Family tree - definition, function and examples | biology dictionary (2023)

Definition of family tree

A family tree is a chart that describes the biological relationships between an organism and its ancestors. It comes from the French "pied de grue" ("crane's foot") because the branches and lines of a family tree resemble a slender crane's foot with its forked toes. A pedigree is used for various animals, such as humans, dogs, and horses. It is often used to study the transmission of genetic diseases.

function of family trees

The purpose of a family tree is to have an easy-to-read chart that describes a specific trait or disorder in an individual. It can be used for a trait like widow's peak or sticky earlobes, or a genetic disorder like color blindness or Huntington's disease. Pedigrees are not only used to represent family traits in humans, but are also important in animals that are selectively bred for certain traits. They visually represent an animal's ancestors and make it easier to understand if that animal is passing certain traits on to its descendants.

Family trees use a standard set of symbols to make them easier to understand. Males are represented by squares while females are represented by circles. Parents are connected by horizontal lines, and vertical lines derived from horizontal lines lead to the symbols of their descendants. The generations are also clearly marked with numbers, with I being the first generation, II the children of the first generation, and III the grandchildren, for example.

Dominant and recessive genes

To understand pedigrees, one must understand dominant and recessive genes. Some characteristics, such as B. height, are influenced by a variety of genes and an individual's environment. Greatness cannot simply be represented by a pedigree. Pedigrees are typically used to represent single dominant and recessive traits. For example, having a widow's peak hairline is dominant. If a person has this trait, their icon will be shaded in the family tree. If she does not have Widow's Peak, her icon is not shaded, as a lack of Widow's Peak is recessive.

Certain traits, such as color blindness, are found on the X or Y chromosome and are called sex-linked. Color blindness is more common in males because males only have one X chromosome. Females are generally not color blind because they have two X chromosomes and would have to inherit a defective X from both their mother and father. However, they can be carriers of the trait, and if they are, their sons will be colorblind. In a family tree, bearers are represented by a half shaded icon or a shaded dot in the center of the icon.

Understanding genes and alleles

Why can two people with a dominant trait sometimes have a child with the recessive trait? This can happen because people have two copies of each gene, one from their mother and one from their father. Different forms of a gene, such as Widow Peak or No Widow Peak, are called alleles. In genetics, the dominant allele is represented by a capital letter like W, while the recessive allele is represented by a lowercase letter like w. There are three different genotypes (inherited dispositions):

  • WW = dominant
  • Ww = dominant
  • ww = recessive

People with WW and Ww have a widow's peak, while people with ww do not have a widow's peak. But if two people with the ww genotype reproduce, they can both pass their ww allele to their offspring, which will then be ww and display the recessive trait.

WW and ww individuals are said to be homozygous because they have two copies of the same allele and always pass that form of the allele to their offspring, while Ww individuals are said to be heterozygous because they have two different alleles and each allele to their offspring. can happen In family trees, heterozygous individuals are represented by half-shaded symbols (as are carriers of sex-linked traits in family trees).

This diagram, called a Punnett square, shows the possible offspring of this heterozygous pea, with purple dominant (represented by B) and white recessive (represented by b).

Family Tree Examples

autosomal dominant

This pedigree shows an autosomal dominant trait or disorder. Autosomal means that the gene is on a chromosome that is not a sex chromosome (X or Y). Not all offspring inherited the trait because their parents were heterozygous, passing two recessive genes to those without the trait. None of the offspring of two recessive individuals have the trait. Examples of autosomal dominant diseases are Huntington's disease and Marfan syndrome.

autosomal recessive

This pedigree exhibits an autosomal recessive trait or disorder. The red square represents a male who is homozygous recessive and has the trait. All semi-shadow individuals are vectors; They do not display the trait because it is recessive, but they can pass it on to their offspring if the partner is also heterozygous. Autosomal recessive diseases include cystic fibrosis and Tay-Sachs disease.

gender connected

This pedigree represents a sex-linked disorder on the X chromosome. Some sex-linked disorders are dominant and others recessive; The above pedigree is derived from a gender-linked recessive disorder. In this pedigree, only the males have the disorder, but some of the females are heterozygous carriers who can pass on the trait even though they do not display it themselves. Color blindness, hemophilia, and Duchenne muscular dystrophy are gender-linked disorders.

  • alleles- a form of a gene. For example, in pea plants, B represents the dominant trait (purple color) and b represents the recessive trait (white color).
  • homocigoto- an individual that has two identical alleles for a gene, for example BB for a purple pea plant or bb for a white pea plant.
  • heterocigoto- an individual with two different alleles, e.g. B. a pea plant that is Bb.
  • autosomal– in relation to a chromosome that is not a sex chromosome.


