Outline7 marksChallenge
A student prepared microscope slides of cells from a plant with a diploid chromosome number of 8 (2n = 8). Two cells undergoing meiosis are observed.
Cell X: Chromosomes are moving towards opposite poles. Each chromosome consists of two sister chromatids joined at the centromere. The four chromosomes visible at each pole are of different sizes.
Cell Y: Chromosomes are moving towards opposite poles. Each chromosome appears as a single chromatid. The eight chromosomes visible at each pole are of two distinct sizes.
Using Cells X and Y as examples, outline:
- the key differences in chromosomal behaviour between anaphase I and anaphase II;
- how crossing over and random orientation (independent assortment) during meiosis produce genetically different gametes;
- how random fusion of gametes at fertilisation produces genetically different individuals.