1 - Genetic Variation

Question 1

How does meiosis increase genetic variation

Answer 1

Crossing over:
-when the homologous chromosomes move twist around each other and exchange alleles

Independent Segregation
-Leads to different combinations of maternal and paternal chromosomes

Mutations

Question 2

Meiosis I

Answer 2

After interphase…

Prophase I
-Chromosomes condense
-Centrioles migrate to opposite poles of the cell
-Nucleolus and nuclear envelope break down

Metaphase I
-Chromosomes line up along the equator of the cell in their pairs (two next to each other)
-Each chromosome attached to the spindle fibres from the centromere

Anaphase I
-Chromosome pairs are separated and pulled to opposite poles of the cell (chromatids stay joined together)

Telophase I
-Chromosomes reach opposite poles of the cell and uncoil
-Nuclear envelope forms around both groups of chromosomes and nucleolus starts to reform
-Cytoplasm divided to form two cells ( cytokinesis)

Question 3

Meiosis II

Answer 3

Prophase II
-Chromosomes condense
-Centrioles migrate to opposite poles of the cell
-Nucleolus and nuclear envelope break down

Metaphase II
-Chromosomes line up along the equator of the cell
-Each chromosome attached to the spindle fibres from the centromere

Anaphase II
-Centromeres divide and separate each pair of chromatids
-Spindle fibres pull chromatids to opposite poles of the cell

Telophase II
-Chromatids reach opposite poles of the cell and uncoil
-Nuclear envelope forms around both groups of chromosomes and nucleolus starts to reform
-Cytoplasm divided to form 4 cells ( cytokinesis)

Question 4

How does courtship increase probability of finding a mate

Answer 4

Attract same species;

Stimulates production of gametes

Attraction of mate

Indication of fertility

Question 5

Hierarchal System

Answer 5

Groups within groups
No overlap

Question 6

Species

Answer 6

Group of similar organisms that produce fertile offspring

Question 7

Phylogenetic System

Answer 7

Grouped according to evolutionary links