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Propose an experiment and suggest a control treatment for the following questions: Is the mineral zinc effective as a possible emergency treatment for deadly Australian box jellyfish stings? Experiment: Control: Does the fear of being attacked by predators have a negative impact on reproduction in nesting birds? Experiment: Control:

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Beverley Smith
Beverley SmithLv2
28 Sep 2019

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Related questions

You and your hypothetical lab partner each develop an experimental plan to test this hypothesis. The two experimental plans are presented below. Evaluate each plan for its pros and cons in the experimental design using the bullet points below. Both experimental plans have some good elements and areas that could be improved.

Experiment A) Mature 2 inch sections (sprigs) of Elodea will be used to measure oxygen production under different light conditions. 5 sprigs will be tested. One will be kept in the dark (no light). The others will be exposed to a light filtered with cellophane. One sprig’s light will be filtered through clear cellophane to receive all wavelengths of light, and the other sprigs’ light will be filtered through red, blue, and green cellophane, respectively. The no-light plant will be kept in a dark cabinet, while the other plants will be together on a counter. Each plant sprig will be placed in equal sized upside-down test tubes in 100ml of tap water so that oxygen bubbles produced by the plant will be trapped at the top of the test tube. A ruler will be used to measure the length of the oxygen pocket collected at the top of the test tube. The experiment will continue until one sprig produces 5 cm of oxygen in the tube.

Experiment B) 3 cm sections (sprigs) of Elodea of various ages will be used to measure oxygen production under different light conditions. 15 sprigs will be divided into 3 groups of 5 sprigs each. One group will receive natural sunlight, one group will be exposed to a blue light bulb under a box to block natural light, and the final group will be exposed to a red light bulb under a similar box to block natural light. Each group of plant sprigs will be trapped under a clear plastic funnel that is covered by an upside-down test tube to collect oxygen bubbles produced by all the sprigs in the group. All groups will be in 100ml of water of the same temperature and pH. The experiment will continue for 24 hours, and then the volume of oxygen gas produced will be measured by multiplying the length of the oxygen pocket by the circle described by the test tube, ?r2. The average volume produced by all groups will be graphed and compared to determine which condition produced the most total volume of oxygen.

Consider the following questions to evaluate experimental plans A and B (DO NOT ANSWER THESE QESTIONS)

What is the independent variable suggested by the hypothesis? Do both plans test the independent variable equally well?

What is the dependent variable in each experiment? Which experiment’s dependent variable best matches the prediction in the hypothesis?

What are the experimental and control groups for each experiment? Which experiment gives the best opportunity to assess the effect of the independent variable?

How does each experiment account for standardized variables? Which experiment do you think is the better controlled experiment?

How is sample size addressed in each experiment? Which would you find to be more convincing?

Does either experiment describe any statistical analyses to be performed on the data?

ANSWER THIS QUESTION: BELOW

Considering your analysis of each of the questions above,write an improved experimental design to test the hypothesis “If blue light is more effective at promoting photosynthesis, then more oxygen gas (O2) will be produced when plants are exposed to blue-filtered light compared to other wavelengths.”You may use elements of the above experiments

Review Questions for Chapter 5: Control of Microbial Growth

1. Consider the following statement: “Thorough handwashing with soap and water is the most important step in stopping the spread of many infectious diseases”.

a. Explain this statement.

b. Following thorough handwashing with soap, are your hands sterile? Why or why not?

2. If pasteurization does not achieve sterilization, why is pasteurization used to treat food? Why not just heat the food instead?

3. Consider the use of salts and sugars to preserve food.

a. How do salts and sugars preserve foods?

b. Why are these considered physical rather than chemical methods of microbial control?

c. Name one food that is preserved with sugar and one preserved with salt.

d. How do you account for the occasional growth of Penicillium mold in jelly, which is 50% sucrose?

4. Consider dried fruit you can buy at the store (e.g., raisins, pineapples, figs, dates, etc.) Dried fruits date back thousands of years B.C.

a. Why is this such an effective method of preserving food? Suggest several possibilities.

b. Fruit is often dried by being placed outside in the open under the sun in conditions that are not exactly sanitized. Why is this practice generally very safe?

5. There is great concern over healthcare-associated infections.

a. Why are healthcare settings such a ‘good’ place to catch infectious diseases? List several reasons.

b. What are several effective approaches that healthcare settings can take to minimize the spread of infectious disease?

