TOAD Anatomy - Practical Report PDF

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TOAD ANATOMY

Case Study You are a research scientist at The University of Queensland, investigating the cardiovascular system (heart and blood vessels). In order to do this, you need a suitable vertebrate model on which to conduct your research. You have chosen to investigate the suitability of the cane toad, due to its status as an invasive species and relative abundance in Southern Queensland.

EXPERIMENT 1 Hypothesis 1 If red blood cells contain haemoglobin (which is dark purple in colour) the organ where red blood cells are stored will appear dark purple.

Prediction of Results for Experiment 1 You predict that red blood cells are stored in: The spleen as it is used to help filter the blood.

Results for Experiment 1 Table 1: External colour of selected B. marinus internal organs Tissue

External Colour

Lungs

Pink/Red

Liver

Dark Purple

Kidney

Red

Spleen

Dark Purple

Pancreas

Yellow

Gall bladder

Dark Blue/Purple

EXPERIMENT 2 Hypothesis 2 The ventricle will have a larger amount of muscle mass in comparison to the atrium.

Prediction of Results for Experiment 2 Provide your prediction about the chamber that will have more muscle and an estimate of how much more it will have. The ventricle will have more muscle than the atrium by 50%, double the size.

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BIOM1050 – TOAD ANATOMY

Materials and Methods 2 MATERIALS 1. Cane Toad – double pithed and skinned 2. Dissection instruments 3. Light microscope 4. Petri dish 5. Dividers and a ruler 6. Frog ringer solution 7. Pen light 8. One decimal place balance for weighing. METHOD 1. Carefully cut from the groin of the toad up to just below the chin, ensuring not to cut any internal organs 2. Locate the heart at the top end of the toad 3. Cut at the top of the atria and at the bottom of the ventricle to ensure the whole heart has been removed 4. Once the heart has been removed, it must be severed in two so that both the atria and the ventricle can be weighed separately 5. Clean both halves of the heart with the Frog ringer solution as to eliminate any excess tissue that may be present 6. Place the severed heart in a petri dish 7. Weigh the atria and ventricle separately on the one decimal place balance and record the results 8. Repeat step 8 two more times to guarantee the most accurate result possible NB: Between each weighing, press the tare button on the scales to make sure it goes back to a zero weight

Results for Experiment 2 Individual Results Table 2: Click here to enter text. Chamber of the Heart

Value 1

Value 2

Value 3

Mean

Ventricle

0.28

0.27

0.29

0.28

Atrium

0.23

0.22

0.23

0.225

Ventricle/Atrium Ratio

1.21

1.23

1.26

1.24

Your results showed that the chamber with greater muscle tissue was: The ventricle, as its muscle was 1.24 times the size of the muscle of the atria

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Comparative Analysis Plot the results you collected from the three groups in Figure 1 below (right-click on the chart; Edit Data). Remember to provide axes labels and a figure legend. N.B. If the data table doesn’t appear, save the file, close it, then open the file and try again.

Ratio

1.4

1.2

1 1

2

3

Mean

Trial Number Figure 1: Graph showing the ratio of the three trials and the mean

Description of Findings for Experiment 2 Write a paragraph of text in the box below, describing the important trends and relationships for all of the results you collected and presented from Experiment 2. As can be seen above in Figure 1, all three of the tests performed produced similar results, only differing by a maximum of 0.05 in the ratio. This shows that the testing was done accurately which therefore gave the most exact results. In trial 1, the results showed that the ventricle was 121% the size of the atria and in trial two it stayed mostly consistent only showing an increase of 2%. Trial three however showed an additional increase of 3% which suggests that something untoward must have occurred to be able to affect the ratio that much.

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BIOM1050 – TOAD ANATOMY

Discussion Remember to treat these questions like short answer questions in the final exam: be specific, clear and concise. 1. Briefly describe (in complete sentences) whether the results of your first experiment confirm or disconfirm your hypothesis. The first experiment, finding out if the haemoglobin from within the red blood cells would turn organs purple, proved our hypothesis was correct. Once we had cut into the toad, it was clear to see that there were many organs that were purple in colour due to the deoxygenated red blood cells present. These organs included the liver, spleen and gallbladder.

2. Based on the criteria of Stanborough (2007), do you think that this was a strong hypothesis? Explain your reasons. According to Stanborough (2007), this hypothesis would be considered strong because it meets both criteria. Stanborough states that for a hypothesis to be considered strong it must meet two requirements, it must be testable given the design and equipment available and it also must be able to be proved wrong. The hypothesis was tested by dissecting a cane toad and looking for the organs that were of a purple colour therefore meeting the first requirement. This hypothesis was also able to be proven wrong if there are purple coloured organs that are not used to store red blood cells. 3. Other than storage of red blood cells, what might be another possible explanation for the colour of the organ in your prediction? Another reason for the colour of the organs may be because of the alternate roles they play with the red blood cells. Although it doesn't store red blood cells, the liver is used for the decomposition of red blood cells which may be why it is coloured purple. The gallbladder is connected closely to the liver and so it would make sense that it shares the same colour.

4. Briefly describe (in complete sentences) whether the results of your second experiment confirm or disconfirm your hypothesis. The results gathered from the second experiment confirm the hypothesis that the ventricle muscle would be larger than that of the two atriums. The results showed that the ventricle was 124% the size of the atria muscle.

5. Why is there more muscle tissue in this particular chamber of the heart? There is more muscle present in the ventricle as opposed to the atria due to the increased load on it. Within the heart, there are two atriums however only one ventricle so it makes sense that the size of the ventricle be larger than that of the atria.

6. What are the biological reasons for variation between data sets in your comparative analysis (Figure 1)?

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The biological reasons for variation between data sets may be due to the person weighing the heart not zeroing the scales before the next measuring stage. There also may be a difference in the data sets because there may be more of the frog ringer solution present on the heart when being weighed.

7. In the case study you are researching the cardiovascular system, how would you explain the roles of the atrium and ventricle of the heart to someone without a scientific background? In relation to the cardiovascular system, the atria and the ventricle are used to pump blood around the body. The oxygenated blood first enters the left atrium and deoxygenated blood through the right. It is then mixed together before entering down through the ventricle and then out through the body.

References List any references you have used in your answers, in the panel below. Click here to enter text.

© 2017 The School of Biomedical Science

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