Name: ________________________________
Per: C
D
E
F
Date: _____________________
Investigation 9: Genetic Variation
(Study Guide)
Following are the focus questions for this Investigation. As we complete this unit you should be able to
answer all of these questions. For homework you should take this sheet each night and see which questions
the class work applied to for that day and try to answer the question.
1.
How are individuals in a population different from one another? Individuals from population are
different because they have different traits for each feature. Variety created by combination of
many traits makes each organism unique.
2. What is heredity? Heredity or inheritance is passing or inheritance traits from parents to offspring.
3. What is a chromosome? Chromosome is coiled up DNA molecule that carries the massage of
inheritance. Chromosomes come in pairs. Humans have 23 pairs in their nucleus or 46 all together.
4. What are alleles? Allelles are the basic unit of heredity. Two alleles work together to make up a gene.
5. What are genes? Genes are combination of alleles that have the code for a trait. The type of gene of
genotype determines the trait the organism will have for a feature such as gene for legs in larkey. If a
larkey has AA then it will have short legs. AA is its genotype for legs.
6. What are recessive alleles? Recessive alleles carry the code for recessive trait. An organism has to
have two recessive alleles to show the trait. For example since long legs is a recessive trait in larkeys,
the larkey must have two recessive alleles “aa” to make up a gene for legs to get long legs.
7. What are dominant alleles? Dominant alleles carry the code for dominant trait. An organism has to
have only one of the two alleles for this trait to show the trait. For example Short leg is dominant in
larkey’s for an organism to have short leg a larkey can have “AA” or “Aa”.
8. Differentiate between genotype and phenotype. Genotype is the combination of alleles that have
the code for the trait such as “AA” and phenotype is what that gene is going to look like on the
organism such as short legs.
9. Differentiate between homozygous and heterozygous genes. Homozygous gene are pure gene for a
trait that means that both alleles are the same such as “AA or aa” whereas heterozygous gene is not
pure it has alleles for two different traits such as “Aa”. In some case when nether trait is dominant or
both are partially dominant this combination may produce a third trait.
10. Explain how organisms inherit features and traits from their parents.
Organisms inherit trait and features from their parents by inheriting genes in nucleus of the cell. Half
of the information comes in the female reproductive cell and half from male reproductive cell. When
the two join the offspring will have full set of information to develop into a new organism with its own
features and traits.
11. Describe how dominant and recessive alleles interact to produce traits in a population.
In a heterozygous gene the dominant allele will show the phenotype and recessive allele phenotype
will be hidden. In the next generation if another set of heterozygous gene or homozygous recessive
organism is the other parent then the offspring has the chance of showing the hidden phenotype.