Acknowledgement:

I would like to express my heartfelt gratitude to my respected teacher Monalisa

Dutta for her constant support, encouragement and guidance throughout this
project. I am also thankful to our honorable Principal Mam, Dr. Shobha Thakur for
providing me the opportunity to undertake this meaningful project titled “Study of
Inherited Traits in a Class”.

This project has helped me to gain valuable insights and knowledge through
extensive research. I would also like to sincerely thank my parents and friends for
their cooperation and support, which helped me complete this project within the
given timeframe.

Certificate:
This is to certify that Aritra Paul of Class XII has successfully completed the
project titled "Study of Inherited Traits in a Class" under my guidance and
supervision.

I am satisfied with their initiative, research, and sincere efforts in the

completion of this project, which is submitted as part of the CBSE Class XII
curriculum for the academic session 2025-26.

Date: ____________

Place: [DURGAPUR]

Signature of Internal Examiner__________________

Signature of External Examiner_________________

Index:
TOPIC PAGE NO
1) Study of inherited traits in

in a class

2) Introduction

3) Theoretical Background

4) Objectives

5) Materials Required

6) Methodology

7) Data Collection

8) Graphical representation

9) Observational analysis

10) Conclusion

11) Bibliography
 Introduction:
Genetics is a fascinating field of biology that deals with the study of heredity and
variation. Heredity is the process by which traits or characteristics are passed from
parents to their offspring through genes. These genes are made of DNA and are
located on chromosomes. Understanding how traits are inherited helps us grasp
why individuals of the same species can look and behave differently.

The foundation of modern genetics was laid by Gregor Mendel, often called the
Father of Genetics. Through his experiments on pea plants, Mendel proposed three
fundamental laws of inheritance:

1) Law of Dominance

2) Law of Segregation

3) Law of Independent Assortment

These principles explain Mendelian inheritance, which describes how traits are
inherited in predictable ratios through dominant and recessive alleles. For example,
traits like tongue rolling or earlobe attachment typically follow Mendelian
patterns.

However, not all traits follow these classical rules. Some traits are influenced by
multiple genes or involve interactions between alleles in more complex ways. This
is known as non-Mendelian inheritance. Examples
include incomplete dominance, codominance,
polygenic traits, and multiple alleles. While most
simple human traits studied in classrooms follow
Mendelian patterns, real-world genetics is often more
complex.

This project involves observing a number of common

inherited traits among students in a class and
analyzing how frequently these traits appear. By doing
so, we aim to understand both the basic principles of
inheritance and appreciate the variation that exists
within a population.
Theoretical Background:

Genetics is the branch of biology that deals with the study of heredity and
variation. Heredity refers to the passing of traits from parents to offspring, while
variation refers to the differences among individuals. The basic unit of heredity is
the gene, which is a segment of DNA located on chromosomes.

The science of genetics was founded by Gregor Johann Mendel, who proposed
the fundamental laws of inheritance through his experiments on pea plants. These
laws — Law of Segregation, Law of Independent Assortment, and Law of
Dominance — form the basis of classical genetics.

Inherited traits are characteristics or features that are passed from one generation
to the next through genes. These traits can be dominant (expressed in the presence
of one allele) or recessive (expressed only in the presence of two identical alleles).
Examples of inherited traits in humans include earlobe attachment (free or
attached), tongue rolling, hitchhiker's thumb, dimples, and mid-digital hair.

In the context of this project, studying the distribution of such traits in a classroom
helps us observe patterns of inheritance in a real-life population. It also helps us
understand how dominant and recessive traits are expressed and passed on, even in
small sample groups.

This investigation gives us a hands-on approach to learn about Mendelian genetics

and human variations, connecting textbook theory to real-world observation.

Fig: DNA structure

 Objectives:

 To identify and observe common inherited traits (such as tongue rolling,

earlobe attachment, dimples, etc.) among students in a classroom.

 To study the frequency of dominant and recessive traits within a small

population.

 To understand Mendelian principles of inheritance through real-life data

collection and analysis.

 To differentiate between Mendelian and Non-Mendelian inheritance based

on the traits observed.

 To encourage awareness and interest in genetics by linking theoretical

concepts to observable human characteristics.

