Biology Final Exam 2025

Pleiotropy

The ability of a single gene to have multiple effects

Law of Independent Assortment

Mendel’s 2nd law; stating that each pair of alleles segregates; or assorts, independently of each other pair during gamete formation

Complete Dominance

The situation in which the phenotypes of the heterozygote and the dominant homozygote are indistinguishable

Genotype

The genetic makeup, or set of alleles, of an organism

Multiplication Rule

A rule of probability stating the probability of two or more independent events occurring together can be determined by multiplying their individual probabilities

F2 Generation

The offspring resulting from interbreeding of the hybrid F1 generation

Incomplete Dominance

The situation in which the phenotype of heterozygotes is intermediate btw the phenotypes of individuals heterozygous for either allele

Addition Rule

A rule of probability stating that the probability of any one of two or more mutually exclusive events occurring can be determined by adding their individual probabilities

Dihybrid

An organism that is heterozygous with respect to two genes of interest

Recessive Allele

An allele whose phenotypic effect is not observed in a heterozygote

Multifactorial

Referring to phenotypic character that is influenced by multiple genes and environmental factors

Character

An observable heritable feature that may vary among individuals

Homozygote

An organism that has a pair of identical alleles for a gene

Carrier

An individual who is heterozygous at a given genetic locus for a recessive inherited disorder, phenotypically normal for the disorder but can pass on the recessive allele to offspring

Sickle-Cell Disease

A recessively inherited human blood disorder in which a single nucleotide change in the B-globin gene causes hemoglobin to aggregate, changing red blood cell shape and causing multiple symptoms

Trait

One of two or more detectable variants in genetic character

True-Breeding

Referring to organisms that produce offspring of the same variety over many generations

Law of Segregation

Mendel’s 1st Law, stating that 2 alleles in a pair segregate into different gametes during gamete formation

Punnett Square

A diagram used in the study of inheritance to show the predicted genotypic results of random fertilization in genetic crosses btw individuals of known genotype

Phenotype

The observable physical and physiological traits of an organism, which are determined by its genetic makeup

Dihybrid Cross

A cross btw organisms that are each heterozygous for both of the characters being followed

Heterozygous

Having two different alleles for a given gene

Dominant Allele

An allele that is fully expressed in the phenotype of a heterozygote

Heterozygote

An organism that has 2 different alleles for a gene

Pedigree

A diagram of a family tree with conventional symbol, showing the occurrence of heritable characters in parent and offspring over several generations

F1 Generation

The 1st, hybrid offspring arising from a P generation cross

Testcross

Breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype, the ratio of phenotypes in the offspring reveals the unknown genotype

Tay-Sachs Disease

A human genetic disease caused by a recessive allele for a dysfunctional enzyme, leading to an accumulation of certain lipids in the brain. Seizures, blindness, and degeneration of motor performance usually become manifest a few months after birth, followed by death within a few years

Huntingtion’s Disease

A human genetic disease caused by a dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10 to 20 years after the onset of symptoms

Allele

Any of the alternative versions of a gene that may produce distinguishable phenotypic effects

P Generation

The true breeding parent individuals from which the F1 hybrid offspring are derived

Monohybrid

An organism that is heterozygous with respect to a single gene of interest

Codominance

The situation in which the phenotypes of both alleles are exhibited in the heterozygote bc both alleles affect the phenotype in separate, distinguisable ways

Cystic Fibrosis

A human genetic disorder caused by a recessive allele for a chloride channel protein; characterized by an excessive secretion of mucus and consequent vulnerability to infection; fatal if untreated

Homozygous

Having two indentical alleles for a given gene

Monohybrid Cross

A cross btw two organisms that are heterozygous for the character being followed

Hemophilia

A human genetic disease caused by a sex-linked recessive allele; resulting in the absence of 1 or more blood clotting proteins; characterized by excessive bleeding following injury

Sex-Linked Gene

A gene located on either sex chromosome. Most are on the X chromosome and show distinctive patterns of inheritance, there are very few on the Y chromosome

X-Linked Gene

A gene located on the X-chromosome; such genes show a distinctive pattern of inheritance

Down Syndrome

A human genetic disease usually characterized by the presence of an extra chromosome 21; characterized by developmental delays and heart or other defects that are generally treatable or non-life threatening

What is a gamete (not for mitosis and meiosis, but for understanding genetics problems)?

