Mastering Biology: Chapter 1 Part 1

A controlled experiment is one that:

tests experimental and control groups in parallel

A scientific theory is __________.

a well-supported concept that has broad explanatory power

How many dark brown mice were caught in the dark-colored soil enclosure on a moonlit night?

12

In the process of science, which of these is tested?

a hypothesis

Repetition of an experiment _________.

is necessary before concluding that a given set of results is correct *Repetition of tests is crucial to the process of science. Only when a result is repeatable can it be considered correct.

Current Events: Focusing on Fruit Flies, Curiosity Takes Flight (New York Times, 10/7/2013) Which of the following is necessary for fruit flies to fly?

leading-edge vortex

Current Events: Image of Hindenburg Haunts Hydrogen Technology (New York Times, 10/29/2013) You purchase a hydrogen fuel-cell vehicle. Which of the following will need to be present for your car to work?

oxygen

Which of the following is not an observation or inference on which Darwin's theory of natural selection is based?

poorly adapted individuals never produce offspring

A localized group of organisms that belong to the same species is called a _____.

population

What is the appropriate term for an interacting group of individuals of a single type occupying a defined area?

population *Only the organisms of a given species that have the opportunity to interact with one another are considered to be within the same population.

Protists and bacteria are grouped into different domains because:

protists have a membrane-bounded nucleus, which bacterial cells lack

Which of the following best demonstrates the unity among all the organisms?

the structure and function of DNA

The energy used by most organisms for metabolism and growth ultimately comes from __________.

the sun *Energy for most living things ultimately comes from the light energy of the sun, used to drive the synthesis of energy storage molecules by photosynthetic organisms.

Agrobacterium infects plants and causes them to form tumors. You are asked to determine how long a plant must be exposed to these bacteria to become infected. Which of the following experiments will provide the best data to address that question?

Measure the number of tumors formed on plants, which are exposed to Agrobacterium for different lengths of time.

A(n) _____________ is a testable explanation for an observation.

hypothesis

An important property of a linear graph is the slope of the graph line. The slope is a value that indicates the steepness of the line, as well as whether the line slants uphill or downhill. A slope with a positive value slants uphill as you move from left to right across the graph. A slope with a negative value slants downhill as you move from left to right across the graph. The slope is the ratio of the rise of the line to the run of the line. It can be expressed algebraically like this: m=y2−y1/x2−x1 where (x1, y1) and (x2, y2) are the coordinates of two points on the line. What is the approximate slope (m) of this line? (For practice finding the slope of a line, try this activity.)

0.5 *The slope is the ratio of the rise of the line to the run of the line. For example, by using the points at 20% GC and 60% GC, you can estimate the slope like this: m=110−90/60−20 The slope indicates the rate of change. In this case, for every 1% increase in GC content, the melting point of the DNA increases by 0.5 ∘C.

GraphIt!: An Introduction to Graphing Between 1966 and 1995, what has been the approximate decrease in stream flow rates in Monteverde?

0.8 m3/sec

GraphIt!: An Introduction to Graphing As stem density increases from about 35,000 stems to about 55,000 stems per hectare, what is the increase in snowshoe hare density?

1 hare per hectare

Using the equation of the line (y = 0.5x + 79), what would be the melting point of DNA with 50% GC content? Enter your answer as a whole number.

104 *The equation of the line is: y = 0.5x + 79 If you want to know the melting point (y) for DNA with a GC content of 50% (x), plug 50 in for x. y = 0.5(50) + 79 y = 104 ∘C

How many dark brown mice were caught in the light-colored soil enclosure on a moonlit night?

19

How many light brown mice were caught in the dark-colored soil enclosure on a moonlit night?

28

Activity: Introduction to Experimental Design Which of the following statements is true of a hypothesis?

A hypothesis can be supported or rejected through experimentation. A hypothesis is supported or rejected based on the outcome of one or more experiments.

Which condition is optimal for predation by the owl on mice?

Dark nights are better for hunting.

Which taxonomic domain includes multicellular photosynthetic organisms?

Eukarya *Plants and certain algae are multicellular photosynthetic organisms included in the kingdom Plantae of the domain Eukarya.

GraphIt!: An Introduction to Graphing For the sooty tern, there is a steady decrease in the percent of diet as fish length decreases from 6 cm to 0 cm.

False

Hint 2. How should a female response appear on the graph?

For this experiment, you devised a scoring system to measure the female response to the male's song. On a scale of 0 to 10, 10 represents the female turning directly toward the singing male and 0 represents no motion or random turning. Which of the following describes what you would see on the graph if the female responded to the male only when she was at 25 °C? The plot would spike near 10 at 25 °C.

Which of the following best describes the logic of scientific inquiry?

If my hypothesis is correct, I can expect certain test results.

Which of the following statements most clearly demonstrates inductive reasoning?

If the animals observed require organic molecules as nutrients, then it can be concluded that all animals require organic molecules as nutrients.

Hint 3. The range of values shown on the x-axis

In this graph, the data you plotted fall between 15 °C and 30 °C, which reflect the range of temperatures that you tested. It does not mean that these crickets do not sing when the temperature is below 15 °C or above 30 °C, only that you did not test their songs at temperatures outside that range.

Which of the following is (are) true of natural selection?

It requires genetic variation, results in descent with modification, and involves differential reproductive success.

Current Events: Image of Hindenburg Haunts Hydrogen Technology (New York Times, 10/29/2013) Why are so many people concerned with using hydrogen as a fuel?

It is flammable.

Which of the following best describes a model organism?

It is well studied, it is easy to grow, and results are widely applicable.

What can you conclude from the graph? Select all that apply.

Large clutch size is strongly correlated with lower chick survival. *The graph shows only that large clutch size is strongly correlated with lower chick survival. To determine whether a large clutch size is a direct cause of lower chick survival would require further study. It may be that the parent birds struggle to find enough food to feed a large number of chicks. Or it may be that a large number of chicks attracts predators to the nest.

Recall the caterpillar experiment in which caterpillars born in the spring looked like flowers, and caterpillars born in the summer looked like twigs. What is the most likely selective advantage for this difference in body shape?

Looking like their food source lets the caterpillars blend into their surroundings, reducing predation.

When a person gets dehydrated while exercising on a hot day, their pituitary gland releases ADH, a hormone that signals the kidneys to retain more water. This is an example of :

Negative feedback regulation

On a moonlit night, would a dark brown mouse be more likely to escape predation by owls on dark- or light-colored soil? What data support your conclusion?

On dark-colored soil; fewer dark brown mice were caught on dark soil than on light soil under a full moon.

On a moonlit night, would a light brown mouse be more likely to escape predation by owls on dark- or light-colored soil? What data support your conclusion?

On light-colored soil; fewer light brown mice were caught on light soil than on dark soil under a full moon.

Which of the following is an example of qualitative data?

The fish swam in a zigzag motion.

Which of the following statements best describes the phenomenon of "emergence"?

The whole is greater than the sum of the parts.

How does a scientific theory differ from a scientific hypothesis?

Theories are usually an explanation for a more general phenomenon; hypotheses typically address more specific issues.

Which of the following is an attribute of living things?

They must be capable of acquiring adaptations through evolution. *One of the attributes that we associate with groups of living things is the ability to adapt by evolving.

GraphIt!: An Introduction to Graphing Even though they live in the same location, these two species probably experience minimal competition for food.

True

Should an experiment test only one variable at a time? Why or why not?

Yes, an experiment should test only one variable at a time. This ensures that the experimental outcome is clearly due to one identifiable factor.

You find yourself standing next to a beautiful rose bush. Which of the following do you and the rose have in common?

You both are multicellular.

Can you organize these terms that describe key ideas about evolution?

a. diversity b. natural selection c. living species d. ancestral species e. heritable variations in a population f. greater reproductive success g. evolutionary adaptions

Which of the following types of cells utilize deoxyribonucleic acid (DNA) as their genetic material but do not have their DNA encased within a nuclear envelope?

archaean

In an ecosystem, nutrients __________ and energy __________.

are recycled ... flows through *Nutrients are always recycled. Energy flows through the system, typically entering as solar energy and leaving as heat.

