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AP Biology Unit 5 Review and Practice Test: Heredity

AP Biology Unit 5, Heredity, covers the fundamental principles of inheritance and gives students the foundation to understand how traits and genes are passed, expressed, and mutated over generations. So, get closer to achieving the perfect 5 with UWorld's AP Bio Unit 5 review, which includes practice questions, study guides, and review videos delivered by experts, all in one place.

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Flip the Script: Make AP Bio Unit 5 Your Genetic Advantage, Not an Inherited Problem

Don’t let Heridity be the unit that throws you off on the text day. Instead, use our comprehensive AP Bio Unit 5 review with clear explanations, video lessons that make you master the concepts in record time, and targeted practice that translates learning into perfection.

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Videos That Make Heridity Click

With topics like meiosis, gene interactions, and chromosomal inheritance, Heredity becomes a complex unit that takes up much time. Not anymore! Each video makes learning Heredity easier, as it comes with step-by-step explanations, directly tying them to the exam, so you're not just watching but learning to answer the question in real time.

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Interactive Heredity Study Guides That Make Learning Stick

Keep your study sessions interactive with visuals, examples, and quick breakdowns of each topic, like Punnett squares, Inheritance patterns, Chromosomal variations, and a lot more. Our AP Bio Unit 5 study guide makes learning easier and fun, as you scroll through with interactivity, not dense chapters.

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Practice

Try These AP Biology Unit 5 Practice Test Questions

The best way to achieve a 5 is to practice with real exam questions that replicate the difficulty and wording the AP Exam uses. Every question comes with clear explanations, so you’re not wondering about the answer, but rather learning how to get more questions right next time.
Try these sample practice questions with detailed answer explanations:
Heredity Practice Tests

Question

The combined expression of several genes has been shown to influence the production of unique fingerprint patterns in each human being. These fingerprint patterns are fully formed approximately two months before birth. Which of the following would confirm that fingerprint pattern is an example of a trait exhibiting phenotypic plasticity?

A. Fingerprint patterns always differ when comparing two individuals that are not related.
B. Identical twins sharing all their DNA sequences still express different fingerprint patterns.
C. If the genes responsible for coding fingerprint patterns are inhibited, fingerprint patterns will not form before birth.
D. Each gene that codes for fingerprint patterns is transcribed at a different time point during embryonic development.

Explanation

Gene expression and the resulting phenotypes in organisms may be affected by several factors, such as:

Phenotypic plasticity occurs when environmental differences cause individuals of the same species with similar or identical genotypes to express different phenotypes.

This question describes fingerprint pattern development in humans due to expression of several genes. If identical twins (ie, individuals who share 100% of their DNA sequences) still express different fingerprint patterns, this would confirm that this trait exhibits phenotypic plasticity. Accordingly, environmental differences experienced by each twin during development (eg, differences in position or access to nutrients within the mother) may alter fingerprint pattern, regardless of their genotype.

The remaining answer choices do not provide evidence that environmental differences in genetically similar individuals affect expression of unique fingerprint patterns.

(Choice A) Fingerprint patterns are unique in each person (regardless of family relationship), but this alone does not suggest that the trait exhibits phenotypic plasticity.

(Choice C) Inhibition of genes encoding fingerprint patterns only prevents formation of these patterns during development.

(Choice D) There is no information given to suggest that genes involved in the development of fingerprint patterns are transcribed at different time points during development.

Things to remember:
Gene expression may be affected by environmental influences, leading to phenotypic plasticity (same species individuals with similar/identical genotypes that express different phenotypes).

Question

The offspring formed by human sexual reproduction possess alleles that were present in the parental gametes. The formation of human gametes requires the separation of homologous chromosomes as well as separation of sister chromatids during meiosis.

Which graph below depicts the number of each kind of chromosome in male human offspring when nondisjunction of chromosomes or chromatids does NOT occur during gamete formation?

A.
B.
C.
D.

Explanation

Gametes (eggs and sperm) form via meiosis, a process of cell division in which a single diploid (2n) parental cell divides to form four haploid (1n) daughter cells. Meiosis occurs in two stages:

  1. Meiosis I: Homologous chromosomes align and are separated to opposite poles of the cell by spindle fibers. Cytoplasmic division (cytokinesis) then yields two haploid cells.

  2. Meiosis II: In each cell resulting from meiosis I, chromosomes align, and sister chromatids are pulled apart by spindle fibers. Cytokinesis then yields four haploid gametes.

Nondisjunction is an error in meiosis that arises when either homologous chromosomes or sister chromatids fail to separate, producing gametes with missing or extra chromosomes that can be passed to offspring, leading to genetic disorders in humans.

