Chapter 11 Review

Meiosis and Sexual Reproduction

Meiosis•Occurs in all sexually reproducing organisms

Genetic Variation• Contributes to genetic variation:– Random fertilization– Independent assortment– Crossing over

– Binary Fission does not lead to genetic variations.

Haploid - Diploid

• In the alternation of generations, spores, gametophytes and egg and sperm are Haploid

• Sporophytes are Diploid

Meiosis• Two successive divisions are responsible for

the formation of four haploid cells.

Asexual Reproduction• DNA does not vary much between

offspring• Many offspring are produced in a

short time• Organisms may not be able to adapt

to new environments

Fragmentation• Is a form of asexual reproduction

Gametes• In humans, each gamete receives one

chromosome from each of 23 pairs

Crossing Over• Portions of a chromatid on one homologous

chromosome break off and trade places with the corresponding portion on one of the chromatids of the other homologous chromosome

Life Cycle• The activities in the life of an organism from

one generation to the next.

Diploid• A cell that contains two sets of chromosomes

Independent Assortment•Random distribution of

homologous chromosomes during meiosis

Homologous Chromosomes• Chromosomes that are similar in shape and

size and have similar gentetic information

Spermatogenesis• The process by which gametes

are produced in male animals

Haploid• A cell that contains one set of chromosomes

Oogenesis• The process by which gametes

are produced in female animals

Fertilization• The union of sperm and egg cells

to produce a diploid zygote

Asexual Reproduction• All copies of the single parent’s

genes are passed to the offspring

Ovum• Female gamete, also called an egg

Test Chapter 11 •Tomorrow