What combination of independent variables led to the highest predation level in enclosures with light-colored soil?

dark brown coat with no moon

Imagine that your car is stalled and will not start. If you add gasoline to the tank to see if that helps, which step of the scientific method are you performing?

experiment

GraphIt!: An Introduction to Graphing For what sizes of fish is there the least amount of overlap in the diets of these two tern species?

greater than 6 cm

The best method for determining whether bean plants require sodium is to __________.

grow bean plants with and without sodium *In hypothesis-based scientific inquiry, the experiment must have an experimental group and a control group. In this case, growing bean plants with sodium would constitute the experimental group, and growing bean plants without the addition of sodium would constitute the control group.

How does DNA (deoxyribonucleic acid) encode information?

in the sequence of nucleotides.

What is the correct order for the hierarchy of biological organization from the least to the most complex?

molecule, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem *Each level of biological structure builds on the level before it.

In the diagram below, "A" is _____ ; "B" is _____.

the common ancestor of all life; the last common ancestor of Archaea and Eukarya

Which of the following attributes is common to both prokaryotic cells and eukaryotic cells?

the use of DNA as the information storage molecule All cells (discovered so far) use DNA to store information.

Which equation most closely approximates the regression line shown in the graph? (For practice approximating the equation of a line, try this activity.)

y = -0.14x + 1.2

Math Practice: Applying Linear Equations to Biological Data

The graph shown here depicts the relationship between the nucleotide composition of a DNA molecule and the temperature at which the DNA molecule denatures (unwinds). The composition of the DNA is measured as the percentage of guanine and cytosine nucleotides (% GC). The temperature at which the DNA denatures is called the melting point.

How is the information encoded in DNA actually used by organisms?

The information in DNA is transcribed to RNA and then usually translated into protein. *The information in DNA is first transcribed to RNA and then translated into protein.

Agrobacterium infects plants and causes them to form tumors. You determine that tumor formation requires a large amount of the plant's energy for tissue formation. How might this change the number of offspring a plant produces, and what is the most likely explanation for this change?

The number of offspring should decrease, because the plant will divert energy from reproduction to tumor formation.

Can you label this diagram showing how nutrients and energy flow in an ecosystem?

a. sunlight b. producers c. chemical energy d. consumers e. heat f. CO2 g. O2

Experimentation is only one part of the process of scientific inquiry, but it is a very important step because it __________.

allows rejection of hypotheses *Experimentation is important because hypotheses can be rejected when contradictory evidence emerges.

Emergent properties of living systems are properties that __________.

are due to the arrangement and interactions of parts as complexity increases *Emergent properties are novel properties not present at the level of biological organization just below. Emergent properties arise from the arrangement and interactions of parts as complexity increases.

Activity: Science, Technology, and Society: DDT In animal populations, DDT causes _____.

birth defects *In animals, long-term exposure to DDT can cause death or severe birth defects.

Which of the following can best be considered a biological system? a pond a single liver cell the biosphere a salmon's cardiovascular system

A system is a combination of components that function together. It can be defined at any scale.

Select the most accurate statement about the interaction between a tree and its physical environment.

A tree and its physical environment alter each other. *This answer is the most accurate statement. Read the themes about the interactions among organisms and their physical environment.

Which of the following is NOT an attribute of living things?

All living things require oxygen.

Which of the following systems does NOT display emergent properties? a drop of water a colony of bees a calculator an organ

All of the listed answers are examples of emergence. Emergence is not restricted to biological systems.

Refer to the accompanying figure. Which one of the following is NOT a plausible hypothesis to explain the differences in caterpillar appearance observed in this population?

Differences in air pressure, due to differences in elevation, trigger the development of different types of caterpillars.

Refer to the accompanying figure. In every case, caterpillars that feed on oak flowers look like oak flowers. In every case, caterpillars that were raised on oak leaves looked like twigs. These results support which of the following hypotheses?

Differences in diet trigger the development of different types of caterpillars.

Interpret the Data: Does Camouflage Affect Predation Rates on Two Populations of Mice?

Hopi Hoekstra and colleagues wanted to test the hypothesis that coloration of beach and inland mice (Peromyscus polionotus) provides camouflage that protects them from predation in their respective habitats. The researchers spray-painted mouse models with either light or dark color patterns that matched those of the beach and inland mice and then placed models with both patterns in each of the habitats. The next morning, they counted damaged or missing models. For each habitat, the researchers calculated the percentage of attacked models that were camouflaged or non-camouflaged. Their results are shown in the graphs.

Which of these is an example of inductive reasoning?

Hundreds of individuals of a species have been observed and all are photosynthetic; therefore, the species is photosynthetic.

Which of the following statements about the graph are true? Select all that apply.

Melting point is on the y-axis, and GC content is on the x-axis. As GC content increases, the melting point increases at a constant rate. The graph shows a linear relationship between GC content and melting point. *A linear relationship means that as one variable changes, the other variable changes at a constant rate, resulting in a straight line on a graph. Here, as the GC content of the DNA increases, the melting point increases at a constant rate.

The bars indicate the percentage of the attacked models that were either light or dark. Assume 100 mouse models were attacked in each habitat. Drag the numbers to the table to indicate the number of models attacked in each environment. Labels may be used once, more than once, or not at all.

Models: beach habitat-inland habitat (light:27-78) (dark:73-24)

Current Events: Genome Detectives Solve a Hospital's Deadly Outbreak (New York Times, 8/22/2012) Which of the following would have most likely prevented so many patient deaths from Klebsiella pneumoniae at this National Institutes of Health hospital?

More thorough disinfection techniques.

Which of the following statements is true about chemical nutrients in an ecosystem? They depend on sunlight as their source. They recycle within the ecosystem, being constantly reused. They exit the ecosystem in the form of heat. They flow through the system, losing some nutrients in the process. They cannot be obtained from decomposition.

They recycle within the ecosystem, being constantly reused. *Nutrients cycle through the ecosystem by processes such as the decomposition of organic debris.

Which of the following is the best description of a control for an experiment?

The control group is matched with the experimental group except for one experimental variable.

Refer to the accompanying figure. Recall that eggs from the same female were exposed to each of the eight treatments used. This aspect of the experimental design tested which of the following hypotheses?

The differences are genetic. A female will either produce all flowerlike caterpillars or all twig-like caterpillars.

Refer to the paragraph on Redi's experiments. In both experiments, flies appeared in all of the open jars and only in the open jars. Which one of the following statements is correct?

The experiment supports the hypothesis that maggots arise only from eggs laid by adult flies.

Do the results of the experiment support the camouflage hypothesis?

Yes; mouse models with camouflage coloration were preyed on less often than non-camouflaged mouse models. In both habitats, the models whose pattern did not match their surroundings suffered much higher "predation" than did the camouflaged models. The results are consistent with the researchers' prediction: that mouse models with camouflage coloration would be preyed on less often than non-camouflaged mouse models. Thus, the experiment supports the camouflage hypothesis.

Which of these examples illustrates deductive reasoning?

You learned in elementary school that as temperature drops, liquids change into solid form. You are given an unfamiliar liquid and hypothesize that it will become solid if you put it in the freezer. *This is deductive reasoning. You are predicting specific results based on general principles.

Activity: Science, Technology, and Society: DDT DDT is _____-soluble so it accumulates in _____.

fat ... milk *Fat-soluble DDT accumulates in the fats of milk and from there can be transferred to children.

Charles Darwin proposed a mechanism for descent with modification that stated that organisms of a particular species are adapted to their environment when they possess _____.

heritable traits that enhance their survival and reproductive success in the local environment

Based on both graphs, what condition(s) are most deadly for both colors of mice?

high contrast between the mouse and its background

At which point in a study is a scientific investigator most likely to use deductive reasoning?

in establishing a test of a hypothesis *In deduction, reasoning flows from the general to the specific. Deductive testing would take the form of "if ... then" logic.

