Bio Exam - Lab Flashcards

Dissecting microscope

A microscope used to observe larger, thicker, or 3D specimens at relatively low magnification.

Compound microscope

A microscope used to observe small, thin, or transparent specimens at higher magnification.

When should you use a dissecting microscope?

Use it for larger or 3D specimens that do not require high magnification, such as insects, leaves, and whole organisms.

When should you use a compound microscope?

Use it for small or thin specimens that require higher magnification, such as cells and microorganisms.

Which microscope has greater magnification?

The compound microscope.

Which microscope should you use to observe a whole insect?

A dissecting microscope.

Which microscope should you use to observe individual cells?

A compound microscope.

Ocular lens (eyepiece)

The lens you look through; it usually provides 10× magnification.

Objective lenses

Lenses on a compound microscope that provide different levels of magnification.

Revolving nosepiece

The part of a compound microscope that holds the objective lenses and rotates to switch magnification.

Stage

The platform where the microscope slide or specimen is placed.

Stage clips

Structures that hold the microscope slide in place.

Light source

Provides light so the specimen can be seen.

Diaphragm

Controls the amount of light passing through the specimen.

Coarse adjustment knob

Moves the stage or objective significantly to bring the specimen into general focus; primarily used at low power.

Fine adjustment knob

Makes small focusing adjustments to sharpen the image; used especially at higher magnification.

What should you do before switching to a higher-power objective?

Center and focus the specimen under low power first.

Should you use the coarse adjustment knob at high power?

No. Use the fine adjustment knob to avoid damaging the slide or objective.

How should you carry a microscope?

Use two hands: one supporting the base and one holding the arm.

How should you clean microscope lenses?

Use lens paper, not regular tissues or paper towels.

What should you do when finished using a compound microscope?

Return it to the lowest-power objective, lower the stage if appropriate, remove the slide, turn off the light, wrap the cord properly, and store the microscope correctly.

Biological organization from smallest to largest

Organism → Population → Community → Ecosystem → Biome → Biosphere.

How is a community different from an ecosystem?

A community includes only living organisms, while an ecosystem includes living organisms AND abiotic/nonliving factors.

What do arrows in a food chain represent?

The direction of energy transfer from the organism being eaten to the organism eating it.

Production efficiency

The percentage of assimilated energy that is converted into new biomass or growth.

Production efficiency formula

Production efficiency = (net production ÷ assimilation) × 100.

What does high production efficiency mean?

A relatively large proportion of assimilated energy is converted into new biomass.

What does low production efficiency mean?

A relatively small proportion of assimilated energy is converted into new biomass because more energy is used for metabolism and other processes.

Trophic efficiency

The percentage of production from one trophic level that becomes production at the next trophic level.

Trophic efficiency formula

Trophic efficiency = (production at higher trophic level ÷ production at lower trophic level) × 100.

Approximately how much energy is commonly transferred from one trophic level to the next?

Often about 10%, although actual trophic efficiency varies among ecosystems.

What happens to available energy as you move up trophic levels?

Available energy decreases.

Biomass

The total mass of living biological material in a particular area or trophic level.

Biomass pyramid

A diagram showing the amount of biomass present at each trophic level.

Why are many biomass pyramids bottom-heavy?

Producers contain the greatest biomass because energy is lost during each transfer to higher trophic levels.

What does a bottom-heavy biomass pyramid look like?

A large producer level at the bottom with progressively smaller levels of consumers above it.

How does trophic efficiency affect biomass pyramids?

Low trophic efficiency means less energy is available to produce biomass at higher trophic levels, causing biomass to decrease toward the top.

Common format for a prediction

If the hypothesis is correct, then [specific measurable outcome] should occur.

What is a predictive graph?

A graph showing the expected relationship between the independent and dependent variables if a prediction is correct.

If you predict that increasing light intensity will increase plant growth, what goes on the x-axis?

Light intensity, because it is the independent variable.

If you predict that increasing light intensity will increase plant growth, what goes on the y-axis?

Plant growth, because it is the dependent variable.

What does a p-value represent?

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

What p-value is commonly considered statistically significant?

p < 0.05.

What does p < 0.05 generally indicate?

The observed difference or relationship would be unlikely under the null hypothesis, so the result is considered statistically significant.

What does p > 0.05 generally indicate?

The result is not statistically significant, meaning there is not enough evidence to reject the null hypothesis.

Does p > 0.05 prove that there is no effect?

No. It means the experiment did not provide sufficient evidence to reject the null hypothesis.

Should you say a hypothesis is "proven"?

No. Results can support or fail to support a hypothesis, but a single experiment does not prove it.

How do group averages help you interpret an experiment?

They show the typical measured response of each group and allow you to compare the direction and size of differences.

If two groups have different averages but p > 0.05, is the difference statistically significant?

No. The observed averages differ, but the statistical test does not provide sufficient evidence that the difference is statistically significant.

If the results match the prediction and p < 0.05, what can you conclude?

The results statistically support the prediction and provide evidence consistent with the hypothesis.

If the results are opposite to the prediction, what does that mean?

The prediction is not supported, even if a statistically significant difference exists.

What are the important components of a scientific figure?

Figure number, descriptive caption, graph or image, clearly labeled axes when applicable, units, legend/key when needed, and displayed data.

What should a graph's x-axis include?

The independent variable and its units when applicable.

What should a graph's y-axis include?

The dependent variable and its units when applicable.

Figure legend/key

Explains what different symbols, bars, lines, patterns, or groups represent.

Figure caption

A description that explains what the figure shows and provides enough information to understand the displayed data.

Error bars

Lines showing variability or uncertainty around an estimate, such as standard deviation, standard error, or a confidence interval; their meaning depends on the figure.

When interpreting a statistical figure, what should you look at first?

Identify the independent and dependent variables, compare the groups or trends, examine the averages and variability, and then use the statistical results such as the p-value to determine whether the observed pattern is statistically supported.