Question

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1. the purpose of meiosis is to make gametes, also known as sperm and egg cells. in humans, your body cells have 46 chromosomes. how many chromosomes are in a sperm or egg cell if, when they come together to form a fertilized zygote, there are 46 chromosomes? write the correct number of chromosomes next to the sperm and egg.

images of sperm and egg cell

1. interphase must occur once before meiosis can happen. (same thing for mitosis). what would happen if interphase didn’t occur first?

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image of a cell with a to - do list for interphase and a thought bubble saying \i need a vacation\

1. a cell that begins meiosis has 23 chromosomes inherited from the mother (shown in green in the cartoon below) and 23 chromosomes inherited from the father (shown in blue in the cartoon below). in the process of meiosis, chromosomes begin to match up in homologous pairs. how would you know if two chromosomes were homologous?

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image of two homologous chromosomes with a gene for eye color

1. crossing over is a very important event in prophase i of meiosis! what happens during crossing over and what is the significance?

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image of chromosomes crossing over with \wow! cool!\ text

1. meiosis does pmat twice! that means there is a prophase i and a prophase ii. there is a metaphase i and a metaphase ii. etc... if the cartoon below has chromosomes in the middle of the cell, how would you know whether it was in metaphase i or metaphase ii?

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image of a cell with chromosomes lined up in the middle

1. meiosis does not always occur without any difficulties. describe what occurs during nondisjunction and the effect on the resulting cells.

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image of a cell with nondisjunction and a speech bubble saying \well howdy - do, neighbor!\
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Explanation:

1. Meiosis halves chromosome number for fertilization (zygote = 46).
2. Interphase replicates DNA; no interphase → no DNA copy for division.
3. Homologous chromosomes have same size/shape and matching genes.
4. Crossing over swaps DNA between homologs, increasing genetic diversity.
5. Metaphase I: Homologous pairs line up; Metaphase II: Single chromosomes line up.
6. Nondisjunction = chromosomes fail to separate; gametes get extra/missing chromosomes.

Answer:

1. Sperm: 23; Egg: 23
2. The cell would lack replicated DNA, so daughter cells would have insufficient genetic material.
3. They have the same size, shape, and carry genes for the same traits (e.g., eye color) at corresponding positions.
4. Homologous chromosomes exchange segments of DNA; significance is genetic variation.
5. If homologous pairs are lined up in the middle → Metaphase I; if single chromosomes are lined up → Metaphase II.
6. Chromosomes do not separate properly during anaphase I/II; resulting cells have abnormal chromosome numbers (aneuploidy).