Biology Flashcards: Explain Genetic Causes Of Variation

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This deck focuses on Explain Genetic Causes Of Variation, giving you a quick way to review the definitions, rules, and examples that matter most for Biology.

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Flashcard 1: What is the primary genetic source of new alleles in a population?

Answer: Mutation. Creates entirely new alleles that didn't exist before.

Flashcard 2: Identify the mutation type: one nucleotide is removed from a coding sequence, shifting codons.

Answer: Frameshift due to deletion. Loss of nucleotide disrupts reading frame downstream.

Flashcard 3: Which type of mutation generally is not inherited because it occurs in body cells?

Answer: Somatic mutation. Only affects the individual, not their offspring.

Flashcard 4: What is a gene pool?

Answer: All alleles present in a population. Contains all possible genetic variants in the group.

Flashcard 5: Which point mutation replaces one nucleotide with another?

Answer: Substitution. One of three types of point mutations affecting single bases.

Flashcard 6: Identify the genetic mechanism: alleles enter a population when individuals migrate and reproduce.

Answer: Gene flow. Movement of individuals introduces new alleles.

Flashcard 7: Identify the mutation type: one nucleotide is removed from a coding sequence, shifting codons.

Answer: Frameshift due to deletion. Loss of nucleotide disrupts reading frame downstream.

Flashcard 8: What is the number of possible chromosome combinations per gamete from independent assortment for $n=4$?

Answer: $2^4=16$ combinations. Formula $2^n$ where $n$ is number of chromosome pairs.

Flashcard 9: What is random fertilization as a source of genetic variation?

Answer: Any sperm can fertilize any egg, creating new genotypes. Combines genetic material from two different parents.

Flashcard 10: Which mutation changes an amino acid in a protein sequence?

Answer: Missense mutation. Results in a different amino acid in the protein product.

Flashcard 11: Identify the genetic mechanism: a DNA base is replaced by a different base at one position.

Answer: Substitution (point mutation). Single nucleotide change at one specific position.

Flashcard 12: Identify the genetic mechanism: homologous chromosomes exchange segments during meiosis.

Answer: Crossing over. Physical exchange of DNA between paired chromosomes.

Flashcard 13: Which two meiosis-related mechanisms create recombination without creating new alleles?

Answer: Crossing over and independent assortment. Both processes occur during meiosis I.

Flashcard 14: Identify the mutation type: a codon becomes a stop codon, shortening the polypeptide.

Answer: Nonsense mutation. Point mutation creates premature termination signal.

Flashcard 15: What is homozygosity in genetics?

Answer: Having two identical alleles at a locus. Reduces genetic diversity at that specific locus.

Flashcard 16: What is independent assortment?

Answer: Random orientation of homologous pairs in meiosis I. Each homolog can go to either pole during division.

Flashcard 17: Which process increases variation by mixing maternal and paternal chromosomes into gametes?

Answer: Independent assortment. Distributes parental chromosomes randomly among offspring.

Flashcard 18: Which type of mutation generally is not inherited because it occurs in body cells?

Answer: Somatic mutation. Only affects the individual, not their offspring.

Flashcard 19: Identify the genetic mechanism: alleles enter a population when individuals migrate and reproduce.

Answer: Gene flow. Movement of individuals introduces new alleles.

Flashcard 20: Which genetic process can introduce alleles from one population into another?

Answer: Gene flow. Migration connects previously isolated gene pools.

Flashcard 21: Which mutation creates a premature stop codon?

Answer: Nonsense mutation. Truncates protein synthesis early, often affecting function.

Flashcard 22: What is an allele?

Answer: An alternative form of a gene at a specific locus. Different versions of the same gene exist.

Flashcard 23: Which process produces gametes and increases genetic variation in sexually reproducing organisms?

Answer: Meiosis. Combines crossing over and independent assortment for variation.

Flashcard 24: What is a locus?

Answer: A gene's specific location on a chromosome. Each gene has a fixed chromosomal address.

