Download Concept Check Answers – Chapter 9

Concept Check Answers – Chapter 9
9.1
1. Dividing skin cells beneath the surface produce new cells that replace dead
skin at the surface.
2. Asexual reproduction involves one cell giving rise to two cells, and the cells
produced are genetically identical to the original cell. Sexual reproduction
involves the union of the two parent cells, and the offspring are not genetically
identical to either parent.
3.Cell division produces new cells, enabling an organism to increase in size.
9.2
1. The genetic material which at first is in the form of long thin fibers, is
duplicated and begins to condense into compact structures. Each chromosome
consists of identical sister chromatids joined at the centromere.
2. A cell is not at rest during interphase because that is when the cell carries
out its metabolic processes and other functions. During interphase, a cell also
increases its size, in the number of organelles, supplies of proteins, and
undergoes duplication of its genetic material.
3.During mitosis the genetic material in the nucleus is divided and distributed
into two new nuclei. During cytokinesis, the cytoplasm is divided into two,
resulting in two new cells.
9.3
1. See notes
2. Cytokinesis in animals is an indentation that becomes a cleavage furrow. In
plants a cell plate forms which eventually becomes the cell wall.
3. Changes in telophase in two cells are reverse of a parent cell in prophase.
9.4
1. Benign tumors – normal cells, tumors do not spread. Malignant tumors –
abnormal rapidly dividing cells that may break away and spread.
2. Prevent cancer cells from reproducing
3. Cell cycle is abnormal and cancer cells divide at an abnormally fast rate.
9.5
1. Homologous chromosomes carry the same type and sequence of information
in corresponding locations. Sister chromatids are exact duplicates of each
other. They carry exactly the same gentetic information.
2. Human gametes have 23 chromosomes. Human body cells have 46.
3. Homologous chromosomes separate from one another into two daughter
cells. Since each cell receives one of each pair, the number of sets of
chromosomes is reduced from two in the parent cell to one in each daughter
cell.
4. Four haploid cells.
9.6
1. Drawing should have 8 possible combinations of three chromosomes each.
2. Genetic information from parents chromosomes are swapped. Gametes
when produced now carry different genetic combinations than the original
parent chromosome.
3. Meiosis has two cell divisions and make four haploid cells. Mitosis has one
cell division and produces two cells that are diploid.