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10.3: Results - Biology

10.3: Results - Biology



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Forehead Cultures

1. Examine the 2 forehead culture plates from your bench. Do you observe different colony types?

2. Select a single colony (if possible, a well-isolated colony) for subculturing from one of the two plates inoculated at your bench. What are the characteristics of this specific colony (colors, elevation, margins, etc.)?

3. Using the bacteria from your chosen colony, streak for single colonies on a second TSA plate. (If you need to review this procedure, see Lab 2.)

4. Incubate the plate until next week (Lab 12). Why do you think it is important to streak this colony out for a second time before proceeding with the identification?

Why do you think it is important to streak this colony out for a second time before proceeding with the identification?


Ultrafast and memory-efficient alignment of short DNA sequences to the human genome

Bowtie is an ultrafast, memory-efficient alignment program for aligning short DNA sequence reads to large genomes. For the human genome, Burrows-Wheeler indexing allows Bowtie to align more than 25 million reads per CPU hour with a memory footprint of approximately 1.3 gigabytes. Bowtie extends previous Burrows-Wheeler techniques with a novel quality-aware backtracking algorithm that permits mismatches. Multiple processor cores can be used simultaneously to achieve even greater alignment speeds. Bowtie is open source http://bowtie.cbcb.umd.edu.


Effects of Acid Rain

Acid rain causes acidification of lakes and streams and contributes to the damage of trees at high elevations (for example, red spruce trees above 2,000 feet) and many sensitive forest soils. In addition, acid rain accelerates the decay of building materials and paints, including irreplaceable buildings, statues, and sculptures that are part of our nation’s cultural heritage. Prior to falling to the earth, sulfur dioxide (SO2) and nitrogen oxide (NOx) gases and their particulate matter derivatives—sulfates and nitrates—contribute to visibility degradation and harm public health.

The ecological effects of acid rain are most clearly seen in the aquatic, or water, environments, such as streams, lakes, and marshes. Most lakes and streams have a pH between 6 and 8, although some lakes are naturally acidic even without the effects of acid rain. Acid rain primarily affects sensitive bodies of water, which are located in watersheds whose soils have a limited ability to neutralize acidic compounds (called “buffering capacity”). Lakes and streams become acidic (i.e., the pH value goes down) when the water itself and its surrounding soil cannot buffer the acid rain enough to neutralize it. In areas where buffering capacity is low, acid rain releases aluminum from soils into lakes and streams aluminum is highly toxic to many species of aquatic organisms. Acid rain causes slower growth, injury, or death of forests. Of course, acid rain is not the only cause of such conditions. Other factors contribute to the overall stress of these areas, including air pollutants, insects, disease, drought, or very cold weather. In most cases, in fact, the impacts of acid rain on trees are due to the combined effects of acid rain and these other environmental stressors.

Figure 2. A gargoyle that has been damaged by acid rain.

Acid rain and the dry deposition of acidic particles contribute to the corrosion of metals (such as bronze) and the deterioration of paint and stone (such as marble and limestone). These effects significantly reduce the societal value of buildings, bridges, cultural objects (such as statues, monuments, and tombstones), and cars (Figure 2).

Sulfates and nitrates that form in the atmosphere from sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions contribute to visibility impairment, meaning we cannot see as far or as clearly through the air. The pollutants that cause acid rain—sulfur dioxide (SO2) and nitrogen oxides (NOx)—damage human health. These gases interact in the atmosphere to form fine sulfate and nitrate particles that can be transported long distances by winds and inhaled deep into people’s lungs. Fine particles can also penetrate indoors. Many scientific studies have identified a relationship between elevated levels of fine particles and increased illness and premature death from heart and lung disorders, such as asthma and bronchitis.

Attribution

Essentials of Environmental Science by Kamala Doršner is licensed under CC BY 4.0. Modified from the original by Matthew R. Fisher.


10.3 – Polygenic Inheritance

Inheritance of phenotypic characters (such as height, eye colour in humans) that are determined by the collective effects of several genes. A single characteristic that is controlled by two or more genes.

10.3.2 – Explain that polygenic inheritance can contribute to continuous variation using two examples, one of which must be human skin colour

Since a single characteristic may be influenced by more than one gene, it may exhibit continuous variation within a population. These genes are collectively called polygenes. Each allele of a polygenic character often contributes only a small amount to the overall phenotype, making study of individual alleles difficult. Phenotypic variation is the result of genotypic variation coupled with environmental variation. Environmental effects smooth out the genotypic variation, giving continuous distribution curves.