Flashcard 25: What is a mutagen?

Answer: An agent that increases the rate of DNA mutation. Environmental factors like radiation or chemicals cause mutations.

Flashcard 26: Which chromosomal mutation reverses a segment within a chromosome?

Answer: Inversion. Flips gene order but keeps genes on same chromosome.

Flashcard 27: During which meiotic phase does crossing over typically occur?

Answer: Prophase I. When chromosomes pair and exchange genetic material.

Flashcard 28: Which source of variation is described: existing alleles are rearranged into new genotypes?

Answer: Recombination in sexual reproduction. Mixes existing alleles without creating new ones.

Flashcard 29: Which meiotic event creates new allele combinations by exchanging DNA between homologs?

Answer: Crossing over (homologous recombination). Occurs between paired homologous chromosomes in meiosis.

Flashcard 30: What is a gene pool?

Answer: All alleles present in a population. Contains all possible genetic variants in the group.

Flashcard 31: What is a mutagen?

Answer: An agent that increases the rate of DNA mutation. Environmental factors like radiation or chemicals cause mutations.

Flashcard 32: Which mutation removes one or more nucleotides from a DNA sequence?

Answer: Deletion. Removes genetic material from the DNA sequence.

Flashcard 33: Which meiotic event creates new allele combinations by exchanging DNA between homologs?

Answer: Crossing over (homologous recombination). Occurs between paired homologous chromosomes in meiosis.

Flashcard 34: Which chromosomal mutation repeats a segment of a chromosome?

Answer: Duplication. Creates extra copies of genes within a chromosome.

Flashcard 35: What is the number of possible chromosome combinations per gamete from independent assortment for $n=4$?

Answer: $2^4=16$ combinations. Formula $2^n$ where $n$ is number of chromosome pairs.

Flashcard 36: Which process produces gametes and increases genetic variation in sexually reproducing organisms?

Answer: Meiosis. Combines crossing over and independent assortment for variation.

Flashcard 37: Which meiotic stage directly produces independent assortment of chromosomes?

Answer: Metaphase I. When homologous pairs align randomly at cell equator.

Flashcard 38: Which mutation adds one or more nucleotides to a DNA sequence?

Answer: Insertion. Adds extra genetic material to the DNA strand.

Flashcard 39: What is aneuploidy?

Answer: An abnormal number of specific chromosomes. Can result from nondisjunction during meiosis.

Flashcard 40: Identify the genetic mechanism: homologous chromosomes exchange segments during meiosis.

Answer: Crossing over. Physical exchange of DNA between paired chromosomes.

Flashcard 41: Which source of variation is described: new alleles are created rather than reshuffled?

Answer: Mutation. Only mutation introduces completely novel genetic material.

Flashcard 42: What is an allele?

Answer: An alternative form of a gene at a specific locus. Different versions of the same gene exist.

Flashcard 43: What is independent assortment?

Answer: Random orientation of homologous pairs in meiosis I. Each homolog can go to either pole during division.

Flashcard 44: What is the number of possible chromosome combinations per gamete from independent assortment for $n=3$?

Answer: $2^3=8$ combinations. Each chromosome can orient independently: $2^n$ possibilities.

Flashcard 45: What is heterozygosity in genetics?

Answer: Having two different alleles at a locus. Provides maximum genetic diversity at that locus.

Flashcard 46: Identify the genetic mechanism: chromosomes line up randomly in meiosis I, forming varied gametes.

Answer: Independent assortment. Random chromosome orientation creates genetic diversity.

Flashcard 47: Which mutation changes an amino acid in a protein sequence?

Answer: Missense mutation. Results in a different amino acid in the protein product.

Flashcard 48: Which chromosomal mutation moves a segment to a nonhomologous chromosome?

Answer: Translocation. Transfers genetic material between different chromosomes.

Flashcard 49: What is the genetic cause of variation in asexual reproduction compared with sexual reproduction?

