Meiosis Labeling





On each of the images, label the phase of meiosis

1. _______________

2. _______________

3. _______________

4. _______________

5. _______________

6. _______________

7. _______________



10. _______________


11. A cell with a diploid number of 20 undergoes meiosis. This will produce ________ daughter cells, each with ________ chromosomes.

12. Synapsis occurs during this phase: _______________________

13 How many different possible combinations are there for a cell that has 10 chromosomes (5 pairs): _____________

14. Tetrads line up along the equator during this phase: ______________

15. At the end of meiosis I, ________ daughter cells are created. These daughter cells are [ diploid | haploid ].

16. Meiosis occurs in what type of cells: ____________________________


Now label the photographs.
17. _______________
18. _______________
19. _____________
20. _______________
21. _______________
22. _____________
23. _______________
24. _______________
24. _____________
25. _______________




Mendelian Genetics
All Materials © Cmassengale 



Mendel 1862Mendel 1868Mendel 1880


Genetic Terminology:

  • Trait – any characteristic that can be passed from parent to offspring
  • Heredity – passing of traits from parent to offspring
  • Genetics – study of heredity
  • Alleles – two forms of a gene (dominant & recessive)
  • Dominant – stronger of two genes expressed in the hybrid; represented by a capital letter (R)
  • Recessive – gene that shows up less often in a cross; represented by a lowercase letter (r)
  • Genotype – gene combination for a trait (e.g. RR, Rr, rr)
  • Phenotype – the physical feature resulting from a genotype (e.g. tall, short)
  • Homozygous genotype – gene combination involving 2 dominant or 2 recessive genes (e.g. RR or rr); also called pure 
  • Heterozygous genotype – gene combination of one dominant & one recessive allele    (e.g. Rr); also called hybrid
  • Monohybrid cross – cross involving a single trait
  • Dihybrid cross – cross involving two traits
  • Punnett Square – used to solve genetics problems

Blending Concept of Inheritance:

  • Accepted before Mendel’s experiments
  • Theory stated that offspring would have traits intermediate between those of its parents such as red & white flowers producing pink
  • The appearance of red or white flowers again was consider instability in genetic material
  • Blending theory was of no help to Charles Darwin’s theory of evolution 
  • Blending theory did not account for variation and could not explain species diversity
  • Particulate theory of Inheritance, proposed by Mendel, accounted for variation in a population generation after generation
  • Mendel’s work was unrecognized until 1900

Gregor Mendel:

  • Austrian monk
  • Studied science & math at the University of Vienna
  • Formulated the laws of heredity in the early 1860’s
  • Did a statistical study of  traits in garden peas over an eight year period


drawing of a flower cross-section showing both male and female sexual structures


Why peas, Pisum sativum?

  • Can be grown in a small area
  • Produce lots of offspring
  • Produce pure plants when allowed to self-pollinate several generations
  • Can be artificially cross-pollinate

Picture of Pisum sativum

Mendel’s Experiments:

  • Mendel studied simple traits from 22 varieties of  pea plants (seed color & shape, pod color & shape, etc.)
  • Mendel traced the inheritance of individual traits & kept careful records of numbers of offspring
  • He used his math principles of probability to interpret results
  • Mendel studied pea traits, each of which had a dominant & a recessive form (alleles)
  • The dominant (shows up most often) gene or allele is represented with a capital letter, & the recessive gene with a lower case of that same letter (e.g. B, b)
  • Mendel’s traits included:

         a. Seed shape —  Round (R) or Wrinkled (r)
            b. Seed Color —- Yellow (Y) or  Green (y)
            c. Pod Shape — Smooth (S) or wrinkled (s)
            d. Pod Color —  Green (G) or Yellow (g)
            e. Seed Coat Color —  Gray (G) or White (g)
            f. Flower position — Axial (A) or Terminal (a)
            g. Plant Height — Tall (T) or Short (t)
            h. Flower color — Purple (P) or white (p)

  •  Mendel produced pure strains by allowing the plants to self-pollinate for several generations
  • These strains were called the Parental generation or P1 strain
  • Mendel cross-pollinated two strains and tracked each trait through two
    generations (e.g. TT  x  tt )