 To analyze variations and understand how genetic diversity exists even in a

small group.
 Materials Required:

For conducting this project, I did not require any laboratory equipment, as it was
based on observation and data collection. The materials I used are as follows:

1. A notebook and pen to record the observations and maintain proper data.

2. A survey sheet or questionnaire listing common inherited traits such as

tongue rolling, earlobe attachment, dimples, hitchhiker’s thumb, etc.

3. A group of classmates who volunteered to be part of the study.

4. Consent from the participants before observing or asking about any traits.

5. A calculator for calculating the percentage and frequency of each trait.

6. Graph paper or a computer (Excel) to represent the data in graphical form

for better understanding.

Methodology:
 I prepared a list of common inherited traits such as:

 Tongue rolling (able or unable)

 Earlobe type (free or attached)
 Presence of dimples (present or absent)
 Hitchhiker’s thumb (present or absent)
 Mid-digital hair (present or absent)
 Widow’s peak (present or absent)

 I created a survey sheet to record the presence or absence of each trait.

 I selected a sample group of classmates (around 30–40 students) who agreed to

participate in the study.

 I observed or asked each participant about these traits and recorded their
responses in the table.

 After collecting the data, I analyzed the frequency of each trait and calculated
the percentage of students showing dominant or recessive traits.

 I presented the data using bar graphs to visualize the results.

 No. of Students Showing Trait No. of Students Not Showing
Trait
(Dominant - 1) Trait (Recessive - 0)

Tongue Rolling 19 11

Free Earlobes 21 9

Dimples 14 16

Hitchhiker’s
17 13
Thumb

Mid-digital Hair 18 12

Widow’s Peak 12 18

Data Collection:
Graph representation:

Trait analysis
25

21

20 19
18 18
17
16

15 14
13
No. of traits

12 12
11

10 9

0
Tongue Rolling Free Ear Lobes Dimples Hitchhiker's Mid-Digital Hair Widow's Peak
Thumb

Types of traits

Dominat Trait Recessive Trait

Observations & Analysis:
From this data, the following observations and analyses were made:

1. Dominant Traits Were More Common

Most dominant traits, such as tongue rolling (63%), free earlobes (70%), and
mid-digital hair (60%), were more frequent than their recessive counterparts.
This supports Mendel's Law of Dominance, which states that dominant alleles are
more likely to be expressed when present.

2. Dimples and Widow’s Peak Showed Lower Dominance

Interestingly, traits like dimples (47%) and widow’s peak (40%) were less
common, showing that dominant traits don’t always appear in the majority. This
highlights how gene frequency in a population can influence trait distribution,
not just dominant-recessive relationships.

Fig: Widow’s peak

3. Variation Exists Even in a Small Group

The data shows significant genetic variation even within a single classroom. This is
due to independent assortment, random fertilization, and the unique genetic
makeup of each individual.
4. Hitchhiker’s Thumb

This trait showed a fairly balanced distribution (57% present, 43% absent),
indicating neither trait is rare, and the genes involved may have near-equal
representation in the population.

Fig: Hitchhiker’s thumb

5. Polygenic and Environmental Influence (Non-Mendelian Aspect)

Some traits that seem simple may actually involve more than one gene or may be
influenced by environmental factors. For example, dimples can fade with age, and
hair on knuckles may vary based on hormonal influences.
 Fig: Mid-digital hair

This analysis helps reinforce how Mendelian genetics applies in real-life

situations but also reminds us of the complexity of inheritance beyond simple
dominant-recessive traits.

Conclusion:
Through this investigatory project, I was able to observe and analyze several
inherited traits among my classmates and understand how traits are passed from
one generation to the next. The data collected supported the basic principles of
Mendelian inheritance, such as the dominance and segregation of alleles.

The results showed that dominant traits like tongue rolling and free earlobes were
more common, while some dominant traits like dimples and widow’s peak were
less frequent, highlighting the role of gene frequency and variation within a
population. The study also helped me recognize that not all traits follow simple
Mendelian patterns, and some may involve non-Mendelian inheritance or
polygenic factors.
This project has deepened my understanding of genetics, allowed me to apply
theoretical knowledge to real-life observations, and shown how even a small
sample can reveal important patterns in human heredity.

Bibliography:
NCERT Biology Textbook for Class 12. National Council of Educational Research
and Training, New Delhi.

Website: www.sciencedaily.com – For recent developments and examples on

genetics and inheritance.

Website: www.ck12.org – For diagrams and simplified explanations of dominant

and recessive traits.

Personal Observations and Class Survey – Conducted among classmates for

collecting data on inherited traits.