Question
question 6- mice have 20 bivalents visible in meiosis 1. fill in the table below indicating how many chromosomes and how many chromatids per chromosome are present in each of the cells
Name Worksheet for Mitosis and Meiosis Lab: Part B Answer the following questions: 1. During meiosis, which division is reductional? a. meiosis I b. meiosis I1 c. both meiotic divisions 2. Which meiotic division is similar to mitosis? a. meiosis I b. meiosis II c. both meiotic divisions 2. 3. Mendel's law of independent segregation depends on the random positioning of centromeres at which meiotic division? a. meiosis I b. meiosisI c. both meiotic divisions 3. 4. Humans have 46 chromosomes in their kidney cells. How many are found in sperm cells? b. 46 C. 48 d. 92 e. none of these 4. 5. How many are found in an egg? a. 23 d. 92 e. none of these 5 6. Mice have 20 bivalents visible in Meiosis I. Fllin the table below indicating how many chromosomes and how many chromatids per chromosome are present in each of the cell types Cell type Metaphase of meiosis I Prophase of meiosis II G1 mitosis G2 mitosis Egg cell # chromosomes # chromatids/ chromosome IO 7. What stage of meiosis is characterized by complete pairing of chromosomes and crossingover? a. zygonema b. pachynema c. leptonema d. diplonema 8. In some grasshopper species there is no Y chromosome. Males of one of these species have only one X chromosome and 5 pairs of autosomes. Females have 2 X chromosomes and 5 pairs of autosomes. Males therefore have 11 chromosomes and females have 12. Meiosis in females produces eggs with: c. 11 chromosomes a. 5 chromosomes d. 12 chromosomes b. 6 chromosomes e. both a and b 8. 9. Meiosis in males produces sperm with: b. 6 chromosomes c. 11 chromosomes a. 5 chromosomes d. 12 chromosomes e. both a and b 10. During meiosis in males of this grasshopper species, how many bivalents and how many unpaired chromosomes are present at metaphase I? c. 11 bivalents, 1 univalent a. 5 bivalents, 1 univalent b. 6 bivalents d. 12 bivalents 10. e. both a and b
Explanation / Answer
A bivalent means a pair of homologous chromosomes which are held together by atleast one cross over point.So a bivale consists of two chromosomes.Therefore, if mice has 20 bivalents, it means there are 40 chromosomes.Furthermore, each chromosome of the bivalent has two chromatids, so there are four chromatids in each bivalent.As such there will be 80 chromatids in 20 bivalents. The other information is summarised in the table below.
Cell type Chromosome Chromatids Metaphase of Meiosis I 40 80 Prophase of meiosis II 20 40 G1 mitosis 40 G2 mitosis 40 80 egg cell 20 40