The best experimental design _____.

includes a large sample size and a control, and alters only one condition between the controls and the experimental condition

A controlled experiment _____.

includes at least two groups, one of which does not receive the experimental treatment

What combination of independent variables led to the highest predation level in enclosures with dark-colored soil?

light brown coat with full moon

Combining the data shown in both graphs, estimate the total number of mice caught in moonlight versus no-moonlight conditions.

moonlight: about 77 caught; no moonlight: about 95 caught

Which of the following lists the steps of the scientific method in their proper order?

observation, question, hypothesis, prediction, experiment

Which of the following is an example of discovery science?

observing what other students in your class are wearing

Under which conditions would a dark brown mouse be most likely to escape predation at night?

on dark-colored soil with full moon light

Under which conditions would a light brown mouse be most likely to escape predation at night?

on light-colored soil with no moon

Which type of graph is best suited to this data?

scatter plot *A scatter plot is best suited to this data because it allows you to plot a discrete data point for each nest. In this case, a scatter plot is better than a line graph because each data point represents a different nest. Line graphs work best when continuous data is collected from one sample over time.

A friend of yours calls to say that his car would not start this morning. He asks for your help. You say that you think the battery must be dead. If so, then jump-starting the car from a good battery will solve the problem. In doing so, you are _____.

stating a hypothesis and using that hypothesis to make a testable prediction

Radon is a radioactive gas that seeps into homes from the soil. It is thought to be a cause of lung cancer. A research team investigates this hypothesis. The members of the team gather large amounts of data on basement radon concentrations and lung cancer rates and conclude that the more radon there is in a home, the more likely are people living in the home to develop lung cancer. After the study is published, other researchers criticize it by asserting that the studied neighborhoods with higher radon concentrations also have a higher percentage of older people and a higher percentage of cigarette smokers than the low-radon neighborhoods. Both advanced age and cigarette smoking increase the risk of lung cancer. This criticism, if correct, shows that the radon study suffered from __________.

uncontrolled variables *An important feature of the scientific process is to control for as many variables as possible. Ideally, the control and experimental groups should differ only in the one variable the study is designed to test.

Systems biology is mainly an attempt to:

understand the behavior of entire biological systems

Which variable would you put on the x-axis, and which variable would you put on the y-axis?

x-axis: clutch size y-axis: chick survival *You can think of clutch size as the independent variable and chick survival as the dependent variable.

Keep in mind that a straight line between two variables can be expressed as y = mx + b, where m is the slope of the line and b is the y-intercept. Which equation correctly expresses the line in the graph?

y = 0.5x + 79

With evolution as the core theme of biology, we can explain traits shared by organisms as evidence of __________ and traits that differ among organisms as evidence of __________.

common ancestor ... adaptation through natural selection *Many shared traits have been derived from common ancestry. The modifications to those shared traits can usually be attributed to adaptive evolution by natural selection.

A team of scientists has devised a new chemical fertilizer that its members believe will increase crop yields. The team planted three garden plots with corn. The soil was similar in each, and equal amounts of water were applied to each plot. One plot was treated with a common commercial fertilizer, another was treated with the new fertilizer, and the third plot was not given any fertilizer. The experimenters measured yields as bushels of corn from each plot. The plot that did not receive fertilizer was the __________.

control plot

What would be the approximate survival rate for a nest with 5 eggs?

0.50 *Because 5 is the clutch size, you plug 5 in for x in the equation. y = -0.14x + 1.2 y = -0.14(5) + 1.2 y = 0.50

How many light brown mice were caught in the light-colored soil enclosure on a moonlit night?

18

Current Events: Image of Hindenburg Haunts Hydrogen Technology (New York Times, 10/29/2013) At this time, what state is leading the way for hydrogen fuel-cell vehicles?

California

The reviewers suggested that you think more carefully about your hypothesis and experimental design. For a chemical to make a good cancer treatment, it is not enough that it harms cancer cells. The chemical needs to have a selective effect on cancer cells--that is, it needs to harm cancer cells much more than it harms normal (noncancerous) cells. You decide to run a new experiment to test the hypothesis that the fungus chemical harms cancer cells selectively. In this controlled experiment, you will test both cancer cells and normal cells under identical conditions. What data would support this hypothesis? Predict the expected results for cancer cells and normal cells by choosing the correct graph lines and dragging them onto the two graphs.

Cancer Cells: - % of cells alive with chemical treatment (magenta) is decreasing at faster rate than those treated without chemical (black) Normal Cells: - chemical treatment (magenta) and no chemical (black) experience same changes: steady negative output *These graphs show that the fungus chemical selectively kills cancer cells, doing relatively little harm to normal, noncancerous cells. The graphs also show that the survival rates of both types of cells are identical under the control conditions (no chemical treatment). These results would support your hypothesis. After running this experiment and correcting the other issues identified by the reviewers, you may now be able to publish your results. But you'll have to go through another round of peer review first!

A statistical measure of how closely data fit a linear relationship is called the correlation coefficient (r). The value of the correlation coefficient can range between -1 and 1. When r > 0, y and x are positively correlated (y becomes larger as x becomes larger). When r < 0, y and x are negatively correlated (y becomes smaller as x becomes larger). The closer r is to either extreme of the range (-1 or 1), the stronger the linear relationship between the variables. When r = 1, all data points fall on the regression line in a perfect positive correlation. When r = -1, all data points fall on the regression line in a perfect negative correlation. As the value of r approaches 0, the data points display more scatter, indicating a weaker linear relationship. When r = 0, the variables do not have a linear relationship. The correlation coefficient of the data on chick survival vs. clutch size is -0.93. How would you interpret that correlation coefficient? Chick survival and clutch size are strongly negatively correlated.

Chick survival and clutch size are strongly negatively correlated. *Because -0.93 is so close to -1, you can conclude that the variables have a strong linear relationship. And because the value of r is negative, you know that it is a negative correlation. You may have also concluded that there is a negative correlation between the two variables because the regression line clearly slopes down to the right, indicating that as clutch size increases, chick survival decreases.

What is the molecule that is responsible for both the unity and the diversity of life?

DNA *The uniformity of coding in DNA is virtually universal. Life's variety arises from variations in the nucleotide sequences of inherited DNA molecules, the substance of genes.

Use the following information when answering the corresponding question.

In 1668, Francesco Redi performed a series of experiments on spontaneous generation. He began by putting similar pieces of meat into eight identical jars. Four jars were left open to the air, and four were sealed. He then did the same experiment with one variation: Instead of sealing four of the jars completely, he covered them with gauze (the gauze excluded the flies while allowing the meat to be exposed to air). In both experiments, he monitored the jars and recorded whether or not maggots (young flies) appeared in the meat.

Hint 1. What is the experimental group?

In a controlled experiment, the treatment or evaluation of the experimental group directly tests the hypothesis. In this experiment, the hypothesis is that the male's song is a form of communication to potential mates. Which of the following groups are potential mates of the male snowy tree cricket? female snowy tree crickets

Refer to the paragraph on Redi's experiments. What hypothesis was being tested in the initial experiment with open versus sealed jars?

Maggots do not arise spontaneously, but from eggs laid by adult flies.

Which of the following is true of a scientific theory? It is a method or device that applies scientific knowledge for some specific purpose. It is formulated by many scientists over drinks at a convention. It is only accepted after the person who came up with it has died. It generates testable hypotheses, is supported by a large body of evidence, and is broad in scope. It must demonstrate the effect of one variable by testing control groups and experimental groups.

It generates testable hypotheses, is supported by a large body of evidence, and is broad in scope. A scientific theory is more than an interesting idea. It must stand up to constant scrutiny from skeptical researchers.

Which three of the following statements are valid conclusions that could be drawn from the graph above?

