Genetic Variation - Middle School Life Science
- Which process moves alleles between populations when individuals migrate and reproduce?
- Gene flow. Migration spreads genetic diversity between groups.
- Which type of selection favors both extremes and can increase variation?
- Disruptive selection. Eliminates the middle, creating two distinct groups.
- Which option describes genetic variation: inherited fur color or a scar from injury?
- Inherited fur color. Fur color is genetic; scars are environmental.
- What is a mutation in genetics?
- A change in the DNA sequence. Can be caused by errors in DNA copying or environmental factors.
- Identify the genotype(s) that are homozygous for a gene with alleles A and a.
- AA and aa. Both have matching alleles (AA has two A's, aa has two a's).
- Which process shuffles alleles during meiosis to increase variation?
- Crossing over (recombination). Chromosomes exchange segments, creating new combinations.
- Which process increases variation by shuffling alleles during meiosis?
- Genetic recombination. Creates new combinations of existing alleles.
- Identify the population with greater genetic variation: all AA vs AA, Aa, and aa present.
- AA, Aa, and aa present. Three genotypes means more genetic diversity than just one.
- Which process randomly separates chromosomes into gametes, increasing variation?
- Independent assortment. Chromosomes sort randomly into sex cells.
- Which process creates new alleles and is the ultimate source of variation?
- Mutation. Only mutations can create brand new genetic variants.
- Which data type most directly measures genetic variation: allele frequencies or population size?
- Allele frequencies. Shows the proportion of each allele variant in the population.
- What is a phenotype?
- Observable trait produced by genes and environment. What you see results from genes plus environmental factors.
- Which type of variation is caused by different alleles (not environment)?
- Genetic variation. Inherited differences, not changes from lifestyle or environment.
- In a population with genotypes AA, Aa, and aa, what shows genetic variation?
- Presence of more than one allele (A and a) in the population. Multiple alleles (A and a) create genetic diversity.
- What is crossing over?
- Exchange of DNA between homologous chromosomes during meiosis. Creates new allele combinations on chromosomes.
- Which situation is an example of gene flow: mutation in one bird or birds migrating and breeding?
- Birds migrating and breeding. Movement and reproduction transfers alleles between populations.
- Which option best indicates genetic variation: different fur colors or different ages?
- Different fur colors. Fur color is genetic; age is environmental.
- Which type of selection favors the average phenotype and reduces variation?
- Stabilizing selection. Eliminates extremes, keeping the middle range.
- Which term means two identical alleles for a gene?
- Homozygous. Same alleles inherited from both parents (AA or aa).
- Identify the best evidence of genetic variation: different eye colors or different suntans?
- Different eye colors. Eye color is inherited; suntans are environmental.
- Identify the genotype that is heterozygous for a gene with alleles A and a.
- Aa. Has two different alleles (one A, one a).
- Which event combines alleles from two parents and increases variation?
- Random fertilization. Any sperm can fertilize any egg, mixing parental genes.
- Which type of selection favors one extreme phenotype and reduces variation?
- Directional selection. Pushes population toward one trait value.
- Which term means two different alleles for a gene?
- Heterozygous. Different alleles from each parent (Aa).
- Identify the best evidence of genetic variation: blood types or calluses from work?
- Blood types. Blood type is genetic; calluses are acquired.
- Which process creates new alleles in a population?
- Mutation. Only mutations can create brand new genetic variants.
- What is a genotype?
- An organism's allele combination for a gene. Written as letters (e.g., AA, Aa, aa).
- If every individual in a population is genotype AA, what is the genetic variation for that gene?
- No variation; only one allele (A) is present. All identical genotypes means no genetic diversity.
- What is a mutation in DNA?
- A change in the DNA sequence. Can be harmful, beneficial, or neutral.
- What is a gene locus?
- The specific location of a gene on a chromosome. Like an address for finding a gene on its chromosome.
- What is gene flow?
- Movement of alleles into or out of a population via migration. Introduces new alleles when organisms move between groups.
- What is genetic variation within a population?
- Differences in DNA (alleles) among individuals of the same species. These differences create the variety we see within a species.
- What is genetic drift?
- Random changes in allele frequencies, strongest in small populations. Like flipping coins - chance affects which alleles survive.
- What is a gene in genetics?
- A DNA segment that influences a trait. Genes are instructions that determine characteristics.
- What is independent assortment?
- Random separation of chromosome pairs into gametes. Each gamete gets a random mix of maternal and paternal chromosomes.