Meiosis and Sexual Reproduction chap13

Question 1

Sexual V Asexual

Answer 1

Asexual reproduction, a single parent produces genetically identical offspring by mitosis. Sexual reproduction combines genes from two parents, leading to genetically diverse offspring.

Question 2

Sexual Reproduction Advantages and disadvantages

Answer 2

Advantages: High genetic variability, facilitates adaptation, “speeds” up evolution.
Disadvantages: Energy costly, courtship is time/resource consuming, usually sacrifices the fitness of one sex to the other.

Question 3

Asexual Reproduction Advantages and disadvantages

Answer 3

Advantages: Saves energy, Courtship is a non-issue, Greatest increase in fitness for each individual.
Disadvantages: Low genetic variability, adaptation to environment is difficult, “retards” evolution.

Question 4

Inheritence

Answer 4

Offspring acquire genes from parents by inheriting chromosomes. Each gene in an organism’s DNA exists at a specific locus on a certain chromosome.

Question 5

Somatic V Sexual

Answer 5

Somatic(body) cells are diploid and have 46 chromosomes made up of two sets of 23 chromosomes, human diploid cells have 22 homologous pairs of autosomes and one pair of sex chromosomes. Sex chromosomes determine which type of gamete an individual produces. Individuals born with XX have ovaries that produce eggs, people born with XY have testes that produce sperm.

Question 6

Chromosomes

Answer 6

Sister chromatids of one duplicated chromatids contain two centromeres, two nonsister chromatids are two centromeres from two different parents. A pair of nonsister chromatids are homologous chromosomes.

Question 7

Alleles

Answer 7

An allele is a form of a trait. We traditionally think of alleles as either dominant or recessive, however most inheritance patterns are much more complex. Combinations of alleles on an individual’s homologous chromosomes determines the genotype of the individual.

Question 8

Fertilization and meiosis

Answer 8

Fertilization and meiosis alternate in sexual life cycles.

Question 9

Haploid and Diploid

Answer 9

All organisms that reproduce sexually alternate between haploid and diploid cycles.

Question 10

Meiosis in parents

Answer 10

Meiosis in father’s testes and mother’s ovaries result in splitting, at the end of the splitting there are 4 copies of a cell with a chromosome in each cell, they bind with another from the other parents to make a fertilized egg.

Question 11

Meiosis in parents cont.

Answer 11

Humans have 46 chromosomes. Chromosomes are duplicated before meiosis begins. Meiosis 1 Homologs are separated. Meiosis 2 sister chromatids are separated.

Question 12

Fertilization

Answer 12

Unites a sperm and egg, re establishing pairs of homologous chromosomes, with both paternal and maternal genes.

Question 13

Meiosis 1

Answer 13

Separates homologous chromosomes; Prophase 1, contains all the materials and stuff needed for the duplication in a jumbled cell. Metaphase 1, chromosomes align at the center, centrosomes align at the north and south side of the cell. Anaphase 1, homologous chromosomes separate, sister chromatids remain together. Telophase 1 and cytokinesis, the cell starts to split and the cleavage furrow starts to show.

Question 14

Meiosis 2

Answer 14

Repeats the same processes up to Anaphase 2, where the sister chromatids split, and then at Telophase 2 and cytokinesis haploid daughter cells start to form. There are two cells that split into four at the second stage of meiosis.

Question 15

Mitosis v Meiosis

Answer 15

Mitosis and Meiosis are similar, however mitosis contains more “order” and NO genetic variability. Mitosis happens in somatic cells and it requires there to be NO genetic variability to maintain the body. Meiosis happens in gamete cells, requiring genetic variability for increased diversity. Meiosis has less “order”.

Question 16

Genetic variation

Answer 16

Genetic variation in meiosis results from independent assortment of homologous chromosomes during prophase 1 of meiosis. Genetic variation also results from crossing over, which occurs during prophase 1 of meiosis.