Unit 2 Biology NAME:

Skin and temperature control practical Pre-lab activity (key concepts)Before you commence this activity, make sure you are familiar with the concepts and terms listed below. In the space provided, write your understanding of each term. Thermoregulation:

Homeostasis:

Evaporation:

Convection:

Negative feedback model:

Introduction:Body temperature in humans is normally around 37 C. This temperature varies little, even when external conditions change dramatically. What are some of the adaptations that mammals have to help them to maintain a fairly constant body temperature?Purpose: This experiment uses modeling to investigate heat loss from an exposed surface such as the skin.

Materials: Each group will require:

- hot water - cardboard cylinder- 4 test tubes - stop watch - 4 thermometers - fan- 4 beakers - spray water bottle of warm water - Measuring cylinder - cotton wool

Procedure:Part A: Effect of insulation on heat loss

Take three test tubes, label them A, B and C, and place each into a separate beaker.

Surround test tube A with cotton wool. Surround test tube B in a cardboard cylinder then the same amount of cotton wool (as test tube A) around the outside of the cylinder (so that there is a layer of air between the test tube and the insulation).Cover the top of the cylinder so the air is trapped.

Test tube C has no insulating material around it. Fill all three test tubes with 20mL of water at approximately 80 C. Insert a thermometer in each test tube and record the temperature as

soon as possible after the water is added. Record the temperature every minute for 10 minutes in the results table below.

Graph your results

Part B: Effect of moisture on heat loss Take four test tubes and surround each with cotton wool. Place one in

each of four beakers labeled 1,2,3 and 4. Spray the outside of test tube1 and 3 with warm water. Place test tubes 1 and 2 in front of a fan and test tubes 3 and 4 in an area

without air movement. Fill all four test tubes with 20mL of water at approximately 80 C. Insert a thermometer into each test tube and record the temperature as

soon as possible after the water is added. Record the temperature every 10 minutes in the results table below.

Graph your results in the space provided.

Results: Part A

Test Tube Start 1min 2min 3min 4min 5min 6min 7min 8min 9min 10min

A (cotton wool)

B (cardboard)

C (no covering)

Results: Part B

Test Tube Start 1min 2min 3min 4min 5min 6min 7min 8min 9min 10min

1 (warm water/fan)

2 (fan)

3 (warm water)

4 (no change)

Discussion questions:1. Which test tube in part A was the more effective at reducing heat loss?

Can you suggest what makes this set up the most effective at reducing heat loss?

2. What structural feature of mammals is the cotton wool simulating?

3. How can an insulating layer of air be achieved by mammals?

4. How can the results from test tube B, in Part A, be used to explain the observation that a cat looks larger on cold days compared to hotter days?

5. Which test tube in Part B was the most effective at increasing heat loss?

6. Which part of this experiment modeled the role of perspiration in maintaining body temperature? Explain.

7. Were any experimental controls used in Part A and Part B of this investigation? If so, explain what these were.

8. Why are animals like frogs at greater risk of perishing on a windy hot day? Explain this, using experimental results to support your answer.

9. When the body temperature in mammals starts to drop, a number of things happen. Describe some of these physiological and behavioural responses. Are any of these responses being modeled in this experimental set-up? Explain.

10.When the body temperature in mammals starts to increase, a different set of physiological and behavioural responses occur. Describe these responses. Are any of these responses being modeled in this experimental set-up? Explain.

Conclusion:Refer back to the purpose of this activity. Have you achieved this purpose? Write a conclusion based on what you have learnt by undertaking this activity.