Practice Tests - BIOLOGY JUNCTION

Paper Chromatography Lab: Separating the Components of Black Ink

Introduction to Chromatography in the Science Classroom

Chromatography is a fundamental technique used in chemistry and biology to separate mixtures into their individual components. In this experiment, we explore how paper chromatography can be used to analyze and isolate the different pigments found in black ink.

The process relies on the movement of a solvent (in this case, water) through a medium (filter paper). As the solvent travels up the paper, it carries along the dissolved components of the mixture. Each substance moves at a different rate based on its molecular characteristics—such as size, solubility, and affinity for the paper. This separation allows for a visual and measurable representation of what the mixture is composed of.

Chromatography is widely used in scientific research for chemical analysis, substance purification, and compound identification. It also plays a role in detecting changes in chemical properties due to biological or chemical reactions. For students and educators, it’s a hands-on way to visualize how mixtures behave at the molecular level.

Hypothesis

Paper chromatography can be used to separate the individual pigments that make up black ink.

Materials

Filter paper strip
Test tube
Rubber stopper
Straightened paper clip (with hook)
Black felt-tip marker
Pencil
Metric ruler
Tap water (used as solvent)
Eraser
Computer (for data analysis or reporting)

Procedure: How to Perform Paper Chromatography

Prepare the apparatus: Straighten a paper clip and add a hook at one end. Insert the other end into the center of the rubber stopper.
Attach the filter paper: Hang a strip of filter paper from the hook. Ensure it hangs freely and doesn’t touch the sides of the test tube.
Draw baseline: Remove the strip and draw a 5-mm-wide black band approximately 25 mm from the bottom using the black felt-tip pen.
Mark solvent limit: Draw a pencil line 10 cm above the ink band. This will be the upper limit for the solvent’s movement.
Add the solvent: Pour 2 mL of water into the test tube. Reinsert the filter paper so the bottom touches the water, but the black band remains above it.
Observe separation: As the solvent moves up the paper, watch the ink pigments begin to separate.
Remove and measure: When the solvent reaches the pencil line, remove the strip. Let it dry and measure how far each color moved.
Record your data: Use a ruler to measure the distance traveled by each pigment and the solvent. Calculate the Rf value (retention factor) for each pigment using the formula:Rf = Distance traveled by pigment / Distance traveled by solvent

Results: Pigment Separation Data

Color	Distance Traveled (mm)	Solvent Distance (mm)	Rf Value
Yellow	70 mm	111 mm	0.63
Pink	82 mm	111 mm	0.74
Red	101 mm	111 mm	0.91
Purple	110 mm	111 mm	0.99
Blue	111 mm	111 mm	1.00

Analysis & Discussion

How many pigments were separated from the black ink?
Five: yellow, pink, red, purple, and blue.
What solvent was used?
Tap water.
What was the first visible color during the separation?
Orange or yellow appeared first, indicating it traveled the fastest.
In what order did the pigments separate (top to bottom)?
Blue, purple, red, pink, and yellow.
How far did the solvent travel?
111 mm.
What does this tell us about black ink?
Black ink is not a pure substance—it’s a mixture of various colored pigments.
Why did the pigments separate?
Differences in molecular size, solubility, and paper affinity cause each pigment to move at a unique rate.
Why did some pigments travel farther than others?
Less absorbent pigments that are more soluble in the solvent moved farther up the paper.

Error Analysis

Some possible sources of error in this paper chromatography experiment include:

Measurement inaccuracies: Small errors in reading distances can affect Rf values.
Solvent volume inconsistencies: Too little or too much solvent may alter the pigment spread.
Filter paper length: A longer strip might have shown additional colors or more precise separations.

Conclusion

The results supported the hypothesis: paper chromatography successfully separated black ink into multiple pigments. The experiment demonstrated how different molecular characteristics—such as solubility and affinity to the filter paper—affect the movement of each component in a mixture. This hands-on experiment reinforces the idea that seemingly simple substances can contain complex chemical compositions.

Chromatography remains an essential tool in both educational and professional laboratory settings. From forensic science to biochemistry, the ability to separate and analyze chemical mixtures is foundational to understanding the materials around us.

Why Fake Frogs in Biology Class Are the Future of Science Education

Fake Frog Dissection — Fake Frogs for Dissection “gross factor”

For decades, frog dissection has been a rite of passage in biology classrooms. But with advances in technology, changing educational standards, and a growing focus on ethical science practices, fake frogs in biology class are becoming a smarter, cleaner, and more compassionate alternative.