                  Trait – plant height

                  Alleles – T tall, t short

    P1 cross    TT  x  tt

    genotype      —    Tt
    ttphenotype    —    Tall
    TTtTtgenotypic ratio –all alike
    TTtTtphenotypic ratio- all alike



  • The offspring of this cross were all hybrids showing only the dominant trait & were called the First Filial or F1 generation
  • Mendel then crossed two of his F1 plants and tracked their traits; known as an F1 cross


              Trait – plant height

              Alleles – T tall, t short

F1 cross    Tt  x  Tt

genotype      —    TT, Tt, tt
Ttphenotype    —    Tall & short
TTTTtgenotypic ratio —1:2:1
tTtttphenotypic ratio- 3:1



  • When 2 hybrids were crossed, 75% (3/4) of the offspring showed the dominant trait & 25% (1/4) showed the recessive trait; always a 3:1 ratio
  • The offspring of this cross were called the F2 generation
  • Mendel then crossed a pure & a hybrid from his F2 generation; known as an F2 or test cross


Trait   –  Plant Height
Alleles – T  tall, t  short

F2 cross       TT  x Tt

F2 cross       tt  x Tt

          genotype – TT, Tt          genotype – tt, Tt
          phenotype  –  Tall          phenotype  –  Tall & short
          genotypic ratio  – 1:1          genotypic ratio  – 1:1
          phenotypic ratio – all alike          phenotypic ratio – 1:1


  • 50% (1/2) of the offspring in a test cross showed the same genotype of one parent & the other 50% showed the genotype of the other parent; always a 1:1 ratio

Problems: Work the P1, F1, and both F2 crosses for all of the other pea plant traits & be sure to include genotypes, phenotypes, genotypic & phenotypic ratios.

  • Mendel also crossed plants that differed in two characteristics (Dihybrid Crosses)
    such as seed shape & seed color
  • In the P1 cross, RRYY  x  rryy, all of the F1 offspring showed only the dominant form for both traits; all hybrids, RrYy


Traits:      Seed Shape & Seed Color

Alleles:     R round                Y yellow
r wrinkled             y green

 P1 Cross:     RRYY          x     r r yy  


ryGenotype:     RrYy
Phenotype:     Round yellow seed
Genotypic ratio:     All alike
Phenotypic ratio:     All Alike


  • When Mendel crossed 2 hybrid plants (F1 cross), he got the following results



Traits:       Seed Shape & Seed Color

Alleles:     R round                Y yellow
r wrinkled             y green

     F1 Cross:     RrYy           x     RrYy                   








r rYY

r rYy


r rYy

r ryy




GenotypesGenotypic RatiosPhenotypesPhenotypic Ratios
RRYY1Round yellow seed
RRyy1Round green seed
r rYY1Wrinkled yellow seed
r rYy2
r ryy1Wrinkled green seed


Problems: Choose two other pea plant traits and work the P1 and F1 dihybrid crosses. Be sure to show the trait, alleles, genotypes, phenotypes, and all ratios. 

Results of Mendel’s Experiments:

  • Inheritable factors or genes are responsible for all heritable characteristics
  • Phenotype is based on Genotype
  • Each trait is based on two genes, one from the mother and the other from the father
  • True-breeding individuals are homozygous ( both alleles) are the same
  • Law of Dominance states that when different alleles for a characteristic are inherited (heterozygous), the trait of only one (the dominant one) will be expressed. The recessive trait’s phenotype only appears in true-breeding (homozygous) individuals


Trait: Pod Color
GGGreen Pod
GgGreen Pod
ggYellow Pod


  • Law of Segregation states that each genetic trait is produced by a pair of alleles which separate (segregate) during reproduction




  • Law of Independent Assortment states that each factor (gene) is distributed (assorted) randomly and independently of one another in the formation of gametes






Other Patterns of Inheritance:

  • Incomplete dominance occurs in the heterozygous or hybrid genotype where the 2 alleles blend to give a different phenotype
  • Flower color in snapdragons shows incomplete dominance whenever a red flower is crossed with a white flower to produce pink flowers

  • In some populations, multiple alleles (3 or more) may determine a trait such as in ABO Blood type
  • Alleles A & B are dominant, while O is recessive




  • Polygenic inheritance occurs whenever many variations in the resulting phenotypes such as in hair, skin, & eye color
  • The expression of a gene is also influenced by environmental factors (example: seasonal change in fur color)


Graph Examples

Examples of Graphs


Line Graph title

A line graph is most useful in displaying data or information that changes continuously over time. The example below shows the changes in the temperature over a week in January. Notice that the title of the graph is “Average Daily Temperature for January 1-7 in degrees Fahrenheit”.