Sexually reproducing organisms

What is an allele?  Give an example.

Any of the alternative versions of a gene

Ex: Aa

Define and give an example of the gametes for the terms homozygous and heterozygous

Homozygous- Both alleles are the same; Ex:BB

Heterozygous- Alleles are different; Ex:Bb

Give the different ways that a test cross can be created. Who discovered this?

1)Crosses btw true breeding homozygous individuals; AA xx aa

2) Crosses between identical heterozygotes; Aa x Aa

Gregor Mendel discovered this

What does true-breeding mean?  Is this the same?

True breeding refers to organisms that produce offspring of the same variety over many generations

True breeding is not the same as test crosses because test crosses involve breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype

Who is the Father of Genetics? 

Gregor Mendel

Why were peas the subject of studying genetics?  What are some traits that people can study in peas?  How was pollination of these plants achieved?

Peas were easy to grow and had a relatively short life cycle with allowed him to conduct experiments over a short time

Peas had distinct traits that could be easily observed (shape of seed, color of seed, color of flower, length of stem, shape of pod, color of pod)

The peas were self-pollinating which means they could be crossed without human intervention. This allowed Mendel to control the breeding and isolate effects of a gene.

Describe Mendel and his life’s work.

He was known as the father of genetics and conducted experiments with pea plants to discover dominant and recessive genes. His work paved the way for future scientists to dive deeper into genetics and heredity.

What did Mendel learn about the predictability of a test cross for the phenotypic ratio?

He observed a 3;1 phenotypic ratio in the offspring of his monohybrid cross

What did Mendel learn about the predictability of a test cross for the phenotypic ratio?

He observed a 9:3:3:1 phenotypic ratio in the offspring of his dihybrid cross

List some disorders that are passed on due to dominance traits.

Huntington’s disease (nervous system), Achondroplasia (small body size)

List some disorders that are passed on due to recessive traits.

Albinism (no melanin), cystic fibrosis (excessive mucus), Tay-Sach’s disease (brain), galactosemia (can’t break down galactose

Explain why recessive traits are harder to see in organisms.

They are harder to see in order for it to be expressed an organism must inherit two copies of a recessive gene

What are some examples of complex inheritance or Non-Mendelian genetics?

Incomplete dominance- a pink flower is produced from red and white flowers

Co -Dominance- sickle-cell anemia

Sex-Linked traits- baldness

Multiple Alleles- blood typing

What does the term heredity mean in terms of genetics?

The passing of traits from parents to their offspring

What does the term ancestry mean in terms of genetics?

Information about the people that an individual is biologically descended from

How many chromosomes does a human have?

46

What is used to study chromosomes, where they are arranged from largest in size and shape to the smallest shape?

Karyotype

Where on a karyotype are the sex chromosomes identified?

23rd pair

True or false:  Punnett squares tell the outcome of a genetic cross? Why or why not?

False; they are used to predict the probabilities of diffrent genotypes and phenotypes

Name examples of sex-linked traits that are dominant:

Male pattern baldness

Name examples of sex-linked traits that are recessive:

Red/green color blindness, hemophilia

What do mutations have a higher chance of doing to genes?

Changes in appearance, behavior, physiology, and health

Why are pedigrees used to study genetics?  Is there only one way to use the information provided in a pedigree?

They are used to determine genotypes and phenotypes, predict how traits will be passed on in the future, trace inheritance patterns backwards

No; you can use the information provided in a pedigree for various things

What symbols are used to make a pedigree universal?

circle= female

square=male

normal/unaffected=white

affected=colored

carrier= half colored

What are telomeres?  How does this influence our chromosomes?

