Introduction

What is Variation?

In general, variation can be defined as the act of varying, process of varying or the result

of varying. However, in biology, variation means a difference or deviation from the normal or

recognized form, function, or structure. Human genetic variation is the genetic diversity of

humans observed within the human species. At the DNA level, humans are both very similar to

and very different from one another. On average, pairs of individual humans share 99.9 percent

DNA sequence identity. However, no two humans are genetically identical.

What Cause Variation in Humans?

There are numerous reasons why genetic variation exists between populations. Causes

of variation between individuals include the exchange of genes during meiosis. During meiosis,

recombination between chromosomes (crossing-over) produce chromosomes with their own

unique sequences that have many new genetic variants of a character. Thus, the offspring will

possess similar and different genetic characteristics from the parents in result of the

combination of genes.

Mutation also cause variation in humans. Mutation is any change occurring in the

message that a gene carries because there are copy errors when DNA is replicated at mitosis

and meiosis. It may be caused by radiation, viruses and mutagenic chemicals that are also

known as carcinogens. Mutation can result in several different types of change in DNA

sequences that either have no effect, alter the product of a gene, or prevent the gene from

functioning properly or completely.

Another cause of genetic variation within a population is gene flow caused by migration.

When individuals arrive from distant parts, they will often have different genotypes from the

local population, thus they provide new genetic variation. An individual organism that migrates

brings its alleles into the new population and some of these alleles may be different from the

alleles that are currently in the population. When new alleles are brought into a population

through gene flow, the genetic variation within the population has increased.

Significance of Variation

Variation in the human population are very significant for many reasons. Genetic

diversity and biodiversity are dependent upon each other, in other words, diversity within a

species is necessary to maintain diversity among different species, and vice versa. If any one

type is compromised, the community may be dominated by a single species. Therefore,

variation is needed to maintain a balance amongst species. Other than that, variation plays a

very important role in survival and adaptability of a species. This is because, when a species’

environment changes, slight gene variations are necessary to produce changes in the

organisms' that enable it to adapt and survive. With the absence of variation within a species,

healthy reproduction becomes difficult and the offspring will not develop adaptations in terms

of immunity and other aspects.

Types of Variation

Variation occurs when individuals within a population differ in their

characteristics.There are two forms of variation, that is continuous and discontinuous variation.

Characteristics showing continuous variation vary in a general way, with a complete

range of values between the extremes. Examples of continuous variation include height,

weight, hand span and shoe size. These type of traits are usually measured with some sort of

numerical unit (e.g. centimeters for height or kilograms for weight). If a sample of data from a

population is taken and a frequency polygon or histogram is plotted, the data will show a typical

bell-shaped normal distribution curve, with the mean, mode and median all being the same and

extreme values are rare.

Figure 1.0 Example of a Frequency Polygon for Continuous Variation

Proportion of Population

Continuously Varying Trait

Trait value (e.g. Height)

Variation in terms of

height in a population

Variation in terms of

height in a population

On the other hand, discontinuous variation are traits that fall into a few very distinct

classes or categories. These traits are not measurable by numerical values and is based on

features that cannot be calculated across a complete range. The person either have the

characteristic or they don’t. For example, the ability to roll the tongue, blood groups, type of

hair (straight or curly) and eye colour. Such data is called discrete or categorical data.

Figure 2.0 Example of a Histogram for Discontinuous Variation

Discontinuously Varying Trait

Proportion of Population

Trait value (e.g. Eye Colour)

Variation in terms of

eye colour.

Variation in terms of

type of hair.

Progress Report

DATE ACTIVITY ATTENDANCE

02.06.2010 Briefing about the project by Puan Rozi Samdin. 25 students

02.06.2010 Collecting raw data for the investigation 25 students

09.06.2010 Writing the reports for each investigation conducted -

05.06.2010 1. Surfing the net:

a) http://en.wikipedia.org/wiki/Human_genetic_variation

b) http://en.mimi.hu/biology/variation.html

c) http://www.biotopics.co.uk/genes/varn.html

-

19.06.2010 Compilation of data among team members. -

20.06.2010 Printing of project report. -

Project Results

Report for Investigating Variation of Weight among Students of 5 Alamanda

Aim:

To investigate the variation of weight among students in 5 Alamanda.

Problem statement:

Is the variation of weight among students in 5 Alamanda continuous?

