Biology Chapter 8

Asexual reproduction requires ________ individual(s), whereas sexual reproduction requires _______ individual(s).

1; 2

How many pairs of autosomes do humans have?

22

In a cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing __________ chromosomes.

5

Imagine that a human skin cell went through mitosis but did not undergo cytokinesis. How many chromosomes would be in the cell? -23 -92 -46 -69

92

define: chromosome

A gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis; also, the main gene-carrying structure of a prokaryotic cell. A chromosome consists of one very long DNA molecule and associated proteins.

define: gamete

A sex cell; a haploid egg or sperm. The union of two gametes of opposite sex (fertilization) produces a zygote.

define: somatic cell

Any cell in a multicellular organism except a sperm or egg cell or a cell that develops into a sperm or egg.

Which statement regarding cell division is false? -Cell division can reproduce an entire organism. -Cell division is the basis of both sexual and asexual reproduction. -Cell division is necessary for development to occur. -Cell division is common in eukaryotes but rare in prokaryotes.

Cell division is common in eukaryotes but rare in prokaryotes.

define: meiosis

In a sexually reproducing organism, the division of a single diploid nucleus into four haploid daughter nuclei. Meiosis and cytokinesis produce haploid gametes from diploid cells in the reproductive organs of the parents.

define: diploid

In an organism that reproduces sexually, a cell containing two homologous sets of chromosomes, one set inherited from each parent; a 2n cell.

define: haploid

In the life cycle of an organism that reproduces sexually, a cell containing a single set of chromosomes; an n cell.

Trisomy for most autosomes is fatal, yet trisomy or even tetrasomy (four copies) of the X chromosome is not. What is the explanation for this difference? -There is a mechanism to keep only two X chromosomes functional, regardless of the total number. -The number of X chromosomes is always balanced by the number of Y chromosomes. -The X chromosome does not carry any genes. -Only one copy of the X chromosome is functional within any given cell, regardless of the total number of X chromosomes.

Only one copy of the X chromosome is functional within any given cell, regardless of the total number of X chromosomes.

Which statement regarding sexual and asexual reproduction is true? -Cell division only occurs after sexual reproduction. -Sexual reproduction typically includes the development of unfertilized eggs. -Only offspring from asexual reproduction inherit traits from two parents. -Sexual reproduction is more likely to increase genetic variation than is asexual reproduction.

Sexual reproduction is more likely to increase genetic variation than is asexual reproduction.

You and your lab partner are observing a cell under a microscope, but you do not know whether it is a eukaryote or a prokaryote. Which observation regarding the chromosomes would allow you to immediately conclude that the cell is a eukaryote? -The chromosomes contain very few proteins. -The chromosomes are circular in structure. -The chromosomes are housed in a membrane-enclosed nucleus. -The chromosomes are very simple in structure.

The chromosomes are housed in a membrane-enclosed nucleus.

define: zygote

The diploid fertilized egg, which results from the union of a sperm cell nucleus and an egg cell nucleus.

define: mitosis

The division of a single nucleus into two genteically identical nuclei. Mitosis and cytokinesis make up the mitotic (M) phase of the cell cycle.

define: crossing over

The exchange of segments between chromatids of homologous chromosomes during synapsis in prophase I of meiosis; also, the exchange of segments between DNA molecules in prokaryotes.

define: homologous chromosomes

The two chromosomes that make up a matched pair in a diploid cell. Homologous chromosomes are of the same length, centromere position, and staining pattern and possess genes for the same characters at corresponding loci. One homologous chromosome is inherited from the organism's father, the other from the mother.

Although in humans there are 22 pairs of autosomal chromosomes, only three different chromosomal trisomies are commonly seen in newborns. Of the remaining 19 autosomes, many trisomies have not been seen in newborns. Why not? -These autosomal chromosomes do not contain the same type of DNA or protein that makes up chromosomes susceptible to trisomy. -Trisomy for the other autosomal chromosomes is often lethal, and the affected embryos are miscarried. -Trisomy for these autosomal chromosomes has no effect and therefore would never be noticed. -Trisomy for these other autosomal chromosomes occurs so rarely that it has never been documented.

