BIO101-Chapter9Smartbook
Select the true statements about meiosis.
-During prophase II, there is no crossing over. -Microtubules can only attach to one side of each homologous chromosome during meiosis I.
How does meiosis I differ from meiosis II? Select all that apply.
-in meiosis II, sister chromatids separate -in meiosis I, homologous chromosomes separate
Select the two unique features that distinguish meiosis from mitosis.
-synapsis -reduction division
If a parent cell contained six chromosomes, how many chromosomes would be present in a haploid gamete produced by the cell?
3
When meiosis is complete, how many haploid cells are produced?
4
If an organism has three homologous pairs of chromosomes, how many different orientations of chromosomes on the metaphase plate are possible?
8
At some point in a somatic cell's life cycle, it will be temporarily haploid.
FALSE
How does a gamete differ from a zygote?
Gametes contain only half of the complement of chromosomes.
At the end of telophase I, the cells are ______.
HAPLOID
What is the significance of meiosis?
Meiosis reduces the number of chromosomes to ensure a consistent number from one generation to the next.
How do somatic cells differ from germ-line cells?
Somatic cells undergo mitosis to produce identical diploid cells and germ-line cells undergo meiosis to produce haploid gametes.
The life cycles of all sexually reproducing organisms alternate between cells with diploid chromosome numbers and cells with haploid chromosome numbers.
TRUE
What describes reduction division of meiosis?
The chromosome homologues do not replicate between the two nuclear divisions.
During meiotic division, chromosome number is reduced in gametes. Why is this important?
This ensures that the zygote has the correct number of chromosomes.
Match the sexual life cycle with the correct organism.
animal- almost all are diploid for the multicellular stage of their life cycle protist- haploid most of their lives plant- spend significant portions of its life cycle as haploid and diploid individuals
In a process called _________________________ ____________ chromosomes break in the same place on non-sister chromatids and sections of chromosomes are swapped between the homologous chromosomes.
crossing over
Select all of the following that describe somatic cells in animals.
diploid; body cells found in non-reproductive organs
A cell taken from animal heart tissue would be ______, whereas a gamete cell would be ______.
diploid; haploid
The fusion of gametes to form a new cell is called_________or syngamy.
fertilization
The haploid eggs or sperm of an organism are called
gametes
From his observations, Pierre-Joseph van Beneden discovered that cells called ________________ (eggs and sperm) each contained half the complement of chromosomes, whereas when they fused, they produced a cell called a ____________________which contains the full complement of chromosomes.
gametes, zygote
Match each term that applies to sexual reproduction with its correct description.
gametes-egg and sperm zygote-the product of fusion of an egg and sperm fertilization - fusion of gametes to form a new cell
What type of cell is found in reproductive organs and undergoes meiosis to form gametes?
germ-line
Match the term that pertains to cell division with the correct description
haploid -one set of chromosomes present diploid- two sets of chromosomes present sexual-reproduction that invovles the alternation of meiosis and fertilization asexual-reproduction by mitotic division
The random orientation of chromosomes on the metaphase plate that results in gametes with different combinations of parental chromosomes is called ______.
independent assortment
What type of cell division reduces the number of chromosomes and ensures a consistent number of chromosomes in offspring? binary fission
meiosis
During what meiotic II phase do spindle fibers bind to both sides of the centromeres and the chromosomes line up along a central plane?
metaphase 11
Match the stages of meiosis or mitosis with the correct description.
metaphase of mitosis- chromosomes line up individually at the cell's central plane metaphase 1- homologous chromosomes pairs line up at the cell's central plane metaphase 11- haploid number of chromosomes lined up at the cell's central plane
In what stage of meiosis does crossing over occur?
prophase 1
Match each meiotic II phase with its correct description.
prophase ll- chromosomes recondense and a new spindle is formed metaphase ll- chromosomes line up along a central plane anaphase ll- sister chromatids move to opposite poles telophase ll-the nuclear envelope reforms around four sets of daughter chromosomes
Independent assortment is a process where the ______.
random orientation of homologues results in gametes with different combinations of parental chromosomes
What is the unique feature of meiosis that alters the number of chromosomes from the diploid cell to the haploid cell?
reduction division
In animals, the diploid cells of the body are called _____ cells, while the diploid, gamete-forming cells are referred to as _____ cells.
somatic; germ-line
What is the process called when homologous chromosomes pair all along their lengths?
synapsis
What process brings homologous chromosomes close enough together to permit crossing over?
synapsis
Match the term that pertains to cell division to the correct definition.
synapsis- homologous chromosomes align along their lengths and are held together by cohesin crossing over- homologous chromosomes exchange parts of their chromatids
During meiosis I, synapsis is _____
the pairing of homologous chromosomes all along their length
The fusion of gametes during fertilization produces a single, diploid cell called a _________
zygote
When an egg and sperm fuse, the resulting single cell is called a(n) ______.
zygote