It is possible for a male snowy tree cricket and a male field cricket to sing with the same chirp rate, but only at different temperatures. The difference between the chirp rates of the two species remains fairly constant across the range of temperatures tested. The change in chirp rate with each change in temperature is similar for the two species. *Conclusions derived from the data in the graph have important biological implications for the crickets. For example, the similarity of the slopes of the two plots suggests a common biological cause for this temperature effect. In fact, the chirp rate increases with temperature for both species because metabolism (and thus the crickets' ability to move their legs or wings past each other) increases with increasing temperature. The observation that the difference between the chirp rates of the two species does not change with temperature indicates that there is no single temperature at which both species chirp at the same rate. However, the two species can produce songs with the same chirp rate at different temperatures.

In order for a hypothesis to be able to be used in science, which of the following must be true? It must be popularly accepted. It must be proven correct. It represents established facts. It is testable and falsifiable. It must be reproducible.

It is testable and falsifiable. *Hypotheses must be phrased in such a way that predictions can be made and tested.

There are many reports that the number of chirps per minute that a cricket produces is correlated with the ambient temperature. Your class decides to test this hypothesis by collecting several males from two species of crickets: the snowy tree cricket (Oecanthus fultoni) and the common field cricket (Gryllus pennsylvanicus). In the laboratory, you measure the chirp rate of each cricket at four different temperatures. The data are shown in the table below. Temp : avg chirp rate (cpm) Temp : snowy tree cricket-common field cricket (20:108-82) (30:128-100)

Plot the data for the two species of crickets, one graph for the snowy tree cricket and a separate graph for the common field cricket.

Current Events: Scientific Articles Accepted (Personal Checks, Too) (New York Times, 4/7/2013) What was the general reaction to open access when it began about 10 years ago?

Positive.

Now suppose you encounter three alien species with different genetic material from living things on Earth. The linear relationships between their genetic material composition and melting point can be expressed by the following equations. y = 3x + 25 y = -6x + 12 y = 1.5x + 17 Drag the correct equation to match each description. The equations may be used once, more than once, or not at all.

This equation represents the steepest line. [y = -6x + 12] This equation represents a line that slopes down to the right. [y = -6x + 12] Of the two equations that slope up to the right, this equation would cross the y-axis closer to the origin. [y = 1.5x + 17] When x = 4 in this equaation, y= 37. [y = 3x + 25]

Current Events: With Shovels and Science, a Grim Story Is Told (New York Times, 3/24/2013) Why did this team hire a geophysicist?

To scan the site with radar and imaging.

Hint 2. Can you compare the difference in chirp rates across the range of temperatures tested?

Which of the following statements best describes the difference between the two species' chirp rates across the range of temperatures tested? The difference between the two species' chirp rates is about the same at each temperature.

Which of the following is the fundamental unit of structure and function in living organisms?

cell *The cell is the fundamental structural and functional unit of both single-celled and multicellular organisms.

Which series of terms is in the correct sequence of biological organization, from the simplest to the most complex?

cell, tissue, organ, population, community

The phylogenetic tree below _____.

depicts the three major domains of life

Cotton-topped tamarins are small primates with tufts of long white hair on their heads. While studying these creatures, you notice that males with longer hair get more opportunities to mate and father more offspring. To test the hypothesis that having longer hair is adaptive in these males, you should _____.

determine if hair length is heritable

Which branch of biology is concerned with the naming and classifying of organisms?

taxonomy

The application of scientific knowledge for some specific purpose is known as _____.

technology

Which of the following is an example of hypothesis-driven science?

testing whether or not dead batteries are preventing a TV remote from working

A company was testing a new drug it thought would help decrease the risk of transmission of viruses from mother to fetus. In an experiment to test the compound, an investigator gave 400 pregnant female rats a small dose of the experimental drug and inoculated each with a type of virus known to cause disease in rats. At the same time, 400 other pregnant rats were given only the virus. Of the rat pups born to the females that received both the virus and the drug, 197 showed no symptoms of the disease; 205 rat pups born to the virus-only females showed symptoms. From these data, we can best conclude __________.

that the drug seems to have little effect on viral transmission at the dosage given *Approximately equal numbers of pups were affected in both groups (experimental group = 197, control group = 205), suggesting that the drug was probably not effective at the dosage given.

What is the dependent variable, the response to the variables being tested?

the number of mice caught *The dependent variable is shown on the y-axis.

The universal genetic language of DNA is common to virtually all organisms on Earth, however diverse. What is the best explanation for this fact?

All living things share a common genetic language of DNA because they share a common ancestry. *The genetic code is arbitrary, at least to some extent. The fact that all organisms share a single genetic code is due to their common ancestry. Read about the core theme of biology: Evolution accounts for the unity and diversity of life.

Which of the following is an example of "unity in diversity"? All organisms, including prokaryotes and eukaryotes, use essentially the same genetic code. The forelimbs of all mammals have the same basic structure, modified for different environments. The structure of DNA is the same in all organisms. All of the above are correct.

All of the above are correct. *These are all examples of unity in diversity.

Activity: Introduction to Experimental Design Suppose that Zonosemata flies whose own wings had been clipped and reattached were attacked more frequently than untreated Zonosemata flies. How would this result affect the reliability of the other experimental results?

All results for the experimental groups involving wing surgery would be invalid. This result suggests that the presence or absence of wing surgery itself may affect the jumping spider's responses. Thus, there is not enough information to draw conclusions from the data because there is an alternative explanation for the results of the experiment.

Current Events: Focusing on Fruit Flies, Curiosity Takes Flight (New York Times, 10/7/2013) Your cousin is a member of a team of scientists studying different species of fruit flies all over the world. Which continent should the team avoid?

Antarctica

Prokaryotes are classified as belonging to two different domains. What are the domains?

Bacteria and Archaea

Current Events: Genome Detectives Solve a Hospital's Deadly Outbreak (New York Times, 8/22/2012) Which of the following is true? Bacteria cannot live in the human body. Bacteria do not mutate. Once inside the human body, bacteria cannot mutate. Bacteria can mutate within the human body.

Bacteria can mutate within the human body.

Current Events: With Shovels and Science, a Grim Story Is Told (New York Times, 3/24/2013) In which of the following ways are you most likely to contract cholera?

By drinking water contaminated with cholera.

Current Events: Scientific Articles Accepted (Personal Checks, Too) (New York Times, 4/7/2013) How do many of these predatory journals find articles to publish and people to serve on their editorial boards?

By sending out email requests.

GraphIt!: An Introduction to Graphing Greater abundance of tree and bush stems results in higher birth rates for snowshoe hares.

Cannot tell from graph

GraphIt!: An Introduction to Graphing Stream flow rates have apparently been decreasing worldwide since 1966.

Cannot tell from graph

GraphIt!: An Introduction to Graphing The sooty tern consumes more fish than the blue-grey noddy tern.

Cannot tell from graph

GraphIt!: An Introduction to Graphing It would have been reasonable to place stream flow on the X-axis instead of year.

False

GraphIt!: An Introduction to Graphing Since the points don't form a straight line, it would have been better to draw this as a scatter plot.

False

Which of the following experiments would best test your hypothesis?In the course of a conversation, you observe that three of your friends like horror movies. Horror movies happen to be your favorite type of movie as well. You also know that all of these friends were born in the same week that you were, even in the same year. An astrology-loving friend hypothesizes that people born in that week like horror movies more than other genres of movies. You decide to use the scientific method to test this hypothesis.

Find other people born in the same week and ask them what their favorite type of movie is.

Current Events: Genome Detectives Solve a Hospital's Deadly Outbreak (New York Times, 8/22/2012) Which of the following did scientists discover about Klebsiella pneumoniae?

It remains latent in the body for longer than originally thought.

Which example illustrates a property that emerges at the community level?

Metabolic cooperation between prokaryotic cells forms a biofilm that allows bacterial colonies to transport nutrients and wastes. Biofilms may damage industrial equipment or cause tooth decay. *This emergent property emerges at the community level, due to the interactions among prokaryotic species forming the biofilm. Read about levels of biological organization in and emergent properties.