1. What genotype represents a heterozygous individual?
D.A y C

Answer to question #1

Bit is right. The individual is heterozygous because it has two different alleles, A and a, for a trait. individuals AA and aa are homozygous; They have two of the same alleles.

2. An individual with a dominant trait can have one of which two genotypes for that trait?
A.and and and
B.You are brave
C.AA of AA

Answer to question #2

Cit is right. Individuals who are AA or Aa have the dominant trait because they have at least one dominant allele, A. Individuals who have the aa genotype have two copies of the recessive allele, a, and have the recessive trait.

3. What does a fully shaded symbol on a family tree mean for an autosomal recessive trait?
A.A person who exhibits the trait
B.A person who does not have the trait
C.Person who does not have the trait but is a carrier unrelated person

Answer to question #3

Ait is right. In a pedigree with an autosomal recessive trait, individuals with a fully shaded symbol are homozygous recessive (aa) and have the recessive trait. Individuals that are heterozygous (Aa) are represented by a half shaded symbol and individuals that are homozygous dominant (AA) are represented by an unshaded symbol.


What is the family tree answer? ›

A family tree is a visual representation of a person's lineage, tracing relationships to common ancestors. Visually similar to an org chart, this diagram is usually presented in a tree structure starting with one individual as the root. From the root, lines representing branches terminate in boxes representing leaves.

What is the definition of family in the dictionary? ›

Family: A family is a group of two or more persons related by birth, marriage, or adoption who live together; all such related persons are considered as members of one family.

What is a family tree explained for kids? ›

In other words, a Family Tree is a chart or drawing that shows how every member of a family is related to each other. Here is what a family tree might look like. All you have to do is fill in the names. The bigger your family, the more branches on the tree!

How do you start a family tree essay? ›

Introduction (Outline): Write a short brief about your family background and why your family is important. Body: Write about your family members, how you live together and who your neighbors. Conclusion: Rehashing your conflict, Sum up your key thoughts, and Give a last remark or reflection about the paper.

What is the structure of a family tree? ›

Based on its name, a family tree is structured like a tree, with the individual as the 'root' and their parents, grandparents, and ancestors making up the 'leaves' one level at a time. In a family tree diagram, lines are used to connect family members and portray their relationships.

What is a family answer question answer? ›

Family is defined as a group of people consisting children, parents, aunts, uncles, cousins and grandparents.

Why is it called a family tree? ›

In the later medieval period, the nobility adopted the tree as a symbol of lineage, and by the eighteenth century, family pedigrees were commonly referred to as “family trees,” although the foliage had disappeared and the “roots” appeared at the top rather than the base of the diagrams.

What is the function of family? ›

The family performs several essential functions for society. It socializes children, it provides emotional and practical support for its members, it helps regulate sexual activity and sexual reproduction, and it provides its members with a social identity.

What is an example of family? ›

We have stepfamilies; single-parent families; families headed by two unmarried partners, either of the opposite sex or the same sex; households that include one or more family members from a generation; adoptive families; foster families; and families where children are raised by their grandparents or other relatives.

What is a word family example? ›

A word family is a group of letters that are combined to make a specific sound. For example, -ack, -am-, and -at are all word families. The purpose of understanding a word family is the notion that if you can identify one word, you should be able to identify many others with the common word family.

What is most important about a family tree? ›

Knowing that your children, grandchildren, nieces, nephews and so on will understand who their ancestors were, where they came from, what they did and how they lived is a great comfort. It's possible to include all sorts of information in one's family history including recipes, songs and personal anecdotes.

Why is family tree important? ›

Family history gives you true identity and learning it is advantageous and beneficial in many ways. For many people, researching their family history gives them strength as they get to know how their ancestors overcame challenges during difficult times.

What are the two types of family tree? ›

There are two different types of family structures, including (a) nuclear family and (b) extended family, which were considered in our simulation study.

What are examples of family history? ›

But a family history can take many forms, including the following: A record of your family with you as a child, containing recollections of your parents and other living ancestors. A record of your family with you as a parent, containing recollections of your children and your other descendants.

How do you make a good family tree? ›

10 Steps to Start Building Your Family Tree
  1. Gather what you already know about your family. ...
  2. Talk to your relatives. ...
  3. Put it on paper. ...
  4. Focus your search. ...
  5. Search the Internet. ...
  6. Explore specific websites. ...
  7. Discover your local Family History Center. ...
  8. Organize your new information.

How can I write about my family? ›

10 Lines on My Family – Essay for Class 1
  1. I have a wonderful family. ...
  2. I live with my grandparents and parents. ...
  3. My father is an engineer. ...
  4. My grandfather is a doctor and my grandmother is a housewife.
  5. My uncle and aunt are lawyers. ...
  6. We love each other.
  7. We go for picnics on holidays.
  8. We eat dinner together every evening.