To the left is a table that shows the date in one column and the corresponding temperature in the second column. The line graph on the right shows the degrees of temperature going up the vertical axis (up and down numbers on the left of the graph) and the days of the week on the horizontal axis (going sideways from left to right). The points for the temperature for each day are connected by a line – thus the graph is a line graph.

Average Daily Temperature for January 1-7 in Degrees Fahrenheit

Line Graoh of Average Temperatures


Bar Graph Animated title


Bar graphs are an excellent way to show results that are one time, that aren’t continuous – especially samplings such as surveys, inventories, etc. Below is a typical survey asking students about their favorite after school activity. Notice that in this graph each column is labeled – it is also possible to label the category to the left of the bar. In this case, the numbers for each category are across the bottom of the chart.

A bar chart is marked off with a series of lines called grid lines. These lines typically mark off a numerical point in the series of numbers on the axis or line. In this case, each grid line going up and down marks a multiple of 20 as the graph is divided.  More gridlines can make it easier to be exact with the amounts being shown on the bar graph, but too many can make it confusing.  Notice that for data that does not fall evenly on a multiple of 20, the bar is in between two grid lines.  Bar graphs are useful to get an overall idea of trends in responses – which categories get many versus few responses.

Favorite Student After School Activity

Visit W/Friends175
Talk on Phone168
Play Sports120
Earn Money120
Use Computers65
Bar Graph

Circle Pie Graph Title


Circle or pie graphs are particularly good illustrations when considering how many parts of a whole are inception. In the table below both the number of hours in a whole day devoted to certain activities is listed as well as the percent of time for each of these activities. The pie chart is then divided very much as a baker’s pie would be into slices that represent the proportional amounts of time spent on each activity.

To the right of the pie chart is a legend that tells which color stands for which category. In addition, the percents are also near the pie slice that stands for that particular amount of time spent.

Percent of Hours of a Day Spent on Activities




Pie Graph of Day's Activities


Loss of Biodiversity Activity


Loss of Biodiversity


Students will make a PowerPoint presentation on the topic of loss of biodiverisity in one of the following areas:

  • Fauna of Arkansas
  • North American Vertebrates
  • North American Invertebrates
  • North American Plants
  • Flora of Arkansas
  • Aquatic Habitats of Arkansas
  • Florida Everglades
  • Alaskan Tundra
  • United States Deserts
  • Along the Mississippi River
  • North American Waterfowl
  • North American Raptors
  • North American Reptiles
  • North American Amphibians
  • North American Mammals

The PowerPoint presentation will be presented to the class and must include 25 slides, 15 of which must include graphics such as images from your web search (save on disk as .jpeg), pictures from books or magazines that you have scanned and inserted into your program, or photographs taken with a digital camera. You should also include three of the following as part of your slide presentation:

  1. Maps
  2. Graphs
  3. Lists
  4. Photograph of a person you interviewed

Your PowerPoint presentation must be accompanied by a written script that corresponds to the numbered order of your slides. The following must be included in your PowerPoint presentation and script:

  1. Name/Description of your chosen area (include a picture if available)
  2. Explanation of the physical environment of the area — climate, water, temperature, etc.
  3. Examples of threatened organisms ( include pictures)
  4. Reasons for organisms endangerment
  5. How the loss of these organisms is affecting other organisms &/or the environment
  6. Conservation measures being taken to prevent the loss of biodiversity in this area