At Biology Junction, we’re committed to helping students, teachers, and schools explore modern tools in science education — and that includes highlighting the many benefits of frog dissection alternatives.

What Are Fake Frogs in Biology Class?

Fake frogs are realistic dissection models or virtual simulations used in place of actual preserved frogs. These tools mimic the anatomical structure of real frogs and offer a hands-on learning experience — without the ethical concerns or mess.

They come in several forms:

🐸 3D anatomical models
💻 Virtual dissection software
📱 Apps and interactive platforms

These tools are designed to provide highly accurate, engaging, and reusable alternatives to traditional dissection.

Why Schools Are Making the Switch

Ethical Education
With increasing awareness around animal welfare, many schools are moving toward ethical biology learning. Using fake frogs eliminates the need to harvest real animals and teaches students respect for life.
Cost-Effective & Reusable
Traditional dissection can be costly year after year. Frog dissection alternatives — like synthetic frogs or virtual tools — are reusable and budget-friendly in the long term.
Clean, Safe, and Inclusive
No chemicals. No odor. No cleanup. Fake frogs make the dissection experience safer and more accessible — especially for students with ethical concerns, allergies, or sensitivities.
Aligned with Digital Learning Trends
Schools are adopting more digital tools post-pandemic. Virtual frog dissections fit perfectly into hybrid or remote learning environments.

Do Fake Frogs Still Teach Students Effectively?

Absolutely. In fact, studies show that students using virtual dissection platforms often perform as well or better than those using traditional methods. Why?

✅ They can repeat the dissection multiple times
✅ They receive instant feedback and guidance
✅ They learn in a stress-free environment

At Biology Junction, we believe learning should be informative, inclusive, and inspiring — and fake frogs help us get there.

Trusted Tools & Resources for Educators

If you’re a teacher looking to introduce frog dissection alternatives into your curriculum, we recommend checking out:

Froggipedia – Award-winning AR app for virtual dissection
SynFrog – Hyper-realistic synthetic frog models
BioDigital Human – Virtual anatomy and biology exploration tool

We’re also working on new lesson plans, guides, and toolkits right here at Biology Junction to help educators integrate fake frogs in biology class effectively and confidently.

Final Thoughts: Building the Future of Biology Together

At Biology Junction, we’re more than just a resource hub — we’re a community of science educators and learners who believe in evolving with the times.

Embracing fake frogs in biology class isn’t just about keeping up — it’s about leading the way in ethical, modern, and effective science education.

Follow us for updates, classroom tools, and trusted tips to bring your biology curriculum into the future — frog-friendly and forward-thinking.

How Much of the MCAT Is Biochemistry?

In this brief guide, we are going to answer the question “How much of the MCAT is biochemistry?” We will introduce you to each of the MCAT sections, the main concepts you will need to learn, and some tips for studying biochemistry.

How Much of the MCAT is Biochemistry?

Biochemistry comprises approximately 25% of the MCAT, with 25 to 35 questions covering biochemistry in two of the four sections of the exam.

The Medical College Admission Test (MCAT) is a standardized test administered to individuals who wish to attend medical school in the United States. Almost all American medical schools require MCAT scores from applicants interested in pursuing careers as physicians.

Therefore, the MCAT is an extremely important exam, and both schools and applicants take it seriously. Members of the Association of American Medical Colleges and the American Association of Colleges of Osteopathic Medicine require MCAT scores from their applicants.

The history of the MCAT is quite long. MCAT Test preparation administrations began in the 1920s when standardized intelligence tests became immensely popular in the United States. Medical school administrators were concerned about the high dropout rate among medical students and decided to design a standardized test to assess readiness for medical school.

Dropout rates dropped dramatically after the implementation of this standardized test, and most medical schools adopted it as part of their admissions process.

The MCAT content assesses several areas. The first, of course, is the basic knowledge of the physical sciences and biology. The test also evaluates the applicant’s analytical and critical thinking skills, presenting various passages and arguments that the examinee must analyze during the test.

The MCAT also assesses reading comprehension and communication skills, which are vital for clinicians.

The modern MCAT is a computerized test, although it is not adaptive like the Graduate Record Examination (GRE). This means that examinees can return to a section once they have completed it, as the questions are set and static.

The MCAT takes around five hours to complete, including breaks, and is administered in secure testing centers so applicants have quiet, distraction-free spaces to work.

