biology chapter 18

In humans, chromosome pairs 1-22 are called ________ and chromosome pair 23 is called _________.

autosomes, sex chromosomes

Sister chromatids are held together in a specific region called the _____________.

centromere

The process of programmed cell death is called

apoptosis

A ______ is a group of symptoms that always occur together

syndrome

Danielle was debating whether to have amniocentesis or chorionic villi sampling. Dr. Ferguson explained that the advantages of CVS include that:

it can be performed sooner in the pregnancy than amniocentesis and the results from karyotyping can be read at an earlier date

During the majority of a cell's life, it is in _________ that was once called the resting stage. However, today it is the interval of time between cell divisions

interphase

Which statement is false

During S (synthesis) of interphase, DNA replication occurs.
During gap 1 (G1) of interphase, the number of orhganelles doubles.
→ During gap 2 (G2) of interphase, the nucleus begins to disintegrate.
During gap 2 (G2) of interphase, the cell synthesizes important proteins used in cell division.
During gap 0 (G0) typically cells are arrested in (G1).

During gap 2 (G2) of interphase, the nucleus begins to disintegrate

In a non-dividing cell, the nucleus contains indistinct and diffuse chromatin, but in a dividing cell, these become short and thick and are called:

chromosomes

The division of the cellular cytoplasm and organelles is called

cytokinesis

The type of cellular nuclear division that produces two daughter cells with the same number and kind of chromosomes is called:

mitosis

The process of mitosis is comprised of four stages. Which statement correctly places the stages in order?

prophase, metaphase, anaphase, telophase

Which statement is false concerning prophase

prophase occurs after interphase
during prophase, chromosomes are randomly placed in the nucleus
during prophase, spindle fibers attach to the centromeres
→ during prophase the DNA is replicated
during prophase the chromosomes shorten and thicken

during prophase the DNA is replicated

During ________ the chromosomes line up along the equatorial plane.

metaphase

Which of the following events occurs during anaphase?

separation of the sister chromatids occurs

Two daughter nuclei are formed from each parent cell during:

telophase

The indentation, or pinching in of the cell membrane, around the circumference of the cell during the end of mitosis is called the:

cleavage furrow

The primary function of the mitotic spindle is to:

move sister chromatids to opposite poles.

During ____________ of the cell cycle, typically the nucleolus disappears

prophase

The cellular process that requires two nuclear divisions, resulting in four daughter cells with half of the parent chromosomal number is

meiosis

____________ are pairs of alike chromosomes that look alike and carry the same genes.

Homologues

During the process of meiosis I the __________ pair up in synapsis

homologous chromosomes

Meiosis is very important for the production of gametes in order to

provide for genetic variation
ensure the proper number of chromosomes exist after fertilization
produce gametes with the haploid number of chromosomes
stabilize the number of chromosomes passed through the generations
* All of the above are correct.

Many biologists emphasize that _____ between non-sister chromatids during synapsis is an important event because it will result in new combinations of genes

crossing-over

Daughter nuclei form from each parent cell during:

telophase I and telophase II

The second meiotic division is essentially mitosis, except that the resultant cells in which this division occurs are:

haploid

Tina's identical twins were the result of:

one egg and one sperm

If a human inherits two X chromosomes, the person will be _______ and if they inherit an X and a Y sex chromosome they will be _____________.

a female, a male

James and Jennifer were fraternal twins, this meant that they

were the product of two eggs and two sperm

The secondary oocyte begins meiosis II but stops at metaphase II and does not complete metaphase II unless:

the fertilization process begins

Nondisjunction occurs when _____________.

homologous pairs do not separate in meiosis I.
crossing-over occurs in sister chromatids.
sister chromatids do not separate in mitosis or meiosis II.
the tetrads form.
Both A and C are correct.

Both A and C are correct.

The inactive X chromosome is distinguishable by the presence of a ___________.

Barr body

Tom has Klinefelter syndrome. An analysis of his chromosomes yielded

the presence of one Barr body

Which of the following is a true statement about Trisomy 21

is more likely to occur in children of older women

While Jessica was completing her rounds, she noticed a child with a small head, facial abnormalities, mental retardation, and made this strange noise similar to a cat's cry. She remembered from her medical genetics class that these symptoms are associated with _________.

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