisms in terms of surface area:volume ratio to include: to include surface area, volume and diffusion distances
B2.2b describe some of the substances transported into and out of a range of organisms in terms of the requirements of those organisms to include: oxygen, carbon dioxide, water, dissolved food molecules, mineral ions and urea
B2.2c describe the human circulatory system to include: to include the relationship with the gaseous exchange system, the need for a double circulatory system in mammals and the arrangement of vessels
B2.2d explain how the structure of the heart and the blood vessels are adapted to their functions to include: the structure of the mammalian heart with reference to valves, chambers, cardiac muscle and the structure of blood vessels with reference to thickness of walls, diameter of lumen, presence of valves
B2.2e explain how red blood cells and plasma are adapted to their transport functions in the blood
B2.2f explain how water and mineral ions are taken up by plants, relating the structure of the root hair cells to their function
B2.2g describe the processes of transpiration and translocation to include: the structure and function of the stomata
B2.2h explain how the structure of the xylem and phloem are adapted to their functions in the plant
B2.2i explain the effect of a variety of environmental factors on the rate of water uptake by a plant to include: light intensity, air movement, and temperature
B2.2j describe how a simple potometer can be used to investigate factors that affect the rate of water uptake
A very good teaching PowerPoint that can be used in the classroom. It has animations on the circulatory system.
Click on the 'Heart and Circulatory System' PowerPoint.
Learners to produce an informative leaflet for patients on behalf of the British heart foundation, explaining how the heart works and the blood vessels.
- Heart structure
- Blood vessels
- Exchange of substances
Use the circulatory marking grid (Learner resource 5) to mark the work.
It can be done as a presentation if not a leaflet.
To understand the function of the circulatory system and the heart learners will need to undertake some initial learning of component structures. Using the dissection help sheet learners can then undertake the dissection of the heart. When dissecting the heart learners use toothpicks and sticky labels to make a flag which can be used to label the heart. Learners may also use string to show direction of blood flow in the heart. Learners could identify the ventricles and thickness of each side. Learners may also fill one of the arteries with water from above to see if the valves close.
Have 5 litres of red dyed water in a large beaker on the desk. As learners walk in pose the question what does this represent? The beaker represents the volume of blood in humans. To have a more hands on approach to teaching blood (B2.2 b,e) allow learners to make a model of blood in a beaker or tray. Learners are provided with a beaker, ping-pong balls 2 or 3, 100ml oil, hand full of small red beads, a few jelly babies. Ask learners to see if they can make blood using the materials provided. (The balls would be WBC, red beads are RBC, oil is Plasma and jelly babies are platelets.
To teach B2.2 (f,g,h,i,j) in a more independent approach for learners, use the following task on transpiration. Learners may work in pairs to complete the task. To illustrate the xylem with a more hands on approach it is possible to complete the straw task. Learners to make a long straw by sellotaping them together. They are to see how far they can ’suck’ up water from a bottle. Snip the straw down until water is drawn. Point out to the learners that plants can draw up water 100m why can they not? They may say that the straw has holes – point out that the xylem has pits.
Common misconceptions or difficulties learners may have
It may be difficult for learners to identify what substances are exchanged when in the blood (B2.2 b) moving around the body. Get learners to read the following statement and tell them it may be correct, partially correct or incorrect. Tell them to underline what they think is incorrect with reasons.
‘At the lungs the oxygen and mineral ions enter the blood whilst carbon dioxide leaves the blood and goes to the lungs. At the body tissues the oxygen and urea enters the cells whilst carbon dioxide leaves the cell’ Ideal opportunity for discussion.
For a smaller group it is possible to draw a heart on the playground in chalk. With vessels to the lungs and tissues. Get the learners to walk the route picking up O2 in the lungs and dropping off in the tissues. Picking up CO2 in the tissues and dropping off in the lungs (this can be done with cards/balloons representing O2 and CO2. Point out the double circulations here. Get learners to discuss what single circulation is.
Learners believe plants absorb water through their leaves. Using the transpiration task it will allow learners to independently identify where water comes from.
Conceptual links to other areas of the specification – useful ways to approach this topic to set learners up for topics later in the course
The knowledge and understanding of photosynthesis (B1.14) is essential for understanding transpiration B2.2 (f,g,h,i,j). Transpiration is greatly affected by photosynthesis.
A task, which focuses on learners independently learning the plant and transpiration.
Learners to answer the questions with means of books and previous KS3 knowledge.
Approaches to teaching the content
Heart disease is a becoming a big killer in the UK. Many contextual approaches can be used to help learners understand the importance of the heart. This topic is ideal for developing dissecting techniques to observe the internal detail of the heart. A dissection help sheet provides a more visual aid. Computerised animations to study heart action enable learners to understand the electrical and ‘mechanical’ activity of the heart.
With the increasing size of the population food production is the biggest it has ever been. Food production depends greatly on the environmental conditions the water levels and nutrient ability. The transport systems in plants are important for us to ensure we produce food. Learners can look at the impact of the food production to both plants with water and without.
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