In the course of a conversation, you observe that three of your friends like horror movies. Horror movies happen to be your favorite type of movie as well. You also know that all of these friends were born in the same week that you were, even in the same year. An astrology-loving friend hypothesizes that people born in that week like horror movies more than other genres of movies. You decide to use the scientific method to test this hypothesis. What should you do next?

Perform experiments to test your hypothesis.

Current Events: Scientific Articles Accepted (Personal Checks, Too) (New York Times, 4/7/2013) You are a toxicologist and wish to publish your recent research concerning the effects of endocrine disruptors on thyroid function. How do you find a reputable journal to publish your findings?

Personally contact the journals you are interested in.

Current Events: Scientific Articles Accepted (Personal Checks, Too) (New York Times, 4/7/2013) Which of the following would likely be the best for limiting the increasing amount of questionable journals publishing studies of unknown scientific value?

Place restrictions on open access.

You want to be as careful as possible that the variable of interest--namely, favorite movie genre--is clearly distinguishable from any other variables. To do so, first you must be careful to find a random sampling of people who share your birth week, avoiding simply talking to friends with whom you share common interests. Second, you need to provide your subjects with a questionnaire on which they are asked to circle their favorite genre from a list, so that you are not tempted to interpret their answers in your favor. You must be certain not to tell them what you are seeking to prove or disprove; that way their answers will not be influenced by your stated goal. You must also make the surveys anonymous to ensure that your subjects aren't simply giving you the answers they think you want them to give. After finding a random sample of 10 people born in the same week as you and your friends, you obtain these results from their questionnaires: 4 of them prefer comedies, 3 of them prefer dramas, 2 of them prefer action movies, and 1 of them prefers westerns. As a control, you also interview 14 random people with birthdays throughout the year. You obtain results similar to the results of your experimental group and your friends: 3 of them prefer comedies, 4 of them prefer dramas, 3 of them prefer action movies, and 1 of them prefers westerns What should you do next?

Refine your hypothesis.

GraphIt!: An Introduction to Graphing For the graph in Step 7 showing fish body lengths and the percentage of tern diets that they comprise, which statement best summarizes the trend shown in the graph?

The blue-grey noddy's diet is composed primarily of smaller fish and the sooty tern's diet is composed mostly of moderate sized fish.

Which of the following best describes what occurred after the publication of Charles Darwin's On the Origin of Species?

The book was widely discussed and disseminated.

GraphIt!: An Introduction to Graphing For the graph of data on stem density and snowshoe hare density in Step 6, which statement best summarizes the trend shown in the graph?

The density of hares increases as the density of stems increases.

Activity: Introduction to Experimental Design Which of the following statements could not be supported or rejected by a scientific experiment?

The first living cell on Earth came from outer space An experiment could not be designed to test this statement. Science neither supports nor rejects this idea.

Activity: Introduction to Experimental Design Which of the following variables did Pasteur change in his experiment to test the hypothesis of spontaneous generation?

The shape of the flask By using a swan-necked flask for the experimental treatment, Pasteur ensured that no cells were entering the flask from the air. Thus, any organisms that appeared in the experimental flask would have arisen spontaneously.

Activity: Introduction to Experimental Design Which of the following statements is not true of scientific experiments?

They must occur under carefully controlled conditions found in a laboratory. Not all experiments are performed under laboratory conditions; many occur outdoors in uncontrolled conditions. Scientists must account for these variations when designing experiments.

Activity: Introduction to Experimental Design In an experiment, investigators try to control all of the variables except one—the one that tests the hypothesis. Which of the following reasons is the primary rationale for controlling variables in an experiment?

To eliminate alternative explanations for the results of an experiment Controlling all variables but one ensures that some other factor is not responsible for the results obtained from an experiment.

Learning Goal:

To understand how the scientific method can be used to search for explanations of nature. The scientific method is a procedure used to search for explanations of nature. The scientific method consists of making observations, formulating hypotheses, designing and carrying out experiments, and repeating this cycle. Observations can be either quantitative or qualitative. Quantitative observations are measurements consisting of both numbers and units, such as the observation that ice melts at 0∘C . In contrast, qualitative observations are observations that do not rely on numbers or units, such as the observation that water is clear. A hypothesis is a tentative explanation of the observations. The hypothesis is not necessarily correct, but it puts the scientist's understanding of the observations into a form that can be tested through experimentation. Experiments are then performed to test the validity of the hypothesis. Experiments are observations preferably made under conditions in which the variable of interest is clearly distinguishable from any others. If the experiment shows that the hypothesis is incorrect, the hypothesis can be modified, and further experiments can be carried out to test the modified hypothesis. This cycle is repeated, continually refining the hypothesis. If a large set of observations follow a reproducible pattern, this pattern can be summarized in a law—a verbal or mathematical generalization of a phenomenon. For example, over the years people observed that every morning the sun rises in the east, and every night the sun sets in the west. These observations can be described in a law stating, "The sun always rises in the east and sets in the west." After a great deal of refinement, a hypothesis can lead to a theory. A theory is an explanation of why something happens. For example, Newton's theory of gravitation explains why objects tend to fall toward the Earth (as well as explaining the interactions between the Earth and the other planets, etc). However, theories can still be further refined or even replaced. Einstein's theory of general relativity was able to better explain certain astronomical observations related to gravity, and therefore it replaced Newton's theory of gravitation (although Newton's theory still holds true under most everyday conditions). Similarly, the geocentric theory (that the Earth is the center of the universe) was replaced by the heliocentric theory (that the Earth revolves around the sun) based on further observations and testing of predictions. Note that a scientific theory is not the same as the popular definition of a theory—namely, a "guess" or "speculation." Instead, a theory is an explanation that can hold up against repeated experimentation. It may not be perfect, but it is the best explanation possible based on available evidence.

GraphIt!: An Introduction to Graphing Increasing density of tree and bush stems has a positive effect on snowshoe hare abundance.

True

Which of the following statements is FALSE regarding the complexity of biological systems? An ecosystem displays complex properties not present in the individual communities within it. An understanding of the interactions between different components within a living system is a key goal of a systems biology approach to understanding biological complexity. Understanding the chemical structure of DNA reveals how it directs the functioning of a living cell. Knowing the function of a component of a living system can provide insight into its structure and organization.

Understanding the chemical structure of DNA reveals how it directs the functioning of a living cell.

Activity: Introduction to Experimental Design What results from the Zonosemata experiment support the sub-hypothesis that wing waving alone reduces predation by jumping spiders?

Zonosemata flies with housefly wings are attacked less frequently. This experimental group tests the effects of wing waving alone.

Darwin's finches, collected from the Galápagos Islands, illustrate which of the following?

adaptive radiation

In comparison to eukaryotes, prokaryotes _____.

are smaller

Current Events: Genome Detectives Solve a Hospital's Deadly Outbreak (New York Times, 8/22/2012) You are an epidemiologist specializing in antibiotic-resistant strains of bacteria. For the best hope in saving a patient's life, you want to stop the infection before it gets where?

bloodstream

Cells are _____.

characteristic of prokaryotic and eukaryotic organisms

Current Events: Focusing on Fruit Flies, Curiosity Takes Flight (New York Times, 10/7/2013) You are an entomologist specializing in the vision of the anthomyiid flies. What is your area of expertise?

compound eyes

Activity: The Levels of Life Card Game Which of these is an organ system?

digestive *The digestive system is composed of structures such as the stomach and small intestine.

