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Week 9, Session 2
Chapter 13: Meiosis
Supplemental Instruction
Iowa State University
Kelsey
Bio 211 (5)
Dr. Holscher
10-20-09
1. __Heredity/Inheritance_________ is the transmission of traits from one generation to the next.
2. What is the term for the specific location on a chromosome where a gene is found?
locus (plural: loci)
3. What are homologs? (What do they have in common?)
2 chromosomes in a pair with same length, staining pattern, and centromere position; both carry
genes controlling same inherited characteristic
4. An ____autosome________________ is any chromosome that is not a sex chromosome.
5. What does the letter n represent (in terms of chromosomes)?
the number of chromosomes in a single set
6. Somatic cells have __44___ autosomes and _22____ pair(s) of autosomes.
7. Somatic cells have __2___ sex chromosomes and ___1__ pair(s) of sex chromosomes.
8. Reproductive cells have __22___ autosomes and __1___ sex chromosome(s).
9. What is the product of meiosis?
4 daughter cells (from 1 parent cell)
10. What occurs during Meiosis I? Meiosis II?
Meiosis I: homologs separate
Meiosis II: sister chromatids separate
11. List the three mechanisms for variation in meiosis:
 Independent assortment of chromosomes
 Crossing over
 Random fertilization
12. What causes independent assortment of chromosomes?
Homologous pairs of chromosomes align randomly at the metaphase plate.
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
13. Calculate the number of possible daughter cell combinations for the given values of n
(remember: 2n).
 n= 1
2
 n=2
4
 n=3
8
 n=4
16
 2n=4
4
 2n=8
16
14. How many possible combinations of daughter cells are there in humans (written in 2n format)?
223
This is due to independent assortment, which is the idea that chromosomes line up randomly on
the metaphase plate during meiosis.
15. What is the function of crossing over? What is produced?
Crossing over produces recombinant chromosomes by combining genes inherited from each
parent. (occurs during synapsis)
key word: chiasma (junction where chromosomes meet/overlap)
16. Due to random fertilization, how many different sperm-egg chromosome combinations are
possible in the zygote? (Write in 2nx2n format).
223 x 223
This is due to two random (rather than systematically-selected) partners mating.