Skin colour is actually determined by more than two genes. However, this example shows only two. It is represented by nine possible genotypes, which form five phenotypes. There are two genes, each with two alleles that control the amount of melanin

There are two genes, each with two alleles that control the amount of melanin A and B code to add melanin

A and B code to add melanin a and b code for no added melanin

a and b code for no added melanin

The amount of pigment produced is directly proportional to the number of dominant alleles for either gene. Having no dominant alleles results in an albino.

However, the phenotype is also influenced by environmental factors. In the case of skin colour, the exposure of the individual to sunlight will slightly alter the amount of melanin produced in their skin. This smooths out the distribution of skin colour into one continuous curve.

Finches eat seeds, breaking them open with their beaks. The depth of a finch’s beak is controlled by a number of genes here, we only look at two: A and B code to add

A and B code to add depth
a and b code for no added depth.

Heterozygous cross: AaBb x AaBb

Darker orange indicates greater beak depth. This will form a similar distribution to that of skin colour seen above. Once again, environmental factors will smooth out the distribution.


Content Preview

In this example, two columns indicate the actual condition of the subjects, diseased or non-diseased. The rows indicate the results of the test, positive or negative.

Cell A contains true positives, subjects with the disease and positive test results. Cell D subjects do not have the disease and the test agrees.

A good test will have minimal numbers in cells B and C. Cell B identifies individuals without disease but for whom the test indicates 'disease'. These are false positives. Cell C has the false negatives.

If these results are from a population-based study, prevalence can be calculated as follows:

Prevalence of Disease= (dfrac<>>>< ext> imes 100)

The population used for the study influences the prevalence calculation.

Sensitivity is the probability that a test will indicate 'disease' among those with the disease:

Sensitivity: A/(A+C) × 100

Specificity is the fraction of those without disease who will have a negative test result:

Specificity: D/(D+B) × 100

Sensitivity and specificity are characteristics of the test. The population does not affect the results.

A clinician and a patient have a different question: what is the chance that a person with a positive test truly has the disease? If the subject is in the first row in the table above, what is the probability of being in cell A as compared to cell B? A clinician calculates across the row as follows:

Positive Predictive Value: A/(A+B) × 100

Negative Predictive Value: D/(D+C) × 100

Positive and negative predictive values are influenced by the prevalence of disease in the population that is being tested. If we test in a high prevalence setting, it is more likely that persons who test positive truly have disease than if the test is performed in a population with low prevalence..

Let's see how this works out with some numbers.

Hypothetical Example 1 - Screening Test A

100 people are tested for disease. 15 people have the disease 85 people are not diseased. So, prevalence is 15%:

Sensitivity is two-thirds, so the test is able to detect two-thirds of the people with disease. The test misses one-third of the people who have disease.

The test has 53% specificity. In other words, 45 persons out of 85 persons with negative results are truly negative and 40 individuals test positive for a disease which they do not have.

The sensivity and specificity are characteristics of this test. For a clinician, however, the important fact is among the people who test positive, only 20% actually have the disease.

For those that test negative, 90% do not have the disease.

Now, let's change the prevalence..

Hypothetical Example 2 - Increased Prevalence, Same Test

This time we use the same test, but in a different population, a disease prevalence of 30%.

  • Prevalence of Disease:
  • (dfrac<>>>< ext> imes 100)
    30/100 × 100 = 30%

We maintain the same sensitivity and specificity because these are characteristic of this test.

  • Sensitivity:
    A/(A + C) × 100
    20/30 × 100 = 67%
  • Specificity:
    D/(D + B) × 100
    37/70 × 100 = 53%

Now let's calculate the predictive values:

  • Positive Predictive Value:
    A/(A + B) × 100
    20/53 × 100 = 38%
  • Negative Predictive Value:
    D/(D + C) × 100
    37/47 × 100 = 79%

Using the same test in a population with higher prevalence increases positive predictive value. Conversely, increased prevalence results in decreased negative predictive value. When considering predictive values of diagnostic or screening tests, recognize the influence of the prevalence of disease. The figure below depicts the relationship between disease prevalence and predictive value in a test with 95% sensitivity and 95% specificity:

Relationship between disease prevalence and predictive value in a test with 95% sensitivity and 85% specificity.
(From Mausner JS, Kramer S: Mausner and Bahn Epidemiology: An Introductory Text. Philadelphia, WB Saunders, 1985, p. 221.)

