AY Honors/Heredity/Answer Key
Heredity
1. What is meant by the term "heredity"?
Heredity refers to the transfer of biological characteristics from a parent organism to offspring, and is practically a synonym for genetics, as genes are now recognized as the carriers of biological information.
2. Draw a picture of an animal cell and label the following parts: Cell membrane, cytoplasm, nucleus, nuclear membrane, ribosomes.
3A. What is a chromosome and where are they located?
A chromosome is a very long, continuous piece of DNA which contains many genes. Chromosomes are located within the nucleus of a cell.
3B. What is a gene and where is it found?
Genes are the units of heredity in living organisms. They are encoded in the organism's genetic material (usually DNA or RNA), and control the physical development and behavior of the organism. They are located on the chromosomes.
4A. What is meant by the term "allele"?
An allele is any one of a number of viable DNA codings of the same gene occupying a given position on a chromosome. Humans have paired chromosomes in their somatic cells, and these contain two copies of each gene. In some cases the two copies of the gene are identical — that is, have the same allele. In other cases, the two copies are different. Humans inherit two copies of every gene, one copy comes from the mother, and the other comes from the father.
4B. How does a dominant allele differ from a recessive allele?
Characteristics associated with a certain allele can sometimes be dominant or recessive, but often they are neither. A dominant trait will be expressed when only one allele of its associated type is present, whereas a recessive trait will only be expressed when both alleles are of its associated type.
4C. Determine which allele you have of the following genetic traits:
Widow's Peak
Free earlobe(left) and attached earlobe (right)
- Dimples.jpg
Dimpled cheeks
- Widow's Peak
- A widow's peak is a descending V-shaped point in the middle of the hairline (above the forehead). The trait is inherited genetically and dominant. The term comes from English folklore, where it was believed that this hair formation was a sign of a woman who would outlive her husband.
- Free earlobe
- The free earlobe is a dominant trait, and its counterpart is the attached earlobe. Geneticists are unsure if it is the result of a single gene or if multiple genes are involved.
- Dimples
- Dimples are small indentations in the cheeks most evident when a person possessing this trait smiles.
- Curved thumb
- Bent pinky
- Digit hair
- Rolling tongue
- Second toe longer
4D. Using a punnet square, predict the ratio of offspring produced from these monohybrid crosses: TT (tall) crossed with tt (short), Tt (tall) crossed with Tt (tall), Tt (tall) crossed with tt (short).
5A. What does the process of mitosis accomplish?
5B. Draw a sequence of cells that shows the process of mitosis including: prophase, metaphase, anaphase, and telophase.
5C. Briefly explain how the DNA in the chromosomes is copied during this process.
6A. What does the process of meiosis accomplish and how does it differ from mitosis?
6B. Draw a sequence of cells that shows the process of meiosis including: prophase I &II, metaphase I &II, anaphase I &II, and telophase I &II.
6C. Do the cells resulting from meiosis remain haploid? Explain.
7. Describe how DNA encodes the specific proteins that result in genetic traits. Demonstrate your knowledge of this process by using diagrams or paper models.
8. What is mutation? Using diagrams or models created in question 7, illustrate the effect of a mutation on the genetic trait.
9. Know at least five genetic disorders and tell a story about a famous person or someone that you know who has had one of these disorders.
10. Is Biological Heredity the only factor contributing to your character, i.e., what makes you who you are?
11. Find 3 statements from Ellen White's writings that relate to the previous question.
References
- K12science.org - Genetic traits