Current Events: With Shovels and Science, a Grim Story Is Told (New York Times, 3/24/2013) You specialize in matching dental records of missing people to teeth and jaws of criminal cases. What are you?

forensic odontologist

Current Events: Focusing on Fruit Flies, Curiosity Takes Flight (New York Times, 10/7/2013) Your friend is an entomologist studying the response to potential predators in the common cricket. To determine if the response is a reflex or a decision, which of the following body parts should he focus on?

legs

Based on the observation that only male crickets produce a song, you hypothesize that a male's song is a form of communication to potential mates. You set up a simple experiment to test this hypothesis. In the laboratory, you place a male snowy tree cricket in enclosure A, which is adjacent to enclosure B. In enclosure B, you place other insects, one at a time, and observe their responses to the male's song. The enclosures are designed so that the two insects being tested cannot see or smell each other, but sound is transmitted from enclosure A to enclosure B. For each insect below, indicate whether it is part of an experimental group or a control group when placed in enclosure B. Labels may be used once, more than once, or not at all.

male snowy tree cricket - control group female snowy tree cricket - experimental group female field cricket - control group *In this experiment, your hypothesis is that the male's song communicates information to potential mates. The experimental group provides a direct test of the hypothesis. Female snowy tree crickets compose the experimental group because they are the potential mates of male snowy tree crickets and therefore would be expected to uniquely respond to the male's song. Failure of the experimental group to respond to the male's song would require you to reject your hypothesis. In addition, control groups test other factors that might influence the experimental outcome. In this experiment, the control groups test whether the male's song functions in frightening potential competitors for mates (other male snowy tree crickets) or competitors for food (female field crickets). If one or both of the control groups respond to the male snowy tree cricket's song, you would have to reject your hypothesis. In the actual experiment, the female snowy tree crickets turn toward the male in response to his song, but the control groups move randomly in response to the song. These results support your hypothesis.

Activity: Heritable Information: DNA DNA is composed of building blocks called _____.

nucleotides *DNA is a composed of nucleotide units.

To understand the chemical basis of inheritance, we must understand the molecular structure of DNA. This is an example of the application of which concept to the study of biology?

reductionism

Activity: The Levels of Life Card Game An organ, such as the liver, is composed of _____.

tissues *Organs are composed of two or more different types of tissues.

Current Events: Genome Detectives Solve a Hospital's Deadly Outbreak (New York Times, 8/22/2012) About how many people die in the U.S. each year from hospital-acquired infections?

99,000

Which of the following are qualities of any good scientific hypothesis? I. It is testable. II. It can be proven beyond a shadow of doubt. III. It produces quantitative data. IV. It produces results that can be replicated.

I only

Which of the following statements best distinguishes hypotheses from theories in science?

Hypotheses usually are relatively narrow in scope; theories have broad explanatory power.

Activity: Introduction to Experimental Design In Pasteur's experiment to test the hypothesis of spontaneous generation, why did he boil the broth in both flasks?

To kill any existing organisms in the broth Pasteur boiled the broth to kill any existing organisms, thus ensuring that the conditions in each flask were identical (i.e., lacking organisms) at the start of the experiment.

Is a dark brown mouse on dark-colored soil more likely to escape predation under a full moon or with no moon? What data support your answer?

Under a full moon; the owl caught more dark mice when there was no moon (about 20) than when there was a full moon (about 12).

Is a light brown mouse on light-colored soil more likely to escape predation under a full moon or with no moon? What data support your answer?

Under no moon; the owl caught more light mice when there was a full moon (about 18) than when there was no moon (about 11).

Activity: Heritable Information: DNA In eukaryotic cells DNA has the appearance of a _____.

double helix *Eukaryotic DNA is organized as a double helix.

Current Events: Focusing on Fruit Flies, Curiosity Takes Flight (New York Times, 10/7/2013) Scientists studying hummingbird flight use the same technique as those studying fruit flies. What do they use?

dynamic scaling

Current Events: Image of Hindenburg Haunts Hydrogen Technology (New York Times, 10/29/2013) Cars that have hydrogen fuel-cells run on which of the following?

electricity

Experiments in environmental toxicology can sometimes be manipulative experiments in which the researcher actively chooses and manipulates the independent variable. In Hunt's study, for example, dosages of BPA were manipulated and the effects were measured. In manipulative studies, the researcher controls all the other variables in the experiment, so any health effects observed in the test subjects can be attributed to differences in the independent variable. In other cases, researchers use natural experiments in which the dependent variable (typically a measure of organism health) is measured under differing contexts that are not manipulated. Say, for example, that an accidental chemical spill contaminates five ponds. To determine the possible effects of the toxic chemical on frogs, a researcher could compare the hatching rate of frog eggs laid in those five ponds to the hatching rate of eggs laid in five uncontaminated ponds nearby. This would be an example of a natural experiment because concentrations of the toxic chemical in the ponds were not controlled by the experimenter, but rather resulted from the chemical spill. Drag the labels to identify the type of experiment each example describes.

1. Blood concentration of BPA in college students are compared to their recent consumption of canned food items. (Natural) 2. The feeding behavior of fish in streams that receive acidic runoff from strip mines is compared to the feeding behavior of fish in unaffected streams. (Natural) 3. The deformity rate in baby birds from nests in pesticide-sprayed fields is compared to the deformity rate in birds from nests in unsprayed fields. (Natural) 4. Tumor development is compared in mice exposed to five dosages of a known carcinogen in the laboratory. (Manipulative) 5. Foraging activity levels are compared in tadpoles exposed to four concentrations of toxic metals in the laboratory. (Manipulative) 6. Growth of corn plants is compared in field plots sprayed with three different dosages of weed killer. (Manipulative) 7. BPA concentrations in the urine of people with diabetes are comparedto BPA concentrations in the urine of people without diabetes. *In a natural experiment, the researcher can conclude that any observed health effects may be related to exposure to the toxic chemical, but establishing direct causation is difficult. Natural experiments are usually limited to establishing correlation, whereas manipulative experiments can more strongly suggest causation.

A straight line between two variables, x and y, can be represented by this mathematical equation: y = mx + b. In this equation, m is the slope of the line and b is the y-intercept (the point at which the straight line crosses the y-axis). In this graph, what is the y-intercept? (For practice finding the y-intercept of a line, try this activity.)

79 *The line crosses the y-axis at 79.

Scientific Thinking: Testing the Safety of Bisphenol A

Bisphenol A (often called BPA) is a chemical found in products that people use every day, from water bottles to food containers to children's toys. Unfortunately, BPA leaches out of its many products and makes its way into our bodies. What are the health effects of BPA exposure? Ongoing research is finding that elevated exposure to BPA can affect a wide variety of developmental and physiological processes, but one of the first studies of BPA's health effects came about because of a simple mistake in the lab. At a laboratory at Case Western Reserve University in 1998, geneticist Patricia Hunt was making a routine check of her female lab mice. As she extracted and examined developing eggs from the ovaries, she began to wonder what had gone wrong. She noticed that many of the eggs showed problems with their chromosomes, and some had irregular amounts of genetic material, which can lead to miscarriages and birth defects in mammals. She learned that a lab assistant had mistakenly washed the plastic mouse cages and water bottles with a harsh soap, releasing BPA from the plastic. Knowing that BPA is an endocrine disruptor, a chemical that can enter organisms and mimic hormones, Hunt set out to discover whether it had adversely affected her mice.

GraphIt!: An Introduction to Graphing Areas with more than 100,000 stems per hectare should have hare densities approaching 4 hares per hectare.

Cannot tell from graph

Excited about the fungus chemical's promise for treating cancer, you write up your experimental results and send the paper to a prestigious scientific journal, hoping it will be published. The journal sends your paper out to several scientists for evaluation--a process known as peer review. The reviewers identify several issues with the experimental design and data presented in your paper. Which of the following criticisms are valid issues of concern that peer reviewers might identify? Select all that apply.

Cell samples were taken from too few patients. The treatment kills cancer cells, but it might simply be a poison that kills all cells—even normal cells. The effect may not be real because we don't know if the results are reproducible. *Most scientific journals use peer review when they consider a paper for publication in order to be sure the studies they publish are of the best quality possible. Peer reviewers, who are impartial experts in the same field as the article's author, evaluate the quality of the research methodology and suggest revisions, if appropriate. A peer-reviewed journal will not publish articles that fail to meet the standards established by the scientific community. In this case, issues detected by peer review included: • The fungus chemical was not tested on normal cells. It's possible that the chemical is simply a poison that kills all cells—even normal cells. • The results may not be reproducible. The experiment included only two replicates (two samples exposed to the fungus chemical and two controls). • Cancer cells were obtained from only a single patient. Cells from additional patients should also be tested.