MCAT Sections

There are four sections on the MCAT. The first tests the applicant’s knowledge of the physical sciences and also challenges the applicant to use their problem-solving skills.

The Verbal Reasoning section, Part Two, provides passages for test-takers to read and analyze, followed by a series of multiple-choice questions that test the applicant’s ability to comprehend and synthesize information. For those looking for additional support, a college paper writing service can help improve writing and analytical skills.

The third section is a writing sample, in which the applicant responds to two short prompts that assess their communication skills and logical thinking. Finally, the life sciences section covers basic topics in biology.

Chemical + Physical Foundations of Biological Systems

The first section of the MCAT focuses on the physical sciences, specifically general chemistry and physics. It covers content in the following proportions:

30% General Chemistry

25% Biochemistry

25% Physics

15% Organic Chemistry

5% Biology

This section lasts 95 minutes and includes 15 standalone questions and 10 passages, each followed by 4 to 7 questions. To prepare for the chemistry portion, examinees need a strong grasp of the periodic table, chemical processes, and molecular bonding. The physics portion requires understanding fundamental physical laws and concepts such as motion, energy, light, and atomic structure.

Critical Analysis + Reasoning Skills

The CARS section is significantly more challenging than SAT-style reading comprehension and the verbal section of the old exams. This section covers:

50% humanities

50% social science

You are not required to have any outside knowledge; everything you need to know to answer the questions will be provided in the passages. You will have a total of 90 minutes to work through nine passages with a total of 53 questions. If you’re struggling with essay writing as part of your test preparation, a paper writing service can help you improve your skills.

In this section, no specific factual knowledge is required. Rather, the questions are designed to test reading comprehension, critical and logical thinking, and analytical skills. In general, test takers prepare for this section of the MCAT primarily by taking practice exams.

Biological + Biochemical Foundations of Living Systems

This section covers:

65% Biology

25% Biochemistry

5% General Chemistry

5% Organic Chemistry

As with the first science section, you’ll have 95 minutes to answer 15 discrete questions and 10 passages with 4 to 7 questions each. The topics in this section vary widely, from enzyme structure to evolution. Test-takers require a thorough understanding of molecular biology, including the structure and function of DNA, as well as microbiology, including the characteristics of viral, bacterial, and eukaryotic cells.

In addition, examinees should be familiar with all major biological systems of larger animals. Finally, organic chemistry topics range from covalent bonds to the characteristics of biological molecules.

MCAT Scores

Each section of the MCAT allows a student to score between a minimum of 118 points and a maximum of 132 points. For the total sum of the four sections, a student can achieve a score ranging from a minimum of 472 to a maximum of 528.

You may have heard scores like 23 or 31 mentioned in the past. However, it’s important to clarify that these scores were used before the MCAT underwent its most recent change in 2015. Currently, all students applying to medical school are doing so with the new scoring system.

What is considered a good GMAT score?

The average for the total MCAT score is 510-511.

The average total MCAT score is 510-511. However, for the most accurate estimate, you should check directly with the programs. Especially for those who must juggle the MCAT alongside other jobs, it helps to know how much effort and time to put into preparing for the exam.

Here are some important questions to consider before beginning your research.

What MCAT Scores Do You Need for Acceptance?

To determine the MCAT score you need, it’s essential to have a target score in mind. Start by contacting the admissions office of the medical schools you’re interested in to request their preferred cutoff score. If the school doesn’t provide a specific cutoff, you can find the average GPA and MCAT scores for accepted students here.

Keep in mind that some schools may use your MCAT scores for course placement or scholarship decisions. In such cases, aiming for a score higher than the minimum requirement may increase your chances of receiving additional benefits.

How can I prepare for the MCAT?

To excel on the MCAT® Biology exam, start by gathering detailed information about the test. This knowledge will help you craft an effective study plan. The MCAT is a standardized exam with primarily multiple-choice questions. Besides biology concepts, it also assesses your understanding of physical sciences, verbal reasoning skills, and writing abilities. There are many MCAT preparation courses available online and in person.

Exploring the Biochemistry Section

For specific details about the MCAT biochemistry section, visit the Association of American Medical Colleges website. The site provides a comprehensive overview of the content covered in the biology and chemistry sections of the MCAT.

Importance of Early Preparation

A high score on the MCAT can significantly enhance your chances of getting accepted into your desired medical school. Therefore, it is beneficial to begin your study preparation early. Many experts recommend starting at least three months before the exam date.

