More Cell Divison Flashcards
What happens during anaphase I of meiosis?
Homologous chromosomes are pulled to opposite poles, reducing the chromosome number by half.
What happens during anaphase II of meiosis?
Sister chromatids are separated, similar to what occurs during mitosis.
What is the key difference in alignment during metaphase in mitosis vs. meiosis I?
• Mitosis: Individual chromosomes align at the metaphase plate.
• Meiosis I: Homologous chromosomes align in pairs at the metaphase
What is the function of meiosis in reproduction?
To produce gametes (sperm and eggs) with half the chromosome number, ensuring stability of the species’ chromosome count across generations.
What key events during meiosis increase genetic variability?
- Crossing over during prophase I.
- Independent assortment of homologous chromosomes during
During which phase does DNA replication occur?
S phase of interphase
What structures are present in animal cells but not in plant cells during mitosis?
Centrioles
What is nondisjunction, and when can it occur?
Nondisjunction is the failure of chromosomes to separate properly, occurring in either anaphase I or anaphase II of meiosis.
What is parthenogenesis?
A type of asexual reproduction where an unfertilized egg develops into an organism, as seen in green aphids.
What is budding?
An asexual process where a new organism grows as a bud from the parent, common in yeast.
What is the dominant phase in a pine tree’s life cycle?
The diploid sporophyte phase.
What is interkinesis, and what happens during it?
A resting phase between meiosis I and meiosis II where no DNA replication occurs.
What is fragmentation, and give an example?
• A form of asexual reproduction where an organism breaks into pieces, and each fragment grows into a new organism.
• Example: Starfish or garden plants from cuttings.
What is vegetative reproduction, and give examples?
• A process in plants where new individuals arise from specialized structures like runners, tubers, or rhizomes.
• Examples: Strawberries (runners) and potatoes (tubers).
What is spore formation, and in which organisms does it occur?
Spore formation involves producing reproductive cells (spores) that can grow into a new organism without fertilization. Example: fungi, mosses, and ferns.
What is alternation of generations?
A life cycle involving the alternation between a haploid gametophyte stage and a diploid sporophyte stage.
What is a gametophyte?
The haploid stage in a plant’s life cycle that produces gametes (sperm and eggs) through mitosis.
What is a sporophyte?
The diploid stage in a plant’s life cycle that produces haploid spores through meiosis.
Which stage is dominant in mosses?
The gametophyte stage is dominant in mosses, with the sporophyte dependent on it.
Which stage is dominant in ferns and seed plants?
The sporophyte stage is dominant in ferns and seed plants
What role do spores play in alternation of generations?
Spores are produced by the diploid sporophyte through meiosis and grow into haploid gametophytes
How do ferns reproduce in the alternation of generations?
- The diploid sporophyte produces haploid spores.
- The spores grow into a haploid gametophyte.
- The gametophyte produces gametes, which fuse during fertilization to form a diploid zygote, developing into a new sporophyte.
What is the significance of alternation of generations?
It promotes genetic diversity through meiosis and fertilization, adapting organisms to different environmental conditions.