The question asks which graph best represents the number of chromosomes present in human offspring in the absence of nondisjunction. Humans typically have 23 pairs of chromosomes, including a pair of sex chromosomes (ie, XX in females or XY in males). Choice A depicts 22 pairs of autosomes (non-sex chromosomes) and a pair of sex chromosomes (one X and one Y), as would be found in male offspring when nondisjunction of chromosomes or chromatids did not occur.

(Choices B, C, and D) These graphs depict offspring possessing either extra copies of chromosome 13 or 18 or missing an X chromosome.

Things to remember:
During meiosis, nondisjunction occurs when homologous chromosomes (in meiosis I) or sister chromatids (in meiosis II) fail to separate, resulting in gametes with missing or extra chromosomes. Nondisjunction can cause genetic disorders in humans.

Question

The Durham breed of cattle (Bos taurus) possesses two codominant alleles, white and red, for an autosomal coat-color gene. If each codominant allele is expressed when present, what percentage of offspring are expected to produce coats containing red hairs and white hairs when true-breeding white Durham cattle are mated with true-breeding red Durham cattle?

A. 0%
B. 25%
C. 75%
D. 100%

Explanation

The alleles inherited by an organism strongly influence the organism's phenotype. Mendel's laws of segregation and independent assortment explain patterns of inheritance based on transmission of dominant or recessive alleles from parents to offspring.

However, some traits exhibit non-Mendelian inheritance patterns. For example, traits controlled by genes on sex chromosomes or outside the nucleus are not inherited equally by males and females. Also, genes located close to each other on a chromosome are frequently inherited together, deviating from Mendel's law of independent assortment. Finally, traits may be controlled by multiple genes or alleles or influenced by the organism's environment or life history (ie, by epigenetics).

The question asks the expected percentage of offspring exhibiting coats with red hairs and white hairs when true-breeding white and true-breeding red Durham cattle are mated. Because codominant alleles are both fully expressed in heterozygotes, true-breeding white and true-breeding red cattle must be homozygous for white and red alleles, respectively.

Therefore, since all offspring inherit one allele from each parent, 100% of the offspring of white and red parents are expected to be heterozygous for the coat-color gene and exhibit coats with red hairs and white hairs.

(Choices A, B, and C) 0%, 25%, and 75% do not reflect the expected pattern of phenotype inheritance.

Things to remember:
Divergence from the expected (Mendelian) distribution of offspring phenotypes suggests non-Mendelian inheritance.

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Frequently Asked Questions (FAQs)

AP Biology Unit 5, Heredity, focuses on inheritance’s fundamentals, how traits are passed between generations, and how genetic outcomes are determined. It covers cellular processes like meiosis to complex inheritance patterns and data interpretations. Some of the key topics include:

  • Meiosis and genetic diversity
  • Mendelian genetics
  • Non-mendelian inheritance
  • Environmental effects on phenotype

UWorld groups these topics similarly to the AP exam, so you practice them in the format you’ll be tested on.

The best way to prepare for Unit 5 is to understand how heredity concepts apply to real data, not to memorize the sequences. Reviewing step-by-step explanations and practice questions as per the study planner and exam format will help you retain the information and answer confidently.
Yes, UWorld offers free sample Unit 5 practice questions to test your understanding, along with preview videos and study guide pages. These resources can elevate your score by multiple folds. You can opt for UWorld’s free trial for 7 days, which gives you access to these resources before you upgrade.

The AP Exam uses Heridity to test your ability to reason, predict, and interpret data through a mix of MCQs and FRQs. Each requires analyzing crosses, explaining outcomes, or interpreting data through genetic scenarios. 

Some common questions you may encounter:

  • Punnet square questions
  • Data table analysis
  • Inheritance-based FRQs
  • Pedigree and probability problems
AP Biology Unit 5 FRQ will require extensive practice writing short and direct explanations of an outcome’s logic and reasoning. Looking at scored examples and revisiting explanations can help you learn what graders expect, and how to align your answers accordingly.
The Heredity unit typically covers 8-11% of the material of the AP Bio exam. A strong performance on this unit can elevate your score and balance out units that you may not be confident in.
UWorld provides the best AP Bio Unit 5 study guides, developed by experts. These guides make learning an interactive experience with visuals, examples, and concise explanations. The topics become easier to retain, and you perform better than when reading a dense textbook.
Yes. UWorld offers specific practice tests for AP Bio Unit-5 with detailed explanations in an environment that mirrors the real AP Exam, so you can review Heredity without the fuss of sorting through unrelated material.
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