Additionally, if you find yourself struggling with other academic tasks, you might consider using an online paper writing service to help manage your workload. Dedicating substantial study time each day can ensure thorough preparation, allowing you to cover all necessary concepts and avoid last-minute cramming, which is generally ineffective for achieving a high score.

Utilizing Study Guides and Practice Tests

Consider obtaining a copy of the Official MCAT Exam Guide, available on the Association of American Medical Colleges website. This guide contains content and questions similar to those on the actual MCAT, along with answers and detailed explanations. It also offers tips for answering questions correctly and insights into how a strong MCAT score can impact medical school acceptance.

Practice tests are an essential tool for preparing for the MCAT® Biology section. The Association of American Medical Colleges website offers practice tests, and additional tests can be found on other preparatory websites and in study guides. If you opt for an MCAT® Biochemistry Prep course, practice tests, and expert commentary are often included in the package.

8 Websites with the Best AP Practice Exams

High school is a challenging time in everyone’s life. And for students enrolled in AP courses, the end of the year is particularly challenging. As high-achieving students gear up for long exams that offer the potential for early college credit, many students are searching high and low for reliable study materials.

One favorite way to practice for an important exam is by taking practice exams. But finding high-quality AP practice exams is challenging. That’s why we curated this list of websites for you. Whether you’re looking for AP Biology practice exams or one for AP Art History, these websites will help you in your quest for a good score.

Why You Should Take a Practice Exam

The best way to gauge how ready you are for an exam is by taking a practice test. While its best to drill yourself with a wide variety of study materials throughout the year, use of a full-length practice test will help you to prepare for the exam in a whole new way. In addition to helping you study, taking a practice exam can offer the following benefits:

Enables you to acclimate to the test format.
Relieves unwanted test anxiety.
Familiarizes you with test content.
Offers an opportunity to customize your study plan.
Gives testers a sense of readiness.

Practice exams are a helpful tool for getting yourself in tip-top test shape. But don’t forget to apply the knowledge you gain from taking practice tests. For example, if you come across the material in the practice test that you don’t understand, bring it up with your teacher as soon as possible.

Source: Pexels.com

Below you’ll find a list of websites that offer AP practice exams in one format or another. Not all of them provide full-length tests, but all of them will help you get ready for your AP exams. Keep in mind, that AP tests are different each year and the practice questions you find online won’t necessarily be the ones you encounter on your exam.

8 Websites with the Best AP Practice Exams

College Board

image by: College Board

If you’re looking for a good starting place when it comes to mastering an AP exam, start with the official College Board website. There are many useful resources available on this website for students who are preparing for any of the AP Exams. In addition to study materials, the College Board website provides all of the information students need about the AP exams.

In addition to general information about each of the AP exams, the College Board website also offers sample questions for curious students. While a limited number of multiple choice sample questions are provided, a wide array of free response questions are typically available. Also, you’ll find a handful of student responses for comparison.

While this website doesn’t provide full-length practice exams, it is a great starting place. College Board is the official company behind all of the AP exams, and therefore the study materials they provide will be most like the AP tests.

APPracticeExams.com

image by: appracticeexams

This website is an all-purpose study site from students preparing for AP exams. From AP Biology practice exams to class notes on Statistics, this website has a little something for everyone. It’s also worth noting that all of the resources on this web page are provided free of charge.

Unlike some websites that maintain their database of practice materials, AP Practice Exams provides links to the best free AP practice exams online. Students love using this site because it is easy to navigate and understand. Parents like this website because all of the materials are free.

While you can find a lot of resources through this web page, it does have its limitations. More specifically, the site is not backed by any testing or tutoring service. This drawback means that you’re on your own with the resources provided. However, for those who are self-driven, this site can be a treasure trove of information.

Also, it’s worth noting that the website is very low-key and doesn’t feature many stunning visual features or modern conventions. However, because the resources are all free, it’s a good option for many.

Albert

image by: albert

Albert is a study and test-prep website designed to help students get the most out of the learning experience. Unlike the sites already mentioned above, the resources available through this website are not free of charge. However, they do offer a comprehensive program for preparing for many of the AP exams.

Pricing for the materials on this website varies by subject area, but for the most part, you can expect it to be relatively affordable. Unfortunately, it doesn’t seem that there are any concessions made for students who can’t afford the costs associated with using Albert.

Albert provides a variety of study materials including practice multiple choice questions, practice free response questions, and at least one full-length practice exam. Additionally, there are numerous study tips and testing tricks to help students make the most of test day. Albert also offers an overview of the core concepts that are tested in each subject.

