Name ______Date ______Period ______# ______

Genetics Web Lab: Mendel’s Pea Plant Experiments

http://www2.edc.org/weblabs/WebLabDirectory1.html

Introduction

1. Mendel chose pea plants (Pisum satvum) because they possess four important qualities. These qualities are:

1. All offspring will have the same 7 characteristics generation after generation.

2. Peas have contrasting traits. (eg. purple vs. white flowers)

3. Peas usually reproduce by ______pollination because of its anatomy.

4. Pea plants grow quickly and do not require much space.

Plant & Cross

2. The seven contrasting traits that Mendel observed in Pisum sativum are:

1. Pea shape (R) - round or wrinkled

2. Pea color (Y) – yellow or green

3. Pod shape (I) – inflated or constricted

4. Pod color (G) – green or yellow

5. Flower color (P) - purple or white

6. Plant size (T) – tall or dwarf

7. Position of flowers (A) – axial or terminal

Predict (Perform the 5 crosses and follow the directions afterward before answering any of these questions.)

3. What type(s) of offspring were produced when a plant with round peas was crossed with itself (self pollination)?

4. What type(s) of offspring were produced when a plant with wrinkled peas was crossed with itself (self pollination)?

5. Explain why one of the crosses resulted in more than one type of pea formed (#3) while the other resulted in only one type of pea formed (#4).

6. When you crossed the two wrinkled offspring, what type(s) of seeds did the next generation (F2) have? Why?

7. The traits that appear to mask or hide other traits are called ______.

8. The traits that seem to be hidden are called ______.

Pedigree

9. What type(s) of offspring are produced when you cross a white flower with itself (self pollination) or with another white flower (cross pollination)?

10. What type(s) of offspring are produced when you cross a purple flower with itself (self pollination) or with another purple flower (cross pollination)?

Explore

11. Fill in the following chart as you cross the other contrasting traits that Mendel collected data on.

Genetic Characteristic / Dominant Trait / Recessive Trait
Pea Shape
Pea Color
Pod Shape
Pod Color
Flower Color
Plant Size
Flower Position

Allele- one letter of an organisms gene that is inherited by one of its parents (one-half of their genotype)

Axial- flowers located near the middle of the plant

Dominant- traits that appear to mask (or hide) other traits.

Genotype- the entire genetic makeup of an organism

Pedigree- A diagram of a family history used for tracing a trait through several generations

Phenotype- the outward appearance of an organism that results from the organism’s genotype

Recessive- traits that can be hidden in one generation and then appear in the next.

Terminal Flowers- located at the ends of the stems

Trait-a distinguishing characteristic