Cell Division and Meiosis Sexual Reproduction Digital Vision Ltd./SuperStock Chapter Menu

Why do living things reproduce? Chapter Introduction

Cell Division Prokaryote cells Fission Asexual Reproduction Eukaryote cells Mitosis Growth Repair Meiosis Sexual Reproduction Chapter Introduction

Sexual Reproduction and Meiosis What is sexual reproduction, and why is it beneficial? What is the order of the phases of meiosis, and what happens during each phase? Why is meiosis important? Lesson 1 Reading Guide

Lesson 1 Reading Guide - Vocab Sexual Reproduction and Meiosis sexual reproduction egg sperm fertilization zygote diploid homologous chromosomes haploid meiosis Lesson 1 Reading Guide - Vocab

What is sexual reproduction? Sexual reproduction is a type of reproduction in which sex cells (often from two different parents) fuse to form an offspring. Sexual reproduction Fuse Lesson 1

What is sexual reproduction? Most cells are body cells, only a few are sex cells. The ovary produces female sex cells called eggs. The testis produces male sex cells called sperm. Organism Body Cells Mitosis Daughter Cells Sex Cells Meiosis Egg Cells Sperm Cells Lesson 1

What is sexual reproduction? (cont.) The egg and sperm combine during fertilization to create a zygote. Lesson 1

Chromosomes The cell’s DNA is packaged in fixed sets of chromosomes. Humans have 46 sets chromosomes. Lesson 1

Lesson 1

Diploid Cells Body cells are diploid because they have the complete set of homologous chromosomes. Each chromosome is inherited from one parent, they have the same genes but can have different traits. Diploid Homologous Genes Traits Mom Dad Lesson 1

Haploid Cells Sex cells are haploid because they only have half the chromosomes from either mom or dad. Sex cells are produced in meiosis where one diploid cell divides two times to make four haploid sex cells. Haploid Meiosis 2 4 1 Cell Diploid 4 Cells Haploid Meiosis Lesson 1

Haploid Cells Meiosis has two rounds of division. Meiosis I Meiosis II 2 4 Meiosis II Lesson 1

The Phases of Meiosis I There are four phases of meiosis I. Lesson 1

The Phases of Meiosis II There are four phases of meiosis II. Lesson 1

Why is meiosis important? (cont.) After fertilization, haploid sex cells combine to produce a diploid zygote. Egg Sperm 23 46 Meiosis Fertilization Zygote Mitosis Lesson 1

Why is meiosis important? Meiosis forms sex cells with the correct haploid number of chromosomes so that fertilization forms a diploid zygote. Meiosis creates genetic variation. Correct Lesson 1

Why is meiosis important? (cont.) Lesson 1

Genetic content compared to parent cell Different Identical Lesson 1

Advantages of Sexual Reproduction Sexual reproduction allows genetic variation that might produce traits that benefit an organism or population. Sexual reproduction allows for the selection of desirable traits. Genetic variation Selection Lesson 1

Advantages of Sexual Reproduction (cont.) Why is sexual reproduction beneficial? Lesson 1

Disadvantages of Sexual Reproduction Organisms have to grow until they are mature enough to produce sex cells. Organisms must search or wait for a mate. Lesson 1

Fertilization occurs when an egg cell and a sperm cell join together. Lesson 1

Organisms produce sex cells through meiosis. Lesson 1

Sexual reproduction results in genetic variation among individuals. Digital Vision Ltd./SuperStock Lesson 1

Cells that have pairs of chromosomes are called ____. A. chromosomes B. body cells C. diploid cells D. sex cells Lesson 1

During which process does one diploid cell divide and make four haploid sex cells? A. osmosis B. fertilization C. reproduction D. meiosis Lesson 1

A. prophase I C. anaphase II B. metaphase I D. anaphase I During which phase of meiosis I do chromosome pairs separate and pull to opposite ends of the cell? A. prophase I C. anaphase II B. metaphase I D. anaphase I Lesson 1

Which type of cells have only one chromosome from each pair of chromosomes? A. haploid cells B. diploid cells C. homologous cells D. zygotes Chapter Review - MC

Which type of reproduction occurs when the genetic materials from two different cells combine to produce offspring? A. asexual C. sexual B. animal D. zygote Chapter Review - MC

What is the name of the new cell formed through fertilization during sexual reproduction? A. an egg B. a sperm C. a chromosome D. a zygote Chapter Review - MC

In which of these organs is a female organism’s egg produced? A. ovaries B. homologous chromosomes C. testes D. haploid cells Chapter Review - MC

A. telophase II C. prophase I B. metaphase II D. telophase I Which of these is the final phase of meiosis in which a nuclear membrane forms around each set of chromatids? A. telophase II C. prophase I B. metaphase II D. telophase I Chapter Review - MC