9a

Question 1

Zygote?

Answer 1

A fertilized egg cell; it is the first cell of a diploid organism

Question 2

Nondisjunction

Answer 2

Failure of chromosomes to separate resulting in extra or missing chromosomes.

Question 3

homologous chromosomes (5)

Answer 3

chromosome pairs, one from each parent, that are similar in length and centromere location and have the same sequence and location of genes

Question 4

autosome

Answer 4

chromosomes that are the same for both sexes, nonsex chromosome

Question 5

sex chromosome

Answer 5

chromosome that carries genes that determine sex

Question 6

Allele

Answer 6

Alternate version of the same gene

Question 7

gametes

Answer 7

A haploid sex cell: sperm or egg cell.

Question 8

fertilization

Answer 8

Union of two gametes resulting in a diploid zygote

Question 9

germ cell

Answer 9

Diploid cells that can produce gametes and occur only in testes and ovaries)

Question 10

somatic cells

Answer 10

body cell that does not give rise to gametes.

Question 11

crossing over

Answer 11

exchange of genetic material between homologous chromosomes during prophase I of meiosis

Question 12

monozygotic

Answer 12

Identical twins, one zygote splits in half

Question 13

dizygotic

Answer 13

Nonidentical twins, two zygotes (two sperm fertilize two different eggs)

Question 14

Polyploid cell

Answer 14

Cell with extra chromosome sets

Question 15

Meiosis

Answer 15

Division of genetic material that halves the chromosome number and yields genetically variable gametes.

Question 16

mitosis

Answer 16

Division of genetic material that yields two genetically identical cells

Question 17

Haploid cell vs. diploid cell

Answer 17

A diploid cell (2n) has two full sets of chromosomes, one set coming from each parent (mitosis). A haploid cell (n) has only one set of chromosomes. (Meiosis)

Question 18

Compare and contrast sexual and asexual reproduction.

Answer 18

Asexual reproduction requires only one parent and produces offspring that are identical, except for mutations. (mitosis) Sexual reproduction requires two parents and produces genetically variable offspring. (meiosis/gamete formation/fertilization)

Question 19

Polyploidy

Answer 19

Polyploidy is an organism or cell having more than twice the haploid number of chromosomes. Polyploidy arises as the result of total nondisjunction of chromosomes during mitosis or meiosis. Common in plants.

Question 20

Aneuploidy

Answer 20

Aneuploidy is any deviation from the exact multiple of the of haploid number of chromosomes. Most aneuploids arise by nondisjunction, a failure of homologous chromosomes to separate at meiosis.
Chromosomes may be present in multiple copies (Trisomy) or one of a homologous pair may be missing in a diploid cell (monosomy).

Question 21

How can deletions, duplications, inversions and translocations cause illnesses?

Answer 21

Deletions, duplications, inversions, and translocations can delete, duplicate, or damage genes, which may affect the normal production of proteins. Affected individuals may lack proteins, produce harmful proteins, or have fertility problems.

Question 22

13. Compare and contrast gamete formation in a man and a woman.

Answer 22

Spermatogenesis results in four equally-sized, very small spermatids that mature into sperm cells. Oogenesis results in one very large egg and three polar bodies. The processes are similar in that they involve an initial mitotic division and then two meiotic divisions to produce haploid gametes.

Question 23

Chromosomal deletions

Answer 23

Results in the loss of one or more genes, may mean that an individual cannot make some proteins

Question 24

Chromosomal duplication

Answer 24

Produces multiple copies of part of a chromosome

Question 25

Chromosomal inversion

Answer 25

Part of a chromosome flips and reinserts changing the gene sequence. Inversion produces symptoms because chromosomes may not align properly during meiosis, causing fertility problems, miscarriage, or birth defects.

Question 26

Chromosomal translocation

Answer 26

Nonhomolygous chromosomes exchange parts. In translocation, chromosomes may be missing parts, or genes can be broken

Question 27

Meiosis/Mitosis - similarities

Answer 27

both divide the chromosomes of a eukaryotic cell and overall, the processes have a similar progression of stages, and similar mechanisms move chromosomes.

Question 28

Meiosis/Mitosis - differences

Answer 28

Stage of life vs. anytime, 1 cell division/2 divisions, 2 daughter cells/4, 1 cytokineis/2, homologous alignment and crossing over only in meiosis, identical vs. genetically variable, growth and repair vs sexual reproduction.

Question 29

Explain how crossing over generates variability among offspring.

Answer 29

In crossing over, homologous chromosomes align and swap segments with each other. After crossing over is complete, the chromosomes have new allele combinations. Crossing over occurs at random so the gametes produced in one round of meiosis are not identical to those produced in a subsequent round of meiosis. (prophase I)

Question 30

Explain how independent assortment generates variability among offspring.

Answer 30

Homologous chromosomes can be attached to either spindle pole in Metaphase I, so each homologue can be packaged into either one of the two new nuclei. (Humans 223 possible combinations of homologous chromosomes)

Question 31

Explain how fertilization generates variability among offspring.

Answer 31

Chance combinations of maternal and paternal chromosomes through fertilization produce a unique combination of genetic information.

Question 32

5.      Explain the role of meiosis in sexual reproduction.

Answer 32

In meiosis, a diploid cell divides twice to produce four haploid nuclei, reducing the chromosome number by half. Meiosis also creates new allele combinations in the haploid nuclei.

Question 33

5.      Explain the role of gamete formation in sexual reproduction.

Answer 33

Gamete formation packages the haploid chromosomes into reproductive cells (sperm and egg cells).

Question 34

5.      Explain the role of fertilization in sexual reproduction.

Answer 34

Fertilization merges haploid gametes from two parents, producing a new diploid cell with half its chromosomes coming from each parent.

Question 35

4.      Describe the role of homologous chromosomes in sexual reproduction.

Answer 35

Homologous chromosomes pair up during sexual reproduction and shuffle genetic information in a process called crossing over.

Question 36

7.      Explain the roles of somatic cells and germ cells in sexual reproduction.

Answer 36

Germ cells are specialized diploid cells that make gametes and are found only in the ovaries and testes. Somatic cells are found in the rest of the body, and do not participate directly in reproduction.

Question 37

3.      Distinguish between autosomes and sex chromosomes.

Answer 37

Autosomes are chromosomes that are the same regardless of sex, whereas the sex chromosomes determine whether an individual is male or female.