Karyotype Lab



Karyotype lab



We can learn a lot by looking at chromosomes! They can tell us everything from the likelihood that an unborn baby will have a genetic disorder to whether a person will be male or female. Scientists often analyze chromosomes in prenatal testing and in diagnosing specific diseases. Fetal cells from an unborn child are contained in the amniotic fluid and can be tested for hereditary disorders such as Tay-Sachs or Phenylketonuria. Chromosomes are compact spools of DNA. If you were to stretch out all the DNA from one of your cells, it would be over 3 feet (1 meter) long from end to end! You can think of chromosomes as “DNA packages” that enable all this DNA to fit in the nucleus of each cell. Normally, we have 46 of these packages in each cell; we received 23 from our mother and 23 from our father. A karyotype is an organized profile of a person’s chromosomes. In a karyotype, chromosomes are arranged and numbered by size, from largest to smallest. This arrangement helps scientists quickly identify chromosomal alterations that may result in a genetic disorder.

To make a karyotype, scientists take a picture of someone’s chromosomes, cut them out and match them up using size, banding pattern and centromere position as guides. Homologous pairs are arranged by size in descending order (largest to smallest) with the sex chromosomes (XX for female or XY for male) as the last or 23 pair. Homologous chromosomes have genes for the same trait at the same location.

Since humans have 46 chromosomes in their somatic or body cells, they have 23 pairs of chromosomes in their karyotype. If chromosomes fail to separate in meiosis, a condition called nondisjunction, a person may have more or less than the normal 46 chromosomes on their karyotype. A disorder called Down Syndrome would be a example of this. A person with Down Syndrome will have 3 chromosomes in their 21st pair. The image below shows chromosomes as they are seen on the slide (left panel) and after arrangement (right panel).


karyotype background (run on colored paper), 1-3 sheets of numbered chromosomes, stick glue, scissors, envelope, black ink pen or fine-point marker


  1. Use your assigned sex and chromosome condition to determine how many of each chromosome you will need for your karyotype. (Assigned conditions include Normal male, Normal female, Female with Turner Syndrome, Male with Klinefelter’s Syndrome, Female with Down Syndrome, Male with Down Syndrome, Female with three X chromosomes, Male with no X chromosome, female with Cri-du-chat, Male with Cri-du-chat)
  2. Cut out this number of chromosomes keeping the homologous pairs together. (Do not cut off the chromosome numbers until you are ready to glue the chromosomes to your karyotype sheet.)
  3. Start arranging the chromosome pairs on the construction paper karyotype sheet in descending order by their size. Do not glue the chromosomes until  all of them are arranged correctly.
  4. Evenly space out 4 rows of chromosomes on your karyotype sheet. Row 1 should contain pairs 1-6, row 2 has pairs 7-12, row 3 has pairs 13-18, and row 4 pairs 19 through the sex chromosomes.
  5. If any additional chromosomes are needed to complete your karyotype, cut these out from additional chromosome sheets.
  6. Make sure ALL PAIRS are in the same direction with their SHORTER END TOWARDS THE TOP OF THE CONSTRUCTION PAPER. 
  7. Cut off the numbers from one homologous pair of chromosomes at a time and glue that pair to your construction paper karyotype sheet.
  8. With your ink pen or marker, neatly number each pair 1-23 below the glued pair.
  9. In the lower left corner of your karyotype, write the sex of your individual and their genetic condition (normal, Cri-du-chat, Down’s…).
  10. In the lower right corner, write the total number of chromosomes for this person.

Karyotype Template: (Click here for additional templates)

Questions & Observations:

  1. What is a karyotype? 


2. How can a karyotype be useful to a couple wanting to have children?


3. What makes up chromosomes?

4. How is a karyotype of an unborn infant obtained?


5. What was the sex of the individual you were assigned?

6. What is this person’s GENOTYPE for sex?

7. What is a mutation?


8. What mutation, if any, occurred in this person’s karyotype?

9. How many chromosomes are in a somatic or body cell of this individual?

10. How many chromosomes are in a gamete or sex cell of this individual?

11. How many chromosomes are in a normal person’s somatic cells?

12. How many chromosomes are in a normal person’s gametes?

13. How many UNPAIRED chromosomes are their in this organism’s somatic cells?

14. What is the sex of an individual with 23 MATCHED pairs of chromosomes?

15. What is the diploid number for this organism?

16. Explain nondisjunction.


17. Name and explain 3 disorders due to nondisjunction of chromosomes.