What is the structure and function of a tree? ›

Trunk – generally a single “stem,” but can be multiple-stemmed. Main functions are materials transport and support. Bark – main function is to protect the living tissue called cambium from damage. Roots – two main functions: (1) collect nutrients and water and (2) anchor the tree.

What are the main tree families? ›

The major tree genera are listed below by taxonomic family.
  • 1 Flowering plants (Magnoliophyta; angiosperms) ...
  • 2 Conifers (Pinophyta; softwood trees)
  • 3 Ginkgos (Ginkgophyta)
  • 4 Cycads (Cycadophyta)
  • 5 Ferns (Pteridophyta)

What are the 4 basic family structures? ›

12.1C: Family Structures
  • Nuclear Family.
  • Single Parent.
  • Step Families.
  • Extended Family.
Feb 19, 2021

Why is a family important answer? ›

Family is important because it provides love, support and a framework of values to each of its members. ... From their first moments of life, children depend on parents and family to protect them and provide for their needs. Parents and family form a child's first relationships.

Who are there in a family answer? ›

A family is a basic social unit consisting of parents and their children. Members living in a family are father, mother, brother, and sisters.

What are family tree characteristics? ›

A family tree can include names, birth dates, marriage dates and pictures. Family trees can be simple and just include your close family members, or they can go back many generations to enable you to see where you came from, who your ancestors were and how you are related to them.

How does a family tree start? ›

Begin by writing down the date and place of your birth (and marriage if applicable) for yourself, spouse and children, and the crucial dates for your parents, including birth, marriage and death. This is the start of your family tree and you can now work back generation-by-generation.

Does everyone have a family tree? ›

In reality, everyone has two family trees. The first is a Genealogical Tree, which is every ancestor in history that had a child who had a child who had a child that ultimately led to you. Every decision made by every person in that tree contributed to who and what you are today.

What are the 4 functions of a family? ›

After emphasizing the universal character of the family, the anthropologist George Murdock (1949) argued that the family has four basic social functions: sexual regulations, reproduction, economic cooperation and socialization/education.

What are the 5 function families? ›

Key Concepts
FamilyParent Function
Absolute Valuef(x)=|x|
Square Rootf(x)=√x
1 more row
Aug 24, 2022

What are 4 examples of a family relationship? ›

Family relationship means any relationship by blood, marriage or adoption, not more remote than first cousin. The term “immediate family” includes the spouse; parents; children; siblings; mothers and fathers-in-law; sons and daughters-in-law; and brothers and sisters-in-law of the person specified.

What is family in simple sentence? ›

A family is a group of people who are related to each other, especially parents and their children. There's room in there for a family of five. [

What are the 37 word family list? ›

There are many combinations of word families, these are 37 of the most common: Ack, ake, all, ale, an, ame, ain, ank, ap, ash, at, ate, aw, ay, eat, ell, est, ice, ick, ight, ill, ide, ill, in, ine, ing, ip, ink, it, ock, op, oke, ore, ot, uck, ug, unk, and ump.

What is the value of family tree? ›

A family tree can be a source of great pride, joy, and can bring an irreplaceable sense of belonging for a lot of people. Family trees keep family traditions alive, tell the stories of past relatives, and are incredibly valuable stores of knowledge.

What is the family tree of life? ›

Wherever they're found, all living things are related because they all share a common ancestor. To show how species are related, scientists create diagrams called cladograms . Like a family tree, a cladogram shows close and distant relatives. Scientists call the family tree for all species on Earth the "Tree of Life."

Why is family most important in life? ›

These bonds are important because family helps us get through the most disastrous times and the best times. Family is important because they can offer support and security coupled with unconditional love; they will always look to see and bring out the best in you even if you cannot see it for yourself.

Why tree is important in our life? ›

Trees are vital. As the biggest plants on the planet, they give us oxygen, store carbon, stabilise the soil and give life to the world's wildlife. They also provide us with the materials for tools and shelter.

Who belongs in a family tree? ›

The term family tree is defined as “a diagram showing the relationships between people in several generations of a family.” Add your parents, grandparents and great grandparents and you're well on your way to building your own tree.

Do you include aunts and uncles in family tree? ›

You can build your branches by adding more relationships (aunts/uncles, cousins, grandparents, etc.), but you must first add the immediate family member who is associated with the distant family member.

How do I know my family tree? ›

Historical and government records can help you trace your heritage. Use these free resources to research and build your family tree. The National Archives and Records Administration has a collection of resources for genealogists.
Research Ancestors (Genealogy)
  1. State censuses.
  2. Native American records.
  3. Pioneer certificates.
Mar 21, 2022


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