Biology 281 Exam 1

Chili peppers are hot because they contain capsaicin, a chemical that activates heat- and pain-sensitive receptors in animals.

Capsaicin is the chemical compound responsible for the pungent or "hot" sensation of chili peppers.

Capsaicin functions as a directed deterrent that discourages harmful consumers while allowing effective seed dispersers to eat the fruits.

Mammals are deterred by capsaicin.

Birds.

Mammals, particularly rodents, consumed much less pungent fruit than birds.

Mammals can destroy chili seeds during digestion or chewing, reducing seed survival.

Birds can disperse viable seeds without destroying them.

The scientific study of interactions among organisms and between organisms and their environment.

The hypothesis that species in an ecosystem are like rivets in an airplane: losing a few may have little obvious effect, but continued species loss eventually causes ecosystem failure.

A testable and falsifiable explanation for an observation or pattern.

Information gathered by measuring or describing something in the natural world without manipulating it.

An experiment in which researchers deliberately alter an independent variable and measure its effect on a dependent variable.

A study in which naturally occurring events or conditions create treatments that researchers compare without directly manipulating them.

A simplified representation of a biological or ecological system used to describe, explain, or predict patterns.

The variable that is manipulated or used as a predictor to determine its effect on another variable.

The response variable that is measured to determine whether it changes in response to the independent variable.

The independent variable is the predictor or manipulated factor, while the dependent variable is the measured response.

A statistical association between two variables.

A relationship in which a change in one variable directly produces a change in another variable.

An observed relationship may be caused by another variable or confounding factor rather than one variable directly causing the other.

A variable associated with both the independent and dependent variables that can provide an alternative explanation for an observed relationship.

A study designed to test a hypothesis, usually by manipulating one or more variables and measuring the resulting response.

A study in which researchers measure naturally occurring variables without assigning treatments or manipulating conditions.

They can identify correlations but generally provide weaker evidence for causation because confounding variables may exist.

The condition or manipulation applied to an experimental group.

A comparison group that does not receive the experimental treatment or receives a standard condition.

It provides a baseline for determining whether the treatment caused an observed effect.

Applying each treatment to multiple independent experimental units.

It allows researchers to estimate natural variation and determine whether treatment effects are consistent.

Assigning experimental units to treatments randomly to reduce bias and distribute confounding factors among groups.

It reduces systematic bias and helps make treatment groups comparable.

Treating non-independent measurements or subsamples as though they were independent replicates.

It artificially inflates sample size and can make statistical evidence appear stronger than it actually is.

The arithmetic average of a set of observations.

Add all observations and divide by the number of observations.

A measure of how spread out observations are around their mean.

The observations are relatively spread out from the mean.

The observations are relatively clustered around the mean.

The probability of obtaining results at least as extreme as those observed, assuming the null hypothesis is true.

0.05.

Reject the null hypothesis because the result is considered statistically significant at the 0.05 level.

Fail to reject the null hypothesis.

No, it only means there is insufficient evidence to reject the null hypothesis at the chosen significance level.

Testing whether the means of two groups differ significantly.

Testing whether there are significant differences among the means of three or more groups.

Quantifying and testing the relationship between a response variable and one or more predictor variables.

Short-term atmospheric conditions at a particular place and time.

The long-term average and variability of weather conditions in a region, typically measured over decades.

Weather describes short-term atmospheric conditions, while climate describes long-term patterns of weather.

A large ecological region characterized by its climate and dominant forms of vegetation and other organisms.

Temperature and precipitation.

Solar radiation strikes the poles at a lower angle, spreading energy over a larger area and passing through more atmosphere.

The timing of seasonal events involving leaves, such as leaf emergence, expansion, coloration, and senescence.

Temperature, although factors such as snowmelt, precipitation, and photoperiod can also influence phenological timing.

Long-term changes in climate and the timing of biological events such as flowering and other phenological patterns.

Changes in temperature, snowmelt, and other environmental cues can shift the timing of seasonal biological events.

Interacting species may respond differently to environmental change, creating mismatches in the timing of events such as flowering, pollination, migration, or food availability.

Change in allele frequencies in a population across generations.

A unit of hereditary information encoded in DNA that can influence a trait.

An alternative version of a gene.

An organism's genetic makeup or combination of alleles.

The observable characteristics of an organism resulting from its genotype and environmental influences.

Genotype contains an organism's genetic information, while phenotype is the observable expression produced by genotype interacting with the environment.

Random change in allele frequencies from one generation to the next due to chance.

Small populations.

Yes, genetic drift changes allele frequencies by chance rather than because certain alleles increase fitness.

The movement of alleles between populations through migration and reproduction.

It often makes populations genetically more similar by transferring alleles between them.

Differential survival and reproduction caused by heritable differences among individuals.

Individuals must vary in traits, some of that variation must be heritable, and the variation must affect survival or reproductive success.

Natural selection acts on differences among individuals, while evolutionary change is observed as changes in populations across generations.

Natural selection that favors individuals at one extreme of a trait distribution, shifting the population mean toward that extreme.

Natural selection that favors intermediate phenotypes and selects against extreme phenotypes.

It tends to reduce variation around the favored intermediate phenotype.

An individual's relative contribution of surviving offspring or genes to future generations.

A heritable trait that evolved through natural selection because it increases fitness in a particular environment.

Natural selection can increase the frequency of heritable traits that improve fitness, causing populations to become better adapted to their environments.

Environmental differences and food availability can favor different heritable beak traits through natural selection.

Different beak forms can improve the ability to obtain particular food resources, affecting survival and reproduction.

Environmental changes can alter available food resources, causing birds with certain beak traits to survive and reproduce more successfully.

Directional selection caused by selective harvesting of larger males.

If body size is heritable and hunters disproportionately remove large individuals before they reproduce, smaller individuals gain a reproductive advantage and alleles associated with smaller size can increase.

Look for the group whose observations are centered around the highest numerical value.

Look for the group whose observations are most widely spread around its mean.

Replication uses independent experimental units, while pseudoreplication incorrectly treats non-independent observations as independent.

Manipulation, an appropriate control, replication, and randomization.

A hypothesis stating that there is no effect, difference, or relationship between the variables being tested.

The observed result would be relatively unlikely under the null hypothesis at the chosen significance threshold.