Suppose you analyzed the same type of data for a different species and found a correlation coefficient of -0.17. How would you describe the relationship between chick survival and clutch size for that species?

Chick survival and clutch size are weakly negatively correlated. *Because -0.17 is close to 0, you can conclude that the variables have a weak linear relationship. And because the value of r is negative, you know that it is a negative correlation.

Hunt and her team designed an experiment to test her hypothesis about the effect of BPA on mice. They administered daily doses of BPA to groups of female mice over three, five, or seven days and then tested these mice for genetic abnormalities that occur during meiosis, the division of chromosomes during egg formation. Drag the labels to identify the components of Hunt's experiment. Labels may be used once, more than once, or not at all.

Dosage: Label (0 ng/g BPA: control) (20 ng/g BPA: treatment) (40 ng/g BPA: treatment) (100 ng/g BPA: treatment) 1. Dosage of BPA administered is a(n) [independent variable]. 2. The eength of time over which mice were exposed to BPA is a(n) [independent variable]. 3. The percentage of mice displaying genetic abnormalities is the [dependent variable]. *Hunt's study found that the percent of mice with chromosomal problems increased with increasing dosage of BPA. She concluded that the mice in the cages scrubbed with harsh soap were exposed to elevated levels of BPA from the damaged plastic, increasing the frequency of genetic abnormalities in these mice. This study, and others like it, gave rise to a thriving line of research which continues to investigate the effects of endocrine-disrupting chemicals such as BPA on the health and development of a diversity of organisms.

Hint 1. Predicting the outcome of the experiment if your hypothesis is supported

First, review your hypothesis. Your hypothesis states that female crickets respond to both the chirp rate of the male's song and the local temperature when identifying potential mates. From this hypothesis, you make the following prediction: If a female cricket is at a different temperature from a male of the same species, she will not respond to the male's song. Another way to state this is that a female cricket must be at the same temperature as the male in order to respond to its song. Now think about what this would look like on a graph in which the independent variable (temperature) is plotted on the x-axis and the dependent variable (female response) is plotted on the y-axis. Remember that the male is kept at 25 °C while the temperature in the female's enclosure varies.

Scientific Thinking: What Role Does Peer Review Play in the Process of Science?

Imagine that you are a scientist hard at work in a cancer research lab. You and many of your colleagues are hoping to discover new powerful drugs that could prevent deaths from cancer. Your research team has observed that cancer cells have a lower survival rate when exposed to samples of a certain species of fungus. To study this further, your team isolated several chemicals from the fungus, including one known to affect cell metabolism. You hypothesize that it is that chemical that lowers the survival rate of cancer cells.

Hint 3. Reviewing independent and dependent variables and how they are graphed

In an experiment, the variable you control is called the independent variable. The variable that changes in response to the independent variable is called the dependent variable. In this experiment, the independent variable is the temperature of the female's enclosure; the dependent variable is the female cricket's response. In a graph, typically, the independent variable is plotted on the x-axis, and the dependent variable is plotted on the y-axis.

The following experiment is used for the corresponding question. A researcher discovered a species of moth that lays its eggs on oak trees. Eggs are laid at two distinct times of the year: early in spring when the oak trees are flowering and in midsummer when flowering is past. Caterpillars from eggs that hatch in spring feed on oak flowers and look like oak flowers. But caterpillars that hatch in summer feed on oak leaves and look like oak twigs. How does the same population of moths produce such different-looking caterpillars on the same trees? To answer this question, the biologist caught many female moths from the same population and collected their eggs. He put at least one egg from each female into eight identical cups. The eggs hatched, and at least two larvae from each female were maintained in one of the four temperature and light conditions listed below. Temp-Day Length Springlike-Springlike Springlike-Summerlike Summerlike-Springlike Summerlike-Springlike

In each of the four environments, one of the caterpillars was fed oak flowers, the other oak leaves. Thus, there were a total of eight treatment groups (4 environments × 2 diets).

Hint 2. Characteristics of control groups

In field experiments or experiments with living organisms, it is often not possible to control (keep constant) every variable except the one being tested. In these cases, controls often serve the more general function of testing alternate explanations for experimental results. In this experiment, some alternate explanations for why the other crickets may respond to the male's song include: The response of male crickets to the songs of other males reduces competition for potential mates. The response of female crickets to the songs of other crickets (regardless of sex or species) minimizes competition for food. Crickets respond to any sounds that resemble cricket songs. The control groups in this experiment test whether the male's song serves a function other than communicating with potential mates. If one or both of the control groups respond to the male snowy tree cricket's song, you would have to reject your hypothesis.

Which of the following observations and inferences led Charles Darwin to his theory of natural selection as a mechanism for evolution?

Individuals in a population of any species vary in many heritable traits. Individuals of a population are unequal in the likelihood of surviving and reproducing. A population of any species has the potential to produce far more offspring than will survive to produce offspring of their own. Individuals with heritable traits best suited to the local environment will generally produce a disproportionate number of healthy, fertile offspring. *Darwin synthesized his theory of natural selection from all of the listed observations and inferences.

Select the correct statement about the process of scientific inquiry.

It is possible to test hypotheses, such as those involving historical events, without conducting experiments. *Although it is not possible to carry out experiments to test hypotheses about evolutionary relationships between living groups or about the timing of the origin of major evolutionary innovations, such hypotheses can be evaluated by making predictions about the expected findings that would result from these hypotheses. Data can then be collected to test whether these predictions are correct. Read about the forms of scientific inquiry and the scientific method.

From looking at this scatter plot, what do you think the regression line represents?

It represents the straight line that fits most closely the trend in the data. *A regression line is a straight line that mathematically fits the data best, which is why it is sometimes called a best-fit line.

Activity: Science, Technology, and Society: DDT Which one of the following statements is true? DDT does not help prevent disease from passing from agricultural animals to humans. Cost was a major factor in the United States government's decision to ban DDT. Many African governments concluded that the potential long-term health effects of DDT were not as serious as the immediate problem of insect control. DDT cannot accumulate in the fat of animals. The DDT ban in the United States has made it very difficult to control agricultural insect pests.

Many African governments concluded that the potential long-term health effects of DDT were not as serious as the immediate problem of insect control. *They concluded that the immediate benefits of DDT outweighed the possible long-term harmful effects.

Scientific Skills Exercise: Interpreting a Pair of Bar Graphs

Nearly half a century ago, D. W. Kaufman investigated the effect of prey camouflage on predation. Kaufman tested the hypothesis that the amount of contrast between the coat color of a mouse and the color of its surroundings would affect the rate of nighttime predation by owls. He also hypothesized that the color contrast would be affected by the amount of moonlight. In this exercise, you will analyze data from his owl-mouse predation studies. Pairs of mice (Peromyscus polionotus) with different coat colors, one light brown and one dark brown, were released simultaneously into an enclosure that contained a hungry owl. The researcher recorded the color of the mouse that was first caught by the owl. If the owl did not catch either mouse within 15 minutes, the test was recorded as a zero. The release trials were repeated multiple times in enclosures with either a dark-colored soil surface or a light-colored soil surface. The presence or absence of moonlight during each assay was recorded.

Researchers studying a species of endangered bird were interested in whether a relationship exists between the number of eggs laid by the mother bird at one time and the proportion of chicks surviving to the following year. The data shown here were collected from 10 different nests in a wild population.

Nest: Avg clutch size[eggs hatched]-Proportion of chicks that survived to following year 1: 3.0-0.80 2: 2.5-0.85 3: 3.8-0.60 4: 4.0-0.58 5: 2.0-0.90 6: 3.9-0.58 7: 5.9-0.42 8: 3.0-0.79 9: 4.3-0.50 10: 3.5-0.57

Can you identify the steps in the scientific method that correspond to Hunt's experiments? Drag each statement under the step in the scientific method that it demonstrates.

