Meiosis
Phases
Structures
Draw & Label
Paper 2 Problems
100
Define Meisosis.
Meiosis is a type of cell division that divides a cell into four non-identical haploid gametic cells.
100
Which phase only occurs once and does not repeat?
Interphase
100
Explain how DNA and chromosomes are the same but different.
Chromosomes are "sausage-like" structures made of up DNA is super coiled around histones. Both carry genetic information.
100
Draw the fertilization of gametes.
Sperm + Egg = Zygote
100
List one disorder caused by non-disjunction.
Down Syndrome
Turner Syndrome
200
What is the main purpose of meiosis in sexual reproduction?
Genetic Variety / Diversity
200
What phases does the nuclear membrane play a role in?
Prophase I
Telophase I
Prophase II
Telophase II
200
What structure is responsible for moving chromosomes to opposite poles during anaphase?
Spindle Fibers
200
Draw the following circles and fill in the correct amount of chromosomes
O
O
O O
O O O O
46
92
46 46
23 23 23 23
200
What is non-disjunction, and when does it occur?
Non-disjunction is a genetic error where chromosomes fail to separate properly during Anaphase I or Anaphase II.
300
What is the result of an error in Anaphase I/II?
Non-Disjunction
300
Which phase does Non-Disjunction occur in?
Anaphase I or II
300
Explain the difference between Synapsis and a Chiasma.
Synapsis is the process of homologous chromosomes pairing up during prophase I of meiosis, while a Chiasma is the specific point of contact between non-sister chromatids from homologous chromosomes where genetic material is exchanged during crossing over.
300
Draw a Bivalent and a Tetrad
300
How can non-disjunction during meiosis I differ from meiosis II in terms of genetic outcomes?
Homologous chromosomes do not separate in nondisjunction errors in meiosis I, but sister chromatids separate properly in meiosis II.
400
How does meiosis differ from mitosis?
Meiosis divides a cell into four non-identical haploid gametic cells. Mitosis divides a cell into two identical diploid somatic cells.
400
What occurs during prophase I that is crucial for genetic diversity?
Crossing Over
400
Explain the difference between a Bivalent and a Tetrad.
Bivalents are homologous chromosomes and Tetrads are when two bivalents are together.
400
Draw Crossing Over and label where the Synapsis and Chiasmata would go.
400
In a certain plant, 2n = 14. How many chromosomes are present in a gamete after meiosis, and why?
7 chromosomes, because meiosis reduces the chromosome number by half in gametes.
500
Use Mendel's laws to explain meiosis.
Mendel’s Law of Segregation states that each gamete receives only one allele from each pair (Meiosis I) where homologous chromosomes separate into different cells.
Mendel’s Law of Independent Assortment occurs during Metaphase I where homologous chromosome pairs align randomly at the metaphase plate,creating genetic variety in the offspring.
500
How is Anaphase I different from Anaphase II?
Anaphase I separates homologous chromosomes, Anaphase II separates sisters chromatids.
500
Explain the difference between a chromosome and chromatid using the words haploid and diploid.
A chromosome is a single, thread-like structure containing genetic information, while a chromatid is one of the two identical copies of a chromosome that are created during DNA replication, essentially making a chromosome composed of two sister chromatids; a "haploid" cell contains only one set of chromosomes, whereas a "diploid" cell contains two sets of each chromosome (one from each parent) which are made up of two chromatids each.
500
Draw and label the phases of meiosis.
____Interphase____
Prophase IMetaphase I
Anaphase I
Telophase I
Prophase II
Metaphase II
Anaphase II
Telophase II
500
Explain why the chromosome number is reduced by half during meiosis but remains the same in mitosis.
Meiosis separates homologous chromosomes in the first division, reducing the chromosome number by half, whereas mitosis only separates sister chromatids, keeping the chromosome number the same.