Alternation of generations is defined as the switching back and forth between the production of:
a. cells by mitosis and meiosis
b. asexual and sexual reproductive cells
c. gametophytes and saprophytes
d. diploid and haploid cells
MY ANSWER "A"
The correct answer is a. cells by mitosis and meiosis.
To arrive at this answer, let's briefly explain the concept of alternation of generations. Alternation of generations is a reproductive strategy found in some organisms, such as plants and algae, where they alternate between two different multicellular stages in their life cycle: the gametophyte and the sporophyte.
The gametophyte is the haploid (having one set of chromosomes) stage of the life cycle that produces gametes (reproductive cells with half the number of chromosomes). The gametes unite during fertilization to form a diploid zygote.
The zygote develops into the sporophyte, which is the diploid (having two sets of chromosomes) stage of the life cycle. The sporophyte produces spores through a process called meiosis. These spores are haploid and give rise to new gametophytes, completing the cycle.
Now, let's analyze the options:
a. cells by mitosis and meiosis: This is the correct answer as alternation of generations involves two processes - mitosis for the growth and development of the multicellular stages (gametophyte and sporophyte) and meiosis for the production of spores and gametes.
b. asexual and sexual reproductive cells: While alternation of generations involves both asexual and sexual reproduction, this option doesn't capture the specific processes (mitosis and meiosis) involved in cell production.
c. gametophytes and saprophytes: Saprophytes are organisms that obtain nutrients by decomposing dead organic matter, and they are not directly related to alternation of generations.
d. diploid and haploid cells: This option describes the difference between the two types of cells involved in alternation of generations, but it doesn't capture the processes of cell production (mitosis and meiosis).
Therefore, the correct answer is a. cells by mitosis and meiosis.