Hypothesis:

The variation of weight among students in 5 Alamanda is continuous.

Material and apparatus:

Weighing machine, genetic variation survey sheet

Technique:

Measuring the weight of each student by using the weighing machine.

Procedure:

1. The weights of each student in 5 Alamanda are recorded in the genetic variation survey.

2. A histogram is constructed for each measured or noted characteristic.

3. The mean, median and mode of the set of data was determined.

Results:

Body Mass (kg) 30-39 40-49 50-59 60-69 70-79

Number of Students 2 13 9 0 1

Number of Students against Body Mass (kg)

2

13

9

0 10

2

4

6

8

10

12

14

30-39 40-49 50-59 60-69 70-79

Body Mass (kg)

Nu

mb

er o

f S

tud

ents

Number of Students

Analysis:

1. Characteristic such as weight shows continuous variation. There is a normal distribution

about a mean and single mode.

2. The lowest measurement of weight amongst the students is 38.5kg and the highest

measurement of weight is 71.0kg.

3. The mode of body mass = 40-49kg.

4. The mean for the set of data is = 48.5kg.

5. The median of the set of data = the class 40-48kg.

Conclusion:

Variation of weight among students in 5 Alamanda is continuous. The hypothesis is accepted.

Report for Investigating Variation of Height among Students of 5 Alamanda

Aim of Experiment:

To investigate the variation in height among students in 5 Alamanda.

Problem statement:

Is the variation of height among students in 5 Alamanda continuous?

Hypothesis:

The variation of height among students in 5 Alamanda is continuous.

Material and apparatus:

Height scale, genetic variation survey sheet

Technique:

Measuring the height of each student by using the height scale.

Procedure:

1. The heights of each student in 5 Alamanda are recorded in the genetic variation

survey.

2. A histogram is constructed for each measured characteristic of student.

Results:

Table Height (cm) Frequency

146-150 4151-155 6156-160 6161-165 7166-170 6171-175 2

Analysis:

6. Characteristic such as height shows continuous variation. There is a normal distribution

about a mean and single mode.

7. The lowest measurement of weight amongst the students is 38.5kg and the highest

measurement of weight is 172.0cm

8. The mode of height = 161-165cm.

9. The mean for the set of data is = 160.1cm

10. The median of the set of data = the class 156-160cm.

Conclusion:

Variation of height among students in 5 Alamanda is continuous. The hypothesis is accepted.

 

Report for Investigating Variation in the Aspect of the Ability of Rolling the

Tongue, Type of Hair and Presence of Dimples among Students of 5 Alamanda

Aim of Experiment:

To investigating variation in the aspect of the ability of rolling the tongue, type of hair and

presence of dimples among students of 5 Alamanda.

Problem Statement:

1. Are tongue rollers more common than non-tongue rollers?

2. Are there more students that have straight hair compared to curly hair?

3. Are there more dimpled-cheek students than those without dimples?

Hypothesis:

1. Most students of 5 Alamanda can roll their tongue.

2. Most students of 5 Alamanda have straight hair.

3. Most students of 5 Alamanda have dimples.

Materials and Apparatus:

Tally sheet to record data

Technique:

Observe and record the amount students that are able to roll their tongue, type of hair and the

presence of dimples.

Procedure:

1. By using a tally sheet, the ability to roll their tongue, type of hair and the presence of

dimples among the students was observed.

2. The data was recorded in a table.

3. The data was interpreted into a diagram and analysed.

Results:

The Ability to Roll the Tongue

TraitRolling of Tongue

Rolled Unrolled

Number of Students 19 6

Type of Hair

TraitType of Hair

Straight Curly

Number of Students 22 3

Presence of Dimples

TraitPresence of Dimples

Present Absent

Number of Students 21 4

Analysis:

a) The Ability to Roll the Tongue

More students are able to roll their tongue compared to students that cannont roll their

tongue. Traits that can roll their tongue are dominant traits while traits that cannot roll their

tongue are recessive traits

b) Type of Hair

The number of students that have straight hair is greater than the number of students that

have curly hair.

c) Presence of Dimples

The number of students that have dimpled-cheeks are greater than the number of students

that have no dimples.

Conclusion:

1. Most students of 5 Alamanda can roll their tongue.

2. Most students of 5 Alamanda have straight hair.

3. Most students of 5 Alamanda have dimples.

The three traits are all discontinuous variation. All the hypothesis are accepted.