Try it!

Minimizing false positives is important when the costs or risks of followup therapy are high and the disease itself is not life-threatening. prostate cancer in elderly men is one example as another, obstetricians must consider the potential harm from a false positive maternal serum AFP test (which may be followed up with amniocentesis, ultrasonography and increased fetal surveillance as well as producing anxiety for the parents and labeling of the unborn child), against potential benefit.

Try it!

We don’t want many false negative if the disease is often asymptomatic and

  1. is serious, progresses quickly and can be treated more effectively at early stages OR
  2. easily spreads from one person to another

What is a good test in a population? Actually, all tests have advantages and disadvantages, such that no test is perfect. There is no free lunch in disease screening and early detection.


10.3 How does sexual selection work?

Sexual selection, the process through which individuals compete for mates, primarily takes two forms: intersexual selection and intrasexual selection. Intersexual selection, often referred to as mate choice, involves individuals of one sex choosing among members of the opposite sex based on the attractiveness of certain traits that those individuals possess. Intrasexual selection, also called mate competition, involves one sex competing with members of the same sex for access to mates.

Typically, the sex that is choosing mates is the one that invests more in gamete production prior to mating. Conversely, the sex that is chosen is also the sex that fights with members of the same sex for access to mates, and is traditionally the one that invests less in gamete production. In many species females produce just a few large and costly eggs, while males produce many, small and less expensive sperm. Because of this difference in gamete production and investment, known as anisogamy, females are typically the choosy sex and males typically compete with other males for access to females.

Figure 10.3 Notice the difference between the size of the human egg versus the human sperm. The difference in gamete size and number can explain why females are choosy about which males to mate with. This is referred to as anisogamy.

Generally, it is unusual for males to be choosy about their mates. There are many reasons for this. Gamete production and investment is one reason. Another reason why females are typically the choosy sex has to do with the level of investment in offspring care, known as parental care. For example, following sexual reproduction and fertilization, most mammals develop within the body of their mothers. The developing offspring of most mammals then get their food and oxygen from the blood of their mothers through a spongy organ called the placenta. Even marsupial offspring, though not fully developed when born, are usually carried by their mothers in a pouch until they are able to walk on their own. I suspect that you have noticed a pattern here- mothers typically invest more than fathers when it comes to caring for developing offspring. This is another major reason why females are choosy about their mates.

However, in some animals, males provide a great deal of parental care to their offspring. For example, in emperor penguins each female produces a single egg. She then transfers the egg to her male mate and leaves to spend the winter in the open ocean in search of food and other resources. During the Antarctic winter, which lasts about four months, male emperor penguins huddle in groups, guarding their eggs and keeping them warm. An extreme example lies in seahorses, among whom males get pregnant and carry their offspring during development, after which they give birth to baby seahorses.

As a result of males investing a great amount of time and energy into caring for their offspring during development, some species of animals show a reversal in who is the choosy sex. For example, in many poison-dart frogs, males are the sole providers of parental care to developing offspring. As such, female poison-dart frogs will fight amongst each other in the presence of calling males, and some have been observed to court a single singing male in the field.

Historically, much of the research on sexual selection has focused on what happens between males and females prior to mating. For example, a lot of work has been dedicated to understanding how males signal to attract females, and what females look for in potential mates. However, it is important to note that sexual selection can occur before and after a female and male mate. Before mating, individuals will signal their quality to potential mates. After mating, individuals can bias paternity in their favor through various processes including cryptic female choice and sperm competition, which we will discuss later in this chapter.


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Bacteria on Skin

Figure 10.3.5 The bacterium Staphylococcus epidermidis is a common microorganism living on healthy human skin.

The surface of the human skin normally provides a home to countless numbers of bacteria. Just one square inch of skin normally has an average of about 50 million bacteria. These generally harmless bacteria represent roughly one thousand bacterial species (including the one in Figure 10.3.5) from 19 different bacterial phyla. Typical variations in the moistness and oiliness of the skin produce a variety of rich and diverse habitats for these microorganisms. For example, the skin in the armpits is warm and moist and often hairy, whereas the skin on the forearms is smooth and dry. These two areas of the human body are as diverse to microorganisms as rainforests and deserts are to larger organisms. The density of bacterial populations on the skin depends largely on the region of the skin and its ecological characteristics. For example, oily surfaces, such as the face, may contain over 500 million bacteria per square inch. Despite the huge number of individual microorganisms living on the skin, their total volume is only about the size of a pea.