Answer: Mainly mutation; little or no recombination. Sexual reproduction adds recombination for greater variation.

Flashcard 50: What is homozygosity in genetics?

Answer: Having two identical alleles at a locus. Reduces genetic diversity at that specific locus.

Flashcard 51: Identify the genetic mechanism: a DNA base is replaced by a different base at one position.

Answer: Substitution (point mutation). Single nucleotide change at one specific position.

Flashcard 52: What is the genetic cause of variation in asexual reproduction compared with sexual reproduction?

Answer: Mainly mutation; little or no recombination. Sexual reproduction adds recombination for greater variation.

Flashcard 53: What is heterozygosity in genetics?

Answer: Having two different alleles at a locus. Provides maximum genetic diversity at that locus.

Flashcard 54: What is aneuploidy?

Answer: An abnormal number of specific chromosomes. Can result from nondisjunction during meiosis.

Flashcard 55: What is a frameshift mutation?

Answer: Insertion or deletion that shifts the reading frame. Changes how codons are read downstream from mutation site.

Flashcard 56: What is the difference between mutation and recombination as sources of variation?

Answer: Mutation creates new alleles; recombination reshuffles alleles. Mutation adds novelty; recombination rearranges existing material.

Flashcard 57: Identify the mutation type: a codon becomes a stop codon, shortening the polypeptide.

Answer: Nonsense mutation. Point mutation creates premature termination signal.

Flashcard 58: Which mutation changes a codon but not the amino acid it codes for?

Answer: Silent mutation. Due to genetic code redundancy, protein remains unchanged.

Flashcard 59: What is the difference between mutation and recombination as sources of variation?

Answer: Mutation creates new alleles; recombination reshuffles alleles. Mutation adds novelty; recombination rearranges existing material.

Flashcard 60: What is a locus?

Answer: A gene's specific location on a chromosome. Each gene has a fixed chromosomal address.

Flashcard 61: What is genetic recombination?

Answer: Formation of new allele combinations in offspring. Shuffles existing alleles into new arrangements.

Flashcard 62: Which source of variation is described: new alleles are created rather than reshuffled?

Answer: Mutation. Only mutation introduces completely novel genetic material.

Flashcard 63: What is a mutation?

Answer: A heritable change in DNA nucleotide sequence. Can be passed to offspring and affect protein function.

Flashcard 64: Which process increases variation by creating new combinations of alleles on the same chromosome?

Answer: Crossing over. Links alleles that were previously on different homologs.

Flashcard 65: What is a mutation?

Answer: A heritable change in DNA nucleotide sequence. Can be passed to offspring and affect protein function.

Flashcard 66: Which meiotic stage directly produces independent assortment of chromosomes?

Answer: Metaphase I. When homologous pairs align randomly at cell equator.

Flashcard 67: Which broad category of mutations affects an entire chromosome segment?

Answer: Chromosomal mutation (structural rearrangement). Involves large-scale DNA changes beyond single nucleotides.

Flashcard 68: What is random fertilization as a source of genetic variation?

Answer: Any sperm can fertilize any egg, creating new genotypes. Combines genetic material from two different parents.

Flashcard 69: What is polyploidy?

Answer: More than two complete sets of chromosomes. Often results from errors in meiosis or mitosis.

Flashcard 70: Which chromosomal mutation reverses a segment within a chromosome?

Answer: Inversion. Flips gene order but keeps genes on same chromosome.

Flashcard 71: Identify the genetic mechanism: chromosomes line up randomly in meiosis I, forming varied gametes.

Answer: Independent assortment. Random chromosome orientation creates genetic diversity.

Flashcard 72: Which two meiosis-related mechanisms create recombination without creating new alleles?

Answer: Crossing over and independent assortment. Both processes occur during meiosis I.

Flashcard 73: Which point mutation replaces one nucleotide with another?

Answer: Substitution. One of three types of point mutations affecting single bases.

Flashcard 74: What is genetic recombination?