6. Flying on an airplane includes lots of individuals in close quarters for potentially long periods of time.

a. What technology do you think airplanes use to reduce the amount of microbes from the air?

b. Despite this control method, there have been a number of documented cases of individuals infected with tuberculosis infecting other passengers during a flight. Explain how you think this happened. Which patients are at highest risk for infection, and what does this tell you about the effectiveness of microbial control on an airplane?

7. The thermal death time for a suspension of Bacillus subtilis endospores is 20 minutes in dry heat and less than 10 minutes in an autoclave. Which type of heat is more effective? Why?

8. A large hospital washes burn patients in a stainless steel tub. After each patient, the tub is cleaned with a quat. It was noticed that 14 of 20 burn patients acquired Pseudomonas infections

after being bathed. Provide an explanation for this high rate of infection.

9. If you’re on a municipal water supply, the water coming out of your faucet is chlorinated at the water treatment plant.

a. Is the water coming out of your faucet sterile?

b. Does the water still contain chlorine?

c. What are advantages and disadvantages of chlorine compared with other approaches (e.g., UV treatment, treatment with ozone).

10. You are a member of Engineers Without Borders, and your local chapter has been asked by a rural village in Thailand to assist them with improving their water supply, which they suspect of making villagers sick. The village has piping infrastructure that delivers water through a series of pipes to each household. Upon your initial site assessment of the village, you and your team determine that the water has high turbidity (particulate material) as well as a high bacterial count.

a. Design a strategy for treating the water to make it safe to drink that still relies upon the distribution system. Note that you may make some reasonable assumptions about conditions in the village (e.g., availability of electricity if you wish).

b. Identify some possible limitations of your approach.

11. A low technology approach to treating water in rural locations is to fill clear plastic soda bottles with water and leave it out all day in the sun (e.g., up on a roof).

a. What two factors are most likely at work in controlling microbes in these conditions?

b. What impact does each factor have on the microbes? Be specific.

The investigator never begins an experiment without a prediction of its outcome. The prediction is always based on the particular experiment designed to test a specific hypothesis. Predictions are written in the form of if/then statements: "lf the hypothesis is true, then the results of the experiment will be…"; for example, "if cactus spines reduce herbivory, then removal of the spines will result in greater surface area removed by herbivores." Making a prediction provides a critical analysis of the experimental design. If the predictions are not clear, the procedure can be modified before beginning the experiment. For the soybean experiment, the hypothesis was: "Exposure to sulfur dioxide reduces reproduction." What should the prediction be? State your prediction.

To evaluate the results of the experiment, the investigator always returns to the prediction. If the results match the prediction, then the hypothesis is supported. If the results do not match the prediction, then the hypothesis is falsified. Either way, the scientist has increased knowledge of the process being studied. Many times the falsification of a hypothesis can provide more information than confirmation does, since the ideas and data must be critically evaluated in light of new information. In the soybean experiment, the scientist may learn that the prediction is true (sulfur dioxide does reduce reproduction at the concentration tested). As a next step, the scientist may now wish to identify the particular level at which the effect is first demonstrated. Review your hypotheses for the numbered questions. Consider how you might design an experiment to test the first hypothesis. For example, you might measure auditory function by performing hearing tests or observing changes in structures in the ear. The prediction might be:

IF cell phone usage reduces auditory function (a restatement of the hypothesis),

then people who use cell phones will score lower on hearing tests than persons who do not (predicting the results from the experiment).

Now consider an experiment you might design to test the second hypothesis. How will you measure "mental advantage"?

State a prediction for this hypothesis and experiment. Use the if/then format:

The actual test of the prediction is one of the great moments in research. No matter the results, the scientist is not just following a procedure but truly testing a creative explanation derived from an interesting question.​

1. Honeybees provide 80% of the pollination services for crops, including almonds, squash, melons, alfalfa, apples, and pumpkins. Migratory beekeepers transport over 2 million hives to farmland as crops begin to flower. In 2006-2007 beekeepers were alarmed when 50% of the honeybee colonies in 26 states were lost. In fact one of the biggest mysteries was that the bees were not found dead in the hives, but rather were simply gone! Scientists have termed this Colony Collapse Disorder (CCD). They are currently considering three alternative hypotheses: emerging pathogens (viruses, bacteria, and/or fungi), environmental toxins or chemicals; or abduction by humans (or aliens). Using the criteria in Lab Study B, Developing Hypotheses, select the hypothesis you would pursue as a scientist and justify your choice.

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