Meiosis And Life Cycles Flashcards
What is the main purpose of sexual reproduction?
Produces genetic variation, essential for evolution and adaptation to environmental changes
Genetic variation allows populations to adapt to changing environments, enhancing survival.
What process generates genetic diversity?
Meiosis
Meiosis is a specialized form of cell division that leads to the formation of gametes.
What type of cells are produced by meiosis?
Haploid gametes (egg and sperm)
Each haploid gamete contains one copy of every chromosome.
How does meiosis contribute to genetic variability?
By shuffling DNA
This shuffling occurs through processes such as crossing over and independent assortment.
What is the outcome of mitosis?
Two genetically identical diploid cells
Mitosis is responsible for growth and restoration of somatic tissues.
What is the outcome of meiosis?
Four genetically unique haploid cells
These cells are the result of two rounds of division.
How many divisions occur in meiosis?
Two divisions (Meiosis I and Meiosis II)
Each division plays a crucial role in the formation of gametes.
Do homologous chromosomes pair in mitosis?
No
In mitosis, there is no pairing of homologous chromosomes.
What happens to homologous chromosomes during Meiosis I?
They pair, recombine, and separate
This process is essential for the generation of genetic diversity.
What feature distinguishes meiosis from mitosis regarding genetic diversity?
Meiosis has high genetic diversity
This is due to crossing over, independent assortment, and random fertilization.
Fill in the blank: The main purpose of mitosis is _______.
[Growth and restoration of somatic tissues]
True or False: Meiosis results in genetically identical cells.
False
Meiosis produces genetically unique haploid cells.
What occurs during Prophase I of Meiosis?
Homologous chromosomes pair (synapsis), forming tetrads and crossing over occurs at chiasmata.
What is the result of Anaphase I in Meiosis?
Homologs separate, reducing chromosome number by half.
What happens during Telophase I and Cytokinesis in Meiosis?
Two haploid cells are formed, each with one set of chromosomes.
What is the first stage of Meiosis II?
Prophase II: Chromosomes condense again in haploid cells.
In Meiosis II, what occurs during Metaphase II?
Sister chromatids align at the metaphase plate.
What happens during Anaphase II of Meiosis?
Sister chromatids separate.
What is produced at the end of Telophase II and Cytokinesis?
Four haploid gametes are produced.
Fill in the blank: In Meiosis I, homologous chromosomes pair during _______.
Prophase I
True or False: Meiosis II is similar to Mitosis.
True
What is crossing over?
Homologous chromosomes exchange genetic material, creating new allele combinations.
This process occurs during Prophase I of meiosis.
What is independent assortment?
Random orientation of homologous pairs at the metaphase plate results in 2^n possible combinations.
In humans, this leads to approximately 8.4 million combinations.
What happens during independent assortment in Metaphase II?
Random orientation of sister chromatids at the metaphase plate results in 2^n possible combinations.
In humans, this results in over 70 trillion combinations.
What is random fertilization?
Any sperm can fuse with any egg, further increasing genetic variability.
This contributes significantly to the genetic diversity of offspring.
Describe the life cycle of animals.
Gametic meiosis produces gametes directly, which fuse during fertilization to form a diploid zygote.
This is a direct cycle from gametes to zygote.
What is the alternation of generations in plants?
Sporic meiosis: Sporophyte (diploid) undergoes meiosis to produce four haploid spores instead of gametes.
Spores grow into a gametophyte (haploid), which produces gametes via mitosis.
What process do fungi and algae undergo for reproduction?
Zygotic meiosis.
Upon fertilization, the zygote undergoes meiosis directly, producing spores instead of gametes.
Fill in the blank: The random orientation of homologous pairs at the metaphase plate results in _______ possible combinations.
2^n
True or False: Crossing over occurs during Metaphase II.
False
Crossing over occurs during Prophase I.
In the alternation of generations, the gametophyte is _______.
haploid
What do spores germinate to form in fungi and algae?
Haploid organisms that undergo mitosis to make their gametes.
Since they are already haploid, meiosis is not needed again.
