1.

J.

Clnpter 1

This module discusses the hierarchy of structural levels into which life is organized. Eachof these levels has unique emergent properties, n'hich arise from the organization of itscomponent parts. Review this structural hierarchy by completing the chart below.

Leoel Desuiption

AII environments on Earth that support life

Ecosystem

AII the organisms in a particular ecosystem

Population

An individual living thing

Organs that work together to perform particular functions

Organ

A group of similar cells with a specific function

A living unit, separated from its environment by a membrane

Organelle

A cluster of atoms held together by bonds

5.

6.

8.

9.

10.

11.

Across2. Chemical

- cycle within the ecosystem's

web of species.4.

-make food that supports the ecosystem.

7, -are

the main producers in a forest.9. Rabbits function as

- in an ecosystem.

10.

- comes into an ecosystem in the form of

sunlight.L1.. Decomposers

- chemical nutrients.

13. Plants carry out . producing food forother organisms.74.

-are consumers: they eat plants and each

other.

Biology : Exploring Life

Down1.

- such as bacteria and fungi convert dead

matter to simpler nutrients.3. The dynamics of an

- involve flow of en-

ergy and recycling of nutrients.5. The exchange of matter and energy in an

ecosystem involves a complex web of

-.6. In an ecosystem, there are many interactionsamong organisms, and between organisms andtheir _ environment.

8. Chemical

- is the fundamental level of

order that underlies all the properties of life.12. Plants absorb mineral nutrients from the

s.3

This module describes how organisms interact with their environments. Review the web ofinteractions by completing this crossword puzzle.

4 Chnpter 1

All living things are built from complex systems called cells. Cells are the smallest unitsthat display the properties of life. AII cells are controlled by the genetic information in DNAmolecules. These two modules briefly discuss the structure and function of cells and DNAand other features shared by all living things. Write a paragraph describing how an or-ganism familiar to you-a college student-displays these features of life.

Rer.iew the three domains of life by matching each statement on the right with the correctdomain. Write your answer in the first column. In addition, name the kingdom for each ofthe organisms in Domain Eukarya, and write your answer in the second column. Choosefrom:

Domain BacteriaDomain ArchaeaDomain Eukarya

protists (several kingdoms)Kingdom Plantae

Kingdom FungiKingdom Animalia

Donmin Kingdont

1. Tree and fern2. Prokaryotes3. Another domain of prokaryotes4. Multicellular eukarvotes that ingest (eat) other organisms5. Molds, yeasts, and mushrooms6. Algae and protozoa7. Organisms whose cells lack a nucleus8. Brown pelican, sloth, and spider9. Multicellular photosynthetic organisms with rigid cellulose cell walls

10. Singie-celled eukaryotes such as an amoeba

DtuLUXV. L-tytvt ttL6 LLJc

Eyolution is biology's core theme. It explains the diversity of life, the relatedness of all liv-ing tirings, and the aclaptation of living things to their environments. Fill in the blanks in

the following story to revier.t' the concepts of errolution.

While investigating the insect life of the rainforest canoPy, a zoologist captured

serreral specimens of a previously unknorvn species of butterfly. The butterfly r'r'as mostly

black but had conspicuous red and yellow stripes on its rt'ings. It rested on bare tree

limbs in plain vier.t'; the zoologist was surprised she had not seen it before. The butterfly

was very similar in structure to that of a much less conspicuous all-black species found in

the same general area, so the zoologist figured that thc tn'o species lvere closely

members of the sarne family.

Biologists have long marveled at the diversity of insect life in the tropics.

, the English biologist tt'iro r,r'rote Tlrc Origirt of Species, \ Ias sur-

prised by the large nurnber of insect species he encountered in the rain forests of South

America. In fact, biologists estimate that most species of living things are rain forest

insects.

Like Darwin, tl-re zooiogist concluded that the black butterfly aud the new

species looked alike because they rvere botir descendecl from a commoll

species. But n'hy the differer-rce in color pattern? When she first en-

countered the striped butterflies, shc speculated that the red and yellon' stripes \\'/ere an

evolutionary adaptation, a beneficial feature that evoir.ed by means of natural selection.

But horv could a bright color pattern be of any possible benefit? Wouldn't brightly col-

ored butterflies be attacked by predators?

Her suspicions intensified rt4ren the zoologist sarv the red and yellorv r,r'inged

butterflyrestilrgorratLeelimb.Apredatorybirdlarrdedrrearbl,alrdpeeredatt}rebtrtter-fly. The butierfly responded by rapidly tlapping its r,r'iugs, displaf ing their striped pat-

tern, and the bird flew off.