In general, the normal microorganisms living on the skin keep one another in check, and thereby play an important role in keeping the skin healthy. If the balance of microorganisms is disturbed, however, there may be an overgrowth of certain species, and this may result in an infection. For example, when a patient is prescribed antibiotics, it may kill off normal bacteria and allow an overgrowth of single-celled yeast. Even if skin is disinfected, no amount of cleaning can remove all of the microorganisms it contains. Disinfected areas are also quickly recolonized by bacteria residing in deeper areas (such as hair follicles) and in adjacent areas of the skin.


10.3: Results - Biology

Figure 1. Processes involved in acid deposition.

Acid rain is a term referring to a mixture of wet and dry deposition (deposited material) from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. The precursors, or chemical forerunners, of acid rain formation result from both natural sources, such as volcanoes and decaying vegetation, and man-made sources, primarily emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) resulting from fossil fuel combustion. Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds. The result is a mild solution of sulfuric acid and nitric acid. When sulfur dioxide and nitrogen oxides are released from power plants and other sources, prevailing winds blow these compounds across state and national borders, sometimes over hundreds of miles.

Measuring Acid Rain

Acid rain is measured using a scale called “pH.” The lower a substance’s pH, the more acidic it is. Pure water has a pH of 7.0. However, normal rain is slightly acidic because carbon dioxide (CO2) dissolves into it forming weak carbonic acid, giving the resulting mixture a pH of approximately 5.6 at typical atmospheric concentrations of CO2. As of 2000, the most acidic rain falling in the U.S. has a pH of about 4.3.

Effects of Acid Rain

Acid rain causes acidification of lakes and streams and contributes to the damage of trees at high elevations (for example, red spruce trees above 2,000 feet) and many sensitive forest soils. In addition, acid rain accelerates the decay of building materials and paints, including irreplaceable buildings, statues, and sculptures that are part of our nation’s cultural heritage. Prior to falling to the earth, sulfur dioxide (SO2) and nitrogen oxide (NOx) gases and their particulate matter derivatives—sulfates and nitrates—contribute to visibility degradation and harm public health.

The ecological effects of acid rain are most clearly seen in the aquatic, or water, environments, such as streams, lakes, and marshes. Most lakes and streams have a pH between 6 and 8, although some lakes are naturally acidic even without the effects of acid rain. Acid rain primarily affects sensitive bodies of water, which are located in watersheds whose soils have a limited ability to neutralize acidic compounds (called “buffering capacity”). Lakes and streams become acidic (i.e., the pH value goes down) when the water itself and its surrounding soil cannot buffer the acid rain enough to neutralize it. In areas where buffering capacity is low, acid rain releases aluminum from soils into lakes and streams aluminum is highly toxic to many species of aquatic organisms. Acid rain causes slower growth, injury, or death of forests. Of course, acid rain is not the only cause of such conditions. Other factors contribute to the overall stress of these areas, including air pollutants, insects, disease, drought, or very cold weather. In most cases, in fact, the impacts of acid rain on trees are due to the combined effects of acid rain and these other environmental stressors. Acid rain and the dry deposition of acidic particles contribute to the corrosion of metals(such as bronze) and the deterioration of paint and stone (such as marble and limestone). These effects significantly reduce the societal value of buildings, bridges, cultural objects (such as statues, monuments, and tombstones), and cars (Figure below).

Figure 2. A gargoyle that has been damaged by acid rain.

A gargoyle that has been damaged by acid rain.

Sulfates and nitrates that form in the atmosphere from sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions contribute to visibility impairment, meaning we cannot see as far or as clearly through the air. The pollutants that cause acid rain—sulfur dioxide (SO2) and nitrogen oxides (NOx)—damage human health. These gases interact in the atmosphere to form fine sulfate and nitrate particles that can be transported long distances by winds and inhaled deep into people’s lungs. Fine particles can also penetrate indoors. Many scientific studies have identified a relationship between elevated levels of fine particles and increased illness and premature death from heart and lung disorders, such as asthma and bronchitis.

