Study Guide Answers: Cell Reproduction
1. DNA is first copied. Then the cell divides into equal halves by adding new
cell membrane between two DNA copies. The growing cell membrane pushes
inward, the cell constricts to form two new, identical cells. A new cell wall
forms around each new membrane.
2. A diploid gamete would result if the nondisjunction affected all the
chromosomes during one of the meiotic divisions.
3. A haploid cell (n) contains one set of chromosomes. A diploid cell (2n)
contains two sets of chromosomes.
4. Crossing over creates recombinant chromosomes having a combination of
genes that were originally on different, though homologous, chromosomes.
Homologous chromosome pairs are oriented randomly at metaphase of
meiosis I.
5. Karyotype of a Down syndrome person has more than two copies of a
chromosome called Trisomy whereas a normal karyotype only has two copies
of a chromosome.
6. G1 phase – cell grows rapidly and carries out routine functions; G2 phase –
preparations are made for the nucleus to divide, microtubules are
assembled; S phase – DNA is copied
7. Chromosomes condense right before a cell divides in mitosis. During most of
interphase chromosomes are not condensed and are harder to see with a
microscope.
8. An organism with more than two sets of homologous chromosomes in its
genome.
9. In mitosis, the duplication of chromosomes is followed by one division of the
cell. In meiosis, homologous chromosomes separate in the first of two cell
divisions; after second division, each new cell ends up with just a single
haploid set.
10. In plant cells, vesicles formed by the Golgi apparatus fuse at the equator
and form the cell plate. A new cell wall forms on both sides of the plate. In
animal cells, the cell is pinched in half by a belt of protein threads.