Chapter 9

Question 1

3 - What is Asexual Reproduction

Answer 1

Offspring clones of the parent, genetically identical

Question 2

3 - What is Sexual Reproduction

Answer 2

Offspring genetically different from parents.
Use meiosis to produce gametes. When these sex cells combine, the offspring are different from the parents and different from each other

Question 3

4 - What type of reproduction do humans use

Answer 3

Humans reproduce Sexually
Each somatic cells have 23 pairs of chromosomes
Each sex cells have 23 individual chromosomes

Question 4

5 - What is Meiosis?

Answer 4

Produces gamete cells:
- Spermatocytes ( Produced by Mitosis but produce Sperm by Meiosis)
- Primary Oocytes ( Produced by Mitosis, Eggs ( Secondary Oocytes) Produced by Meiosis)
Meiosis produce cells that:
Have half the number of chromosomes than the parent cells
are genetically different from parents and eachother

Question 5

6- Why are the cells produced by Meiosis have half the # of cells than the parent cells

Answer 5

Number of chromosomes would double each generation since sperm and eggs would merge and double the # of chromosomes. Meiosis keeps chromosomes # constant between each new generation (offspring)

Question 6

7 - What are homologous Chromosomes?

Answer 6

Homologous chromosomes code for the same genes but may have different alleles for that gene, different versions of that gene, one chromosome from each parent, the chromosome from each aprent are homologous.

Question 7

9 - What are alleles?

Answer 7

Alternative versions of a gene are called alleles. They control the same character but do not contain the same information.

Question 8

10 - What is the goal of Meiosis?

Answer 8

Converting diploid parent cells(2n) from the ovary/testis into haploid sex cells (1n)

Somatic cells have 46 chromosomes arranged in sets of 2, but offspring only get one set from each parent

Question 9

11 - How long does each type of reproduction take

Answer 9

Somatic cells average 12-24 hrs
Miosis occurs in cells that produce gametes, takes more than 48 days

Question 10

What are the different cycles in Meiosis?

Answer 10

Meiosis I: Results in 2 daughter cells
Meiosis II: Results in 4 daughter cells, sex cells

Question 11

What are the different stages of Meiosis?

Answer 11

Prophase
Metaphase
Anaphase
Telophase
I and II

Question 12

13 - What happens before Meiosis I?

Answer 12

Meiosis I is preceded by Interphase (G1, S, G2): Duplication of chromosomes, 2 chromatids held together with centromeres, centrioles are replicated (form centrosomes)

Question 13

14 - What happens in Prophase 1?

Answer 13

Similar to Mitosis:
Nucleolus and Nuclear membrane dissapear
Spindles attach to Kinetochore
Centrioles continue separating

Different to Mitosis:
Homologous pairs of chromosomes line up with other homologous pairs forming Tetrads
Tetrads have homologous chromosomes pairs, one maternal and one paternal
The process where homologous chromosomes come together is called sypnosis it is followed by crossing over: the exchange of paternal and maternal genes