Update:

September 24, 2016: “New research shows that human pollution of the atmosphere with acid is now almost back to the level that it was before the pollution started with industrialization in the 1930s. The results come from studies of the Greenland ice sheet.” Science Daily

Attribution

Essentials of Environmental Science by Kamala Doršner is licensed under CC BY 4.0. Modified from the original by Matthew R. Fisher.


Lab 10 – Physiology of the Circulatory System

Introduction: The human circulatory system is a collection of structures thorough which oxygen and nutrient rich blood flows to all tissues of the body for metabolism and growth, and to remove metabolic wastes. The blood is pumped to these tissues by the heart through a circuit composed of arteries, arterioles, capillaries, venules, and veins. Oxygenated blood is pumped to the tissues from the left side of the heart, whereas deoxygenated blood is pumped to the lungs from the right side of the heart. This circuit where gas exchange takes place within the alveoli of the lung is very important and is known as the pulmonary circuit. When the body is exercised changes can take place in the circulatory system that allow more blood to pass to actively respiring muscle cells and less to nonmuscular tissue. Increased heart rate, arterial pressure, body temperature, and breathing rate also occur during exercise.

Arterial blood pressure is directly dependant on the amount of blood pumped by the heart per minute and the resistance to blood flow through the arterioles. This is an important measurable aspect of the circulatory system and it is measured using a sphygmomanometer. This device has an inflatable cuff that connects to a hand pump and a pressure gauge, graduated in millimeters of mercury, by rubber tubing. The cuff is wrapped around the upper arm and inflated, the person taking the pressure then listens for two sounds and observes the gauge to determine what the blood pressure is. The systolic number is determined by the first noise heard as the cuff is deflated, and the diastolic number is determined by the last distinct noise heard.

Hypothesis: From this experiment it is expected that a subject’s heart rate and blood pressure will change during rest and exercise based on how physically fit they are. If the subject is in good shape the heart rate will not increase significantly and the blood pressure will increase. The opposite is true of someone in poor shape.

Materials: The materials used in this experiment include a blood pressure kit, alcohol swabs, a stopwatch, two depression slides, a cotton ball, four rubber bands, a pipet, a petri dish, a Daphnia culture, a stereomicroscope, and some ice.

A. Measuring Blood Pressure: To measure blood pressure, one member of the lab group sat down in a chair, rolled up his sleeve, and then the sphygmomanometer cuff was placed around his upper left arm at heart level. The cuff was then pumped to 200mm Hg, which is safely higher than the blood pressure of the subject. The stethoscope was then placed in the well of the subject’s elbow, where the brachial artery is located, and pressure was slowly released as the taker listened for a pulse. The pressure on the gauge was noted when first sound of Korotkoff was heard, which is the pressure that blood is first able to pass through the artery during systole, representing systolic pressure. The sounds of Korotkoff are heard between the systolic and diastolic blood pressures. The diastolic pressure is the reading of the gauge at the time the sounds of Korotkoff can no longer be heard. The subject’s blood pressure was taken two more times and an average was calculated and recorded in Table 1.

B. Physical Fitness Test: The first numbers recorded from this section of the experiment were those of standing vs. resting blood pressure. To do this a member of the lab group had to lie down on a table for five minutes. After five minutes the subject’s blood pressure was taken while he was still lying down and the numbers were recorded in Table 2. The subject remained lying down for another two minutes, stood up, and their blood pressure was taken again. The standing systolic pressure was subtracted from the resting systolic pressure and recorded in Table 2. A chart was used to determine the number of points received by the subject and recorded in Table 3.

The next part of this section is where the subject’s standing heart rate was determined. Taken by the subject was the radial artery pulse by counting the number of beats for 30 seconds. That number was multiplied by 2 to obtain the number of beats per minute. That number was recorded in Table 3. Another chart was used to determine the amount of points the subject received for this section and that number was also recorded in Table 3.

Next the resting heart rate was determined by having the subject lie down on a table for five minutes. After five minutes the subject’s pulse was taken and recorded in Table 3. Once again a chart was used to determine the number of points the subject received for this section of the experiment and the number was recorded in Table 3.

Next the Baroreceptor reflex test was given to the subject. The subject had to lie down for five minutes, stand up quickly, and record the pulse. From this number the resting heart rate was subtracted and recorded in Table 3. A chart was then used to determine the number of points the subject received for this section and recorded in Table 3.