Observation: The eggs of mice in plastic cages washed with harsh soap displayed during cell division that caused genetic abnormalities. Question: Could bisphenol A from the plastic be affecting the mice in the damaged cages? Hypothesis: The frequency of genetic abnormalities in mice is affected by exposure to bisphenol A. Prediction: If mice are exposed to elevated levels of bisphenol A, the frequency of genetic abnormalities in these mice will increase. Test: Hunt set up an experiment to test her prediction. Results: Hunt gathered experimental data and analyzed her findings.

Why is a scientific topic best discussed by people of varying points of view, from different subdisciplines, and representing diverse cultures?

Robust and critical discussion between diverse groups improves scientific thinking.

In presenting data that result from an experiment, a group of students show that most of their measurements fall on a straight diagonal line on their graph. However, two of their data points are "outliers" and fall far to one side of the expected relationship. What should they do?

Show all results obtained and then try to explore the reason(s) for these outliers.

Based on your hypothesis, you predict that the chemical isolated from the fungus will successfully kill cancer cells. To test this prediction, you design the following experiment. You isolate cancerous cells from the colon of a patient from North Carolina and culture (grow) the cells in your lab. You divide the cultured cells into four separate culture dishes. You treat two of the dishes with the fungus chemical and the other two with a control solution that does not contain the chemical. Over the next ten days, you collect data on the percentage of cells that remain alive in each culture dish. This graph displays the data you collected. Determine which statements are supported by the data in the graph. Drag each statement into the appropriate bin.

Statement(s) supported by the data: Cancer cells treated with the chemical have a lower survival rate than cells that are not treated. After 5 days of chemical treatment, less that 50% of the cancer cells are alive. Statement(s) NOT supported by the data: Cancer cells treated with the chemical have a higher survival rate than cells that are not treated. This chemical will be useful for treating colon cancer, but not necessarily for other types of cancers. This chemical will be useful for treating all types of cancers. After10 days without chemical treatment, more than 90% of the cancer cells are alive. *The data show that cancer cells isolated from a patient and then grown in a lab did not survive as well when treated with the chemical compared to a control lacking the chemical. You and the other scientists in your lab know that this finding does not necessarily mean the fungus chemical will be useful in treating colon cancer (or other types of cancer). Nonetheless, you are very excited by these promising experimental results.

Hint 1. How to interpret the change in chirp rate with each change in temperature

The change in the number of chirps per minute (the chirp rate) with each change in temperature is just another way of describing the slope of the line. The slope is the change in the value of the y-axis variable per change in the x-axis variable.

Hypothesis: Female crickets respond to both the chirp rate of the male's song and the local temperature when identifying potential mates. Prediction: If the female is at a different temperature from the male, she will not respond to the male's song even if it is a male of the same species. To test your hypothesis, you use the same laboratory setup that you used in Part A. The only difference is that now the temperature of the two enclosures can be independently controlled. In your proposed experiment: A male snowy tree cricket will be placed in the first enclosure and kept at 25 °C. A sexually mature female snowy tree cricket will be placed in the second enclosure, and its response to the male's song will be determined at several different temperatures between 15 °C and 30 °C. Based on your observations in Part A, you score the response of the female on a scale of 0 to 10, where 10 represents the female turning directly toward the singing male and 0 represents no motion or random turning. Assuming your hypothesis is supported, which of the following graphs predicts the response of the female cricket to the male's song as the temperature of the female's enclosure varies?

The graph with a spike near 10 at 25 °C. *In Part A, you did an experiment that supported your hypothesis that male crickets' songs communicate information to females of the same species. In Part B, you graphed chirp rate versus temperature for two species of crickets. Then in Part C, you observed that the chirp rate of a male cricket's song varies with temperature and that this temperature dependence is different for different species. In this final part, you hypothesized that the male and female of a single species must be at the same temperature in order for the female to respond to the male's song. If your hypothesis is supported, you would expect to see the strongest female response at 25 °C and very little response at any other temperature. In the field, it would be unusual for a female cricket to be close enough to a male to hear his song while at the same time experiencing a significantly different temperature. However, in the laboratory, it is possible to set up an experiment to test your hypothesis. Every good hypothesis must lead to a prediction that can be tested and either verified or rejected. This experiment is waiting to be done!

Drag the terms to their correct location in the paragraph.

The scientific study of life, called [biology], can be organized around several themes. As the biological hierarchy builds from molecules on up to ecosystems, each level has [emergent properties] that result from interactions among component parts. Life's basic unit of [structure and function] is the cell, which occurs in two basic forms--prokaryotic and eukaryotic. As organisms interact with the environment, [chemical nutrients] cycle within an ecosystem, while [energy] flows one way from sunlight->chemical energy->heat. According to the core theme of [evolution], all of life is related by common descent. Life has diversified as [natural selection] has led to the gradual accumulation of adaptions that fit populations to the environment.

Building Vocabulary: Word Roots - Metric Prefixes Can you match these prefixes, suffixes, and word roots with their definitions?

measure: metr- (or -meter) large: mega- giant: giga- one thousand (1,000): kilo- one hundred (100): hecto- ten (10): deka- (or deca-) one-tenth (1/10): deci- one-hundredth (1/100): centi- one-thousandth (1/1,000): milli- small: micro-

The graph shows data from the light-colored soil enclosure. There is one dependent variable and more than one independent variable on the graph. What are the independent variables, the variables that were manipulated by the researcher?

mouse coat color and the presence or absence of moonlight *Coat color is indicated by the color of the bars, and the presence or absence of moonlight is shown on the x-axis.

Experimental Inquiry: What Can You Learn About the Process of Science from Investigating a Cricket's Chirp?

Most species in the insect order Orthoptera (crickets, grasshoppers, locusts) produce a song by rubbing their wings or legs against each other. In most of the species that sing, only the male produces a song. Crickets are a common example; their songs are a familiar night sound in most parts of the continental United States. Some crickets produce a song that is continuous for several seconds or more, while others break their song into a sequence of chirps, typically with 10-50 chirps per minute.

Current Events: Scientific Articles Accepted (Personal Checks, Too) (New York Times, 4/7/2013) You are a graduate student in plant physiology and wish to learn how to discern reputable scientific publications from those not reputable. Which of the following journals recently created a checklist to help get you started?

Nature

Competition is central to the theory of natural selection. Why does competition occur?

Organisms typically produce too many offspring, and resources are limited. *Resource competition is one of the main ingredients for natural selection. Organisms must compete for limited resources, and only the best adapted will survive and reproduce.

All the organisms on your campus make up:

a community

Current Events: With Shovels and Science, a Grim Story Is Told (New York Times, 3/24/2013) Which of the following led researchers to send John Ruddy's remains back to Ireland?

a dental abnormality

Current Events: With Shovels and Science, a Grim Story Is Told (New York Times, 3/24/2013) The cholera outbreak at the shanty was attempted to be controlled by what?

a forced quarantine

Current Events: Image of Hindenburg Haunts Hydrogen Technology (New York Times, 10/29/2013) You start a job working as a specialist for Ore Design and Technology. What are you trying to use to obtain hydrogen to use as a fuel?

algae

No amino acid molecule by itself can speed up or catalyze reactions between other molecules; however, when amino acids are joined together to make a protein with catalytic properties, the new structure (enzymatic protein) can speed up the rate of a specific chemical reaction. What does this illustrate?

emergent properties *A molecule such as a protein has attributes not exhibited by any of its component parts (e.g., amino acids). Therefore, novel properties are emerging that were not present at a simpler level of organization.

Which of these provides evidence of the common ancestry of all life?

near universality of the genetic code

Which of the following is a correct sequence of levels in life's hierarchy, proceeding downward from an individual animal?

nervous system, brain, nervous tissue, nerve cell

Activity: The Levels of Life Card Game What are the two main types of cells?

prokaryotes and eukaryotes *Prokaryotic cells lack the nucleus and other organelles found in eukaryotic cells.