Telomeres are caps that consist of DNA associated with proteins, they serve as a protective function for the structure of chromosomes, protection helps aging

What are some examples of real uses in selective breeding?  Genetic engineering?

Selective breeding- production of milk in cattle

Genetic engineering- jellyfish glow to bacteria

List some pros and cons to selective breeding:

Pros- improved quality, disease resistance, desired traits

Cons- reduced genetic diversity, ethical concerns

List some pros and cons to genetic engineering:

Pros- medical advancements, enhanced productivity

Cons- ethical concerns, biodiversity risk

With plants and animals, explain what a hybrid is.  List an example.

Offspring of two organisms belonging to different species, Ex: mule (horse +donkey)

Explain why it is unfair to say that science goes against the Catholic faith.

Science and religion work together,

Ex: Creation/Genesis tells us why, science tells us how.

Speak about one disorder caused by the disruption of one’s genes.  Describe the effect on the person.  Can it be treated?  If so, how?  If not, what do you know about the treatment of the disorder?  How is this passed on genetically?

Progeria: dramatic, premature aging, slowed growth, loss of fat tissue, appear healthy at birth cannot be cured but physical and occupational therapy can help stiff joints, it is not passed on genetically, but it is a mutation in the LMNA gene

What are the ways (from mitosis and meiosis chapter) that we can stay away from causing changes in our genes?

Wear sunscreen, limit exposure to x-ray radiation, don’t smoke or use tobacco

Nondisjunction

Cell division during which sister chromatids fail to separate properly, down syndrome (21st set)

Incest

Marrying someone within your own ancestry

Klinefelter’s Syndrome

Nondisjunction, male is born with extra X chromosome, XXY

Turner’s Syndrome

Nondisjunction, female is born with only one X chromosome, XO

Eukarya

The domain that includes all eukaryotic organisms

Biosphere

The entire portion of Earth inhabited by life; the sum of all the planet’s ecosystems

Bacteria

One of two prokaryotic domains, the other being Archaea

Climate Change

A directional change in temperature, precipitation, or other aspect of the global climate that lasts for three decades or more

Geonomics

The study of whole sets of genes and their interactions within a species, as well as genome comparisons between species

Independent variable

A factor whose value is manipulated or changed during an experiment to reveal possible effects on another factor (dependent variable)

Gene

A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses)

Population

A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring

Controlled Experiment

An experiment designed to compare an experimental group with a control group; ideally the two groups differ only in the factor being tested

Hypothesis

A testable explanation for a set of observations based on available data and guided by inductive reasoning. A hypothesis is narrower in scope than a theory

Archaea

One of the prokaryotic domains, the other being bacteria

Technology

The application of scientific knowledge for a specific purpose, often involving industry or commerce but also including uses in basic research

Molecule

Two or more atoms held together by covalent bonds

Organ

A specialized center of body function composed of several different types of tissues

Proteomics

The systematic study of the full protein sets (proteomes) encoded by genomes

Prokaryotic Cell

A type of cell lacking a membrane-enclosed nucleus and membrane enclosed organelles. Organisms with prokaryotic cells (bacteria and archaea) are called prokaryotes

Systems Biology

An approach to studying biology that aims to model the dynamic behavior of whole biological systems based on a study of the interactions among the system’s parts

Evolution

Descent with modification; the process by which species accumulate differences from their ancestors as they adapt to different environments over time; also defined as a change in genetic composition of a population from generation to generation

Eukaryotic Cells

A type of cell with a membrane-enclosed nucleus and membrane enclosed organelles. Organisms with eukaryotic cells (protists, plants, fungi, and animals) are called eukaryotes

Inductive Reasoning

A type of logic in which generalizations are based on a large number of specifc observations

Ecosystem

All the organisms in a given area as well as the abiotic factors in which they interact; one or more communities and the physical environment around them

Science

An approach to understanding the natural world

Theory

An explanation that is broader in scope than a hypothesis, generates new hypotheses, and is supported by a large body of evidence