Life Science Chapter 6

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  1. What is genetics?
    the study of the inheritance, or the passing from parents to offspring, of traits
  2. When did Modern Genetics study start?
    mid 1800's
  3. Who is the father of genetics?
    Gregor Mendel
  4. What does Gregor Mendel study?
    he studied genetics using pea plants
  5. Who was Gregor Mendel?
    A catholic monk who studied genetics
  6. How did Gregor Mendel cross breed his pea plants? List the steps in order.
    He cut off the pollen-containing structures from the short pea plant

    He collected the tall plant pollen using a brush

    He placed the tall plant pollen into the pistils of the short plant flowers.
  7. Review the plant chart from your text book for Mendel's experiments.
  8. What are the male gametes called?
  9. What are the female gametes called?
  10. What kind of cells are gametes?
    Haploid cells
  11. How many chromosomes do haploid cells have?
  12. How many chromosomes do diploid cells have?
  13. How many chromosomes do human cells have?
    Most human cells have 46 chromosomes. except for the gametes or human sex cells (gametes) which contain 23 chromosomes.
  14. Why do haploid cells only have 23 chromosomes?
    Because they only have one copy of a chromosome pair.
  15. When two diploid gamete cells combine at fertilization what is formed?
    a diploid zygote
  16. What type of reproduction combines two haploid cells to form a diploid zygote
    sexual reproduction or meiosis
  17. In Mendel's theories what are his "factors" commonly known as today?
  18. The traits in that Mendel was studying were controlled by what?
    factors (known as genes today)
  19. How many genes do diploid organisms have for a specific trait?
    They have two genes. One from each parent.
  20. What are the different forms of the gene for a trait called?
  21. What does it mean to be purebred for a particular trait?
    It is when the organism's two alleles for a particular trait are the same.
  22. If an organism's two alleles are not coded the same for a particular trait then the organism is known as a?
  23. In a hybrid organism what trait will be displayed in the organism?
    The dominant trait
  24. The trait that is shown or displayed is called the?
  25. Each allele in the set of two alleles for a trait is either __________________ or ____________.

  26. In a genotype what does an upper case letter represent?
    it represents the dominant allele
  27. Ina genotype what does a lower case letter represent?
    it represents the recessive allele
  28. In a hybrid genotype what phenotype would be displayed?
    The phenotype that matches the dominant allele would be seen. The recessive allele would be masked.
  29. What is a phenotype?
    It is an organism's physical appearance; the physical expression of an organism's genes
  30. What is a genotype?
    It is a organism's genetic makeup
  32. Genes are arranged on what?
  33. Where are chromosomes located?
    in the nucleus
  34. Chromosomes occur in ___________.
  35. In sexual reproduction the haploid sperm and egg cells contribute how many chromosomes?
    23; They contribute 1 member of each set of chromosomes.
  36. The diploid zygote has how many chromosomes?
    two of each chromosome for a total of 46 (2 pairs of 23)
  37. What are punnett squares used for?
    They are used to show genetic crosses
  38. What do the number of squares in a Punnet Square represent?
    the individual squares represent the genetic possibilities of the offspring for two parents
  39. What is incomplete dominance?
    It is a type of inheritance in which the alleles for a particular characteristic are neither dominant nor recessive, resulting in a “blending” of the two expressions of the gene. Ex. pink snapdragons
  40. What is codominance?
    It is the expression of both alleles for a trait in an organism. Ex. roan cattle.
  41. Why does codominance occur?
    Because both alleles are dominant and can not mask each other.
  42. What is polygenic inheritance?
    It is an inheritance pattern in which two or more genes work together to produce a single trait.
  43. What is an example of polygenic inheritance?
    human hair color.
  44. What is an example of codominance?
    roan cattle
  45. What is an example of incomplete dominance?
    snapdragon color
  46. What are multiple alleles?
    It is an inheritance pattern in which there are more than two possible alleles for a singe trait
  47. What is an example of multiple alleles?
    human blood type
  48. What are sex chromosomes?
    They are the chromosomes that determine if an organism is male or female.
  49. What chromosomes are responsible for determining if humans are male or female?
    The 23rd set of chromosomes
  50. What sex chromosomes do females have?
    Females have two X chromosomes
  51. What sex chromosomes do males have?
    They have 1 X and 1Y chromosomes.
  52. What chromosomes is larger; the X chromosome or the Y chromosome?
    The Y chromosomes is smaller
  53. Do female eggs have an X chromosome or a Y chromosome on their 23rd chromosome?
    They have the X chromosome
  54. Do male sperm have an X chromosome or a Y chromosome on their 23rd of chromosome?
    They have a Y chromosome
  55. Which parent determines the sex or gender of the offspring?
    The male sperm determines the gender of the offspring
  56. What are sex-linked traits?
    It is a characteristic that is coded for by a gene on the X chromosome or the Y chromosome.
  57. What is an example of a sex-linked trait
  58. Are most sex-linked traits carried on the X chromosome or the Y chromosome?
    Most are carried on the X chromosome, but there are some that are carried on the Y chromosome.
  59. Study the sex linked chart for color blindness on p. 124 in text
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Life Science Chapter 6
BJU Life Science Chapter 6
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