This is r.r'hat first caused the zoologist to suspect that the bright wing pattern \ /as

an example of "tt,arning coloration," oftetr seen in harmful or bad-tasting animals-forexample, the conspicuor-rs yel1on and black stripes of bees aird rn'asPs. How could such a

color pattern finyg g1zsl1'gd in this species of butterfly? The zooiogist speculated that at

one time a 4 of black butterflies existed in this area, breeding among

themselves but not tt'ith other mernbers of their species. These butterflies exhibited

traits-siightly different wing shapes, sizes, behaviors, and so on'

They also may have tasted different. Perhaps sol11e \,vere able to rnake a bad-tasting sub-

stance or store a bad-tasting substance obtained from food plants. just as Darwin rea-

soned, the zoologist realized that 6 variation mttst be present in tire

population for natural selection to operate. Also like Darn'in, she realized that there is

great overproduction of offspring-many more btttterflies are produced each year than

can possibly surrrive. In this population, it appeared that among this abundance of but-

terfly prey, the good-tasting buttelflies r.t'ere more likely to be eaten by

thtrn bad-tasting oues. The surviving bad-tasting butterflies r.vere

more likely to surr,il'e to 8 , and they passed their ability to make the

. Ovel timc, thisbad-tasiing chemical on io their 9

6

10

Chopter 1

trait accumulated in the population-the bad-tasting butterfliesbecame more numeroLrs.

What about the difference in color pattern? The zoologist speculated that among

the bad-tasting butterflies, there may have been variation in wing coloration. Butterflies

n'ith bright colors on their r.r'ings were easier for predators to remember and avoid. The

colorful butterflies had more offspring than less-conspicuous individuals-they hadi1 reproductive success, Eventually bright-colored, bad-tasting but-terflies became the norm in the population. In this situation, as in others expiained by

Charles Darn'in, 12 occurs as heritable 13 are ex-

posed to 14 factors that far.or the 15 success ofsome individuals over others.

The zoologist speculated that, over a long period, the changes in palatability,wing pattern, and other characteristics must have combined, and a whole new16

17

of butterfly came into existence. According to Danvin, the

of new species results from the accumulation of minute changes

resulting from natural selection over 18 . This short story is just one

illustration of evolution, biology's core 19 Evolution is an importantidea, because it explains both the 20 of life (descent from a commonancestor) and 2i

ancestors).

of life (modification as species diverged from their

Review the scientific method by filling in the blanks in the following story. Choose fromfactor, hypothesis, question, inductive reasoning, control, prediction, deductivereasoning, discovery, observation, experiment, experimental, and scientific method.Answers may be used more than once.

In Exercise 5, you read how a zoologist identified a previously unknown species

of butterfly. This species was mostly black, but had conspicuous red and yellow stripes

on its wings. It was very similar in appearance and structure to an all-black species foundin the same area. Carefully comparing the trvo species, the zoologist concluded that theywere closely related-members of the same family. Looking at many examples (of butter-flies) and deriving a general principle (the characteristics of the butterfly family) employsa kind of logic called r

a scientist does 2

. This kind of thinking is often involved whenscience, which is mostly concerned with describing

nature.

A different process is followed when a scientist seeks to develop an explanation

for natural events. This second method of inquiry is called 3

science. It employs a process of inquiry sometimes called the 4

Although it is not a single method, its key element is the kind of logic called5

In our example, like many examples of hypothesis-based science, the process

started rvith a simple 6 : The zoologist noticed that predatory birdsavoided the brightly colored butterflies even though they rested in tree branches in plain

-based

sight. This evoked a 7 : Is there something about the butterflies that

Lt L6 L.J c

the birds don't like? The researcher had a hunch; she suspected that the striped butter-flies tasted bad and that their bright colors acted as a sort of "warning" to predators tostay away. This kind of tentative explanation is called a 8--.--.-.-.

The zoologist decided to test this in the laboratory, under conditions that shecould manipulate and monitor. Such a test is called a controlled 9

She captured insect-eating birds native to the area and put them in cages at a nearby re-search station. Then she netted a number of brightly striped butterflies and their blackcousins. For her first experiment, she allor,r,ed the birds to choose between a black butter-fly and a striped one. The birds invariably chose the black butterflies and avoided thestriped ones. This confirmed her field observations.

But did the striped butterflies taste bad? The researcher set up another controlledexperiment, designed to compare an 10 group-striped butterfl iesrn'ith their wings painted black-with a i1 group of "normal" stripedbutterflies. (Actually, the "normal" butterflies were also handled and painted with clearpaint, so that only one 12 wouid differ between the two groups.) Herhypothesis led the zoologist to make a 13 about how she thought theexperiment would turn out: f the stripes really acted as a warning, then the birds wouldbe fooled and eat the butterflies when the stripes were co\rered-and that f the stripedbutterflies tasted bad, then the birds would spit them out. Such "if-then" thinking iscalled la and is an important feature of hypothesis-driven science.

]ust as the researcher hypothesized, the birds chose the black-painted butterfliesin every trial. Also, most of the birds quickly spat out the black-painted butterflies, andthose that swallowed the butterflies became ill. Just to cover things, the zoologist per-formed another experiment in which she painted the wings of the edible black-wingedbutterflies. The birds ate them with gusto, demonstrating that the paint itself was not dis-tasteful and produced no ill effects.

After repeating the experiments several times, the researcher wrote a paper de-scribing her hypothesis, experiments, results, and conclusions. It was published in thelournnl of Tropicnl Entotnology. There other scientists could read about the experiments,repeat and expand upon them, even challenge the results-all part of the process ofscience.

After reading these modules, and without referring back to the text, list six ways in whichyou think the science of biology and its technological applications may affect society inthe next decade. Which of these are primarily scientific? Which are technological? Are anyof them related to evolution, the core theme of biology? \A/hich do you think will have themost effect on you personally in the coming years?