Biology ch. 7

What does crossing over cause? What does it exchange?

It causes variation and genes are exchanged.

homologous =

MEIOSIS 1

What is meiosis? What do the number of chromosomes and what does it produce?

Meiosis is a form of cell division that halves the # of chromosomes when forming specialized reproductive cells (gametes) It allows for new genetic variation through indep. assortment, crossing over and random fertilization REDUCE # OF CHROMOSOME IN HALF

Compare meiosis and mitosis

Mitosis- no pairing of homologous chromosomes occurs, associated with growth and asexual production, one division, two daughter cells produced, involves duplication of chromosomes, chromosome number is maintained, crossing over between homologous chromosomes may occur, daughter cells are identical to parent cells, Meiosis- two divisions, four daughter cells produced, associated with sexual reproduction, two daughter cells produced, involves duplication of chromosomes, chromosome number is halved, crossing over between homologous chromosomes may occur, daughter cells are not identical to parent cell, produces gametes, synapsis occurs in prophase

What is female meiosis called? Where does it occur? What does is produce? How many viable cells does it produce? What is split unevenly during cytokinesis I and cytokinesis II of this process?

Oogenesis. Occurs in ovaries. Produces 1 viable egg cell and makes 3 polar bodies. Cytoplasm divides unevenly.

Compare PMAT II and PMAT I (General)

PMAT I- homologous chromosomes PMAT II- not homologous chromosomes

What is formed at the end of sexual reproduction for cells- haploid or diploid cells?

Parents form reproductive cells that halve half the number of chromosomes. HAPLOID Offspring have traits of both parents but are not exactly like either parent.

Differentiate between spermatogenesis and oogenesis

Spermatogenesis occurs in males, occurs in the testicles, makes sperm cells, makes 4 viable cells Oogenesis occurs in females, occurs in ovaries, makes egg cells or ovum, makes 1 viable ovum and 3 polar bodies

What is male meiosis called? Where does it occur? What does it produce? How many viable cells does it produce?

Spermatogenesis. Occurs in testicles. Produces 4 equally sized, viable haploid sperm cells

Why is variation important?

The more variation within a species, the more likely it will survive and the more adaptations it will have and be able to deal with challenges

How many parents are involved in asexual reproduction? What do they pass on to their offspring and do they pass all or some of it?

There is one parent involved. Passes exact copies of its genes to each of its offspring. Offspring is identical to parents and to each other

How can cells reproduce during alternations of generations?

They produce by meiosis or mitosis (ALTERNATE)

When does the separation of homologous chromosomes take place- meiosis I or meiosis II?

anaphase 1

Pros and cons of asexual reproduction

asexual pros: -Don't need a mate -Quicker cons: -no variation in offspring -> species extinction?

How do hydras reproduce asexually?

budding ASEXUALLY

Sperm cells and egg cells collectively are what type of cells?

gametes

What stage of meiosis do homologous chromosomes line up at the equator?- be specific

metaphase 1

What is the difference between metaphase, metaphase I and metaphase II of meiosis?

metaphase- chromosomes line up metaphase I - homologous chromosomes line up at equator metaphase II- chromosomes line up at equator

What is another name for an egg cell?

ovum

When does crossing over occur?- be specific

prophase I CHROMOSOMES anaphase 2 CHROMATIDS

Pros and cons of sexual reproduction

sexual pros: -Variation= more adaptations to certain challenges cons: - find a mate -Takes longer

How many cells are produced at the end of meiosis? Are they genetically identical? Haploid or diploid?

Cells are haploid and produces 4 cells by the end

What would happen if the chromosome number were not reduced before sexual reproduction? Give the number of chromosomes it would have, if it would be human, and if it would survive.

92 chromosomes NOT human and would NOT survive

What are 3 types of asexual reproduction? Define each

1. binary fission- separation of parent into two or more individuals of about equal size. (BACTERIA) 2. fragmentation- body breaks into several pieces, some or all of these fragments later develop into complete adults when missing parts are regrown (STARFISH/ FLATWORM) 3. budding- individuals split off from existing ones. Can break off or remain attached to original and form a colony. (HYDRA)

What are three ways meiosis creates genetic variation. Define

1. independent assortment- random distribution of homologous chromosomes during meiosis 2. crossing over- DNA exchange during prophase I 3. random fertilization- random joining of two gametes which allow for genetic variation, which is important for evolution.

When a haploid egg cell joins with a haploid sperm cell, it results in the restoration of the what number of chromosomes in the zygote?

2 haploid # restore the diploid number