Trisomy for the other autosomal chromosomes is often lethal, and the affected embryos are miscarried.

Which of the following indicates Turner syndrome? -XO -XXY -XXX -XYY

XO

A benign tumor and a malignant tumor differ in that _____. -cells of a benign tumor remain within the tumor, whereas cells of a malignant tumor can spread to other body tissues -a benign tumor only forms from solid tissues such as skin or muscle and a malignant tumor only forms from blood and lymphatic tissue -cells of a benign tumor spread by metastasis and cells of a malignant tumor spread by expansion of the tumor mass -benign tumors are harmless and malignant tumors are lethal

cells of a benign tumor remain within the tumor, whereas cells of a malignant tumor can spread to other body tissues

Meiosis differs from mitosis in that _____ only occurs in meiosis. -the fragmentation of the nuclear envelope -crossing over -the formation of a spindle -cytokinesis

crossing over

Which type of organisms commonly demonstrates polyploidy? -mammals -reptiles -fish -flowering plants

flowering plants

Two chromosomes in a nucleus that carry genes controlling the same inherited characteristics are -complementary chromosomes -sister chromatids -homologous chromosomes

homologous chromosomes

Eukaryotic cells spend most of their cell cycle in which phase? -interphase -telophase -prophase -metaphase

interphase

A fragment of chromosome 21 reattaches to chromosome 21, but in the reverse direction. What is the name given to this change? -inversion -duplication -deletion -trisomy 21

inversion

Variation occurs when chromosomes are shuffled in _____. -mutation -mitosis -genetic drift -meiosis

meiosis

During which phase of mitosis do the chromosomes line up on a plane equidistant from the two spindle poles? -prophase -telophase -metaphase -anaphase

metaphase

After fertilization, the resulting human zygote begins to divide by __________. -mitosis -binary fission -meiosis -cell plate formation

mitosis

During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as _____. -nondisjunction -gametic infertility -chiasmata that do not disconnect -meiotic failure

nondisjunction

*What happens during synapsis? -the centrosomes move to opposite poles of the cell -the chromosomes cross over to the opposite cell poles -the spindle fibers attach to the centromeres -parts of the homologous chromosomes switch

parts of the homologous chromosomes switch

Independent orientation of chromosomes at metaphase I results in an increase in the number of -homologous chromosomes -possible combinations of characteristics -gametes -sex chromosomes

possible combinations of characteristics

The term binary fission is best applied to _____. -prokaryotes -plants -mitosis -nuclear chemistry

prokaryotes

Crossing over occurs during _____. -prophase II -prophase I -metaphase I -metaphase II

prophase I

Synapsis occurs during _____. -telophase I -prophase II -anaphase I -prophase I

prophase I

Which of the following shows mitosis in the correct chronological order? -prometaphase, metaphase, prophase, telophase, anaphase -anaphase, prometaphase, metaphase, prophase, telophase -telophase, prophase, anaphase, prometaphase, metaphase -prophase, prometaphase, metaphase, anaphase, telophase

prophase, prometaphase, metaphase, anaphase, telophase

One version of a gene may encode __________, whereas a different version of the same gene may encode __________. -red eyes; white coat -white eyes; brown coat -white eyes; white coat -red eyes; white eyes

red eyes; white eyes

*What separates during meiosis 1? -the homologous chromosome pairs -sister chromatids -the cell organelles -the spindle fibers

sister chromatids

Prior to mitosis and after S phase, each chromosome of a eukaryotic cell consists of a pair of identical structures called -chromatin -sister chromatids -nucleoli -sister chromosomes

sister chromatids

*Which of these events only occur in meiosis and not in mitosis? -formation of spindle fibers -splitting of sister chromatids -synapsis -breakdown of nuclear membrane

synapsis

Cancer is caused by -sexual reproduction -formation of eggs and sperm -uncontrolled cell division -rapid binary fission

uncontrolled cell division

Homologous chromosomes possess the same genes arranged in the same order but may possess different __________ of some of these genes. -ploidy numbers -numbers -versions -loci

versions