The endurance test was the last leg of this section of the experiment. To do this the subject stepped up with one foot onto an 18 inch high surface and then brought up the other foot onto the surface. This was continued for 15 seconds, and then his pulse was taken at several intervals. First the pulse was taken right after the exercise for 15 seconds and multiplied by four. This was repeated one more time after that as well. Then the pulse was taken every 30 seconds for 120 seconds after that. The data was recorded in Table 4. The amount of time it took for the subject’s heart rate to return to normal was figured and a chart was used to award points. These heart rates were then compared to the standing heart rate. Next, the standing heart rate was subtracted from the rate taken right after exercise, and yet another chart was used to award points.

C. Investigating Heart Rate in Daphnia: Two depression slides were obtained and a small piece of cotton was placed in the center of one of the slides. Several Daphnia were placed on the slide with a pipet and the other slide was placed on top of this slide and wrapped together with a rubber band on each end. A petri dish was filled with room-temperature water, 1cm deep and the slides were placed into it. The heart of the largest Daphnia was then located under the stereomicroscope and the number of beats in 15 seconds was determined, multiplied by four, and the results placed in Table 5. Into the dish was then added ice water and the same Daphnia’s heart rate was determined and recorded in Table 5. Gradually warm water was added and the heart rate was taken at five minute intervals until the normal heart rate is noted. These results were put in Table 5.

Blood Pressure Systolic Diastolic
Trial 1 115 72
Trial 2 115 70
Trial 3 115 74
Average 115 72

Standing vs. Resting Blood Pressure

Position Systolic Diastolic
Lying Down 5 min. 110 72
Lying to Standing 120 72
Change 10 0

Activity Result Fitness Points
Change in Blood Pressure 10 3
Standing Pulse Rate 78 3
Resting Pulse Rate 64 3
Baroreceptor Reflex 76 3
Heart Rate Recovery After Exercise 28 4
Heart Rate Increase After Exercise 18 2
Total Points 18

Heart Rate After Exercise

Interval No. of Beats Heart Rate
0 to 15 sec. 24 X4= 96
16 to 30 sec. 19 X4= 76
31 to 60 sec. 35 X2= 70
61 to 90 sec. 35 X2= 70
91 to 120 sec. 35 X2= 70

Total Score Cardiovascular Fitness
17 to 18 Excellent
14 to 16 Good
8 to 13 Fair
7 or less Poor

1. What changes occur in the circulatory system when a person stands up from a prone position? How do these changes affect the heart rate and blood pressure of the individual?

The circulatory system is not working very hard when a person is at rest so when that person stands up suddenly the blood pressure and heart rate of that person increase.

2. How does the circulatory system, and the heart in particular, of a conditioned athlete differ from that of a person in poor shape?

The heart of a conditioned athlete is stronger because it has been worked harder pumping more blood when that person exercises. The heart of a person in poor shape has not been worked as hard.

3. Why is high blood pressure dangerous? What health problems does it lead to?

High blood pressure is dangerous because the heart has to work to hard to push the blood through the various veins and arteries and a heart attack can occur.

4. What sort of behaviors encourage high blood pressure? Why?

Eating fatty foods and not exercising cause high blood pressure because the heart is not working hard to pump the blood, which makes it weak.

Temperature (C) Heartbeats per Minute
Room Temperature 200
0 to 5 84
10 160
15 152
20 204
25 200
30 212
35 216

Temperature Range Rate of the reaction (change in heart rate)
0-10 Q10 =1.9
10-20 Q10 =1.275
20-30 Q10 =1.04

1. Why does the rate of activity of ectothermic organisms increase with a rise in the temperature of its environment? How is this different from an endothermic organism?

Ectothermic organisms’ body heat is determined by the environment, so their metabolic rates also change with this. Endotherms have a constant body temperature and do not change their metabolic rate strictly based on environmental conditions.

2. If this experiment were performed on a human subject, what results would you expect? Explain.

A human’s heart would also be affected by the temperature changes, but not to the extent that the Daphnia heart did.

Error Analysis: The only possible source of error in this lab would have been the slight misreading of the gauge on the sphygmomanometer.

Conclusions: Cardiovascular fitness is very important to living a healthy life. If one doesn’t exercise and eat healthy foods they run a risk of being in poor shape and having a heart attack or other serious things. Heart rate and blood pressure readings can give a person a good idea about how healthy they are or how healthy they need to be. Blood pressure is so important to a person’s health it is checked at every visit to the doctor or hospital.


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