Answer: Formation of new allele combinations in offspring. Shuffles existing alleles into new arrangements.

Flashcard 75: Which process increases variation by mixing maternal and paternal chromosomes into gametes?

Answer: Independent assortment. Distributes parental chromosomes randomly among offspring.

Flashcard 76: What is genetic variation within a population?

Answer: Differences in alleles and genotypes among individuals. Describes the diversity of genetic forms within a species.

Flashcard 77: Which mutation creates a premature stop codon?

Answer: Nonsense mutation. Truncates protein synthesis early, often affecting function.

Flashcard 78: Which mutation adds one or more nucleotides to a DNA sequence?

Answer: Insertion. Adds extra genetic material to the DNA strand.

Flashcard 79: Which broad category of mutations affects an entire chromosome segment?

Answer: Chromosomal mutation (structural rearrangement). Involves large-scale DNA changes beyond single nucleotides.

Flashcard 80: What is gene flow?

Answer: Movement of alleles between populations via migration. Increases allelic diversity between connected populations.

Flashcard 81: What is nondisjunction in meiosis?

Answer: Failure of homologs or sister chromatids to separate. Results in gametes with incorrect chromosome numbers.

Flashcard 82: Which process increases variation by creating new combinations of alleles on the same chromosome?

Answer: Crossing over. Links alleles that were previously on different homologs.

Flashcard 83: Which mutation removes one or more nucleotides from a DNA sequence?

Answer: Deletion. Removes genetic material from the DNA sequence.

Flashcard 84: During which meiotic phase does crossing over typically occur?

Answer: Prophase I. When chromosomes pair and exchange genetic material.

Flashcard 85: Which source of variation is described: existing alleles are rearranged into new genotypes?

Answer: Recombination in sexual reproduction. Mixes existing alleles without creating new ones.

Flashcard 86: Which genetic process can introduce alleles from one population into another?

Answer: Gene flow. Migration connects previously isolated gene pools.

Flashcard 87: Which chromosomal mutation repeats a segment of a chromosome?

Answer: Duplication. Creates extra copies of genes within a chromosome.

Flashcard 88: Which type of mutation changes a single nucleotide in DNA?

Answer: Point mutation. Affects only one DNA base position at a time.

Flashcard 89: What is the number of possible chromosome combinations per gamete from independent assortment for $n=3$?

Answer: $2^3=8$ combinations. Each chromosome can orient independently: $2^n$ possibilities.

Flashcard 90: What is the primary genetic source of new alleles in a population?

Answer: Mutation. Creates entirely new alleles that didn't exist before.

Flashcard 91: Which mutation changes a codon but not the amino acid it codes for?

Answer: Silent mutation. Due to genetic code redundancy, protein remains unchanged.

Flashcard 92: Which chromosomal mutation moves a segment to a nonhomologous chromosome?

Answer: Translocation. Transfers genetic material between different chromosomes.

Flashcard 93: What is genetic variation within a population?

Answer: Differences in alleles and genotypes among individuals. Describes the diversity of genetic forms within a species.

Flashcard 94: What is polyploidy?

Answer: More than two complete sets of chromosomes. Often results from errors in meiosis or mitosis.

Flashcard 95: Which term describes a new allele arising in a gamete that can be inherited by offspring?

Answer: Germ-line mutation. Can be passed to next generation through reproduction.

Flashcard 96: What is nondisjunction in meiosis?

Answer: Failure of homologs or sister chromatids to separate. Results in gametes with incorrect chromosome numbers.

Flashcard 97: Which term describes a new allele arising in a gamete that can be inherited by offspring?

Answer: Germ-line mutation. Can be passed to next generation through reproduction.

Flashcard 98: What is a frameshift mutation?

Answer: Insertion or deletion that shifts the reading frame. Changes how codons are read downstream from mutation site.

Flashcard 99: Which type of mutation changes a single nucleotide in DNA?

Answer: Point mutation. Affects only one DNA base position at a time.