Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 37m
3. Water1h 26m
4. Biomolecules2h 23m
5. Cell Components2h 26m
6. The Membrane2h 31m
7. Energy and Metabolism2h 0m
8. Respiration2h 40m
9. Photosynthesis2h 49m
10. Cell Signaling59m
11. Cell Division2h 47m
12. Meiosis2h 0m
13. Mendelian Genetics4h 44m
14. DNA Synthesis2h 27m
15. Gene Expression3h 6m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 53m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport1h 2m
- Water Potential
  1h 2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 49m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

12. Meiosis

Meiosis II

General Biology

12. Meiosis

Meiosis II

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1:28 minutes

Problem 7

Textbook Question

Norway rats have 42 chromosomes in their diploid cells. If such a cell enters meiosis, how many chromosomes and double-helical molecules of DNA will be present in each daughter cell at the end of meiosis II?
a. 21 chromosomes and 21 double-helical DNA molecules
b. 21 chromosomes and 42 double-helical DNA molecules
c. 42 chromosomes and 42 double-helical DNA molecules
d. 42 chromosomes and 84 double-helical DNA molecules

Verified step by step guidance

Step 1: Understand the concept of diploid and haploid cells. Diploid cells contain two sets of chromosomes (one from each parent), while haploid cells contain only one set of chromosomes. Meiosis reduces the chromosome number from diploid (2n) to haploid (n).

Step 2: Recall the chromosome number in Norway rats. The diploid number is 42 chromosomes (2n = 42). During meiosis, this number is halved, resulting in haploid cells with 21 chromosomes (n = 21).

Step 3: Consider the process of meiosis. Meiosis consists of two divisions: meiosis I and meiosis II. At the end of meiosis I, homologous chromosomes are separated, but each chromosome still consists of two sister chromatids. At the end of meiosis II, sister chromatids are separated, resulting in daughter cells with single chromatids.

Step 4: Determine the number of double-helical DNA molecules. At the end of meiosis II, each chromosome consists of a single chromatid, which corresponds to one double-helical DNA molecule. Since there are 21 chromosomes in each haploid daughter cell, there will also be 21 double-helical DNA molecules.

Step 5: Match the findings to the answer choices. Based on the analysis, the correct answer is: 21 chromosomes and 21 double-helical DNA molecules.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Meiosis

Meiosis is a specialized type of cell division that reduces the chromosome number by half, resulting in four genetically diverse daughter cells. It consists of two sequential divisions: meiosis I and meiosis II. During meiosis I, homologous chromosomes are separated, while meiosis II resembles mitosis, where sister chromatids are separated. This process is crucial for sexual reproduction, producing gametes with half the diploid number of chromosomes.

Chromosome Number

In diploid organisms, chromosomes exist in pairs, with one set inherited from each parent. Norway rats have 42 chromosomes in their diploid cells, meaning they have 21 pairs. During meiosis, the diploid number is halved, resulting in haploid gametes that contain only one chromosome from each pair. Thus, after meiosis, each daughter cell will have 21 chromosomes.

Double-Helical DNA Molecules

Each chromosome consists of a single double-helical DNA molecule. During the S phase of the cell cycle, before meiosis begins, each chromosome is replicated, resulting in two sister chromatids per chromosome. However, during meiosis II, the sister chromatids are separated, leading to each daughter cell containing one double-helical DNA molecule per chromosome. Therefore, at the end of meiosis II, each daughter cell will have 21 double-helical DNA molecules.

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Related Practice

Textbook Question

Select True or False for each statement.

Sister chromatids are homologous chromosomes.

Non-sister chromatids are found on two different homologs.

Crossing over occurs between sister chromatids.

A chiasma forms between two of the four molecules of double-stranded DNA on duplicated homologous chromosomes.

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Textbook Question

If we continue to follow the cell lineage from question 4, then the DNA content of a single cell at metaphase of meiosis II will be

a. 0.25x

b. 0.5x

c. x.

d. 2x

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Textbook Question

If you followed a woman's cells through meiosis, at what stage of meiosis would the amount of DNA in one of these cells be equal to the amount of DNA in one of her G1 phase (before DNA replication) kidney cells?

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Textbook Question

Norway rats have 42 chromosomes in their diploid cells. If such a cell enters meiosis, how many chromosomes and double-helical molecules of DNA will be present in each daughter cell at the end of meiosis II?a. 21 chromosomes and 21 double-helical DNA moleculesb. 21 chromosomes and 42 double-helical DNA moleculesc. 42 chromosomes and 42 double-helical DNA moleculesd. 42 chromosomes and 84 double-helical DNA molecules

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Textbook Question

A micrograph of a dividing cell from a mouse showed 19 chromosomes, each consisting of two sister chromatids. During which of the following stages of cell division could such a picture have been taken? (Explain your answer.)

a. Prophase of mitosis

b. Telophase II of meiosis

c. Prophase I of meiosis

d. Prophase II of meiosis

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Multiple Choice

During anaphase II of meiosis, what do the spindle fibers pull apart?

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Multiple Choice

What is the result of Meiosis II?