Genes & Alleles

Alternate forms of the same gene are called:

a) Chromatids.

b) Centromeres.

c) Chromosomes.

d) Alleles.

A cell that has 2 copies of each chromosome is called a __________ cell:

a) Sperm.

b) Diploid.

c) Haploid.

d) Gamete.

All human cells, except sex cells, are diploid and have 23 pairs of chromosomes. Human sex cells, such as egg and sperm, are haploid and have _______ chromosomes.

a) 23

b) 12

c) 11.5

d) 46

The human karyotype shown below:

a) Is of a haploid cell.

b) Is from a gamete.

c) Shows 23 chromosomes.

d) All of the above.

How might the two members of a pair of homologous chromosomes differ from each other?

a) In the sequence of the DNA making up each of the chromosomes.

b) In the relative position of the genes present on each of the chromosomes.

c) They cannot differ if they are homologous.

d) In the kinds of genes present on each of the chromosomes.

All eukaryotic sexual life cycles include:

a) Mitosis, gamete formation, and fertilization.

b) Mitosis, meiosis, gamete formation, and fertilization.

c) Mitosis, meiosis, and gamete formation.

d) Mitosis, fertilization, and meiosis.

e) Mitosis, meiosis, apoptosis.

f) Gamete formation, meiosis, mitosis.

Which of the following steps must occur before Meiosis I in germ cells?

In Meiosis I, cytokinesis usually occurs after telophase I and produces:

a) Four diploid cells.

b) Two haploid cells.

c) Four haploid cells.

d) Two diploid cells.

In Meiosis II, ________ cells are divided into 4 ___________ daughter cells.

a) Diploid; Haploid.

b) Haploid; Diploid.

c) Haploid; Haploid.

d) Diploid; Diploid.

A daughter cell is created by meiosis I and the first round of cytokinesis. This daughter cell is just beginning meiosis II. Which of the following is an appropriate description of this daughter cell’s genetic contents?

a) It has half the amount of DNA as the parent cell.

b) It has half the chromosomes but twice the DNA of the parent cell.

c) It has one-fourth the DNA and one-half the chromosomes as the parent cell.

d) It is genetically identical to the parent cell.

Which diagram represents anaphase I of meiosis?

a) I

b) II

c) III

d) IV

e) V

f) VI

Which statement describes a major difference between meiosis II and mitosis in a diploid animal?

a) Homologous chromosomes align on the metaphase plate in meiosis II.

b) Sister chromatids separate in mitosis, and homologous chromosomes separate in meiosis II.

c) Meiosis II occurs in a haploid cell, while mitosis occurs in diploid cells.

d) Meiosis II is known as “reductional division” while mitosis is known as “equatorial division”.

During which of the following stages of meiosis do homologous chromosomes pair up and align along the metaphase plate of the cell?

a) Metaphase I of meiosis.

b) Telophase I of meiosis.

c) Anaphase I of mitosis.

d) Metaphase II of meiosis.

What separates during Anaphase II?

a) The cytoplasm.

b) Sister Chromatids.

c) Homologous chromosomes.

d) Daughter nuclei.

Which of the following processes occurs when homologous chromosomes cross over in meiosis I?

a) Two sister chromatids get tangled, resulting in one re-sequencing its DNA.

b) Two sister chromatids exchange identical pieces of DNA.

c) Maternal alleles are "corrected" to be like paternal alleles and vice versa.

d) Corresponding segments of non-sister chromatids from homologous chromosomes are exchanged.

Crossing over involves each of the following EXCEPT:

a) The transfer of DNA between two non-sister chromatids.

b) The transfer of DNA between two sister chromatids.

c) The formation of a synaptonemal complex.

d) The alignment of homologous chromosomes.

e) All of the above are involved in crossing over.

How many genetically unique gametes can be created in an organism with 4 chromosomes?

a) 256.

b) 23.

c) 16.

d) 1 million.

e) 4.

During which of the following processes does independent assortment of chromosomes occur?

a) In meiosis I only.

b) In meiosis II only.

c) In mitosis and meiosis I.

d) In mitosis and meiosis II.

e) In meiosis I and meiosis II.

Independent assortment of chromosomes is a result of which of the following processes?

a) The random way each pair of homologous chromosomes lines up at the metaphase plate.

b) The random combinations of eggs and sperm during fertilization.

c) The random distribution of the sister chromatids into the two daughter cells.

d) The diverse combination of alleles that may be found within any given chromosome.

Non-disjunction means that chromosomes:

a) Do not cross over during synapsis.

b) Do not replicate during interphase.

c) Have serious mutations.

d) Do not separate correctly from one another during anaphase.

During meiosis, if nondisjunction occurs during anaphase II (shown below in cell #3) what are the possible gametes that can be produced from cell #3?

a) A only.

b) B only.

c) C only.

d) A & C.

e) B & C.

f) A & B.

g) All three.

________ cells have an extra or missing chromosomes after meiosis due to nondisjunction during Meiosis I.

a) Somatic cells.

b) Gametes.

c) Diploid Cells.

d) Aneuploid Cells.

e) Haploid Cells.

f) Sperm Cells.

During which of the following processes do sister chromatids separate from each other?

a) During meiosis I only.

b) During meiosis II only.

c) During both mitosis and meiosis I.

d) During both mitosis and meiosis II.

Which of the following statements describes a difference between meiosis II and mitosis in a diploid organism?

a) Sister chromatids align along the metaphase plate in mitosis while homologous chromosomes align in meiosis II.

b) Sister chromatids separate in mitosis and homologous chromosomes separate in meiosis II.

c) Meiosis II occurs in a haploid cell, while mitosis occurs in a diploid cell.

d) Crossing over of chromosomes takes place in meiosis II and does not take place in mitosis.

Which of the following processes occurs in meiosis but not in mitosis?

a) Chromosome replication during interphase.

b) Synapsis of chromosomes during prophase.

c) Alignment of chromosomes at the center of the cell.

d) Condensation of chromosomes during prophase.

e) None of the above.

What does it mean when we say that mitosis and meiosis II are forms of “equational division” while meiosis I is a form of “reductional division”?

a) Daughter cells of mitosis and meiosis II are both diploid while the daughter cells of meiosis I are haploid.  

b) The number of chromosomes in daughter cells of meiosis I is half the number of chromosomes of the parent cell.  

c) The number of chromosomes in daughter cells of mitosis and meiosis II is equal to the number of chromosomes in the parent cells.  

d) A and B.

e) B and C.

f) All of the above.