This website features an attractive and easy-to-use interface that simplifies the study process. However, the fact that you must pay to use these study materials means that many students won’t be able to take advantage of this program. All in all, this is a good website for students whose parents have a little extra cash to spare.

Get A Five

image by: getafive

Get A Five is a web-based tutoring program that is available to students and teachers free of charge. However, unlike some other websites, this one is somewhat limited in scope. But, if your AP class is available, we highly recommend taking advantage of this valuable resource.

Unlike other programs, Get A Five offers a virtual study room, a diagnostic test, practice tests, and video-based lessons. Each program available in this online resource is customized to provide users with the ultimate learning experience.

Despite being limited to the few materials available, this website is an excellent resource for AP students in the classes offered. And, for a small fee, you can have your practice free response questions hand graded. We love that this resource doesn’t cost anything to use, but provides excellent value nonetheless.

Get A Five currently offers four courses for students preparing for the AP exam period. The subjects offered include AP Calculus AB, AP Biology, AP US History, and AP World History. While this selection is limited, it’s worth checking back from time to time to see if new courses become available later on.

High School Test Prep

image by: highschooltestprep

High School Test Prep is another free resource available for students preparing to take an AP exam. The materials available on this website are relatively limited but can prepare you for the general idea of how the test will be. However, it’s worth noting that this resource does not provide full-length exams. Also, it only covers multiple choice questions.

To help students understand the subject area they are testing over, each multiple choice question on this website gives a brief explanation of the correct answer. And while we wouldn’t recommend relying on this website alone, it serves as an excellent way to see where you stand.

After reviewing the materials on this website, you’ll be better prepared to formulate a study plan that will adequately prepare you for your upcoming test. Once you’ve studied the areas that are more difficult for you, use one or more of the other resources listed here to prepare yourself even more.

Study.com

image by: study.com

Study.com offers students a variety of materials for preparing for several different AP exams. They even provide several short practice exams to help you evaluate where you stand concerning the test you’ll be taking later in the school year.

In addition to the short practice tests they offer, study.com also offers test prep services. However, it’s worth noting that these services are not free of charge. Information on pricing is not disclosed without starting a “free trial” so explore these options carefully.

We like that there are several free practice tests available, but the lack of clarity when it comes to plans and pricing seems a bit dubious. Still, if you’re willing to spend a little money, it may be worth it to explore this option.

If you feel that you still need extra practice after thoroughly searching through these websites, consider visiting your local library. There, you may find practice books that contain additional practice questions or exams.

Keep in mind, not all study resources are free, and you should be extremely cautious when choosing how to spend your extra money. Also, always use caution when you have to input a credit card number online. And never purchase online materials without your parent’s permission.

With the resources listed above, you should be well on your way to finding the practice exam that’s right for you. Also, don’t forget that practice exams are only part of the study equation. Remember to brush up on necessary vocabulary and time management strategies as well.

Introduction to Biology Quiz

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Introduction to Biology

1. Ultimately, all scientific knowledge comes from:
experimentation
observation
textbooks
both experimentation & observation

2. A hypothesis must be:
proven correct
testable
observed
experimental

3. A scientist testing the affects of a chemical on apple yeild sprays an orchard with the chemical. A second orchard does not receive the chemical. In the fall, the number of apples harvested from each forest is counted. Which of the following is the independent variable in the experiment?
the chemical
the number of apples
the first orchard
the second orchard

4. The orchard sprayed with the chemical yeilds an average of 60 apples per tree, the other orchard yields an average of 40 apples per tree. Based on the data, the scientist would:
report his data
test the chemical on other plants
determine that the chemical increases apple yield
determine that the results were inconclusive

5. In order for the apple tree experiment to be valid scientifically, both orchards must:
receive the same amount of sunlight
receive the same amount of water
have the same species of apple tree
all of these

6. Theories help scientists to:
explain large bodies of data
prove hypotheses
determine truth from lies
propose new ideas about how the world works

7. If a theory is challenged by new evidence, which of the following could occur?
the theory could be altered
the theory is accepted, not the evidence
the evidence is wrong
a vote is taken on whether to accept the new evidence

8. All living things must:
move
have two parents
eat food
maintain homeostasis

9. The mechanism by which evolution occurs is called:
creationism
natural selection
interdependence
metabolism

10. The smallest unit capable of carrying out life functions is:
a cell
tissue
DNA
blood

Score =
Correct answers: